BOREAS RSS-19 1994 CASI At-sensor Radiance and Reflectance Images Summary The RSS-19 team collected CASI images from the Chieftain Navaho aircraft in order to observe the seasonal change in the radiometric reflectance properties of the boreal forest landscape. CASI was deployed as a site-specific optical sensor during BOREAS field campaigns. Image data were collected with CASI on 36 days during five field campaigns between February and September 1994, primarily at flux tower sites located at study sites near Thompson, Manitoba, and Prince Albert, Saskatchewan. A subset of the data is available from the BOREAS Information System (BORIS). Radiance and reflectance images have been provided. This subset corresponds to the data for CASI Mission 3 described in Section 4.1.3. A variety of CASI data collection strategies were used to meet the following scientific objectives: 1) canopy bidirectional reflectance, 2) canopy biochemistry, 3) spatial variability, and 4) estimates of up and downwelling PAR and spectral albedo, as well as changes along transects across lakes and transects NSA and SSA. The images are stored as binary image files. A subset of the 1994 CASI acquisitions have been compressed and included on the BOREAS CD-ROM set. This subset includes 3 images for the NSA-OBS site on 06- Jun-94, 08-Aug-94, and 06-Sep-94; one image for the SSA-OBS site on 24-Jul-94; and one image for the NSA-Fen site on 08-Aug-94. The CASI imagery on the BOREAS CD-ROMs have been compressed using the Gzip program. See section 8.2 for details. The rest of the 1994 BOREAS CASI archive are not contained on the BOREAS CD-ROM set. Inventory listing files are supplied on the CD-ROM to inform users of the data that were collected. See Sections 15 and 16 for information about how to acquire the data. Also see Section 11.2 for notes about anomalies found with a few of the image sizes. 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 RSS-19 1994 CASI At-sensor Radiance and Reflectance Images 1.2 Data Set Introduction The Compact Airborne Spectrographic Imager (CASI) was deployed as a site- specific optical sensor as part of the Boreal Ecosystem-Atmosphere Study (BOREAS). The overall objective of the CASI deployment was to observe the seasonal change in the radiometric reflectance properties of the boreal forest landscape. A subset of the data is available from the BOREAS Information System (BORIS). This BORIS subset contains one spatial image per tower site per Intensive Field Campaign (IFC) per study area. All the data have been collected at approximately 1800-m above ground level (AGL). The images have been geocorrected and resampled to 2-meter square pixels using onboard Global Positioning System (GPS) data. Radiance and at-ground modeled reflectance images have been provided. This subset of CASI-processed data corresponds to the data for CASI Mission 3 described in Section 4.1.3. 1.3 Objective/Purpose CASI was used to generate reflectance images from radiance images collected during the February to September 1994 time period. These images will be used along with Airborne Visible and Infrared Imaging Spectrometer (AVIRIS), Special Sensor Microwave/Imager (SSM/I), Landsat Thematic Mapper (TM), Geostationary Operational Environmental Satellite (GOES), Advanced Very High Resolution Radiometer (AVHRR), and Satellite Pour l'Observation de la Terre (SPOT) images to determine: (i) image-based methods to obtain surface reflectances from airborne optical imagery; (ii) the effect of temporal/spatial variability of site albedo of the boreal forest; (iii) the utility of the areal and spectral properties of beaver ponds for spatial scaling of measured trace gas emissions; (iv) the role of seasonal changes in understory components to changes in reflectance of open boreal canopies; and (v) the seasonal/temporal variation in closed canopy reflectance as a function of canopy architecture, species composition, canopy biophysical parameters of Leaf Area Index (LAI) and biomass, and phenologic development and chemistry of foliar components. 1.4 Summary of Parameters Radiance and at-ground modeled reflectance images. 