BOREAS Level-3a Landsat TM Imagery: Scaled At-sensor Radiance in BSQ Format Summary: For BOREAS, the level-3a Landsat TM data, along with the other remotely sensed images, were collected in order to provide spatially extensive information over the primary study areas. This information includes radiant energy, detailed land cover, and biophysical parameter maps such as FPAR and LAI. Although very similar in content to the level-3s Landsat TM products, the level-3a images were created to provide users with a more usable BSQ format and to provide information that permitted direct determination of per-pixel latitude and longitude coordinates. Geographically, the level-3a images cover the BOREAS NSA and SSA. Temporally, the images cover the period of 22-Jun-1984 to 30-Jul-1996. The images are available in binary, image-format 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 Level-3a Landsat TM Imagery: Scaled At-sensor Radiance in BSQ Format 1.2 Data Set Introduction The BOReal Ecosystem-Atmosphere Study (BOREAS) Staff Science effort covered those activities that were BOREAS community-level activities, or required uniform data collection procedures across sites and time. These activities included the acquisition of the relevant satellite data. Data from the Landsat Thematic Mapper (TM) instruments on the Landsat satellites were acquired by the Canada Centre for Remote Sensing (CCRS) and provided for use by BOREAS researchers. BOREAS Information System (BORIS) and CCRS personnel subsequently processed the acquired images to the level-3a products described here. 1.3 Objective/Purpose For BOREAS, the Landsat TM imagery, along with the other remotely sensed images, was collected in order to provide spatially extensive information over the primary study areas. This information includes detailed land cover and biophysical parameter maps such as biomass, Fraction of Photosynthetically Active Radiation (FPAR), and Leaf Area Index (LAI). The BORIS staff processed the seven-band level-3s and level-3p Landsat TM imagery to level-3a products. 1.4 Summary of Parameters Landsat TM level-3a data in BORIS contain the following parameters: Original image header information, image coordinates, gains and offsets for each band for at-sensor radiance derivations, georeferencing information summary, control point coordinates used to georeference the image, and image bands 1 - 7. 1.5 Discussion Use and distribution of the level-3a Landsat TM images are subject to copyright restrictions. CCRS and Radarsat International (RSI) granted permission to BOREAS to place a subset of the Landsat TM images on the BOREAS CD-ROM series. The remaining images may not be available for public access. Please see Sections 15 and 16 for further details. BORIS staff created the Landsat TM level-3a imagery by: 1) Extracting pertinent header information from the level-3s or 3p image product and placing it in the level-3a American Standard Code for Information Interchange (ASCII) header file, 2) Reformatting the level-3s or -3p image data into a band sequential (BSQ) file on disk, 3) Reviewing the image bands for cloud cover and band quality, 4) Selecting control points to calculate an improved set of georeferencing coordinates, 5) Appending the georeferencing information to the level-3a ASCII header file, 6) Writing the ASCII header file and seven image bands to tape. 1.6 Related Data Sets BOREAS Level-3s Landsat TM Imagery: Scaled At-sensor Radiance in LGSOWG Format BOREAS Level-3b Landsat TM Imagery: At-sensor Radiance in BSQ Format BOREAS Level-3p Landsat TM Imagery: Geocoded and Scaled At-sensor Radiance BOREAS Level-3s SPOT Imagery: Scaled At-sensor Radiance in LGSOWG Format 2. Investigator(s) 2.1 Investigator(s) Name and Title BOREAS Staff Science 2.2 Title of Investigation BOREAS Staff Science Satellite Data Acquisition Program 2.3 Contact Information Contact 1 ---------- Jeffrey A. Newcomer NASA/Goddard Sp. Fl. Ctr. Greenbelt, MD (301) 286-785 (301) 286-0239 Jeffrey.Newcomer@gsfc.nasa.gov Contact 2 ---------- Josef Cihlar Canada Centre for Remote Sensing Ottawa, Ontario Canada (613) 947-1265 Josef.Cihlar@geocan.emr.ca 3. Theory of Measurements The Landsat series of satellites began with the Earth Resources Technology Satellite (ERTS) launched in July 1972. This satellite was renamed Landsat 1 in 1975 to reflect its primary use as a land resource observatory. Through its onboard instruments, Landsat monitors Earth's mountain ranges, deserts, forests, and crops by measuring the light waves they reflect. The second generation of Landsat satellites (4 and 5) marked a significant advance in remote