BOREAS TE-12 Leaf Optical Data for SSA Species Summary The BOREAS TE-12 team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, and gas exchange of boreal vegetation. This data set contains measurements of hemispherical spectral reflectance and transmittance factors of individual leaves, needles (ages: current and past 2 years' growth, i.e., for 1993, the growing seasons of 1993, 1992, and 1991 were measured; in 1994, the growing seasons of 1994, 1993, and 1992 were measured), twigs (reflectance only), and substrate at near-normal incidence measured using a LI-COR LI-1800-12 integrating sphere attached to a Spectron Engineering SE590 spectroradiometer. Procedures of Daughtry et al. (1989) were followed. These procedures permitted measurement of samples that: 1) filled the entire integrating sphere sample port, and 2) were narrow with a length greater than the sample port diameter. Optical properties were measured at the SSA Fen, YJP, YA, and OBS sites. The data are stored in tabular ASCII files. Table of Contents * 1 Data Set Overview * 2 Investigator(s) * 3 Theory of Measurements * 4 Equipment * 5 Data Acquisition Methods * 6 Observations * 7 Data Description * 8 Data Organization * 9 Data Manipulations * 10 Errors * 11 Notes * 12 Application of the Data Set * 13 Future Modifications and Plans * 14 Software * 15 Data Access * 16 Output Products and Availability * 17 References * 18 Glossary of Terms * 19 List of Acronyms * 20 Document Information 1. Data Set Overview This data set includes measurements of leaf optical properties of individual leaves and needles collected during the growing seasons of 1993 and 1994. 1.1 Data Set Identification BOREAS TE-12 Leaf Optical Data for SSA Species 1.2 Data Set Introduction Hemispherical spectral reflectance and transmittance factors of individual leaves, needles (ages: current and past 2 years' growth, i.e., for 1993, the growing seasons of 1993, 1992, and 1991 were measured; in 1994, the growing seasons of 1994, 1993, and 1992 were measured), twigs (reflectance only) and substrate at near-normal incidence measured using a LI-COR LI-1800-12 integrating sphere attached to a Spectron Engineering SE590 spectroradiometer. Each SE590 has a unique wavelength associated with each of its 252 bands. A cubic spline interpolation was applied to the 252-bands to standardize the wavelengths to every 5 nm from 400 to 1000 nm, so that wavelength-to-wavelength comparisons can be made between SE590s. 1.3 Objective/Purpose The purpose of this work was to characterize optical properties of boreal forest canopy and substrate elements. 1.4 Summary of Parameters Hemispherical reflectance and transmittance factors of needles and twigs (from current and past years' growth) and individual leaves and substrate elements. Measurements were made for both tops and bottoms of leaves and needles. 1.5 Discussion Intensive Field Campaign (IFC)-1993: Optical properties were measured at two sites in the BOReal Ecosystem-Atmosphere Study (BOREAS) Southern Study Area (SSA): at or near the Nipawin Fen (FEN) and Nipawin Jack Pine [Young-Dry] (YJP). Canopy access was limited to only ground level collection of samples. Samples from trees were from various heights within the tree, but generally were from the lower third of the entire canopy height. Black spruce [Picea mariana], jack pine [Pinus banksiana], Labrador tea [Ledum groenlandicum], and aspen [Populus tremuloides] were sampled near the SSA-FEN site. Bog birch [Betula pumila], buck bean [Menyanthes trifloiate], marsh marigold [Caltha palustris], and cinquefoil [Potentilla palustris] were sampled in the SSA-FEN site. Jack pine needles and substrate (dead needles, bark, blueberry [Vaccinium sp.], and bearberry [Arctostaphylos uva-ursi]) were sampled at the SSA-YJP site. Procedures of Daughtry et al. (1989) were followed. These procedures permitted measurement of two sample types: type 1, which filled the entire integrating sphere sample port, and type 2, which were narrow with a length greater than the sample port diameter. One of the two external light sources was used with the integrating sphere: a standard illuminator with a beam (11.4-mm diameter spot size) and a modified illuminator with a restricted beam spot (slitted illuminator--3.5-mm x 11-mm spot size). Sample type 1 used the standard light source, while sample type 2 used either the standard or the modified light source depending on sample length. Optical properties measured for sample type 1 were reflectance and transmittance of the adaxial (top) and abaxial (bottom) surfaces. Measurement procedures limited to sample type 2 reflectance and transmittance measurements to only one surface of a sample; generally, the adaxial surface was measured. Focused Field Campaign (FCC)-Winter (W): Optical properties were measured at two sites in the SSA: Old Jack Pine (OJP) and Old Black Spruce (OBS). The measurement methods described above were used. Jack pine trees were sampled at SSA-OJP, and black spruce trees were sampled at SSA-OBS. Adaxial and abaxial surfaces of the needles were measured. FFC-Thaw (T): Optical properties were measured at two sites in the SSA: OJP and OBS. Jack pine trees were sampled at SSA-OJP, and black spruce trees were sampled at SSA- OBS. Measurements were made following the modified procedures of Daughtry et al. (1989) in which an image analysis system was used to measure the nonintercepted illumination beam. Reflectance and transmittance of the adaxial and abaxial surfaces of the samples were measured. IFC-1, #-2, and #-3: Optical properties were measured at five sites in the SSA: YJP, FEN, OBS, Old Aspen (OA), and Young Aspen (YA). Jack pine, bearberry, and fuzzy-spiked wild rye [Elymus Innovatus] and some substrate components (dead needles and bark) were sampled at SSA-YJP. Bog birch (of various senescing stages), buck bean, and a sedge [Carex sp.] were measured at SSA-FEN. Black spruce, wildrose [Rosa woodsii], Labrador tea [Ledum groenlandicum], and blueberry were sampled at SSA- OBS. Mature aspen was measured at SSA-OA during IFC-1 only. Young aspen, hazelnut [Corylus cornuta], alder [Alnus crispa], and balsam poplar [Populus balsamifera] were measured at the SSA-YA (IFC-2 and -3); aspen, hazelnut, and balsam poplar were measured at various senescent stages during IFC-3 only. Optical properties were measured following the modified procedures of Daughtry et al. (1989). An image analysis system was used to measure the nonintercepted illumination beam area. Reflectance and transmittance of the adaxial (top) and abaxial (bottom) surfaces were measured for sample types 1 and 2. Generally, the adaxial surface was measured. 1.6 Related Data Sets BOREAS TE-12 SSA Shoot Geometry Data BOREAS TE-12 SSA Water Potential Data BOREAS TE-10 Leaf Optical Properties 2. Investigator(s) 2.1 Investigator(s) Name and Title. Elizabeth A. Walter-Shea Associate Professor 2.2 Title of Investigation Radiation and Gas Exchange of Canopy Elements in a Boreal Forest 2.3 Contacts Information Contact 1: Mark A. Mesarch University of Nebraska- Lincoln Lincoln, NE (402) 472-5904 (402) 472-0284 (402) 472-6614 (fax) mmesarch@unlinfo.unl.edu Contact 2: Elizabeth A. Walter-Shea University of Nebraska- Lincoln Lincoln, NE (402) 472-1553 (402) 472-6614 (fax) agme012@unlvm.unl.edu Contact 3: Cynthia J. Hays University of Nebraska- Lincoln Lincoln, NE (402) 472-6701 (402) 472-6614 (fax) agme025@unlvm.unl.edu Contact 4: Shelaine Curd Raytheon STX Corporation NASA GSFC Greenbelt, MD (301) 286-2447 (301) 286-2039 (fax) shelaine.curd@gsfc.nasa.gov Contact 5: Andrea Papagno Raytheon STX Corporation NASA GSFC Greenbelt, MD (301) 286-3134 (301) 286-2039 (fax) apapagno@pop900.gsfc.nasa.gov 3. Theory Of Measurements Leaves, needles, and bark are canopy elements that are important in scattering radiation in boreal forest vegetation (Norman and Jarvis, 1974). Needle and bark properties can vary considerably depending on age and height in the canopy; elements deep in the canopy may be covered with algae and fungi, and shade-induced effects on shoot development may exist (Norman and Jarvis, 1974; Smith and Carter, 1988). In the near-infrared portion of the electromagnetic spectrum, little radiation is absorbed; thus, scattering by canopy elements will be significant. In contrast, leaves and needles absorb a large portion of photosynthetically active radiation (PAR) (Daughtry et al., 1989; Williams, 1991). Conifer needles absorb more PAR than deciduous leaves; twigs, especially the current year's growth, also absorb PAR (Williams, 1991). Thus, the scattering component of PAR may be small except in sparse canopies with high underlying surface albedo. In the LI-COR 1800-12 integrating sphere (LI-COR, Inc., Lincoln, Nebraska), the sample is held to the outside of the sphere, with a small section of the sample acting as part of the sphere wall. The interior of the sphere is coated with barium sulfate to make a uniform diffuse reflector. In this type of sphere, the sensor, in this case the SE590, does not directly observe the sample. The field of view of the sensor is a section of the sphere wall. To calculate reflectance, a comparison of the wall illumination caused by a beam of radiation reflected by the sample material to that reflected from the reference material is calculated. The