1.5 Discussion Image data were collected with CASI on 36 days during five IFCs between February and September 1994. Data were collected primarily at flux tower sites located within the Northern Study Area (NSA) near Thompson, Manitoba and the Southern Study Area (SSA) near Prince Albert, Saskatchewan. In order to aid BOREAS team collaborators in locating additional information pertaining to the Canadian optical remote sensing component of the BOREAS project, a BOREAS Global Hypermedia Research Information System (B/GHRIS) is under construction at York University/Centre for Research in the Earth and Space Technology (CRESTech) (Dunlop and Shepherd, 1995). It uses World Wide Web (WWW) client/server software to allow collaborators to search, browse, and retrieve distributed network-accessible documents. Radiometrically and/or spatially subsampled CASI images are provided for browsing directly at the collaborator's site. Other information describing the sensors, sensor deployment, flight lines, calibration, field campaigns, field data, calendar of events, bibliography, and more are all now available online (http://www.eol.crestech.ca/), providing up-to-date status on CASI data processing and data delivery to BORIS and collaborators. 1.6 Related Data Sets BOREAS RSS-02 Level-1b ASAS Imagery: At-sensor Radiance in BSQ Format BOREAS RSS-18 Level-1b AVIRIS Imagery: At-sensor Radiance in BIL Format BOREAS RSS-19 1996 CASI At-sensor Radiance and Reflectance Images BOREAS Level-2 MAS Surface Reflectance and Temperature Images in BSQ Format BOREAS Level-2 NS001 TMS Images: Reflectance and Temperatures in BSQ Format 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. John R. Miller 2.2 Title of Investigation Variation in Radiometric Properties of the Boreal Forest Landscape as a Function of the Ecosystem Dynamics 2.3 Contact Information Contact 1 --------- Jim R. Freemantle Project Scientist Earth Observations Laboratory Center for Research in Earth and Space Technology North York, Ontario Canada (416) 665-5405 (416) 665-2032 (fax) freemant@eol.crestech.ca Contact 2 --------- Dr. John R. Miller Dept. of Physics and Astronomy York University North York, Ontario Canada (416) 736-2100 x 77729 (416) 736-5626 (fax) miller@eol.crestech.ca Contact 3 ------------- Jaime Nickeson Raytheon ITSS NASA GSFC Greenbelt, MD (301) 286-3373 (301) 286-0239 (fax) Jaime.Nickeson@gsfc.nasa.gov 3. Theory of Measurements A more complete discussion of the theory behind the measurements can be found in Miller et al., 1995. A short summary is presented here. The CASI sensor is an airborne imaging spectrometer sensor with flexible operational characteristics. It was determined that four CASI operating modes and 12 specific mission plans were needed to best meet the scientific objectives of the Remote Sensing Science (RSS)-19 group and its collaborators. The operating modes were: (i) Full Spectral Mode (39L_288C): 39 noncontiguous cross-track pixels (looks), spacing 12 pixels, 288 spectral bands, 2.5-nm resolution (ii) Hyperspectral Mode (101L_72C): 101 contiguous cross-track pixels, 72 spectral bands, 7.8-nm resolution (iii) Hyperspectral Mode (404L_72C): 404 contiguous cross-track pixels, 72 spectral bands, 7.8-nm resolution (iv) Spatial Mode: (512L_#C): 512 contiguous cross-track pixels, 3 band sets as described in the following table: Spatial band set name: CASI-BOREAS CASI-CIR High Resolution CASI-Winter (FFC-W) (FFCT15) (CIR) (FFCW7) Ch. Center HalfBndwidth Ch. Center HalfBndwidth Ch. Center HalfBndwidth ------------------------- ------------------------- ------------------------ 1 409.66 5.90 2 443.17 5.91 3 490.89 5.93 1 485.62 36.01 4 520.14 6.82 2 543.23 22.82 5 565.44 5.95 1 565.44 5.95 3 583.26 18.43 6 619.83 5.07 4 635.92 15.81 7 665.47 5.98 2 665.47 5.98 5 666.37 15.84 8 682.51 3.30 9 709.47 3.30 10 741.90 3.30 11 750.02 6.01 3 750.02 6.01 12 768.99 5.12 13 799.76 5.13 6 798.87 22.34 14 880.71 7.89 7 865.23 25.20 15 905.39 8.82 ------------------------------------------------------------------------------- Table 1: CASI Spatial Bandsets Used during BOREAS 94, units are nm. Note that only CASI data collected in Spatial Mode were submitted as part of the BOREAS archive. Those interested in data gathered in other CASI modes specified above and in Section 4.1.3 should contact the Principal Investigator (PI), contact 1 in Section 2.3, or see the Web page address given in Section 1.5. 4. Equipment 4.1 Sensor/Instrument Description The CASI instrument (Itres, 1992) is composed of nine components weighing a total of 55 kg. The components of the sensor system augmented at CRESTech and as deployed at BOREAS consist of: • Instrument Control Unit • Keyboard Unit • Power Supply Unit • Sensor Head Unit • Video Display Unit • 60-Hz Inverter • Downwelling Irradiance Probe • Upwelling Irradiance Probe • Fiber-Optic Switch Box The Charge-Coupled Device (CCD) sensor is a P86520 series frame transfer device (EEV, Inc., Chelmsford, UK). The array is thermoelectrically cooled to reduce dark current. The imaging area of the array is 512 x 288 pixels with each element measuring 15.5 by 22 µm. The instrument can be run on 110 volts at 2.4 amps. For Direct Current (DC) operation, the inverter supplied with the system requires 28 VDC, 13 amps peak. For the optional gyro, another inverter supplies 400-Hz Alternating Current (AC). The 512 