sensing through the addition of the more sophisticated TM sensor, with higher spectral and spatial resolution, and faster data processing at a highly automated data processing facility at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) in Greenbelt, MD. For BOREAS, the CCRS receiving station in Prince Albert, Saskatchewan collected the raw data. Processing of the raw data to the imagery used as input for the BOREAS level-3a processing was performed with the Geocoded Image Correction System (GICS; Friedel, 1992) at the CCRS facility in Ottawa As Landsat's instrument mirrors scan Earth's surface, light enters the instrument optics, where it is focused on specially calibrated detector arrays. Onboard electronics encode the detector voltage as binary digits or bits. These digital image data are then relayed back to Earth to be processed into film and Computer-Compatible Tape (CCT) products which are subsequently used for Earth resources analysis. 4. Equipment 4.1 Sensor/Instrument Description The TM sensor system records radiation from seven bands in the electromagnetic spectrum. It has a telescope that directs the incoming radiant flux obtained along a scan line through a scan line collector to the visible and near-infrared focal plane, or to the mid-infrared and thermal-infrared cooled focal plane. The detectors for the visible and near-infrared bands (1 to 4) are four staggered linear arrays, each containing 16 silicon detectors. The two mid-infrared detectors are 16 indium-antimonide cells in a staggered linear array, and the thermal-infrared detector is a four-element array of mercury-cadmium-telluride cells. The spectral regions, band widths, and primary use of each channel are given in the following table: Channel Wavelength (µm) Primary Use ------- --------------- ------------------------------------------ 1 0.451 - 0.521 Coastal water mapping, soil vegetation differentiation, deciduous/coniferous differentiation. 2 0.526 - 0.615 Green reflectance by healthy vegetation. 3 0.622 - 0.699 Chlorophyll absorption for plant species differentiation. 4 0.771 - 0.905 Biomass surveys, water body delineation. 5 1.564 - 1.790 Vegetation moisture measurement, snow and cloud differentiation. 6 10.450 - 12.460 Plant heat stress measurement, other thermal mapping. 7 2.083 - 2.351 Hydrothermal mapping. 4.1.1 Collection Environment The BOREAS Landsat TM level-3s and -3p images were acquired through the CCRS. Radiometric corrections and systematic geometric corrections are applied to produce the images in a path-oriented, systematically corrected (level-3s) or precision-corrected (level-3p) form. A full TM image contains 6920 pixels in each of 5728 lines (see Section 11.2). Before any geometric corrections, the ground resolution is 30 m for bands 1, 2, 3, 4, 5, and 7 and 120 m for band 6 at nadir. The pixel values of the images can range from 0 to 255. This allows each pixel to be stored in a single-byte field. The level-3s and level-3p images were processed through the CCRS GICS. The Landsat satellite orbits Earth at an altitude of 705 km. 4.1.2 Source/Platform Although the majority of the BOREAS Landsat TM imagery was acquired by the instrument onboard Landsat-5, some imagery was obtained with the TM sensor on the Landsat 4 platform. 4.1.3 Source/Platform Mission Objectives The Landsat TM is designed to respond to and measure both reflected and emitted Earth surface radiation to enable the investigation, survey, inventory, and mapping of Earth's natural resources. 4.1.4 Key Variables Reflected radiation, emitted radiation, temperature. 4.1.5 Principles of Operation The TM is a scanning optical sensor operating in the visible and infrared wavelengths. It contains a scan mirror assembly that directly projects the reflected Earth radiation onto detectors arrayed in two focal planes. The TM achieves better image resolution, sharper color separation, and greater in- flight geometric and radiometric accuracy for seven spectral bands simultaneously than the previous generation sensor, the MultiSpectral Scanner (MSS). Data collected by the sensor are beamed back to ground receiving stations for processing. 4.1.6 Sensor/Instrument Measurement Geometry The TM sensor depends on the forward motion of the spacecraft for the along- track scan and uses moving mirror assembly to scan in the cross-track direction (perpendicular to the spacecraft). The instantaneous field-of-view (IFOV) for each detector from bands 1 - 5 and band 7 is equivalent to a 30-m square when projected to the ground at nadir; band 6 (the thermal infrared band) has an IFOV equivalent to a 120-m square at nadir. 