LI-COR 1800-12 uses the same illumination source for both cases. The source is moved between ports to illuminate the sample and reference material. Under ideal conditions, the sample reflectance is given by the ratio of the illuminated sample output and the reference output. In reality, other factors must be considered. First, the reference material is not a perfect reflector. Also, not all of the incoming radiation beam hits the sample or reference; some radiation is scattered off of the sphere walls without hitting the target. Finally, adjustments must be made if the sample does not cover the entire port of the integration sphere. Transmittance is calculated by comparing the wall illumination from radiation passed through the sample to the illumination when no sample was present. As with reflectance measurements, corrections must be made to the ideal case. Daughtry et al. (1989) describes the measurement methods for the three cases of leaf sizes. Case 1 is for leaves that can completely cover the sample port of the integration sphere; case 2 is for leaves that are too narrow to cover the sample port but are long enough to be attached to a sample holder outside of the view through the sample port. The difficulty in determining the reflectance and transmittance of leaves that are too small to cover the sample port (case 2) is that what is observed in the sample port now consists of a combination of the leaves and the material between the leaves; air for case 2. The problem in this case is to determine the area of leaves covering the sample port and adjust the measured reflected and transmitted fluxes by that fractional area. The fractional area of the needles was determined using a solid-state camera. The image of the sample was transferred to a PC, where the areas were calculated. 4.Equipment 4.1 Instrument Description The Spectron Engineering SE590 is a portable battery- or A/C-operated spectroradiometer consisting of a CE500 data analyzer/logger controller, CE390 spectral detector head, and an external battery charger/power supply. The CE500 is a self-contained microprocessor-based controller that processes the signal from the detector head, amplifying and digitizing it with 12-bit resolution. For each spectral scan, the controller actuates the CE390 shutter, measures and stores the dark current, calculates optimum integration time, acquires the spectrum, and automatically subtracts the noise for all 256 spectral elements. A series of scans can be taken and automatically averaged; for these measurements, four scans were averaged for full leaf samples and eight scans were averaged for all other samples. The entire 12-bit binary spectrum is stored in a double-precision register until it is transmitted through the RS- 232C port. The spectral detector head uses a diffraction grating as the dispersive element; the spectrum is imaged onto a 256-element photodiode array. Each element integrates simultaneously, acquiring the spectrum in a fraction of a second. The interconnect cable from the spectral head to the controller couples the spectral signals to the controller, and the timing and control signals to the detector head. A shutter in the detector head, operated by the controller, closes the light path for dark current measurements. For further information, consult the SE590 operating manual. Serial Number 1571 was used. The LI-COR LI-1800-12 Integrating Sphere is an instrument for collecting radiation that has been reflected from or transmitted through a sample material. An external light source illuminates a spot on the sample. Either a standard light source (11.4-mm diameter) or a modified light source that restricts the illumination spot size (3.5-mm x 11-mm) was used. The lamp used in the external light source is a 6-Volt 10-Watt glass-halogen. For a further description, see the LI-COR Integrating Sphere Instruction Manual. Serial Number IS115-8304 was used in 1993, and IS319 was used in 1994. An image analysis system was used to measure the gaps between sample elements (e.g., needles, twigs) when a sample did not fill the entire integrating sphere sample port or a single sample element was too narrow to be completely encompassed by the modified light source. A Coho solid-state camera (model 4812-2000/ES16) with a 60-mm focal 1ength:2.8 Nikon lens was used to view a sample. A near-infrared filter was added to the lens after 20-August-1994. The camera was mounted approximately 24.1 cm above the sample. The lens was set at an aperture of 11 mm. The sample was placed on a Wolff two-bulb fluorescent light table. Red transparencies were placed under the sample to restrict the total amount of light in the system to an area of peak response (608 nm) to avoid saturating the signal from the camera. After 30-August-1994, a black cloth was draped around the camera lens down to the light table to reduce the amount of extraneous light shining on the sample or into the lens. A Data Translation frame grabber board (UM-08128-B) was used to input the signal from the camera to an IBM 80286. SPSS’ software JAVA version 1.4 was used to measure the areas of the gaps between needles. The display monitor was an IBM VGA with 640- by 480- pixels. 4.1.1 Collection Environment Measurements of black spruce and jack pine needles were made in the control environment of the laboratory. Aspen leaves were measured on-site at the SSA-YA and SSA-OA site. Other samples were measured at the site where they were collected or back at the lab. 4.1.2 Source/Platform The Spectron Engineering SE590 was connected to the LI-COR integrating sphere. This assembly was mounted on a camera tripod and adjusted to ensure that the light source was level. 4.1.3 Source/Platform Mission Objectives None given. 4.1.4 Key Variables Specular reflectance, transmittance and absorbance of needle and leaf elements. 4.1.5 Principles of Operation The SE590 spectral detector head uses a diffraction grating as the dispersive element; the spectrum is imaged onto a 256-element photodiode array. Each element integrates simultaneously, acquiring the spectrum in a fraction of a second. The LI-COR LI-1800-12 integrating sphere is an external integrating sphere, which means that the sample is external to the sphere; when it is in place, a small part of the sample actually makes up part of the sphere wall. For further information, see the LI-COR 1800-12 Integrating Sphere Instruction Manual. The Cohu solid state camera transmits a signal to the frame grabber board, which translates the intensity of each pixel to a gray scale from 0 (black) to 255 (white) levels. The JAVA software program was set up to count the number of pixels in a defined area of interest for a range of gray scales that represent the "white" gaps between the sample needle elements. 4.1.6 Instrument Measurement Geometry The SE590 was mounted on the LI-COR LI-1800-12 integrating sphere. A tripod is attached to the support connecting the SE590 and integrating sphere. A modified external light source with a slitted beam (3.5 mm x 11 mm) was used to illuminate narrow samples and associated reference. A standard external light source with a circular beam (11.4-mm diameter spot size) was used to illuminate all other samples and associated reference. The light source was kept in a horizontal position according to integrating sphere manual requirements. 4.1.7 Manufacturer of Instrument Spectron Engineering SE590 Spectroradiometer: Spectron Engineering, Inc. 25 Yuma Court Denver, CO 80223 (303) 733-1060 LI-COR LI-1800-12 Integrating Sphere: LI-COR, Inc. Box 4425 Lincoln, NE 68504 (402) 467-3576 Cohu Solid State Camera: Cohu, Inc., Electronics Division 5755 Kearny Villa Road P.O. Box 85623 San Diego, CA 92138-0221 (619) 277-6700 (619) 277-0221 (fax) Frame Grabber Board: Data Translation, Inc. 100 Locke Drive Marlboro, MA 01752-1192 (508) 481-3700 SPSS, Inc. 233 S. Wacker Drive 11th Floor Chicago, IL 60606-6307 (800) 543-2185 (800) 841-0064 (fax) 4.2 Calibration 4.2.1 Specifications Each SE590 has a unique wavelength associated with each of its 252 bands. A cubic spline interpolation was applied to the 252 bands to standardize the wavelengths to every 5 nm from 400 to 1000 nm, so that wavelength to wavelength comparisons can be made between SE590s. 4.2.1.1 Tolerance The SE590 response was checked periodically using neutral density filters of known transmittances (Mesarch et al., 1991). For all measurement periods, no corrections were made to the SE590 response, because mean relative errors were less than 0.2 percent across wavelengths. The collimation of the LI-COR LI- 1800-12 integrating sphere illuminator was checked daily by making a stray light measurement (LI-COR, 1983). Results from a temperature dependency study indicate that measurements at 1000 nm may result in discrepancies of approximately 50- W/m2/sr/µm if the instrument temperature varies for 16 to 43.5 ° C (Blad et al., 1990). The temperature effect should be negligible because the suite of measurements required to calculate reflectance and transmittance ratios is acquired in a short period of time, during which temperature change is minor to nonexistent. 4.2.2 Frequency of Calibration Transmittance filter tests were conducted before, during, and after field measurements. A preseason wavelength characterization was performed at Goddard Space Flight Center (GSFC) in April 1993 and March 1994. 