image pixels across the 35-degree field of view (FOV) give a 1.23-meter ground resolution (cross-track) per 1-km altitude AGL. The along-track ground resolution is approximately the product of the integration time and the aircraft speed. The required integration time is directly proportional to the number of spectral bands and the number of spatial views. The spectral range of the CASI instrument used in the BOREAS project was 391 to 916 nm. The spectral resolution was 2.5-nm full width, half maximum (FWHM), with 288 pixels sampled at 1.8-nm intervals. The 2.5-nm FWHM is nominal; the bandwidth changes with wavelength (Achal, 1991). Measurements of the bandwidth of the CASI used for BOREAS have been taken at CRESTech and are being analyzed. Channel-to- wavelength registration is subject to slight deviations at large view angles because of spectral sag (Harron et al., 1992; Freemantle et al., 1991). The CCD sensor is read out and digitized to 12 bits by a programmable electronics system that is controlled by an internal single-board computer. Data are recorded on a built-in digital recorder (Exabyte) that uses 8-mm cassette tapes as the recording medium. The frame rate is configuration-dependent up to a maximum of 85 lines/sec. The CCD can be read out to select and sum rows, to create high spatial resolution bands, or sample columns from the array, to create high spectral resolution views. The CCD sampling configuration can be easily changed by the CASI instrument operator and often several different sampling configurations are used during a data collection experiment. Additional information about the CASI sensor can be obtained from Itres instruments (http://www.itres.com). 4.1.1 Collection Environment Data were collected at various altitudes from 150-m AGL to 2600-m AGL. The CASI sensor can be tilted forward or aft of the aircraft. Data have been collected at a number of different sensor view angles for investigations of Bidirectional Reflectance Distribution Function (BRDF) effects. Several CCD sampling configurations were used to collect imagery. Imagery for BOREAS has been collected at the tower flux sites and auxiliary sites, and along the transect between the NSA and SSA. 4.1.2 Source/Platform The CASI sensor was flown aboard the Chieftain Navaho aircraft operated by the Ontario Provincial Remote Sensing Office (PRSO). Data were collected at various altitudes from 150-m AGL to 2600-m AGL. 4.1.3 Mission Objectives The complete set of mission objectives for the RSS-19 study is listed below. Note that only Mission 3 data have been submitted as part of the BOREAS archive data set. Contact the PI or see the CASI Web page for availability of other mission data. CASI Missions: Mission 1: Flux Tower Sites: Multiview Canopy Bi-directional Reflectance Data CASI Operating Modes: Spatial Mode or Hyperspectral Mode CASI Mission Flights: 57 Pixel Size: 2 x 4 m or 2 x 11 m Swath Width: 1000 m CASI imagery was collected over each site at 1675-m altitude AGL for at least two different azimuth angles with respect to the solar plane and at multiple sensor view angles in order to characterize the seasonal changes in the bidirectional reflectance properties of each flux-tower forest stand. Wherever possible, CASI data were collected coincident with data from the Advanced Solid- state Array Spectroradiometer (ASAS) sensor National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) onboard the C-130 aircraft, and over the Portable Apparatus for Rapid Acquisition of Bidirectional Observations of Land and Atmosphere (PARABOLA) field instrument NASA GSFC, both of which are specifically designed to measure surface bidirectional reflectance properties. For virtually all missions, CASI imagery was collected in the solar plane with sensor view angles at 45, 30, 15, 0, -15, and -30 degrees and at a 45-degree angle oblique to the solar plane with view angles at +45, 0, and -30 degrees. Note that these angles are with respect to the airplane axis, and will vary somewhat due to aircraft attitude. The operational goal established was to obtain overlapping multiview images of at least 200 m in the along track direction, centered on the site flux tower. With CASI view angle changes made manually by the sensor operator, this objective demanded synchronized tower sighting (aircrew) and sensor tilting at intervals (operator) during a pass over each flux tower to achieve three overlapping image views per pass. Thus three passes of each flux tower were required for the BRDF sampling described above. Initial comparisons between the Li and Strahler (1992) model and the CASI BRDF data for the SSA Old Jack Pine (OJP) site in the winter campaign are reported by Soffer et al. (1995), with further analysis underway. Mission 