4.1.7 Manufacturer of Sensor/Instrument NASA GSFC Greenbelt, MD 20771 Hughes Santa Barbara Remote Sensing (SBRS) Goleta, CA. 4.2 Calibration The internal calibrator, a flex-pivot-mounted shutter assembly, is synchronized with the scan mirror, oscillating at the same 7-Hz frequency. During the turnaround period of the scan mirror, the shutter introduces the calibration source energy and a black direct-current restoration surface into the 100- detector field-of-view (FOV). The calibration signals for bands 1 - 5 and 7 are derived from three regulated tungsten-filament lamps. The calibration source for band 6 is a blackbody with three temperature selections, commanded from the ground. The method for transmitting radiation to the moving calibration shutter allows the tungsten lamps to provide radiation independently and to contribute proportionately to the illumination of all detectors. 4.2.1 Specifications Radiometric Band Sensitivity [NE(dP)]* ---- -------------------- 1 0.8% 2 0.5% 3 0.5% 4 0.5% 5 1.0% 6 0.5 K [NE(dT)] 7 2.4% Ground IFOV 30 m (Bands 1-5, 7) 120 m (Band 6) Avg. altitude 699.6 Km Data rate 85 Mbps Quantization levels 256 Orbit angle 8.15 degrees Orbital nodal period 98.88 minutes Scan width 185 km Scan angle 14.9 degrees Image overlap 7.6% Note: The radiometric sensitivities are the noise-equivalent (NE) reflectance differences for the reflective channels expressed as percentages [NE(dP)] and temperature differences for the thermal-infrared bands [NE(dT)] in Kelvins. 4.2.1.1 Tolerance The TM channels were designed for a NE differential represented by the radiometric sensitivity shown in Section 4.2.1. 4.2.2 Frequency of Calibration The absolute radiometric calibration between bands on the TM sensor is maintained by using internal calibrators located between the telescope and the detectors that are sampled at the end of a scan. 4.2.3 Other Calibration Information Relative within-band radiometric calibration, to reduce "striping," is provided by a scene-based procedure called histogram equalization. Because of the absolute accuracy and relative precision of this calibration scheme, it is assumed that any changes in the optics of the primary telescope or the "effective radiance" from the internal calibrator lamps are insignificant in comparison to the changes in detector sensitivity and electronic gain and bias with time and that the scene-dependent sampling is sufficiently precise for the required within-scan destriping from histogram equalization. Each TM reflective band and the internal calibrator lamps were calibrated prior to launch using lamps in integrating spheres that were in turn calibrated against lamps traceable to calibrated National Bureau of Standards lamps. The absolute radiometric calibration constants in the "short-term" and "long-term" parameter files used for ground processing were modified after launch if there was an inconsistency within or between bands, a change in the inherent dynamic range of the sensors, or a desire to make quantized and calibrated values from one sensor match those from another. 5. Data Acquisition Methods The BOREAS Landsat TM level-3s and -3p images were acquired through the CCRS. Radiometric corrections and systematic or precision geometric corrections are applied to produce the images in a path-oriented form. A full TM image contains 6920 pixels in each of 5728 lines (see Section 11.2). Before any geometric corrections, the ground resolution is 30 m for bands 1-5 and 7 and 120 m for band 6 at nadir. The pixel values of the images can range from 0 to 255. This allows each pixel to be stored in a single-byte field. 6. Observations 6.1 Data Notes None. 6.2 Field Notes Not applicable. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage The BOREAS level-3a Landsat TM images cover the NSA and SSA. The SSA and the NSA are located in the southwest and northeast portions of the overall region. A full TM scene covers approximately 31,000 square kilometers. The North American Datum of 1983 (NAD83) corner coordinates of the SSA are: Latitude Longitude -------- --------- Northwest 54.321 N 106.228 W Northeast 54.225 N 104.237 W Southwest 53.515 N 106.321 W Southeast 53.420 N 104.368 W The NAD83 corner coordinates of the NSA are: Latitude Longitude -------- --------- Northwest 56.249 N 98.825 W Northeast 56.083 N 97.234 W Southwest 55.542 N 99.045 W Southeast 55.379 N 97.489 W 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution New Summary of Documentation (added January 20, 2006): The level-3a image collection contains both level-3s images (systematic spatial corrections applied in