BOREAS HYD-06 Moss/Humus Moisture Data Summary: This data set contains water content measurements of the moss/humus layer, where it existed. These data were collected along various flight lines in the Southern and Northern Study Areas (SSA and NSA) during 1994. The data are available 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 1.1 Data Set Identification BOREAS HYD-06 Moss/Humus Moisture Data 1.2 Data Set Introduction This document describes the in-situ water content measurements of the moss/humus layer along flight lines. 1.3 Objective/Purpose The objectives of this research were: 1) to obtain improved estimates of the soil moisture (SM) conditions for the BOREAS experimental areas, 2) to develop techniques for measuring the water content (WC) of the moss/humus layer, 3), to provide assistance to HYD-04 to measure the water equivalent (WE) of the snow cover, 4) to provide information for validating and calibrating other remote sensing methods, and 5) to provide information on the SM of the mineral soil, the WC of the Moss/Humus layer, and the WE of the snow cover to other investigators. 1.4 Summary of Parameters Transect identifier, sample identifier, latitude and longitude of the in-situ ground measurements of the water content of the moss/humus layer. 1.5 Discussion As part of the BOREAS experiment, natural terrestrial gamma radiation data over a network of 48 flight lines were collected. For each of these flight lines, ground in-situ SM measurements of the mineral soil and WC of the moss/humus layer were collected and used, along with other available measurements, to establish one-time calibration of the natural terrestrial radioisotope signal over the flight line network. 1.6 Related Data Sets BOREAS HYD-06 Aircraft Gamma Ray Soil Moisture Data BOREAS HYD-6 Ground Gravimetric Soil Moisture Data 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. Eugene L. Peck Hydex Corporation Dr. Thomas Carroll National Weather Service 2.2 Title of Investigation Remote Sensing of Hydrologic Variables in Boreal Areas 2.3 Contact Information Contact 1 -------------- Dr. Eugene L. Peck Hydex Corporation Vienna, VA (703) 281-6284 (703) 281-7014 genepeck@aol.com Contact 2 -------------- Dr. Thomas Carroll NOHRSC, Office of Hydrology NWS, NOAA Chanhassen, MN (612) 361-6610, ext. 225 (612) 361-6634 tc@nohrsc.nws.gov 3. Theory of Measurements In-situ ground samples of the WC of the moss/humus layer are obtained using the gravimetric method (percent by weight of dry soil). The moss/humus layer samples are placed in one or more plastic containers and are later dried out for 24 hours in a drying oven at 105 degrees Celsius. 4. Equipment: 4.1 Sensor/Instrument Description An ESC-30 (Eastern Snow Conference) snow tube having an orifice of 30 cm2 is used to collect samples of the moss/humus layer. Depths of the moss/humus layer are measured by a ruler after digging down to the mineral soil. 4.1.1 Collection Environment The airborne and ground measurements of soil moisture and moss/humus layer were planned before each days surveying. The airborne and ground measurements were taken as simultaneously as possible. Ground measurements for calibration purposes were obtained when the flight line areas were fairly dry and never during rain occurrences. 4.1.2 Source/Platform Human. 4.1.3 Source/Platform Mission Objectives To collect cores of moss/humus at various locations. 4.1.4 Key Variables Moss/Humus moisture content. 4.1.5 Principles of Operation Unknown. 4.1.6 Sensor/Instrument Measurement Geometry ESC-30 snow tube having an orifice of 30 cm2 4.1.7 Manufacturer of Sensor/Instrument Unknown. 4.2 Calibration Unknown. 4.2.1 Specifications Unknown. 4.2.1.1 Tolerance Unknown. 4.2.2 Frequency of Calibration Unknown. 4.2.3 Other Calibration Information Unknown. 5. Data Acquisition Methods Ground measurements were collected at over 1100 locations along 42 of the 48 BOREAS airborne gamma radiation flight lines during the field experiments. Maps showing locations of most BOREAS established flight lines are shown on Figures 5.2.1.4a, 5.2.1.4b 5.2.1.4c, and 5.2.1.4c of version 3.0 of the BOREAS Experimental Plan. Revised computerized maps of all of the 48 flight lines prepared by NOHRSC (March 1995) are available in BORIS (containing a few additional lines that were established during the field experiments). The flight lines are numbered BP100 to BP123 and CR954 to CR960 in the southern study area (SSA) and BP201 to BP213 in the northern study area (NSA). Flight lines BP301 to BP305 are located along the transect between the SSA and NSA. The CR lines in the SSA are part of the operational snow measurement program of the Atmospheric Environment Service, AES, of Canada. See section 9.2.1 for details on how the ground samples were processed. 