2: Flux Tower Sites: Canopy Biochemistry CASI Operating Mode: Full Spectral Mode CASI Mission Flights: 37 Pixel Size: 2 x 11 m Swath Width: 1000 m Reflectance signatures of forest canopies at high spectral resolution in the CASI visible/near-infrared (VIS/NIR) spectral region can be related to canopy chlorophyll and nitrogen levels (e.g., Matson et al., 1994). CASI spectral mode imagery was collected for this purpose over each tower site in the solar plane on two flights: (i) nadir viewing at 1675-m AGL to obtain a spectral signature of the canopy as for a satellite sensor, and (ii) viewing in the antisolar direction at 45-degree view zenith and 1150-m AGL to minimize spectral effects of the canopy understory; the change in altitude is required to maintain constant pixel size in the two cases. Mission 3: Flux Tower Sites: Site Mapping CASI Operating Mode: Spatial Mode, 15 channels CASI Mission Flights: 48 Pixel Size: 2 x 4 m and (0.7 x 3 m *) Swath Width: 1000 and (370 m *) CASI imagery is expected to be the highest spatial resolution optical data available in the BOREAS data base and therefore has been of particular interest to a number of collaborators for quantifying the spatial heterogeneity of site- specific field measurements of parameters such as LAI, biomass, and canopy cover. This is of particular importance to the scaling up of boreal forest ecosystem state and process parameters using remote sensing data. For these purposes, CASI multiband (15 channels) imagery has been collected at two altitudes (600 and 1675-m AGL) to cover the 1-km target area around each flux tower site at two spatial resolutions. Note*: The lower altitude, higher resolution data was not submitted as a part of this BOREAS archive data set. Mission 4: Flux Tower Sites: Stem Mapping CASI Operating Mode: Spatial Mode, three channels (CIR spatial mode) CASI Mission Flights: 28 Pixel size: 0.2 x 1 m Swath Width: 90 m For detailed studies a sub-meter spatial resolution is required: for canopy modeling, such detail is required to resolve individual trees and to identify shadow and sunlit canopy and sub-canopy components, as well as for community mapping of fen vegetation. This objective is beyond the CASI sensor's normal performance, but by limiting the number of spectral bands to three and flying between 150-m and 300-m AGL, this spatial resolution is approached. For the canopy modeling studies, such CASI data were collected along a specific ground transect line established by J. Chen (RSS-07) at each tower site. For the fen vegetation community studies, a few survey lines were collected for mosaicking into large high-resolution images. Mission 5: Flux Tower Sites : PAR and Albedo CASI Operating Mode: Hyperspectral Mode 404L_72C CASI Mission Flights: 53 Pixel Size: 0.2 x 10 m Swath Width: 90 m With the CASI sensor modifications permitting collection of up and downwelling spectral irradiance data simultaneously with the normal imagery, flights at low altitude (150-m AGL) generate a measure of the spatial variability of the spectral albedo as well as the up and downwelling Photosynthetically Active Radiation (PAR). These data will also be used to measure the ratio of radiance in the GOES visible band to the total albedo for each canopy type, thereby enabling E. Smith (RSS-14) to generate seasonal albedo maps for the entire BOREAS region from GOES imagery. These same data are of interest to J. Cihlar (Terrestrial Ecology (TE)-16) and coworkers to validate models for satellite estimates of canopy absorbed PAR. Mission 6: Lake Image Transects CASI Operating Modes: Hyperspectral Mode 404L_72C CASI Mission Flights: 10 Pixel Size: 2 x 11 m Swath Width: 800 m For IFCs 1 and 2, CASI imaging spectrometer data were collected on transects across Waskesiu and Candle Lakes at the SSA. This data collection was simultaneous with in situ water sampling and optical measurements of the above- surface and below-surface, up and downwelling spectral radiance and irradiances by R. Bukata and J. Jerome (TE-15). These combined data will be used for critical evaluation of models and algorithms to derive water constituent information such as concentrations of chlorophyll, dissolved organic content, and total suspended solids for Case 2 waters. This algorithm validation/evaluation activity is directly applicable to future satellite sensors such as the Medium Resolution Imaging Spectrometer (MERIS) and Sea- viewing Wide Field-of-view Sensor (SeaWiFS). During IFC-1, data from NASA's Airborne Ocean Color Imager (AOCI) (a prototype SeaWiFS satellite sensor) were flown simultaneously with CASI, offering the potential for evaluation of the critically important atmospheric correction algorithms for interpretation of water imagery. Mission 