resampling) and level-3p images (precision geometric corrections applied in resampling). The difference between the 3s and 3p is that the 3p images have had ground control added. By definition, the 3s images have internal integrity, but require some shift and/or rotation overall to get the ground aligned (as indicated in the original documentation below). Users should carefully check the information in the ASCII header files of the 3a images. If the ASCII header does not show if the source image was '3s' or '3p', the user would need to look at the list of 3s and 3p images by site and date to determine the source of the level-3a image in question. (End of January 20, 2006 addition.) Original Documentation: Before any geometric corrections, the spatial resolution at nadir is 30 m for bands 1-5 and 7 and 120 m for band 6. These values increase with scan angle away from the nadir path. The level-3s and -3p Landsat TM images have had geometric corrections applied so that the spatial resolution for all pixels is 30 m in all bands. The level-3s images have a high level of internal spatial integrity but the actual geographic coordinates contained on the tape can be offset from their actual positions by as much as 20 km. The level-3p images have a high level of internal spatial integrity and have had ground control added to improve the accuracy of the geographic coordinates provided on the tape. In processing the level-3s and -3p images to level-3a products, BORIS has provided equations for calculating the latitude, longitude of any image pixel but has not performed any further geometric corrections or spatial resampling of the image data. The image pixels retain their 30 meter spatial resolution with some leveling of the geographic accuracy of the pixel positions. 7.1.4 Projection The level-3a Landsat TM images are in a Universal Transverse Mercator (UTM) projection based on NAD83. Detailed projection parameter information for the individual images is contained in the ASCII header file. Ground control point locations and least squares equations to calculate the latitude and longitude of any pixel in the image were included in the ASCII header file by BORIS personnel (see Sections 9.2.1 and 9.2.2). 7.1.5 Grid Description The pixel/grid spacing for each pixel in the level-3a Landsat TM images is 30 m in the UTM projection. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage The entire set of BOREAS Landsat TM acquisitions cover 22-Jun-1984 to 30-Jul- 1996. Imagery acquired before the BOREAS field campaigns were conducted is included in the BOREAS archive with imagery collected during the project. Historical Landsat data have been acquired by CCRS routinely since the launch of Landsat 1 and are kept in the CCRS archive. Since the mid-1980s, CCRS has been acquiring and archiving all Landsat data over Canada during the growing season; however during the winter, only requested data were obtained. For BOREAS, this policy was modified to obtain data throughout the year over the BOREAS region. The acquired data are archived by CCRS and can be interrogated to ascertain which scenes were archived and their characteristics. 7.2.2 Temporal Coverage Map The following two lists provide dates for all the level-3a Landsat TM images that are available from BOREAS. Date Study Area ----------- ---------- 11-Jul-1984 SSA 12-Aug-1984 SSA 07-Jul-1985 SSA 11-Aug-1986 SSA 18-Aug-1986 SSA 30-Aug-1987 SSA 20-Jun-1988 SSA 06-Jul-1988 SSA 23-Aug-1988 SSA 02-Jul-1989 SSA 04-Sep-1989 SSA 06-Aug-1990 SSA 06-Aug-1990 SSA 29-Aug-1990 SSA 05-May-1991 SSA 06-Jun-1991 SSA 24-Jul-1991 SSA 09-Aug-1991 SSA 10-Sep-1991 SSA 15-Jun-1992 SSA 18-Jan-1993 SSA 29-Jul-1993 SSA 06-Feb-1994 SSA 20-Apr-1994 SSA 07-Jun-1994 SSA 29-Mar-1995 SSA 03-Jul-1995 SSA 21-Sep-1995 SSA 27-Jan-1996 SSA 02-May-1996 SSA 30-Jul-1996 SSA Date Study Area ----------- ---------- 22-Jun-1984 NSA 19-Aug-1985 NSA 15-Aug-1986 NSA 01-Jun-1988 NSA 20-Aug-1988 NSA 05-Sep-1988 NSA 07-Aug-1989 NSA 25-Jul-1990 NSA 28-Jul-1991 NSA 06-Aug-1992 NSA 02-Aug-1993 NSA 10-Feb-1994 NSA 09-Jun-1994 NSA 13-Feb-1995 NSA 09-Apr-1995 NSA 11-May-1995 NSA 21-Jun-1995 NSA 22-May-1996 NSA 09-Jul-1996 NSA 7.2.3 Temporal Resolution The Landsat TM satellite revisit frequency is 16 days for each path/row; however, in the BOREAS region the overlap between adjacent scene paths is about 50%. 7.3 Data Characteristics (Need to update with CD-ROM Inv file info???) Data characteristics are defined in the companion data definition file (ltm_ii3a.def). 7.3.1 Parameter/Variable The main parameter contained in the image data files is scaled at-sensor radiance. 