BOREAS HYD-08 DEM Data over the NSA-MSA and SSA-MSA in the UTM Projection Summary These DEMs were produced from digitized contours at a cell resolution of 100 meters. Vector contours of the area were used as input to a software package that interpolates between contours to create a DEM representing the terrain surface. The vector contours had a contour interval of 25 feet. The data cover the BOREAS MSAs of the SSA and NSA and are given in a UTM map projection. The data are stored in binary, image format files. Note that the binary files of this data set on the BOREAS CD-ROMs have been compressed using the Gzip program. See section 8.2 for details. 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-08 DEM Data over the NSA-MSA and SSA-MSA in the UTM Projection 1.2 Data Set Introduction These data are provided as part of the BOReal Ecosystem-Atmosphere Study (BOREAS) Staff Science Geographic Information System (GIS) Data Collection Program, which included the collection of pertinent map data, in both hard copy and digital form. 1.3 Objective/Purpose The objective of these Digital Elevation Models (DEMs) is to provide the BOREAS investigators with a data product that characterizes the topography of the Northern Study Area (NSA) and Southern Study Area (SSA) Modeling Sub-Areas (MSAs). These data are to be used for modeling purposes. 1.4 Summary of Parameters Elevation above mean sea level in meters. 1.5 Discussion The input vector data were acquired through the Canadian Centre for Remote Sensing (CCRS) from the National Topographical Data Base (NTDB) in Standard Interchange Format (SIF). The vector data were digitized from 1:50,000-scale topographic maps and had a contour interval of 25 feet. The BOREAS HYD-08 team gridded the data into a Universal Transverse Mercator (UTM) projection. 1.6 Related Data Sets BOREAS Regional DEM in Raster Format and AEAC Projection BOREAS DEM Data over the NSA-MSA and SSA-MSA in the AEAC Projection 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. L.E. Band, Professor 2.2 Title of Investigation Simulation of Boreal Ecosystem Carbon and Water Budgets: Scaling from Local to Regional Extents 2.3 Contact Information Contact 1 ----------- Xuewen Wang Dept. Geography, U. Toronto Toronto, Ontario (416) 978-5070 wangx@esker.geog.utoronto.ca Contact 2 ----------- L.E. Band Dept. Geography, U. Toronto Toronto, Ontario (416) 978-3375 lband@eos.geog.utoronto.ca Contact 3 ----------- David Knapp NASA/GSFC Greenbelt, MD (301) 286-1424 (301) 286-0239 (fax) David.Knapp@gsfc.nasa.gov 3. Theory of Measurements The user is referred to the NTDB to obtain information about the processes used to create the vector contour data. 4. Equipment 4.1 Sensor/Instrument Description Unknown. 4.1.1 Collection Environment Unknown. 4.1.2 Source/Platform Unknown. 4.1.3 Source/Platform Mission Objectives Unknown. 4.1.4 Key Variables Unknown. 4.1.5 Principles of Operation Unknown. 4.1.6 Sensor/Instrument Measurement Geometry Unknown. 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 The data were acquired from the NTDB and received from CCRS. The data came in SIF, digitized from 1:50,000-scale topographic maps. These vector contour data were used by the HYD-08 team to produce the DEMs in this data set. 6. Observations 6.1 Data Notes Unknown. 6.2 Field Notes Unknown. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage NSA: The image area that was modeled covers an area that is approximately 54 km x 37 km. This area includes areas just northwest of Thompson, extending as far south as Nelson House, Manitoba. The North American Datum 1927 (NAD27) corners of the data set are as follows. The following UTM coordinates are in UTM zone 14. UTM Corner Easting Northing Longitude Latitude --------------------------------------------------------------- Northwest 503100 6212100 98.95022W 56.05600N Northeast 556900 6212100 98.08645W 56.05263N Southwest 503100 6175500 98.95064W 55.72715N Southeast 556900 6175500 98.09414W 55.72382N SSA: The image area that was modeled covers an area that is approximately 54 km x 44 km. This area is located northeast of Prince Albert, Saskatchewan. The NAD27 corners of the data set are as follows. The following UTM coordinates are in UTM zone 13. UTM Corner Easting Northing Longitude Latitude --------------------------------------------------------------- Northwest 484800 5993800 105.23240W 54.09410N Northeast 538300 5993800 104.41442W 54.09290N Southwest 484800 5949500 105.23020W 53.69594N Southeast 538300 5949500 104.41996W 53.69475N 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution These data were gridded in the UTM projection to a cell size of 100 meters in both the X and Y directions. 