7: Beaver Ponds CASI Operating Mode: Spatial Mode, 15 channels CASI Mission Flights: 9 Pixel Size: 0.7 x 3 m Swath Width: 370 m CASI multispectral imagery was collected, normally at 600-m AGL, at three NSA beaver pond sequences that were undergoing detailed field examination by N. Roulet (Trace Gas Biogeochemistry (TGB)-04). Differences and changes in dissolved organic carbon of these water bodies are expected to be manifested in spectral reflectance changes, particularly at blue wavelengths. The goal is to use CASI to determine whether there is sufficient distinction in the spatial/spectral domain to resolve beaver ponds and permit quantification of the areal extent of beaver ponds in the boreal landscape. Mission 8: Auxiliary Sites CASI Operating Mode: Spatial Mode, 15 channels CASI Mission Flights: 135 Pixel Size: 2 x 4 m Swath Width: 1000 m CASI multispectral imagery (15 channels) was collected when possible (within aircraft and campaign time constraints), on a second priority basis, over some of the more than 65 BOREAS auxiliary sites identified to test and validate models. Mission 9: Transects between SSA and NSA CASI Operating Modes: Spatial Mode (15 channels) or Hyperspectral Mode CASI Mission Flights: 5 Pixel Size: 3 x 5 m or 3 x 12 m Swath Width: 1500 or 1160 m CASI imagery was collected at least once in each of the Focused Field Campaign - Thaw (FFC-T), IFC-1, IFC-2, and IFC-3 campaigns at 2450-m AGL along the regional transect bridging the NSA and SSA. These data will be used to generate, where possible, transect profiles of surface parameters (and variability with 1-km- wide track swath) for comparison with similar parameters inferred from satellite imagery by collaborators. Mission 10: Snow Course Lines CASI Operating Mode: Spatial Mode, 7 channels CASI Mission Flights: 37 Pixel Size: 2 x 4 m Swath Width: 1000 m CASI imagery was collected at 1675-m AGL along snow course lines that: (i) were ground sampled by B. Goodison (Hydrology (HYD)-04) for snow physical properties and (ii) were the subject of airborne profile sampling of gamma radiation (HYD- 06) and microwave emissions (HYD-02). The optical CASI data will be used to map snow extent and snow depth in open areas. Mission 11: Agriculture Line CASI Operating Mode: Spatial Mode, 15 channels CASI Mission Flights: 4 Pixel Size: 2 x 4 m Swath Width: 1000 m A transect was selected to characterize the agriculture to boreal forest transition at the SSA. This transect was subjected to intensive sampling by flux aircraft (Airborne Fluxes and Meteorology (AFM)-04) and was imaged with the CASI sensor in order to characterize the trends and variability of the vegetation growth along it. Mission 12: Atmospheric Correction CASI Operating Modes: Spatial Mode, 15 channels; 2 Hyperspectral Modes CASI Mission Flights: 40 Pixel Size: various Swath Width: various A variety of multi-altitude, multi-view CASI flights were conducted, supported by surface-based and aircraft optical depth measurements, in order to evaluate methodologies being used to correct optical airborne and satellite data from at- sensor radiance to surface reflectance. A system for acquiring downwelling radiance and total downwelling irradiance was installed alongside CASI on the aircraft to collect needed supplementary atmospheric optical data. These data were collected over (i) the RSS-19 site at the Prince Albert airport, which included canvas standard reflectance panels and an asphalt apron (for which BRDF characterization was conducted by RSS-19 personnel from Centre d'Applications et de Recherches en Teledetection (CARTEL), led by University of Sherbrooke researchers Dr. N.T. O'Neill and Dr. A. Royer); (ii) a tilled and rolled farmer's field used as an AVIRIS (NASA Jet Propulsion Laboratory (JPL)) calibration site (RSS-18); and (iii) a transect that included a new asphalt road, black spruce stands, and lakes (characterized by CARTEL researchers). 4.1.4 Key Variables The CASI sensor directly measures the following quantities; target at-sensor radiance, and downwelling and upwelling irradiance. The irradiance measurements are experimental and are undergoing intensive investigation at CRESTech. These data may not be available for the 1994 BOREAS campaign. 4.1.5 Principles of Operation CASI is a VIS/NIR push-broom imaging spectrograph with a reflection grating and a 2-D CCD solid-state array detector. The instrument operates by looking down in a fixed direction and imaging successive lines of the scene from the platform, building a 2-D image as the platform moves forward (Anger et al., 1990). The CASI instrument has been used in a variety of applications from forest cover mapping to pollution monitoring. 