7.3.2 Variable Description/Definition For the image data files: Scaled at-sensor radiance - The scaled value representing the radiant energy incident on the sensor aperture at the time of data collection in the specific TM wavelength regions. 7.3.3 Unit of Measurement The units for the scaled at-sensor radiance values vary by band. To obtain at- sensor radiance values in Watts/(m2 * sr * µm) use the formula: At-sensor Radiance = Scaled Value * Gain + Offset where the gain and Offset values are contained in the ASCII header file. 7.3.4 Data Source The data contained in the level-3a Landsat TM data files come from various portions of the Landsat satellite, the TM instrument, and the ground processing components. The level-3a Landsat TM images were created by BORIS and CCRS personnel from the level-3s and level-3p images supplied by CCRS. 7.3.5 Data Range The maximum range of scaled at-sensor radiance values in each level-3a Landsat TM image band is limited from 0 (zero) to 255 so that the values can be stored in a single 8-bit (byte) field. 7.4 Sample Data Record Sample data format shown in the companion data definition file (ltm_ii3a.def). 8. Data Organization 8.1 Data Granularity The smallest unit of data tracked by BORIS for the level-3a Landsat TM imagery is a full TM scene. 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 marks. There are no spaces between the fields. Sample data records are shown in the companion data definition file (ltm_ii3a.def). 8.2.1 Uncompressed Data Files A level-3a Landsat TM image produced by BORIS contains eight files, an ASCII header file followed by seven BSQ format image data files. FILE 1 (90 byte ASCII text records) - Description of level-1a product files - Original image header information (tape values are decoded based on the conventions outlined in the User's Guide for Landsat Thematic Mapper Computer-Compatible Tapes, 1985; EOSAT). - Level-3a image coordinates - Calibration information summary (gain and offset per band) - Georeferencing information summary (minimum and maximum latitude/longitude) - Coordinates (pixel, line and longitude, latitude) of the control points used to provide improved georeferencing information. FILES 2 - 8 (A band sequential set of files containing image bands 1 to 7, respectively.) - Each of the 5728 records in each file contains 6920 bytes. - Each of the 6920 byte records contains 6920 8-bit/one-byte pixel values - Each pixel value is in units of digital counts (See section 11.2) - Each image is oriented so that pixel 1, line 1 is in the upper left-hand corner (i.e., northwest) of the screen display. Pixels and lines progress left to right, and top to bottom so that pixel n, line n is in the lower right-hand corner. 8.2.2 Compressed CD-ROM Files On the BOREAS CD-ROMs, file 1 listed above is stored as ASCII text; however, files 2 - 8 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 Not applicable. 9.2 Data Processing Sequence 9.2.1 Processing Steps BORIS staff created the level-3a Landsat TM images by : 1) Inventorying the level-3s or level-3p image by date and time in the online data base, 2) Extracting the seven image bands and pertinent header information to online files from the digital tape, 3) Identifying a set of ground control points, 4) Deriving a second-degree least squares fit to calculate latitude, longitude coordinates from pixel, line values, 5) Writing the files of information to tape. Some cloud cover and image quality assessment information is generated when BORIS staff processed the level-3s images to level-3a products. This information is entered into the BORIS data base but is not included with the images on tape. To obtain this information, see the inventory file included on the CD-ROMs or see Section 15.1. The ground control points for the SSA were selected from 1:50,000-scale National Topographic System (NTS) maps. Different maps will tend to have different levels of accuracy; however, all of the control points that were used for each image have an error of no more than 1.5 pixels (45 meters). The ground control points for the NSA were selected using 13 ground control points located in the field with a global positioning system (GPS). Most of these points are road intersections within the study area that are easily identifiable on the imagery. Because they are of such high precision, 13 points are sufficient to produce an acceptable transformation equation. These GPS coordinates were determined and used in the NSA due to unexplainable discrepancies that resulted when points digitized from the 1:50,000-scale NTS maps over the western portion of the NSA were used. The NSA images from Path/Row 34/21 did not cover the entire study area and only a portion of the 13 GPS points fell within these images. For such cases, another image of the NSA that had been georeferenced using GPS points was used to perform an image-to-image registration. This made it possible to select enough ground control points to produce a good transformation equation. 