7.1.4 Projection UTM zone 13 under NAD27. 7.1.5 Grid Description The data are gridded in the UTM projection (zone 14 in the NSA, zone 13 in the SSA) at a cell size of 100 meters in both the X and Y directions. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Most of the elevation data from which the DEM was produced were collected in the 1970s or 1980s. 7.2.2 Temporal Coverage Map Not available. 7.2.3 Temporal Resolution These elevations represent the state of the terrain at a point in time. Most of the elevation data from which the DEM was produced were collected in the 1970s or 1980s. 7.3 Data Characteristics 7.3.1 Parameter/Variable Elevation above mean sea level 7.3.2 Variable Description/Definition Elevation above mean sea level - The vertical distance between a plane at mean sea level and a parallel plane intersecting the given location. 7.3.3 Unit of Measurement Meters. 7.3.4 Data Source The HYD-08 team received the original data from CCRS, who acquired them from the NTBD. 7.3.5 Data Range Not available. 7.4 Sample Data Record Not applicable to binary image data. 8. Data Organization 8.1 Data Granularity The smallest amount of data that can be obtained from this data set is the entire data set. 8.2 Data Format(s) 8.2.1 Uncompressed Data Files This data product contains the following three files: File 1: American Standard Code for Information Interchange (ASCII) Header File listing the files that are on the tape. The file contains 9 records of 80 bytes each. File 2: DEM data file for the NSA. This is a binary file containing 1,076 bytes in each of 366 records. Each binary record is a line of the image file and contains 538 2-byte (16-bit) values stored as low-order byte first. Each binary value is the mean elevation above sea level of the location in meters. File 3: DEM data file for the SSA. This is a binary file containing 1,070 bytes in each of 443 records. Each binary record is a line of the image file and contains 535 2-byte (16-bit) values stored as low-order byte first. Each binary value is the mean elevation above sea level of the location in meters. 8.2.2 Compressed CD-ROM Files On the BOREAS CD-ROMs, file 1 is stored as ASCII text; however, files 2 and 3 have been compressed with the Gzip compression program (file name *.gz). These data have been compressed using gzip version 1.2.4 and the high compression (-9) option (Copyright (C) 1992-1993 Jean-loup Gailly). Gzip (GNU zip) uses the Lempel-Ziv algorithm (Welch, 1994) used in the zip and PKZIP programs. The compressed files may be uncompressed using gzip (-d option) or gunzip. Gzip is available from many websites (for example, ftp site prep.ai.mit.edu/pub/gnu/gzip-*.*) for a variety of operating systems in both executable and source code form. Versions of the decompression software for various systems are included on the CD-ROMs. 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms The Topog software package was used to interpolate between contours and create these DEMs. Any details beyond this information is unknown. 9.2 Data Processing Sequence 9.2.1 Processing Steps HYD-08 used the Topog software to interpolate elevations between the contours. BOREAS Information System (BORIS) personnel processed the data by: 1) Visually reviewing the data on a display system. 2) Inventorying the data in the online data base. 3) Documenting the data contents. 4) Copy the ASCII and compress the binary files for release on CD-ROM. 9.2.2 Processing Changes None. 9.3 Calculations 9.3.1 Special Corrections/Adjustments None. 9.3.2 Calculated Variables None. 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error The Topog program interpolates the values to grid cells from vector and point data (digitized contours). Errors occur where the original vector data are too sparse spatially, particularly in flat lowland areas. 10.2 Quality Assessment 10.2.1 Data Validation by Source See Section 10.1. 10.2.2 Confidence Level/Accuracy Judgment See Section 10.1. 10.2.3 Measurement Error for Parameters See Section 10.1. 10.2.4 Additional Quality Assessments See Section 10.1. 