4.1.6 Instrument Measurement Geometry Data were collected at various altitudes from 160-m AGL to 2600-m AGL. The CASI sensor can be tilted forward or aft of the aircraft. Data have been collected at a number of different sensor view angles from -45 to +45 degrees for investigations of BRDF effects. 4.1.7 Manufacturer of Instrument Itres Instruments #155, 2635-37th Avenue N.E. Calgary, Alberta, Canada T1Y 5Z6 (403) 250-9944 (403) 250-9916 (fax) 4.2 Calibration The CASI instrument has been calibrated in the Instrument Services Laboratory at CRESTech. A two-stage approach was used to determine the absolute and relative radiometric response of the instrument. An integrating sphere (Thomas et al., 1991) was used to determine the relative response of the CCD array. For an absolute radiometric calibration, a calibrated Spectralon reflectance panel (Labsphere) and a National Research Council (NRC) traceable calibrated lamp were used. Dark current data were taken to remove any instrument-related anomalies. A more detailed description of the calibration can be found in Harron et al. (1995), Babey and Soffer (1992), and Gray et al. (1997). Rare gas lamps were used as narrow line sources to determine the spectral calibration of the instrument. A narrow bandwidth tiltable filter was used to determine the spectral bandpass of the instrument at selected wavelengths. The transmission of the window used during data collection was characterized at a range of view angles to enable correction of CASI data to at-aircraft radiance. Radiance imagery is converted to at-ground measured reflectance using a variant of the 5S radiative transfer code, referred to as CAM5S (O'Neill et al., 1996). This procedure allows correction of the imagery at aircraft altitudes for each pixel in the scene. This is a collaborative project between the University of Sherbrooke, the Canadian Space Agency, CRESTech, and the Canadian Centre for Remote Sensing (CCRS). Further details can be found in Gray et al., 1997. For an estimate of the absolute calibration error, we used measurements of the NASA field calibration sphere. In June of 1994, the CASI collected imagery of the sphere. Analysis of these images shows that between 500 and 800 nm, the difference between the CASI measured value and the NASA Calibration Sphere expected value (Schafer, 1994) was less than 5%. Only one set of radiance scale factors (or calibration coefficients) was used throughout the 1994 BOREAS field season. However, the calibration exercise was repeated several times during 1994. If we assume that the calibration setup did not change, analysis of this data reveals that the CASI response characteristics did not change by more than 3% during the time of the 1994 BOREAS project. We expect that the result for BOREAS 1996 imagery would be the same as 1994. 4.2.1 Specifications (As given by instrument manufacturer Itres) Field of View: 35.4 degrees across-track, 0.076 degrees along-track Spectral Range: 545-nm spectral window between about 400 and 1000 nm Spectral Samples: 288 max at 1.9-nm intervals Spectral Resolution: 2.2-nm FWHM @ 650 nm Aperture: f/2.8 to f/11.0 Dynamic Range: 12 bits Noise Floor: 1.4 DN Signal-to-Noise Ratio: 420:1 peak Data Throughput: 420 Kb or greater Operating Modes: Spatial Mode: 512 spatial pixels, 19 spectral band maximum Spectral Mode: 288 spectral pixels, 101 adjacent looks 48 spectral pixels, 511 adjacent looks Full Frame Mode: 288 spectral pixels, 512 spatial pixels Environmental Operating Conditions: Temperature: 5 to 40 °C operating, -20 to +60 °C storage Relative Humidity: 20% to 80% non-condensing, 10% to 90% non-condensing storage Maximum Altitude: 3048 m above sea level (unpressurized) 4.2.1.1 Tolerance None given. 4.2.2 Frequency of Calibration Calibration data were collected for CASI before each IFC. While only one set of calibration data has been used to calculate the radiance scale factors, the other calibration data allow tracking of any changes in the instrument response. 4.2.3 Other Calibration Information The CASI sensor viewed the NASA GSFC large integrating sphere during IFC-1. An interagency calibration experiment was conducted at the Instrument Services Laboratory involving CRESTech, NASA GSFC, and CCRS (Harron et al., 1995), that compared the calibration radiance sources used at these institutions. See Harron et al. (1995) for details. 