9.2.2 Processing Changes After processing several Landsat TM images to level-3a products, an error was discovered in the software that caused the level-3a images to contain 6930 pixels in each image line versus the correct 6920 pixels per image line. After the software problem was discovered, the number of pixels in the subsequently processed images was set at 6920. However, the images processed prior to the software change still contain 6930 pixels per line. The extra 10 pixels are located at the end of each line and contain values of zero. 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 Errors could arise in the acquired imagery from location inaccuracy, distortion of lengths, anisomorphism, the instrument's local coherence, and multispectral registrability. Other errors could arise from inherent radiometric imperfections of the sensors. 10.2 Quality Assessment 10.2.1 Data Validation by Source Whatever the processing level, the geometric quality of the image depends on the accuracy of the viewing geometry and the ground control points as required to adjust the viewing model. Spectral errors could arise from image-wide signal-to-noise ratio, saturation, cross-talk, spikes, and response normalization caused by change in gain. 10.2.2 Confidence Level/Accuracy Judgment Assessment of accuracy of the absolute radiometric constants is difficult. The uncertainties in prelaunch and postlaunch updates of the absolute calibration constants are nominally specified to be less than 10%. A root mean square (rms) summing of known errors in the prelaunch calibration suggests that this may be a reasonable estimate of overall uncertainty in the prelaunch calibration. There are also known, but as yet uncorrected, effects associated with temperature-dependence of the TM internal calibrator that may be contributing to apparent discontinuous changes at launch and to the continuous changes of gain while in orbit. Additional uncertainties for exoatmospheric reflectances are probably less than 2% in the visible/near-infrared and less than 5% in the shortwave infrared portion of the spectrum as judged by the current differences in estimates of the solar irradiance. 10.2.3 Measurement Error for Parameters The rms errors for the latitude and longitude least-squares equations are listed in the ASCII header file of each image. The rms error for the selected points was approximately 1.5 pixels (i.e. 45 meters) in the X and Y directions. Therefore, the overall RMS error for each scene should be below this threshold. 10.2.4 Additional Quality Assessments The ability to reproduce coincident TM and ground measurements made for five dates at White Sands, NM, to about 5% for bands 1-4 suggests a potential for monitoring sensor change for the system with time. The images were screened for cloud cover before BORIS processing. Each level-3a image has a minimum of cloud cover over the study areas. 10.2.5 Data Verification by Data Center BORIS checked the image files by visually inspecting them on a display screen and reading the ASCII header files for correctness. 11. Notes 11.1 Limitations of the Data None. 11.2 Known Problems with the Data To date, the following discrepancies/problems have been noted in the data: ? Because of a software error, the first several level-3a Landsat TM images created contain 6930 pixels rather than the correct 6920 pixels. The last 10 pixel values may or may not contain spurious values but should be ignored. ? The ASCII header files for the level-3a products contain gain and offset values for the seven TM bands. The units as given in the header files for the gain and offset values are in error. The proper units for the offset value are watts/(m2 * sr * µm). The proper units for the gain value are watts/(m2 * sr * µm * DN). ? Some header files refer to level-1A rather than level-3A or to L1A rather than L3A because they were created by software prior to BORIS finalization of data categories. ? Level-3a images for the BOREAS NSA (Path/Row 33/21) have ground control points in the ASCII header file numbered 601 through 629. The updated coordinates for these points should be: Point Number Longitude Latitude ---------------------------------- 601 98.82064W 55.88655N 602 98.82180W 55.88114N 