6. Observations 6.1 Data Notes Unknown. 6.2 Field Notes Field notes for the ground sampling of the WC of the moss/humus layer by members of HYD-06 and HYD-04 are contained in the comments of the data itself. Ground samples of the water equivalent of the snow cover and other measurements obtained during the 1993 and 1994 IFC-Ws are being placed in BORIS by HYD-04. 7. Data Description 7.1 Spatial Characteristics These data were collected along various flight lines within the NSA and SSA. The data that provides the location of these flight lines is described in the HYD-06 Airborne Estimate of Soil Moisture Document. 7.1.1 Spatial Coverage The ground samples of moss/humus water content were made at point locations throughout the NSA and SSA. The bounding coordinates of these areas are: There is a reference table called HYD06_TRANSECT_REF that contains information about the location of the various flight lines. NSA Spatial Coverage (North American Datum 1983 (NAD83)) Longitude Latitude --------- ------- Upper Left -98.82 56.247 Upper Right -97.24 56.081 Lower Right -97.49 55.377 Lower Left -99.05 55.54 SSA Spatial Coverage Longitude Latitude --------- -------- Upper Left -106.23 54.319 Upper Right -104.24 54.223 Lower Right -104.37 53.419 Lower Left -106.32 53.513 7.1.2 Spatial Coverage Map See figures 5.2.1.4a, 5.2.1.4b, 5.2.1.4c, 5.2.1.4c in version 3.0 of the BOREAS Experiment Plan. 7.1.3 Spatial Resolution The ground samples of moss/humus water content were made at point locations throughout the NSA and SSA. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage The data was collected for as many flight lines as possible during the following periods: 8-Sep-1993 to 11-Sep-1993 in the SSA 7-Feb-1994 to 11-Feb-1994 in the SSA and NSA (in cooperation with HYD-4) 24-Jul-1994 to 5-Aug-1994 in the SSA and NSA 30-Aug-1994 to 10-Sep-1994 in the SSA 7.2.2 Temporal Coverage Map Not available. 7.2.3 Temporal Resolution Ground samples were collected on a daily basis. For those ground samples collected by members of HYD-06 the observational times the ground samples were obtained are included in the files Mastergd.DAT and Mastermh.DAT. Times of sampling were not noted for those collected by members of HYD-04. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (h06grmsd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (h06grmsd.def). 8. Data Organization 8.1 Data Granularity All of the Moss/Humus Moisture Data are contained in one dataset. 8.2 Data Format(s) The data files contain numerical and character fields of varying length separated by commas. The character fields are enclosed with a single apostrophe mark. There are no spaces between the fields. Sample data records are shown in the companion data definition files (h06grmsd.def). 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms 9.2 Data Processing Sequence 9.2.1 Processing Steps The moss/humus layer samples in the sealed plastic containers obtained in the field are weighed (M-H total), the lids are removed, and the samples are dried in ovens and weighed again (dry). The weight of the water (water) in the moss/humus layer for each portion of the sample (A, B, etc.) is determined by subtracting the dry weight (dry) and the weight of an average plastic lid for that day from the total weight (M-H total) for the portion of the sample. The weight of the plastic lids and the plastic containers vary from shipment to shipment and the average weights of those being used each day are recorded on the laboratory form with the total and dry weights. The WC of the portion of the sample is obtained by dividing the water in the portion of the sample by 30 (the cross sectional area (in square centimeters) of the ESC sampler). This is multiplied by 10 to yield WC in millimeters. The WC of each sample is computed by adding the WC of all of the portions (A, B, etc.) of the sample. Samples processed by members of HYD-04 are sealed and taken to AES offices in Downsview, Ontario for processing. The measurements obtained by members of HYD- 04 do not have entries in column water or WC part. They compute the WC of a sample directly, ((M-H total minus dry)/(30))*10. BORIS processed the data by: 1) Reviewing the initial data files and loading them on-line for BOREAS team access, 2) Designing relational data base tables to inventory and store the data 3) Loading the the data into the relational data base tables, 4) Performing the following conversions on measurements into System International (SI) units. 