10.2.5 Data Verification by Data Center BORIS Staff visually reviewed the images to verify that they did appear to represent DEMs without any obvious anomalies. The only quantitative assessment made was to see that the minimum and maximum elevation values in the raster file approximated those shown on topographic maps of the area. 11. Notes 11.1 Limitations of the Data Elevation variations exist within the lakes, especially large lakes, as explained in Section 10.1. 11.2 Known Problems with the Data Elevation variations exist within the lakes, especially large lakes, as explained in Section 10.1. 11.3 Usage Guidance Elevation variations exist within the lakes, especially large lakes, as explained in Section 10.1. Before uncompressing the Gzip files on CD-ROM, be sure that you have enough disk space to hold the uncompressed data files. Then use the appropriate decompression program provided on the CD-ROM for your specific system. 11.4 Other Relevant Information None. 12. Application of the Data Set The data can be used to perform analyses of terrain and related effects on hydrology and vegetation. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description TOPOG Version 5.0 Division of Water Resources, CSIRO Canberra, Australia Gzip (GNU zip) uses the Lempel-Ziv algorithm (Welch, 1994) used in the zip and PKZIP commands. 14.2 Software Access Contact Division of Water Resources, CSIRO Canberra, Australia Gzip is available from many websites across the net (for example) ftp site prep.ai.mit.edu/pub/gnu/gzip-*.*) for a variety of operating systems in both executable and source code form. Versions of the decompression software for various systems are included on the CD-ROMs. 15. Data Access 15.1 Contact Information Primary contact: Ms. Beth McCowan BOREAS Data Manager NASA/GSFC Greenbelt, Maryland (301) 286-4005 (301) 286-0239 (fax) beth@ltpmail.gsfc.nasa.gov 15.2 Data Center Identification See Section 15.l . 15.3 Procedures for Obtaining Data Users may place requests by telephone, electronic mail, or fax. 15.4 Data Center Status/Plans The HYD-08 DEM data are available from the Earth Observing System Data and Information System (EOSIDS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory Oak Ridge, TN (423) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 16. Output Products and Availability 16.1 Tape Products The DEM data can be made available on 8-mm, Digital Archive Tape (DAT), or 9- track tapes at 6250 or 1600 Bytes Per Inch (BPI). 16.2 Film Products None. 16.3 Other Products These data are available on the BOREAS CD-ROM series. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Topog User Guide (Version 5.0) 1994. Division of Water Resources, CSIRO. Canberra, Australia. Welch, T.A. 1984, A Technique for High Performance Data Compression, IEEE Computer, Vol. 17, No. 6, pp. 8 - 19. 17.2 Journal Articles and Study Reports Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 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. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Halland 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. and 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 ASCII - American Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System BPI - Bytes Per Inch CCRS - Canadian Centre for Remote Sensing CD-ROM - Compact Disk-Read-Only-Memory DAAC - Distributed Active Archive Center DAT - Digital Archive Tape DEM - Digital Elevation Model EOS - Earth Observing System EOSDIS - EOS Data and Information System GSFC - Goddard Space Flight Center MSA - Modeling Sub-Area NAD27 - North American Datum of 1927 NASA - National Aeronautics and Space Administration NSA - Northern Study Area NTDB - National Topographic Data Base ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park SIF - Standard Interchange Format SSA - Southern Study Area URL - Uniform Resource Locator UTM - Universal Transverse Mercator 20. Document Information 20.1 Document Revision Dates Written: 03-Nov-1994 Last Updated: 26-Feb-1998 20.2 Document Review Dates BORIS Review: 05-Jun-1997 Science Review: 20.3 Document ID 20.4 Citation These data originated as vector data from CCRS. This data product was gridded from the original vector data by the BOREAS Science Team HYD-8, led by Prof. L.E. Band at the University of Toronto. 20.5 Document Curator 20.6 Document URL Keywords GIS DEM ELEVATION HYD08_UTM_DEM.doc 04/17/98