4.2.3 Other Calibration Information Wavelengths, in nanometers, used for data reduction for IFC-1993 and FFC-W were: channel wavelength ch. wavelength ch. wavelength ------- ---------- --- ---------- --- ---------- 1 369.0514 2 371.7167 3 374.3852 4 377.0569 5 379.7318 6 382.4099 7 385.0912 8 387.7756 9 390.4633 10 393.1541 11 395.8481 12 398.5453 13 401.2457 14 403.9493 15 406.6561 16 409.3661 17 412.0792 18 414.7955 19 417.5151 20 420.2378 21 422.9637 22 425.6928 23 428.4250 24 431.1605 25 433.8992 26 436.6410 27 439.3860 28 442.1342 29 444.8856 30 447.6402 31 450.3980 32 453.1590 33 455.9231 34 458.6905 35 461.4610 36 464.2347 37 467.0116 38 469.7917 39 472.5750 40 475.3615 41 478.1512 42 480.9440 43 483.7400 44 486.5393 45 489.3417 46 492.1473 47 494.9561 48 497.7680 49 500.5832 50 503.4016 51 506.2231 52 509.0478 53 511.8757 54 514.7068 55 517.5411 56 520.3786 57 523.2193 58 526.0631 59 528.9102 60 531.7604 61 534.6138 62 537.4704 63 540.3302 64 543.1932 65 546.0594 66 548.9288 67 551.8013 68 554.6770 69 557.5560 70 560.4381 71 563.3234 72 566.2119 73 569.1035 74 571.9984 75 574.8965 76 577.7977 77 580.7021 78 583.6097 79 586.5205 80 589.4345 81 592.3517 82 595.2721 83 598.1956 84 601.1224 85 604.0523 86 606.9854 87 609.9217 88 612.8612 89 615.8039 90 618.7498 91 621.6989 92 624.6511 93 627.6065 94 630.5652 95 633.5270 96 636.4920 97 639.4602 98 642.4315 99 645.4061 100 648.3839 101 651.3648 102 654.3489 103 657.3362 104 660.3267 105 663.3204 106 666.3173 107 669.3174 108 672.3206 109 675.3271 110 678.3367 111 681.3495 112 684.3655 113 687.3847 114 690.4071 115 693.4327 116 696.4615 117 699.4934 118 702.5285 119 705.5669 120 708.6084 121 711.6531 122 714.7010 123 717.7520 124 720.8063 125 723.8638 126 726.9244 127 729.9882 128 733.0552 129 736.1254 130 739.1988 131 742.2754 132 745.3552 133 748.4381 134 751.5243 135 754.6136 136 757.7061 137 760.8018 138 763.9007 139 767.0028 140 770.1081 141 773.2166 142 776.3282 143 779.4430 144 782.5611 145 785.6823 146 788.8067 147 791.9343 148 795.0650 149 798.1990 150 801.3362 151 804.4765 152 807.6200 153 810.7667 154 813.9166 155 817.0697 156 820.2260 157 823.3855 158 826.5481 159 829.7140 160 832.8830 161 836.0552 162 839.2306 163 842.4092 164 845.5910 165 848.7760 166 851.9642 167 855.1555 168 858.3500 169 861.5478 170 864.7487 171 867.9528 172 871.1601 173 874.3705 174 877.5842 175 880.8011 176 884.0211 177 887.2443 178 890.4707 179 893.7003 180 896.9331 181 900.1691 182 903.4083 183 906.6506 184 909.8962 185 913.1449 186 916.3968 187 919.6519 188 922.9102 189 926.1717 190 929.4364 191 932.7043 192 935.9753 193 939.2495 194 942.5270 195 945.8076 196 949.0914 197 952.3784 198 955.6685 199 958.9619 200 962.2585 201 965.5582 202 968.8611 203 972.1672 204 975.4765 205 978.7890 206 982.1047 207 985.4236 208 988.7456 209 992.0709 210 995.3993 211 998.7309 212 1002.0650 213 1005.4030 214 1008.7440 215 1012.0890 216 1015.4360 217 1018.7870 218 1022.1410 219 1025.4980 220 1028.8590 221 1032.2220 222 1035.5890 223 1038.9590 224 1042.3320 225 1045.7080 226 1049.0870 227 1052.4700 228 1055.8560 229 1059.2450 230 1062.6370 231 1066.0320 232 1069.4310 233 1072.8330 234 1076.2380 235 1079.6460 236 1083.0570 237 1086.4720 238 1089.8890 239 1093.3100 240 1096.7340 241 1100.1620 242 1103.5920 243 1107.0260 244 1110.4620 245 1113.9020 246 1117.3460 247 1120.7920 248 1124.2420 249 1127.6940 250 1131.1500 251 1134.6090 252 1138.0720 Wavelengths, in nanometers, used for data reduction for FFC-T and IFC-1, -2, and -3 were: channel wavelength ch. wavelength ch. wavelength ------- ---------- --- ---------- --- ---------- 1 369.1879 2 371.884 3 374.5831 4 377.285 5 379.9898 6 382.6975 7 385.4081 8 388.1217 9 390.8381 10 393.5574 11 396.2796 12 399.0047 13 401.7327 14 404.4635 15 407.1973 16 409.934 17 412.6736 18 415.4161 19 418.1614 20 420.9097 21 423.6609 22 426.4149 23 429.1719 24 431.9317 25 434.6945 26 437.4601 27 440.2286 28 443.0001 29 445.7744 30 448.5516 31 451.3317 32 454.1147 33 456.9007 34 459.6895 35 462.4812 36 465.2758 37 468.0733 38 470.8737 39 473.6769 40 476.4831 41 479.2922 42 482.1042 43 484.9191 44 487.7368 45 490.5575 46 493.3811 47 496.2075 48 499.0369 49 501.8691 50 504.7043 51 507.5423 52 510.3832 53 513.2271 54 516.0738 55 518.9234 56 521.7759 57 524.6313 58 527.4897 59 530.3509 60 533.215 61 536.082 62 538.9519 63 541.8247 64 544.7003 65 547.5789 66 550.4604 67 553.3448 68 556.2321 69 559.1222 70 562.0153 71 564.9113 72 567.8101 73 570.7119 74 573.6165 75 576.5241 76 579.4345 77 582.3478 78 585.2641 79 588.1832 80 591.1052 81 594.0301 82 596.9579 83 599.8887 84 602.8223 85 605.7588 86 608.6982 87 611.6405 88 614.5857 89 617.5337 90 620.4847 91 623.4386 92 626.3954 93 629.3551 94 632.3176 95 635.2831 96 638.2515 97 641.2227 98 644.1969 99 647.1739 100 650.1539 101 653.1367 102 656.1224 103 659.1111 104 662.1026 105 665.097 106 668.0943 107 671.0945 108 674.0977 109 677.1037 110 680.1126 111 683.1244 112 686.1391 113 689.1567 114 692.1771 115 695.2005 116 698.2268 117 701.256 118 704.2881 119 707.323 120 710.3609 121 713.4017 122 716.4453 123 719.4919 124 722.5413 125 725.5937 126 728.6489 127 731.707 128 734.7681 129 737.832 130 740.8988 131 743.9685 132 747.0411 133 750.1167 134 753.1951 135 756.2764 136 759.3606 137 762.4477 138 765.5377 139 768.6305 140 771.7263 141 774.825 142 777.9266 143 781.0311 144 784.1384 145 787.2487 146 790.3619 147 793.4779 148 796.5969 149 799.7187 150 802.8435 151 805.9711 152 809.1016 153 812.2351 154 815.3714 155 818.5106 156 821.6527 157 824.7977 158 827.9457 159 831.0965 160 834.2502 161 837.4068 162 840.5663 163 843.7287 164 846.8939 165 850.0621 166 853.2332 167 856.4072 168 859.5841 169 862.7638 170 865.9465 171 869.1321 172 872.3205 173 875.5119 174 878.7061 175 881.9033 176 885.1033 177 888.3062 178 891.5121 179 894.7208 180 897.9324 181 901.1469 182 904.3643 183 907.5847 184 910.8079 185 914.034 186 917.263 187 920.4949 188 923.7297 189 926.9673 190 930.2079 191 933.4514 192 936.6978 193 939.9471 194 943.1992 195 946.4543 196 949.7123 197 952.9731 198 956.2369 199 959.5035 200 962.7731 201 966.0455 202 969.3208 203 972.5991 204 975.8802 205 979.1642 206 982.4511 207 985.7409 208 989.0337 209 992.3293 210 995.6278 211 998.9292 212 1002.233 213 1005.54 214 1008.85 215 1012.163 216 1015.479 217 1018.798 218 1022.12 219 1025.444 220 1028.772 221 1032.102 222 1035.435 223 1038.771 224 1042.11 225 1045.452 226 1048.797 227 1052.145 228 1055.496 229 1058.849 230 1062.206 231 1065.565 232 1068.927 233 1072.292 234 1075.66 235 1079.031 236 1082.405 237 1085.782 238 1089.161 239 1092.544 240 1095.929 241 1099.317 242 1102.709 243 1106.103 244 1109.5 245 1112.899 246 1116.302 247 1119.708 248 1123.116 249 1126.528 250 1129.942 251 1133.359 252 1136.78 5. Data Acquisition Methods The CANOPY_LOCATION parameter of the data set is a relative measure based upon the height of the sample location relative to the height of the canopy. Therefore, a sample collected from the top of a short tree in a tall canopy and a sample collected from the bottom of a short tree in a short canopy can both be designated as "low" for the HEIGHT parameter. CANOPY_LOCATION parameters used are HIGH, LOW, MIDDLE, GROUND, AND UNDER. UNDER refers to an understory component being measured. GROUND refers to the lower third of the total canopy height. For IFC-1993 and IFC-1, -2, and -3: Samples were cut from plants, covered with damp cheesecloth, sealed in a Ziploc- type storage bag, and stored and transported in a cool ice chest to the lab for processing. Generally, processing of conifer needles and twigs required 2 to 3 days to complete. If the samples were not measured on the same day they were cut from the plant, they were stored in a refrigerator for processing in the next 1 or 2 days. The cut end of the samples from YA and FEN (i.e., aspen, bog birch, buck bean, marsh marigold, cinquefoil, and sedge) were placed in water-filled vials upon cutting and remained so until completion of optical measurements, generally within 10 minutes of cutting. For FFC-W and FFC-T: Samples were collected from trees and placed in Ziploc-type storage bags containing damp paper towels. The samples were packed in ice and shipped to Lincoln, NE, for measurement. Adaxial leaf surfaces of aspen, buck bean, bog birch, and substrate element samples typically were brighter in color and had a glossier sheen than the abaxial surfaces. The abaxial surface of Labrador tea leaves was heavily pubescent; the current year's growth was white pubescent, and the prior years' growth having rust-colored pubescent. The black spruce surface without the whitish lines was defined as the adaxial surface. Jack pine needles were attached to twigs in paired fascicles and generally had a semicircular cross- sectional shape. The outer semicircular convex, curved side of the needle was considered the adaxial surface. (For a more detailed description of the shape of the needles, see the BOREAS TE-12 shoot geometry document.) Approximately 40 needles for a particular age class (e.g., 1994 growth, 1993 growth) were selected from three shoots on a cut sample and placed in a bag. Needles were randomly sampled from this mixture to produce three samples per age class. A sample mount was designed to maintain