4) Working with the HYD-06 team to document the data set, and 5) Extracting the standardized data into logical files. 9.2.2 Processing Changes Not applicable. 9.3 Calculations The following equation yields water content in millimeters. Water Content = (Moss Humus total weight - dry weight of soil)/30 * 10 9.3.1 Special Corrections/Adjustments None. 9.3.2 Calculated Variables None. 9.4 Graphs and Plots Maps of the BOREAS flight lines, digitized by NOHRSC, are in BORIS. 10. Errors 10.1 Sources of Error There are many possible sources of error measuring the water content (WC) of the moss/humus layer. Obtaining a sample in deep layers of moss/humus can be very difficult. In some cases the depth is greater than the length of the ESC snow tube and the moss/humus layer has to be dug down to the mineral soil and more than one core of the layer cut. In some cases the root system in the moss/humus layer is so heavy it is impossible to cut through the layer with the ESC tube. In other cases there are air pockets in the moss/humus layer that may not be representative of the average layers in the area. Selecting a measurement site that represents the general conditions is also difficult. For this reason, four extra measurements of the depth of the moss/humus layer were made at 5 meter distances from the measuring site. Even though there are difficulties in obtaining the measurements of the WC of the moss/humus layer, the data for most flight lines appear to be a reasonable indication of the average for the flight lines (and bins). In one case measurements were made at different times over the same bin of the flight line with a heavy moss/humus layer. It was evident that two of the measurement sites had depths much greater than the average for the entire bin of the flight line (BP115, bin 3, 31 August 1994) and the computed average of the WC for the bin for that day was greater than expected. 10.2 Quality Assessment 10.2.1 Data Validation by Source Confidence in the in-situ measurement of the WC of the moss/humus layer depends on many factors regarding the accuracy of locating the sampling points along the flight line as well as the experience and training of the field personnel. 10.2.2 Confidence Level/Accuracy Judgement The confidence level varies with the experience of the person selecting the flight line and marking the location of the ground measurement. In very flat areas, the exact location of a ground measurement is more difficult to identify on a map than for a location near a stream or in areas of variable terrain. 10.2.3 Measurement Error for Parameters A precise estimate of the error of a WC measurement of the moss/humus layer can not be determined. The selection of sites for in-situ measurements of the WC of the moss/humus layer along a flight line is very critical in determining the calibration data for flight lines with considerable depth of moss/humus. Experience with the airborne gamma radiation system during the recent field experiments (FIFE) in Kansas (Carroll, et. al, 1988) illustrates the need to obtain ground measurements representative of the average of the area from which ground based gamma are received by the airborne detectors. During the BOREAS field experiments careful attention has been given to obtaining as representative measurements of WC of the moss/humus layer as possible for flight lines having considerable depth of moss/humus. For the flight lines over the primary tower sites in the SSA more than one set of ground measurements were obtained. 10.2.4 Additional Quality Assessments None. 10.2.5 Data Verification by Data Center None. 11. Notes 11.1 Limitations of the Data None given. 11.2 Known Problems with the Data None given. 11.3 Usage Guidance The WC and depths of the moss/humus layer may be only representative for the soil and vegetative conditions of the particular flight line. Considerable change in moss/humus conditions may be found over very small distances (10s of meters). Careful review of the soil and vegetative conditions are necessary to transfer the moss/humus estimates to nearby areas. However, the use of the moss/humus measurements for similar conditions for flux analyses and other studies can add considerable information on the spatial and temporal variation in the the moss/humus layer. For some flight lines the number of depth measurements of the moss/humus layer probably has more reliability than fewer measurements of the WC of the moss/humus layer. There is merit in applying the average WC as a density to the average depth determined from the larger number of depth measurements. The average density (WC/average depth) for one flight line correlates well with average density for nearby lines. 