5. Data Acquisition Methods The CASI sensor is an airborne imaging spectrometer sensor with flexible operational characteristics. The spectral range of the CASI instrument used in the BOREAS project was 391 to 916 nm. The CASI sensor was flown aboard the Chieftain Navaho aircraft operated by the Ontario PRSO. Data were collected at various altitudes from 150-m AGL to 2600-m AGL. The CASI sensor can be tilted forward or aft of the aircraft. Data have been collected at a number of different sensor pitch angles for investigations of BDRF effects. Several CCD sampling configurations were used to collect imagery. The CCD sensor is read out and digitized to 12 bits by a programmable electronics system that is controlled by an internal single-board computer. Data are recorded on a built-in digital recorder (Exabyte) that uses 8-mm videocassettes as the recording medium. The frame rate is configuration- dependent up to a maximum of 85 lines/sec. The CCD can be read out to select and sum rows, to create high spatial resolution bands, or sample columns from the array, to create high spectral resolution views. The CCD sampling configuration can be easily changed by the CASI instrument operator, and often several different sampling configurations are used during a data collection experiment. 6. Observations 6.1 Data Notes None given. 6.2 Field Notes CASI operator comments are recorded in flight logs stored as part of the CRESTech BOREAS CASI image database. Examination of the incident light probe (ILP) data suggests that the atmospheric conditions varied by more than 10% but not more than 20% for the images, which are part of the current BORIS submission. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage Imagery was collected at the NSA and SSA tower flux sites and auxiliary sites, and along the transect between the NSA and SSA. The imagery swath width depends on acquisition aircraft altitude but is typically between 1 and 2 km. Imagery swath length depends on duration of data acquisition. Over the tower sites, images are usually less than 10 km long. Transect images, on the other hand, can be many tens of kilometers long. 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 The 512 image pixels across the FOV of 35 degrees give a 1.23-meter ground resolution (cross-track) per 1-km AGL altitude. The along-track ground resolution is approximately the product of the integration time and the aircraft speed. CASI image pixels are not generally square. 7.1.4 Projection The imagery has been geocorrected and resampled to a Universal Transverse Mercator (UTM) NAD83-grid using GPS and attitude data. This geocorrection was performed to reorient the imagery to a map grid to aid in the interpretation of the imagery. The absolute positional accuracy of the imagery should not be considered high because of the limitations of the GPS and attitude data, but the relative positional accuracy is good. 7.1.5 Grid Description The CASI data supplied to BORIS have been geocorrected using the onboard GPS and attitude data. The imagery has been resampled to UTM coordinates with a square pixel size of 2.0 meters. This correction is only to aid in the interpretation and seasonal comparison of the imagery. The absolute positional accuracy of the imagery should not be considered high. A study of the accuracy of the geocorrection methodology was undertaken using 1996 CASI data of the NSA Fen (Zarco, 1998). Targets, 30 cm square, were placed throughout the Fen area. The coordinates of the targets were acquired by University of Nebraska researchers R. Steinauer and D. Jelinski (TF-10) using differential GPS. A comparison of the calculated location and the measured (GPS) location of the targets showed that the absolute error was about 30 m. The average relative error, i.e., error in the distance between two points, is estimated to be about 10 m. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Image data were collected on 36 days during five field campaigns in 1994 between 07-February and 15-September. 7.2.2 Temporal Coverage Map The following table contains the dates of the image data provided to BORIS. The entire CASI BOREAS image archive at CRESTech is more extensive. Please contact the PI or browse CRESTech's Web site for a complete list of dates of CASI image acquisitions (http://www.eol.crestech.ca). Site FFC-W* FFC-T IFC-1 IFC-2 IFC-3 -------- ----------- ----------- ----------- ----------- ----------- SSA-OJP 07-Feb-1994 17-Apr-1994 31-May-1994 24-Jul-1994 13-Sep-1994 SSA-YJP 08-Feb-1994 17-Apr-1994 01-Jun-1994 24-Jul-1994 13-Sep-1994 SSA-Fen 07-Feb-1994 17-Apr-1994 04-Jun-1994 24-Jul-1994 13-Sep-1994 SSA-OBS 08-Feb-1994 19-Apr-1994 27-May-1994 24-Jul-1994 13-Sep-1994 SSA-OA 09-Feb-1994 16-Apr-1994 26-May-1994 23-Jul-1994 15-Sep-1994 NSA-OJP 10-Feb-1994 20-Apr-1994 06-Jun-1994 08-Aug-1994 07-Sep-1994 NSA-YJP 11-Feb-1994 20-Apr-1994 06-Jun-1994 08-Aug-1994 06-Sep-1994 NSA-Fen n/a 20-Apr-1994 06-Jun-1994 08-Aug-1994 07-Sep-1994 NSA-OBS 10-Feb-1994 20-Apr-1994 06-Jun-1994 08-Aug-1994 06-Sep-1994 NSA-OA @ n/a n/a 06-Jun-1994 08-Aug-1994 06-Sep-1994 * Obstacles encountered when attempting to process the winter data set to reflectance were not overcome and thus these data exist only as at-sensor radiance. @ The BORIS archive does not contain the NSA-OA radiance data, BORIS has reflectance only for this site, please contact CRESTech for the radiance data. 7.2.3 Temporal Resolution CASI imagery represents the measured instantaneous irradiance and reflected target at-sensor radiance. Frequently, multiple image acquisitions over a target were obtained during one day. On some occasions, data collections were repeated on more than one day during an IFC or FFC. Please refer to the image acquisition list provided to BORIS. 