the sample elements in the same orientation relative to one another for all measurements. Two types of sample mounts were constructed, one for each light source. One sample mount had an aperture the same size as the integrating sphere sample port and slightly larger than the illumination spot of the full lamp (e.g., 11.4-mm diameter); the second sample mount had an aperture (5.5 mm x 15 mm) designed to hold the short black spruce needles and slightly larger than the beam dimensions of the slitted illuminator (3.5 mm x 11 mm) for the integrating sphere. Approximately 6-11 sample elements (e.g., needles or twigs) were placed on the sample mount using transparent tape to affix the needle ends to the sample mount in such a way that the tape would not be visible in the integrating sphere sample port. The elements were placed so that gaps between elements were approximately equal. Prior to 20-Jul-1994, elements were spaced a sample element apart. Samples made after 20-Jul-1994 were constructed so that the sample elements were evenly spaced, but the fraction of nonintercepted illumination beam was approximately 5-15-% of the total beam area. Stray light was measured at the beginning of each day and/or at the beginning of a set of measurements with each light source used. The color of the needles and twigs was coded using the Munsell color chips (Munsell, 1977) prior to optical measurements. The method of sample measurement varied based on physical size of the sample element: For sample type 1, the sample element filled the integrating sphere sample port (samples included were aspen, hazelnut, balsam poplar, alder, blueberry, wildrose, bearberry, sedge, bog birch, and buck bean). Procedures for optical property measurements are described by Daughtry et al.(1989). During the measurement, individual leaves remained attached to the branch that was cut from the plant. Each leaf measured was inserted into the integrating sphere sample port with the adaxial (top) surface facing the inside of the sphere. Three measurements followed: 1) light reflected from the reference for the adaxial surface, 2) light reflected from the adaxial surface, and 3) light transmitted through the abaxial (bottom) surface. The sample was removed from the sample port and reinserted so that the abaxial surface faced the inside of the sphere; the sample was arranged so that the same portion of the sample as for the adaxial surface was measured. Three additional measurements followed: 1) light transmitted through the adaxial surface, 2) light reflected from the abaxial surface, and 3) light reflected from the reference for the abaxial surface. The modified external light source was used for narrow leaf samples (e.g., wildrose, blueberry, and bearberry). All other samples were illuminated with the standard external light source. For sample type 2, the sample elements were narrow and the tape holding the needles was not visible in the sample holder (samples included were jack pine and black spruce needles and twigs). Prior to 20-Apr-1994: The fraction of nonintercepted illumination beam was determined using the painting technique described in Daughtry et al. (1989). This method allowed only one surface to be measured per sample. Either the standard or the modified light source was used depending on the sample mount used. The sample mount was inserted into the integrating sphere sample holder with the adaxial needle surfaces facing inside the sphere. Light reflected from the adaxial needle surface and from the reference with the sample in place (adaxial reference) was measured. The sample mount was removed from the sphere. Light reflected from the reference without a sample and integrating sphere wall (transmitted mode without sample) was measured. The sample mount was placed back into the integrating sphere sample holder with the adaxial needle surfaces facing toward the inside of the sphere. Light transmitted through the abaxial surfaces was measured. The sample was turned so that the abaxial needle surfaces of the sample were facing the inside of the sphere. Three additional measurements followed: 1) light transmitted through the adaxial needle surfaces, 2) light reflected from the reference with the sample in place (abaxial reference), and 3) light reflected from the abaxial needle surfaces. After the entire suite of measurements was made, the sample mount was removed from the integrating sphere. The intended measured surface was painted with Testors (1149) black paint, with care taken not to paint the other side of the sample element. The sample mount was placed in the integrating sphere sample holder with the blackened surface facing away from the sphere. Light transmitted through the blackened sample was measured. After 20-Apr-1994: A modified set of procedures for optical property measurements described by Daughtry et al. (1989) was used. The sample mount was attached to a mask with an aperture the size of the illumination light source beam. This assembly was placed on the light table underneath an image analysis system's camera. The image was captured and the gap area measured by counting the number of "whitish" pixels. The area was ratioed to the total area of the incident beam (i.e., the area of the mask) to give the gap fraction (area of nonintercepted illumination beam). The sample was then placed in the integrating sphere sample holder and the suite of measurements, described above, was made. The measurement of the blackened sample was not made. Prior to 20-Apr-1994: To calculate the fraction of nonintercepted illumination beam, the painting technique described in Daughtry et al. (1989) was used. The standard light source was used for all samples. Multiple measurements of the transparent tape alone were made of reflectance and transmittance properties; little variation was found between pieces of tape. Thus, a sample, constructed of tape only, was used to characterize the light reflected and transmitted through the tape for each sample in the suite of measurements described below. The tape sample was placed in the integrating sphere with the adhesive side of the tape facing the inside of the sphere. The light reflected from the tape and the light reflected from the reference with the sample in place (adhesive side) were measured. The tape sample was turned so that the adhesive side was facing away from the inside of the sphere. The light reflected from the reference with the sample in place (nonadhesive side) and the light transmitted through the tape were measured. The needle sample mount was placed in the sample holder with the sample elements facing away from the inside of the sphere. Light transmitted through the sample was measured. The sample mount was removed from the sphere. The light transmitted through the sample port without the sample (i.e., a sphere wall reference) and the light reflected from the reference (without the sample) were measured. Then, the sample mount was placed in the sample holder with the sample elements facing away from the inside of the sphere. Light reflected from the reference with the sample in place (for transmittance calculation) was measured. Then the sample mount was placed in the sample holder with the sample elements facing toward the inside of the sphere. Light reflected from the reference with the sample in place (for reflectance calculation) and the light reflected from the sample were measured. After the entire suite of measurements was made, the sample mount was removed from the integrating sphere. The intended measured surface was painted with Testors (1149) black paint, with care taken not to paint the tape. The sample mount was placed in the integrating sphere sample holder with the blackened surface facing away from the sphere. Transmitted radiation through the blackened sample was measured. After 20-April-1994: This method allows measurement of only one side of the sample. The image analysis system was used, in the same manner as type 2, to measure the fraction of nonintercepted illumination beam. The sample was then placed in the integrating sphere, and the suite of measurements, as described above, was made except for the measurement of the blackened sample. For more details on the LI-COR LI-1800-12 integrating sphere configuration for each measurement, see Mesarch et al. (1991). 6. Observations 6.1 Data Notes None given. 6.2 Field Notes Needle ages measured in 1993 were 1993 growth, 1992 growth and 1991 growth. Needle and twig ages measured in 1994, unless otherwise noted, are 1994 growth, 1993 growth, and 1992 growth. Sampled: 04-Aug-1993 Measured: 04-Aug-1993 Leaf optical properties from aspen near SSA-FEN; 3 trees x 3 branches x 3 replications; both adaxial and abaxial surfaces. First replication was for a leaf at the top of the branchlet, second replication was for a leaf in the middle of the branchlet, and third replication was for a leaf on the lowest part of the branchlet. Branches were selected from the north side of the trees. Sampled: 04-Aug-1993 Measured: 05-Aug-1993 Needle optical properties from jack pine near SSA-FEN; 3 trees x 1 branch x 3 ages x 3 replications of adaxial needle surfaces; several measurements of abaxial needle surface and adaxial twig surface. Branches from trees 1 and 2 were sunlit, and the branch from tree 3 was shaded. Sampled: 06-Aug-1993 Measured: 07-10-Aug-1993 Coordinate measurements of leaf gas exchange and needle optical properties from black spruce near SSA-FEN. 3 trees x 4 branches x 3 ages x 3 replications of adaxial needle surface. Tree 1 was sunlit, tree 2 was lightly shaded, and tree 3 was deeply shaded. All trees were about 3 to 3.5 m tall in a grove of trees about 10 m tall. Needles from the shoots that were measured for photosynthesis rates were not used for optical property measurements. Instead, needles from a shoot near those sampled for gas exchange were used. Sampled: 16-Aug-1993 Measured: 17-18-Aug-1993 Optical properties from jack pine needle and substrate elements at SSA-YJP. 9 trees x 1 branch x 3 ages x 1 replication of adaxial needle surface; several measurements of abaxial needle surface and adaxial twig surface. 