603 98.78512W 55.88217N 604 97.91873W 55.81210N 605 97.85946W 55.78508N 606 98.83772W 55.77294N 607 97.83192W 55.76364N 608 97.90285W 55.69227N 609 97.89372W 55.70106N 610 97.86028W 55.73037N 611 97.85835W 55.72543N 612 98.09482W 55.51495N 613 98.05691W 55.53442N 620 98.92360W 55.70465N 621 98.85014W 55.80254N 622 98.42479W 55.91969N 623 98.08685W 55.86547N 624 98.37678W 55.68005N 625 98.45378W 55.84137N 626 98.54973W 55.70142N 627 98.35490W 55.72299N 628 98.36780W 56.13641N 629 98.36713W 56.01236N 11.3 Usage Guidance 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 level-3a Landsat TM images are useful for anyone interested in high spatial resolution imagery over the entire NSA or SSA. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description BORIS staff developed software and command procedures to: 1) Process level-3s and -3p Landsat TM images on tape to level-3a products on disk, 2) Write the level-3a Landsat TM products from disk to tape, 3) Extract header information from level-3a Landsat TM images on tape, 4) Copy level-3a Landsat TM images from tape to disk, 5) Log level-3a Landsat TM image products into the Oracle data base tables. 6) Convert image header coordinates between the geographic systems of (latitude, longitude), UTM (northing, easting), and BOREAS (x,y) grid locations. The software mentioned under items 1 to 5 is written in C and is operational on VAX 6410 and MicroVAX 3100 systems at GSFC. The primary dependencies in the software are the tape input/output (I/O) library and the Oracle data base utility routines. The geographic coordinate conversion utility (BOR_CORD) has been tested and used on Macintosh, IBM PC, VAX, Silicon Graphics, and Sun workstations. Gzip (GNU zip) uses the Lempel-Ziv algorithm (Welch, 1994) used in the zip and PKZIP commands. 14.2 Software Access All of the described software is available upon request. BORIS staff would appreciate knowing of any problems discovered with the software, but cannot promise to fix them. 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 Ms. Beth Nelson NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) beth@ltpmail.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 level-3a Landsat TM image data are available from the Earth Observing System Data and Information System (EOS-DIS) 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 Although the BOREAS level-3a Landsat TM images are being held in a public archive, copyright restrictions limit the distribution and use of the data. The BOREAS CD-ROM series is publicly available and the Landsat TM images on the CD- ROMs are available for unrestricted use. However, the other images in the collection are only available to official BOREAS project personnel. Please contact the ORNL DAAC User Services office to get the most recent information. 16. Output Products and Availability 16.1 Tape Products The level-3a Landsat TM data can be made available on 8-mm, Digital Archive Tape (DAT), or 9-track tapes at 6250 or 1600 Bytes per Inch (BPI). Although the BOREAS level-3a Landsat TM images are being held in a public archive, copyright restrictions limit the distribution and use of the data. The BOREAS CD-ROM series is publicly available and the Landsat TM images on the CD- ROMs are available for unrestricted use. However, the other images in the collection are only available to official BOREAS project personnel. Please contact the ORNL DAAC User Services office (see Section 15.4) to get the most recent information. 16.2 Film Products None. 16.3 Other Products Although the entire level-3a image inventory is contained on the BOREAS CD-ROM set, only some of the images are included there. See section 15 for information about how to obtain images not on the CD-ROMs. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Multispectral Scanner System for ERTS. 1972. HS324-5214. Hughes Aircraft Corporation. Santa Barbara, CA. User's Guide for Landsat Thematic Mapper Computer-Compatible Tapes. 1985. Earth Observation Satellite Company. Lanham, MD. 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 Byrne, G.F., P.F. Crapper, and K.K. Mayo. 1980. Monitoring land-cover change by principal component analysis of multitemporal Landsat data. Remote Sens. Environ. 10:175-184. Chavez, P.C., S.C. Guptill, and J.A. Bowell. 1984. Image processing techniques for Thematic Mapper data. Technical Papers. 50th Annual Meeting of the Amer. Soc. of Photogr. 2:728-743. Crist, E.P. and R.C. Cicone. 1984. Application of the Tasseled Cap concept to simulated Thematic Mapper data. Photogr. Engr. & Rem. Sens.50:343-352. Engel, J.L. and O. Weinstein. 