11.4 Other Relevant Information Ground measurements collected by members of HYD-06 are collected under slightly different methods than those collected by members of HYD-04. Those observed by members of HYD-04 have observation times of 0000 hours. Members of HYD-04 follow sampling procedures established for the operational airborne gamma radiation snow surveys that have been collected in the BOREAS area for many years, Sampling points are selected on a set distance from the beginning of the flight line (either at one km or two km intervals depending on the length of the flight line). This approach has proven useful for the operational snow measuring program. Using this approach the measurement sites are selected at nearly the same location along the flight line during snow and non-snow periods. Members of HYD-06 collect only during non snow periods and select measurements sites that tend to best represent the average conditions along the entire 305 meter wide foot path of the area measured by the airborne gamma radiation surveys. 12. Application of the Data Set None given. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description None given. 14.2 Software Access None given. 15. Data Access 15.1 Contact Information Primary contact: Ms. Beth McCowan BOREAS Information System NASA Goddard Space Flight Center Greenbelt, Maryland (301) 286-4005 (301) 286-0239 beth@ltpmail.gsfc.nasa.gov 15.2 Data Center Identification See 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 HYD-06 moss moisture data are available from the EOSDIS ORNL DAAC (Earth Observing System Data and Information System) (Oak Ridge National Laboratory) (Distributed Active Archive Center). 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 Video tapes taken over each flight line during calibration showing the area directly under the aircraft are available (at NOHRSC). At the present time no decision has been made on storing these tapes in BORIS. 16.3 Other Products Maps showing the flight lines for which Gamma data were obtained, have been digitized by NOHRSC and submitted to BORIS. The HYD-06 ground moss moisture data are available in tabular ASCII files. 17. References Carroll, T. R., E. L. Peck, and D. M. Lipinski. 1988. Airborne time-series measurements of soil moisture using terrestrial gamma radiation. Proc. Ann. Conf. Am. Soc. Photogram. Remote Sens., St. Louis, MO 17.1 Platform/Sensor/Instrument/Data Processing Documentation None. 17.2 Journal Articles and Study Reports Sellers, P., F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). Sellers, P., F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P., F. Hall, K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall, K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). 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. 1997. BOREAS Overview Paper. JGR Special Issue (in press). 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms AES - Atmospheric Environment Service of Canada BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System BPI - Byte per inch CCT - Computer Compatible Tape CD-ROM - Compact Disk (optical), Read-Only Memory DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System ESC - Eastern Snow Conference EXP - Experiment FIFE - First ISLSCP Field Experiment FIS - FIFE Information System (NASA) GMT - Greenwich Mean Time GPS - Global positioning system GSFC - Goddard Space Flight Center HYD-04 - Group 4, BOREAS Hydrology science team HYD-06 - Group 6, BOREAS Hydrology science team ISLSCP - International Satellite Land Surface Climatology Project Mev - Million Electronic Volts NAD27 - North American datum of 1927 NAD83 - North American datum of 1983 NASA - National Aeronautics and Space Administration NOHRSC - National Operational Hydrologic Remote Sensing Center NSA - Boreas northern study area NWS - National Weather Service ORNL - Oak Ridge National Laboratory SM - Soil moisture, percent by weight, of the mineral soil SSA - Boreas sourthern study area URL - Uniform Resource Locator USGS - U. S. Geological Survey WC - Water content of the moss/humus layer WE - Water equivalent of the snow layer 20. Document Information 20.1 Document Revision Dates Written: 08-Jun-1995 Last Updated: 26-Feb-1998 20.2 Document Review Dates BORIS Review: 07-Nov-1997 Science Review: 12-Dec-1997 20.3 Document ID 20.4 Citation Eugene L. Peck, President, Hydex Corporation Thomas Carroll, Chief, NOHRSC 20.5 Document Curator 20.6 Document URL Keywords MOSS MOISTURE SOIL MOISTURE HYD06_GRNDMH.doc Page 13 of 13