9 samples were measured of dead needles, bark, blueberry, bearberry, and leafy lichen; both adaxial and abaxial surfaces were measured of all substrate elements except the dead needles. Sampled: 19-Aug-1993 Measured: 19-Aug-1993 Coordinated measurements of leaf gas exchange and leaf optical properties on aspen near SSA-FEN (11 trees x 1 branch x 1 replication on both adaxial and abaxial leaf surfaces). Trees were approximately 2 m tall. Also leaf optical properties of bog birch (5 plants x 3 color classes x 1 replication of adaxial and abaxial leaf surface) and buck bean (9 plants x 1 replication of adaxial and abaxial leaf surface). Sampled: 20-Aug-1993 Measured: 21-Aug-1993 Coordinated measurements of leaf gas exchange and needle optical properties on black spruce near SSA-FEN. 5 trees x 1 branch x 3 ages x 1 replication of adaxial needle surface; several measurements of abaxial needle surface and adaxial twig surface. Needles measured for photosynthesis rates were not used for optical property measurements; instead, needles from shoots close to the shoot used for gas exchange were used. Leaf optical properties of other vegetation in or near the SSA-FEN (e.g., marsh marigold, cinquefoil and Labrador tea) were measured (5 plants x 1 replication of adaxial and abaxial leaf surface). Sampled: 03-Feb-1994 Measured: 13-Feb-1994 Needle optical properties on jack pine collected at SSA-OJP. 7 trees x 1 branch x 3 ages x 3 replications; measurement of both adaxial and abaxial surfaces. Needles were from the 1993, 1992, and 1991 growth. Sampled: 07-Feb-1994 Measured: 14-Feb-1994 Needle optical properties from black spruce collected at SSA-OBS. 8 trees x 1 branch x 3 ages x 3 replications; measurement of both adaxial and abaxial surfaces. Needles were from the 1993, 1992, and 1991 growth. Sampled: 14-Apr-1994 Measured: 20-21-Apr-1994 Needle optical properties from jack pine collected at SSA-OJP. 1 tree x 3 branches x 3 ages x 3 replications; measurement of both adaxial and abaxial surfaces. Needles were from the 1993, 1992, and 1991 growth. Sampled: 15-Apr-1994 Measured: 20-21-Apr-1994 Needle optical properties from black spruce collected at SSA-OBS. 6 trees x 2 branches x 3 ages x 3 replications; measurement of both adaxial and abaxial surfaces. Needles were from the 1993, 1992, and 1991 growth. Sampled: 26-May-1994 Measured: 27-29-May-1994 Needle leaf optical properties on jack pine collected at SSA-YJP. 9 trees x 1 branch x 3 ages x 3 replications; measurements of both adaxial and abaxial surfaces. Trees were located about 150 m east of the hut and 20-50 m north of access road. Branches were from the south side of the trees and generally in full sunlight at 1230-1600 local time. Branches were collected 2-4 m from the soil surface. Needles were from the 1993, 1992, and 1991 growth. Sampled: 29-May-1994 Measured: 29-May-1994 Leaf optical properties from aspen collected at SSA-YA. 3 trees x 3 branches x 3 replications; measurements of both adaxial and abaxial surfaces. Leaves were from branches sampled from the south side of the trees and 1.5-2 m from the soil surface. Sampled: 01-Jun-1994 Measured: 2-4-Jun-1994 Needle optical properties from black spruce collected at SSA-OBS. 3 trees x 3 branches x 3 ages x 3 replications; measurements of mostly adaxial surfaces. Needles were from the 1993, 1992, and 1991 growth. Samples were collected from the top of the trees via th canopy access tower and on the south- facing side of the trees. Branches were sunlit. Sampled: 04-Jun-1994 Measured: 04-Jun-1994 Needle optical properties from jack pine samples that were coordinated with shoot gas exchange measurements. Samples were collected at SSA-YJP. 4 trees x 1 branch x 2 ages x 3 replications; measurements of both adaxial and abaxial surfaces. Needles were from the 1993 and 1992 growth. In addition, reflectance was measured from 1994's unexpended growth (the entire unexpended shoot); 1 replication for each tree. Sampled: 06-Jun-1994 Measured: 06-Jun-1994 Measurements of leaf optical properties on aspen collected at SSA-OA. 3 trees x 3 branches x 3 replications for the top of the canopy and 1 tree x 3 branches x 3 replications from the lowest leaf level in the canopy. Measured adaxial and abaxial surfaces. Sample collection was made from the canopy access tower. Sampled: 07-Jun-1994 Measured: 8-9-Jun-1994 Needle optical properties from black spruce collected at SSA-OBS. 3 trees x 3 branches x 3 ages x 3 replications; measurements of mostly adaxial surfaces. Needles were from the 1993, 1992, and 1991 growth. Samples were collected from lower in the canopy (approximately 9 m from the soil surface) via the canopy access tower. Branches from trees 1 and 2 were mostly shaded. Branches from tree 3 were sunlit most of the time. Measured reflectance properties of black spruce twigs. Sampled: 07-Jun-1994 Measured: 07-Jun-1994 Leaf optical properties from aspen collected at SSA-YA. 3 trees x 3 branches x 3 replications from sunlit branches at the top of the canopy; measured adaxial and abaxial surfaces. Sampled: 10-Jun-1994 Measured: 10-12-Jun-1994 Needle optical properties from jack pine collected at SSA-YJP. 9 trees x 1 branch x 3 ages x 3 replications; measurements of both adaxial and abaxial surfaces. Trees were located about 150 m east of the hut and 20-50 m south of the access road. Branches were collected near the top of the south side of trees. Needles were from the 1993 and 1992 growth. In addition, reflectance was measured from 1994's growth (the shoot was just expanding) for the entire shoot. Measured reflectance for 3 replications of male cones from each tree. Sampled: 15-Jun-1994 Measured: 15-Jun-1994 Leaf optical properties from aspen collected at SSA-YA. 3 trees x 3 branches x 3 replications for the top of the canopy; measured adaxial and abaxial surfaces. The optical property system was set up inside the van because rain prevented "outdoor" measurements. Sampled: 21-Jul-1994 Measured: 23-24-Jul-1994 Needle optical properties from jack pine collected at SSA-YJP. 9 trees x 1 branch x 3 ages x 3 replications; measurements of both adaxial and abaxial surfaces. Trees were located about 250 m east of the hut and 80 m south of the access road. Branches were collected from the south side of sunlit trees, 1.5-2 m from the soil surface. Needles from 1994, 1993, and 1992 growth were measured. Sampled: 25-Jul-1994 Measured: 26-27-Jul-1994 Needle optical properties from jack pine collected at SSA-YJP. 9 trees x 1 branch x 3 ages x 3 replications; measurements of both adaxial and abaxial surfaces. Trees were located about 150 m east of the hut and 20-40 m north of the access road. Branches were collected from the south side of sunlit trees at the top of the canopy. Twig reflectance was measured. Needles from 1994, 1993, and 1992 growth were measured. Sampled: 29-Jul-1994 Measured: 29-Jul-1994 Leaf optical properties from aspen collected at SSA-YA. 3 trees x 3 branches x 3 replications from the top of the canopy; measured adaxial and abaxial surfaces. Branches were sunlit. Leaf optical properties on understory components (hazelnut, balsam poplar, and alder) collected at SSA-YA. 9 trees x 1 replication. Samples were shaded within the aspen canopy. Sampled: 30-Jul-1994 Measured: 31-Jul-02-Aug-1994 Needle optical properties from black spruce collected at SSA-OBS. 3 trees x 3 branches x 3 ages x 3 replications; mostly adaxial surfaces. Samples were collected from sunlit branches at the top of the canopy via the canopy access tower. Needles were from the 1994, 1993, and 1992 growth. Sampled: 02-Aug-1994 Measured: 02-04-Aug-1994 Needle optical properties from black spruce collected at SSA-OBS. 3 trees x 3 branches x 3 ages x 3 replications; mostly adaxial surfaces. Samples were collected from shaded branches lower in the canopy (approximately 9 m from the soil surface) via the canopy access tower. Needles were from the 1994, 1993, and 1992 growth. Reflectance properties of black spruce twigs were measured. Optical properties of understory components were also measured (e.g., wildrose, Labrador tea, and blueberry); 5 samples of each component. Sample: 05-Aug-1994 Measured: 05-Aug-1994 Leaf optical properties on species (e.g., bog birch, buck bean, buck bean with dried, rusty residue {rimpis}, and sedge) at SSA-FEN. 5 samples of each species; adaxial and abaxial surfaces were measured. Sampled: 04-Sep-1994 Measured: 05-06-Sep-1994 Needle optical properties from black spruce