1983. The Thematic Mapper: An Overview. IEEE Transactions on Geoscience and Remote Sensing. GE-21:258-265. Friedel, J. 1992. System description of the Geocoded Image Correction System. Report GC-MA-50-3915, MacDonald Detwiller and Associates, Richmond, B.C. Holmes, R.A. 1984. Advanced sensor systems: Thematic Mapper and beyond. Remote Sens. Environ. 15:213-221. Kanemasu, E.T., J.L. Heilman, J.O. Bagley, and W.L. Powers. 1977. Using Landsat data to estimate evapotranspiration of winter wheat. Environmental Management. 1:515-520. Lulla, K. 1983. The Landsat satellites and selected aspects of Physical Geography. Progress in Phy. Geogr. 7:1-45. Malila, W.A. 1985. Comparison of the Information Contents of Landsat TM and MSS Data. Photogrammetric Engineering and Remote Sensing. 51:1449-1457. Pollock, R.B. and E.T. Kanemasu. 1979. Estimating leaf-area index of wheat with Landsat data. Remote Sens. Environ. 8:307-312. Robinov, C.J. 1982. Computation with physical values from Landsat digital data. Photogr. Engr. & Rem. Sens. 48:781-784. Salomonson, V.V. 1984. Landsat 4 and 5 status and results from Thematic Mapper data analysis. Proceedings. Machine Processing of Remotely Sensed Data Symposium. Lab. for the Applications of Remote Sensing. West Lafayette, IN. p 13-18. Satterwhite, M.B. 1984. Discriminating vegetation and soils using Landsat MSS and Thematic Mapper bands and band ratios. Technical Papers. 50th Annual Meeting of the Amer. Soc. of Photogr. 2:479-485. 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. and F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue (in press). Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall, and 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. Singn, A.N., and R.S. Dwived, 1986. The Utility of LANDSAT Imagery as an Integral Part of the Data Base for Small Scale Soil Mapping. Int. J. Remote Sensing. 7:1099-1108. Taranik, J.V. 1978. Characteristics of the Landsat Multispectral Data System. U.S. Dept. of the Interior. Open File Report 78-187. Sioux Falls, SD. Thompson, D.R. and O.A. Wehmanen. 1980. Using Landsat digital data to detect moisture stress in corn-soybean growing region. Photogr. Engr. & Rem. Sens. 46:1082-1089. Williams, D.L., J.R. Irons, B.L. Markham, R.F. Nelson, D.L. Toll, R.S.Latty, and M.L. Stauffer. 1984. A statistical evaluation of the advantages of Landsat Thematic Mapper data in comparison to Multi-spectral Scanner data. IEEE Transactions on Geoscience and Remote Sensing. GE-22. 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 - Byte per inch BSQ - Band Sequential CCRS - Canada for Remote Sensing CCT - Computer Compatible Tape CD-ROM - Compact Disk-Read-Only Memory DAAC - Distributed Active Archive Center DAT - Digital Archive Tape DN - Digital Number EOS - Earth Observing System EOSDIS - EOS Data and Information System ERTS - Earth Resources Technology Satellite FOLD - Federally Owned Landsat Database FOV - Field of View FPAR - Fraction of Photosynthetically Active Radiation GICS - Geocoded Image Correction System GPS - Global Positioning System GSFC - Goddard Space Flight Center IFOV - Instantaneous Field-of-View I/O - Input/Output LAI - Leaf Area Index LGSOWG - Landsat Ground Station Operations Working Group LTWG - LGSOWG Technical Working Group MSS - Multispectral Scanner NAD27 - North American Datum of 1927 NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NE - Noise Equivalent NSA - Northern Study Area NTS - National Topographic System ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park rms - root-mean-square SBRC - Santa Barbara Research Center SSA - Southern Study Area TIPS - Thematic Mapper Image Processing System TM - Thematic Mapper URL - Uniform Resource Locator UTM - Universal Transverse Mercator WWW - World Wide Web 20. Document Information 20.1 Document Revision Dates Written: 18-Oct-1994 Last Updated: 20-Mar-1998 20.2 Document Review Dates BORIS Review: 20-Feb-1998 Science Review: 27-Feb-1998 20.3 Document ID 20.4 Citation The Landsat TM level-3a images resulted from a joint development and processing effort between BOReal Ecosystem-Atmosphere Study (BOREAS) staff at the Canada Centre for Remote Sensing (CCRS) and the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC). The original level-3s and -3p data were acquired by CCRS and processed by RADARSAT International under an agreement with CCRS. The respective contributions of the above individuals and agencies to completing this data set are greatly appreciated. 20.5 Document Curator 20.6 Document URL Keywords LANDSAT LANDSAT THEMATIC MAPPER EMITTED RADIATION REFLECTED RADIATION LANDSAT_TM_L3A.doc 04/17/98