collected at SSA-OBS. 3 trees x 3 branches x 3 ages x 3 replications; mostly adaxial surfaces. Samples were collected from lower in the canopy (approximately 9 m from the soil surface) via the canopy access tower. Trees 1 and 3 are sunlit samples, and tree 2 is shaded. Measurements were not made on tree 3 branch 2. Needles from 1994, 1993, and 1992 growth were measured. Sampled: 04-Sep-1994 Measured: 04-Sep-1994 Leaf optical properties from aspen collected at SSA-YA. 3 trees x 3 branches x 3 replications from sunlit branches at the top of the canopy; adaxial and abaxial surfaces were measured. Sampled: 07-Sep-1994 Measured: 08-11-Sep-1994 Needle optical properties from black spruce collected at SSA-OBS. 3 trees x 3 branches x 3 ages x 3 replications. Samples were collected from the top of the canopy via the canopy access tower. Reflectance properties of black spruce twigs were measured. Optical properties of understory components (e.g., wildrose, Labrador tea, and blueberry); 5 samples of each component. Sampled: 07-Sep-1994 Measured: 07-Sep-1994 Coordinated measurements of leaf optical properties and gas exchange on aspen, hazelnut, and balsam poplar collected at SSA-YA. 3 leaf color classes x 3 replications from the middle of the canopy. The color classes were leaves that were identified as Strong Yellow Green (5GY 4/4 to 5GY 6/8), Moderate Yellow Green (2.5GY 5/6 to 2.5GY 7/4), and Strong Yellow (5Y 8/6 to 5Y 8/12). Sampled: 11-Sep-1994 Measured: 11-13-Sep-1994 Needle optical properties from jack pine collected at SSA-YJP. 9 trees x 1 branch x 3 ages x 3 replications; both adaxial and abaxial surfaces were measured. Needles were from 1994, 1993, and 1992 growth. Trees were located about 150 m east of the hut and 20-40 m north of the access road; branches were collected from the top of the canopy. Twig reflectance was measured. Understory components (e.g., brown and yellow jack pine needles, bark, bearberry, and fuzzy-spiked wild rye) were measured. Sampled: 14-Sep-1994 Measured: 14-15-Sep-1994 Needle optical properties from jack pine collected at SSA-YJP. 9 trees x 1 branches x 3 ages x 3 replications; both adaxial and abaxial surfaces were measured. Trees were located about 100 m east of the hut and 20-40 m north of the access road (near the canopy access scaffolding). Sunlit branches were collected from the south side of the trees approximately 2-3 m from soil surface. Twig reflectance was measured. 7. Data Description 7.1 Spatial Characteristics See below. 7.1.1 Spatial Coverage The measurement sites and associated North American Datum 1983 (NAD83) coordinates are: SSA-OBS canopy access tower located at the flux tower site, site id G8I4T, Lat/Long: 53.98717 N, 105.11779 W, Universal Transverse Mercator (UTM) Zone 13, N:5,982,100.5 E:492,276.5 SSA-FEN site id F0L9T, Lat/Long: 53.80206 N, 104.61798 W, UTM Zone 13, N:5,961,566.6 E: 525,159.8 SSA-OA canopy access tower located 100 m up the path to the flux tower site, site id C3B7T, Lat/Long: 53.62889 N, 106.19779 W, UTM Zone 13, N:5,942,899.9 E:420,790.5 SSA-YA canopy access tower, site id D0H4T, Lat/Long: 53.65601 N, 105.32314 W, UTM Zone 13, N:5,945,298.9, E:478,644.1 SSA-YJP near the flux tower site, site id F8L6T, Lat/Long: 53.87581 N, 104.64529 W, UTM Zone 13, N:5,969,762.5 E:523,320.2 7.1.2 Spatial Coverage Map. Not available. 7.1.3 Spatial Resolution The standard external light source has a spot size 11.4 mm in diameter. The modified external light source has a spot size restricted to 3.5 mm x 11 mm. Jack pine needles were longer than the spot size of 11.4 mm, while the black spruce needles were slightly longer than the 3.5-mm narrow part of the modified external light source. Broad leaves easily fit into the 11.4-mm diameter of the standard light source. 7.1.4 Projection None given. 7.1.5 Grid Description None given. 7.2 Temporal Characteristics Aspen, hazelnut, balsam poplar, alder, marsh marigold, cinquefoil, sedge, buck bean, and bog birch leaves were measured on the same day that the samples were cut from the plant. Samples of aspen, hazelnut, and poplar were measured at least once every IFC; the other species were measured at least once during BOREAS. Substrate elements were measured up to two days after they were collected. Black spruce and jack pine samples were measured between 1 and 4 days after they were collected. Jack pine and black spruce samples were collected two times each IFC. 7.2.1 Temporal Coverage. Branches were collected from 1530-0023 Greenwich Mean Time (GMT). Leaf, needle, and twig optical properties measurement times ranged from 1130-0500 GMT. Measurements were not made continuously (IFC-1993: 04-Aug-1993 through 21-Aug- 1993; IFC-1 1994: 26-May-1994 through 15-Jun-1994; IFC-2: 21-Jul-1994 through 05-Aug-1994; IFC-3: 04-Sep-1994 through 11-Sep-1994). The following list gives the date, site, and type of samples collected: Date Site Species ---------- ------- ---------- 04-AUG-1993 SSA-FEN Jack Pine 04-AUG-1993 SSA-FEN Aspen 06-AUG-1993 SSA-FEN Black Spruce 16-AUG-1993 SSA-YJP Jack Pine 19-AUG-1993 SSA-FEN Aspen 19-AUG-1993 SSA-FEN Buck Bean 19-AUG-1993 SSA-FEN Bog Birch 20-AUG-1993 SSA-FEN Black Spruce 21-AUG-1993 SSA-FEN Ledum 26-May-1994 SSA-YJP Jack Pine 29-May-1994 SSA-YA Aspen 01-JUN-1994 SSA-OBS Black Spruce 04-JUN-1994 SSA-YJP Jack Pine 06-JUN-1994 SSA-OA Aspen 07-JUN-1994 SSA-OBS Black Spruce 07-JUN-1994 SSA-YA Aspen 10-JUN-1994 SSA-YJP Jack Pine 15-JUN-1994 SSA-YA Aspen 21-JUL-1994 SSA-YJP Jack Pine 25-JUL-1994 SSA-YJP Jack Pine 29-JUL-1994 SSA-YA Aspen 29-JUL-1994 SSA-YA Hazelnut 29-JUL-1994 SSA-YA Alder 29-JUL-1994 SSA-YA Balsam Poplar 30-JUL-1994 SSA-OBS Black Spruce 02-AUG-1994 SSA-OBS Black Spruce 02-AUG-1994 SSA-OBS Ledum 02-AUG-1994 SSA-OBS Wild Rose 02-AUG-1994 SSA-OBS Blueberry 05-AUG-1994 SSA-FEN Bog Birch 05-AUG-1994 SSA-FEN Buck Bean 05-AUG-1994 SSA-FEN Sedge 04-SEP-1994 SSA-OBS Black Spruce 04-SEP-1994 SSA-YA Aspen 07-SEP-1994 SSA-OBS Black Spruce 07-SEP-1994 SSA-OBS Ledum 07-SEP-1994 SSA-OBS Wild Rose 07-SEP-1994 SSA-OBS Blueberry 07-SEP-1994 SSA-YA Aspen 07-SEP-1994 SSA-YA Hazelnut 07-SEP-1994 SSA-OBS Balsam Poplar 08-SEP-1994 SSA-YJP Jack Pine 11-SEP-1994 SSA-YJP Jack Pine 7.2.2 Temporal Coverage Map None given. 7.2.3 Temporal Resolution Measurements of sample type 1 required approximately 3 minutes. Measurements of sample type 2 required a minimum of 7 minutes. The most time-consuming part of the procedure was creating the sample. The optimum time interval between sample measurements was a few minutes during a measurement period. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (te12lod.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (te12lod.def). 8. Data Organization 8.1 Data Granularity All of the Leaf Optical Data for SSA Species are contained in one dataset. 8.2. Data Format The data files contain numerical and character fields of varying length separated by commas. The character fields are enclosed in single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition file (te12lod.def). 9. Data Manipulations 9.1 Formulae None given. 9.1.1 Derivation Techniques/Algorithms For sample type 1: sample fills the integrating sphere sample port: REFL(I) = [(R(I) - STR(I)) / (REF(I) - STR(I))] * 100 [1] where REFL = hemispherical reflectance of adaxial or abaxial leaf surface (percent) I = channel R = adaxial or abaxial reflected measurement (counts) STR = stray light measurement (counts) REF = adaxial or abaxial reference measurement (counts) TRAN(I) = [T(I) / (REF(I)-STR(I))] * 100 [2] where TRAN = hemispherical transmittance adaxial or abaxial leaf surface (percent) T = adaxial or abaxial transmitted measurement (counts) REF = abaxial or adaxial reference measurement (counts) Measurements of nonintercepted beam fraction for sample types 2 and 3 after 20- Apr-1994: The image analysis system was used to measure the gaps between the sample elements. The ratio of the total gap area to the incident beam area was used as a measure of the fractional area of nonintercepted beam, FRACT. For sample type 2: REFL(I) = {[R(I) - STR(I)] * [1 - FRACT] / [REFR(I) - STR(I)]} * 100 [3] where I = channel R = adaxial or abaxial reflected measurement (counts) STR = stray light measurement (counts) REFL = hemispherical reflectance of surface (percent) REFR = reference measurement with surface (intended to be calculated) facing toward the sphere (counts) FRACT = fractional area of nonintercepted beam TRAN(I) = {[T(I) / (REFT(I) - STR(I))] - [(W(I) * FRACT) / (REF(I) - STR(I))]} * [1.0 / (1.0 - FRACT)] * 100 [4] where TRAN = hemispherical transmittance of surface (percent) REFT = reference measurement with surface (intended to be calculated) facing away from sphere (counts) REF = adaxial or abaxial reference measurement (counts) W = integrating sphere wall reference measurement (transmitted without a sample) (counts) T = transmitted measurement of sample (counts) For sample type 2 and measurements made before 20-Apr-1994: the fractional area of nonintercepted beam is calculated from a measurement of the painted sample. FRAC1 = TBLACK(ii) / {[REFT(ii) - STR(ii)] * W(ii) / [REFN(ii) - STR(ii)]} [5] where FRAC1 = first iteration of fraction of beam not intercepted by sample ii = channel centered at approximately 680 nanometers TBLACK = transmitted measurement of painted sample (counts) REFT = reference measurement with surface facing away from sphere (counts) W = integrating sphere wall reference measurement (transmitted without a sample) (counts) REFN = reference measurement without sample (count) STR = stray light measurement (counts) TRAN680 = {[T(ii) / (REFT(ii) - STR(ii))] - [(W(ii) * FRAC1) / (REFN(ii) - STR(ii)]} / (1.0 - FRAC1) [6] where TRAN680 = transmittance of sample at 680 nanometers T = transmitted measurement of unpainted sample (counts) FRACT = {[T(ii) / (REFT(ii) - STR(ii))] - TRAN680} / {[W(ii) / [REFN(ii) - STR(ii)] - TRAN680} [7] where FRACT = fractional area of nonintercepted beam For instrument check using the neutral density filters: TRAND(I) = {[T(I) / (REF(I) - STR(I))] * [(X(I) - STR(I)) / W(I)]} * 100.0 [8] where TRAND = transmittance of the neutral density filter (percent) T = transmitted measurement of unpainted sample (counts) I = channel W = integrating sphere wall reference measurement (transmitted without a sample) (counts) REF = reference measurement with filter in sample port (counts) X = reference measurement with nothing in sample port (counts) STR = stray light measurement (counts) 9.2 Data Processing Sequence 9.2.1 Processing Steps For sample type 1, where the sample filled the integrating sphere sample port (e.g., aspen, buck bean, bog birch, bearberry, and lichen). Equation 1 was used to calculate the hemispherical reflectance for the adaxial and abaxial surfaces. Equation 2 was used to calculate the hemispherical transmittance for adaxial and abaxial surfaces. Note that the transmittance calculations use the reference from the opposite surface (e.g., adaxial transmittance uses reference with abaxial surface facing into the sphere). For sample type 2, where the narrow sample was not completely covering the sample port, but was long enough to extend across the sample mount (e.g., jack pine and black spruce), equations 3 and 4 were used to calculate hemispherical reflectance and transmittance, respectively, based on the fraction of nonintercepted beam. For sample type 2, where the narrow sample was not completely covering the sample port and the date was before 20-Apr-1994, the fraction of the nonintercepted beam was calculated using the measurement from the painting technique (e.g., jack pine and black spruce). Equation 5 was used to make a first estimate of the fraction of the illumination beam not intercepted by the sample. Measurements from the instrument channel that was centered around 680 nm (i.e., channel 109 was centered at 678.97 nm and 677.10 nm in 1993 and 1994, respectively) were used, because minimal transmitted radiation through the sample at this wavelength was assumed (Daughtry et al., 1989). Equation 5 was used to calculated the actual transmittance for the channel close to 680 nm, based on the estimate of the fraction of beam not striking the sample calculated in Equation 5. The actual fraction of nonintercepted beam was calculated with Equation 7. For the neutral density filter test of the integrating sphere and spectroradiometer, equation 8 was used to calculate the hemispherical transmittance of the neutral density filter. Each filter was measured three times. The results were compared to the known transmittances of the filters. For all sample measurements: Each SE590 has a unique centered wavelength associated with each of its 252 channels that varies over time. A cubic spline interpolation was applied to the 252 channels to standardize the centered wavelength to every 5 nm from 400 to 1000 nm, so that from wavelength to wavelength and year to year, comparisons could be made among measurements from various SE590s used in BOREAS. The measurements submitted are individual sample measurements or averaged by replication and/or branch. Individual sample measurements are listed when a corresponding gas exchange measurement was made. Average values were submitted for other measurements. Averages are composed of all replications for a tree/age. For example, black spruce samples collected on 01-Jun-1994 included 3 trees by 3 branches/tree by 3 ages by 3 replications/age for one height in the canopy. Nine files would be submitted for this collection, one file for each tree and age class for this height. All understory and substrate elements were averaged together per sampling date, unless age or color classification is stated. Files that include averages also include standard deviations. 9.2.2 Processing Changes For sample type 2, where the narrow sample was not completely covering the sample port and the date was before 20-Apr-1994, the fraction of the nonintercepted beam was calculated using the measurement from the painting technique (e.g., jack pine and black spruce). 9.3 Calculations None given. 9.3.1 Special Corrections/Adjustments None given. 9.3.2 Calculated Variables None given. 9.4 Graphs and Plots None given. 10. Errors 10.1 Sources of Error Errors can result if the sample thickness does not permit proper sealing around the sample holder of the integrating sphere (this can be a problem especially in the midvein area of leaves or with twigs and bark). Light entering or exiting from the loose seal can result in erroneous values. If the light source is not maintained in a horizontal position, the light output can vary, leading to errors as the light source is placed in different configurations in the suite of measurements to calculate reflectance and transmittance. Samples of bark and lichen tended to crack when placed in the integrating sphere sample holder thus allowing light to pass through the sample; reflectances could be biased lower and transmittances could be biased higher than if no cracks were present. Sample type 2 measurements had a greater chance of error than sample type 1 measurements, especially in the calculation and measurement of the fraction of nonintercepted beam. The measurement method requires that the sample always be placed in the integrating sphere sample holder in the same orientation relative to the integrating sphere for each measurement; otherwise, the fraction of nonintercepted illumination beam will not be representative of the true gap fraction between elements throughout the suite of measurements. The sample mount was designed to minimize this error. The lower light intensity of the modified external light source (compared to the standard light source) and the low reflectance and transmittance of the samples (particularly in the blue region of the spectrum; 400 to 500 nm) result in low illumination levels in the sphere that approach the sensitivity level of the SE590. Samples created with large gap fractions complicated the transmittance measurements. Large fractions allowed more nonintercepted light into the sphere than small gap fractions, dominating the transmitted light signal. Variations in the sample transmitted component may be masked by the nonintercepted light and/or be below the sensitivity of the SE590. Errors in the calculation of the fraction of the nonintercepted beam using the image analysis system were due to the variability of the light intensity of the fluorescent light source, resolution of the solid-state camera with respect to the individual gap areas to be measured, and the pixel-counting selection process. These errors resulted in approximately 10 to 30 percent relative error when estimating the fraction. Larger relative errors tended to occur when samples were created with small fractions (i.e., 5 to 20 percent). However, the sensitivity of the optical property calculations to the error in the fraction is minimal at the small fractions. Reflectance calculations are negligibly affected across the wavelength range of 400 to 1000 nm. Transmittance calculations vary 1 to 1.5 percent absolute for small fractions with relative errors of 10 percent in fraction estimation. Samples made before 20-Jul-1994 were constructed with a wide range of fractions, 30 to 80 percent, and the relative error in fraction measurement was also large (i.e., 10 to 30 percent). Optical properties, especially transmittance, are more sensitive to errors in the gap fraction estimation when the gap fraction is large than when it is small. A 10 percent relative error in large gap fraction measurement gives a 1 to 5 percent and 5 percent absolute error in reflectance and transmittance calculations, respectively, across the wavelength range. The following table lists the range of gap fractions that were measured/calculated, the extreme relative error of the gap fraction, and the resulting error in the calculation of optical properties using these gap fractions. Gap Relative Optical Visible Near Infrared Range Error Measurement Abs . Rel. Abs. Rel. ---------------------------------------------------------------- 1. Round Aperture 5 to 15 10% Refl <0.5 <3 1 2 Trans 1.25 16 1.25 4.6 20% Refl <0.5 <3 1.25 2.5 Trans 2 >20 2 5 30 to 60 10% Refl 1.5 8.5 4.5 8.5 Trans 6.5 >20 5.5 14.5 20% Refl 2 11.7 7 15.5 Trans 10 >20 8 20 40 to 80 10% Refl 7.5 >20 12.5 20 Trans 15 >20 14 >20 30% Refl 15 >20 22 >20 Trans >20 >20 25 >20 2. Slitted Aperature 5 to 15 15% Refl <1 <6 1.25 2.5 Trans 1.5 20 1.75 5.8 30% Refl 1.5 8 2 4 Trans 4 >20 2.5 7.7 Where Abs is Absolute and Rel is Relative. Additional information may be found in the report by Mesarch et al., 1991. 10.2 Quality Assessment The integrating sphere/SE590 system response changed little between the measurement periods as indicated by the transmittance measurements of neutral density filters. Mean bias errors of known transmittances using the standard external light source averaged over the Thematic Mapper (TM) waveband regions were 0.13%, -0.09%, -0.09% and -0.03% (450-520, 520-600, 630-690, and 760-19900 nanometers, respectively). Mean bias errors of known transmittances using the modified external light source averaged over the TM waveband regions were 0.13%, -0.09%, -0.13% and -0.07%. 10.2.1 Data Validation by Source None given. 10.2.2 Confidence Level/Accuracy Judgment None given. 10.2.3 Measurement Error for Parameters None given. 10.2.4 Additional Quality Assessments None given. 10.2.5 Data Verification by Data Center Data were examined for general consistency and clarity. 11. Notes None. 11.1 Limitations of the Data None given. 11.2 Known Problems with the data. Transmittance measurements for sample type 2 occasionally have negative values, which resulted from errors in the measurement of the fraction of nonintercepted illumination beam and the sensitivity of the SE590, especially in the visible region of the spectrum (400 to 700 nm). 11.3 Usage Guidance Reflectance measurements for all measurement are usable. Transmittance measurements for sample type 2 may occasionally contain negative values and should be used with discretion. Transmittance measurements made before 20-Jul- 1994, especially in the visible region of the spectrum (400 to 700 nm) may not show the small changes based on canopy location or light environment (shaded or unshaded), whereas measurements after 20-Jul-1994 may show more nuances of transmittance. 11.4 Other Relevant Information Acknowledgment of other research staff who assisted in measurements: Liquang Chen, UNL Graduate Student Brian P. Lang, UNL Undergraduate Student 12. Application of the Data Set This data set can be used to examine the optical properties of boreal vegetation. 13. Future Modifications and Plans None given. 14. Software 14.1 Software Description SPSS’ software JAVA version 1.4. 14.2 Software Access None given. 15. Data Access 15.1 Contact Information Ms. Beth Nelson BOREAS Data Manager NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) Elizabeth.Nelson@gsfc.nasa.gov 15.2 Data Center Identification See Section 15.1. 15.3 Procedures for Obtaining Data Users may place requests by telephone, electronic mail, or fax. 15.4 Data Center Status/Plans The Terrestrial Ecology (TE)-12 Leaf optic data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 16. Output Products and Availability 16.1 Tape Products None. 16.2 Film Products None. 16.3 Other Products Tabular American Standard Code for Information Interchange (ASCII) files. 17. References 17.1 Platform/Sensor//Instrument/Data Processing Documentation LI-COR LI-1800-12 Integrating Sphere Instruction Manual. 1983. Pub. No. 8305- 0034. LI-COR, inc., Lincoln, NE. Spectron Engineering, Inc. Operating Manual: SE590 field-portable data-logging spectroradiometer, Spectron Engineering, Denver, CO 80223. 17.2 Journal Articles and Study Reports Blad, B.L., E.A. Walter Shea, C.J. Hays, and M.A. Mesarch. 1990. Calibration of field reference panel and radiometers used in FIFE 1989. AgMet Progress Report 90-3. Department of Agricultural Meteorology. University of Nebraska-Lincoln. Lincoln, Nebraska 68583-0728. Daughtry, C.S.T., L.L. Biehl, and K.J. Ranson. 1989. A new technique to measure the spectral properties of conifer needles. Remote Sens. Environ. 27:81-1991. Mesarch, M. A., E.A. Walter-Shea, B.F. Robinson, J.M. Norman and C.J. Hays. 1991. Performance evaluation and operation of a field-portable radiometer for individual leaf optical measurements. AgMet Progress Report 91-2. Department of Agricultural Meteorology, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0728. Munsell Color Charts for Plant Tissue. 1977. MACBETH Div. of Kollmorgen Instrument Corp., Baltimore, MD. Norman, J.M. and P.G. Jarvis. 1974. Photosynthesis in Stika Spruce [Picea Sitchenis (Bong.) Carr.] III. Measurements of canopy structure and interception of radiation. J. Appl. Ecol. 11:375-398. Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and early results from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P.and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). Sellers, P.J., F.G. Hall, R.D. Kelly, A. Black, D. Baldocchi, J. Berry, M. Ryan, K.J. Ranson, P.M. Crill, D.P. Lettenmaier, H. Margolis, J. Cihlar, J. Newcomer, D. Fitzjarrald, P.G. Jarvis, S.T. Gower, D. Halliwell, D. Williams, B. Goodison, D.E. Wickland, and F.E. Guertin. 1997. BOREAS in 1997: Experiment overview, scientific results, and future directions. JGR BOREAS Special Issue, 102 (D24), 28731-28769. Smith, W.K. and G.A. Carter. 1988. Shoot structural effects on needle temperatures and photosynthesis in conifers. Amer. J. of Bot. 75:496-500. Williams, D.L. 1991. A comparison of spectral reflectance properties at the needle, branch and canopy level for selected conifer species. Remote Sens. Environ. 35:79-1993. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms Abaxial: The bottom surface of a leaf or needle. For aspen, buck bean, bog birch, and substrate element samples, this side was not as bright in color and had a less glossier sheen than the adaxial surfaces. The abaxial surface of Labrador tea leaves was heavily pubescent; the current year's growth was white pubescent, and the prior years' growth having rust-colored pubescent. For black spruce, this was the surface with the whitish lines. Jack pine needles were attached to twigs in paired fascicles and generally had a semicircular cross- sectional shape. For jack pine needles, the inner semicircular concave, curveed side was considered to be the abaxial surface. Absolute (Abs) Error: Percent absolute error. Adaxial: The top surface of a leaf or needle. For aspen, buck bean, bog birch, and substrate element samples, this side was typically brighter in color and had a glossier sheen than the abaxial surfaces. The adaxial surface of Labrador tea leaves was the least pubescent surface. For black spruce, this was the surface without the whitish lines. Jack pine needles were attached to twigs in paired fascicles and generally had a semicircular cross-sectional shape. The outer semicircular convex, curved side of the needle was considered the adaxial surface. Adaxial Transmittance: The light shines on the adaxial surface, goes through the needle, and then passes into the integrating sphere. The spectroradiometer then measures the integrated light that is bouncing around in the sphere. Adaxial Reflectance: The light shines on the adaxial surface, bounces off this surface, and then bounces around in the integrating sphere. The spectroradiometer then measures the integrated light that is bouncing around in the sphere. Abaxial Transmittance: The light shines on the abaxial surface, goes through the needle, and then passes into the integrating sphere. The spectroradiometer then measures the integrated light that is bouncing around in the sphere. Abaxial Reflectance: The light shines on the abaxial surface, bounces off this surface, and then bounces around in the integrating sphere. The spectroradiometer then measures the integrated light that is bouncing around in the sphere. Channel (ch): One band on the SE590, each having a unique wavelength. Reflectance (Refl): The light shines on the specified surface and bounces off this surface and then bounces around in the integrating sphere; the spectroradiometer then measures the integrated light that is bouncing around in the sphere Relative (Rel) Error: Percent relative error. Transmittance (Trans): The light shines on the specified surface, goes through the needle and then passes into the integrating sphere; the spectroradiometer then measures the integrated light that is bouncing around in the sphere. 19. List of Acronyms ASCII - American Standard Code for Inforamtion Interchange BOREAS - BOReas Ecosystem-Atmosphere Study BORIS - BOREAS Information System DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System FEN - Nipawin Fen site FFC-T - Focused Field Campaign/Thaw 1994 FFC-W - Focused Field Campaign/Winter 1994 GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center IFC - Intensive Field Campaign NAD - North American Datum of 1983 NASA - National Aeronautics and Space Administration NSA - Northern Study Area OA - Old Aspen OBS - Old Black Spruce OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park PAR - Photosynthetically Active Radiation SSA - Southern Study Area Stdev - Standard Deviation TE - Terrestrial Ecology TM - Thematic Mapper UNL - University of Nebraska - Lincoln URL - Uniform Resource Locator UTM - Universal Transverse Mercator YA - Young Aspen YJP - Young Jack Pine 20. Document Information 20.1 Document Revision Date Written: 30-Sept-1996 Last Updated: 14-Sep-1998 20.2 Document Review Date(s) BORIS Review: 30-Apr-1997 Science Review: 27-Jul-1998 20.3 Document ID 20.4 Citation Please acknowledge the efforts of E.A. Walter-Shea, M.A. Mesarch, and L. Chen at the University of Nebraska-Lincoln 20.5 Document Curator 20.6 Document URL Keywords Reflectance Transmittance Optical Properties Integrating Sphere TE12_Leaf_Optic.doc 09/14/98