7.3 Data Characteristics 7.3.1 Parameter/Variable Data characteristics are defined in the companion data definition file (r19cas94.def). The image parameters are: Scaled radiance. Scaled reflectance. 7.3.2 Variable Description/Definition The CASI at-sensor radiance imagery pixel digital numbers represent scaled at- aircraft radiance values. The CASI reflectance imagery pixel digital numbers represent scaled at-ground reflectance values. 7.3.3 Unit of Measurement Radiance Imagery Units are Hundredths of W/(m2 * µm * sr). That is, divide the scaled values by 100 to get at-sensor radiance values in W/(m2 * µm * sr). Reflectance Imagery Units are % reflectance * 500. That is divide the scaled values by 500 to get percent reflectance values. 7.3.4 Data Source The sources of the CASI image data were the CASI sensor and the Center for Research in Earth and Space Technology (CRESTECH). 7.3.5 Data Range The digital numbers in the image files will range from 0 - 65,536. 7.4 Sample Data Record Sample data format shown in the companion data definition file (r19cas94.def). 8. Data Organization 8.1 Data Granularity The smallest unit of data is a set of 1994 at-sensor radiance or reflectance data collected at a given site on a given day. 8.2 Data Format 8.2.1 Uncompressed Data Files The image inventory listing file consists of numerical and character fields of varying length separated by commas. The character fields are enclosed with single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition file (r19cas94.def). Each CASI image product consists of the following two files: File 1: Header file containing American Standard Code for Information Interchange (ASCII) characters (80 bytes per record) File 2: Binary image data file in Band Interleaved by Line (BIL) format with two-byte (16-bit) integer pixel values (high order byte first). The following a sample CASI header file. *** BOREAS CASI IMAGE HEADER *** ---------------------------------- Comment : BOREAS - NSA, FEN BOREAS Site Identifier : FEN Image Identifier : Tape: 197 File: 14 DATE AND MISSION INFORMATION ---------------------------- Date (DD-MM-YYYY) (GMT) : 07-09-1994 Start Time (GMT) (HH:MM:SS) : 21:18:42.000000 Stop Time (GMT) (HH:MM:SS) : 21:21:10.000000 Study Area : BOREAS - NSA Altitude (m) (ASL) : 1754.30 Heading (deg CW from North) : 49.3353 Ground speed (m/s) : 61.8243 Site Name : FEN Frame Rate (1/s) : 19.27 Platform : C-GCJX Navaho Image Mode : Imaging Start Latitude, Longitude : 55.9362, -98.3755 Stop Latitude, Longitude : 55.8827, -98.4863 CALIBRATION INFORMATION ----------------------- Is data calibrated ? : yes Calibration file : e223f40.rad Calibration Date (DD-MM-YYYY) : 01-11-1996 Calibration Scale Factor : 50000 Calibration Units : Reflectance Along track look angle (deg) : 0 Across track look swath (deg) : 35.4 Center pixel size across track (m) : 1.82 Center pixel size along track (m) : 3.20 Wavelengths (nm) : 409.70 443.17 490.90 520.10 565.40 619.80 Wavelengths (nm) (continued) : 665.50 682.51 709.47 742.0 750.00 769.00 Wavelengths (nm) (continued) : 799.80 880.70 905.40 Fstop : 4.0 Bandset : ffct15 Lens Identifier : Not Specified IMAGE SIZE AND FORMAT INFORMATION --------------------------------- Number of lines original image : 2660 Number of pixels original image : 512 Num lines (Geocorrected image) : 1760 Num pixels (Geocorrected image) : 672 Num of lines offset original : 68 Num of lines from original : 2008 Number of bands : 15 Data type : 2 byte, big endian, integer Interleave mode : BIL Bands Present : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Tape Record Size : Image Record Size : Number of Header Records : 0 Number of Bytes / Header Record : 0 BORIS personnel processed the media files to reduce the image file record sizes because of limitations of some machines/devices. The 'Tape Record Size' information in the header file may not match those of the image data file you obtain on tape. Please read the rest of this section for details. The pixel values in the image data files are stored in 2-bytes (high-order byte first). The image size and number of bands varies depending on the CASI CCD sampling configuration. The ASCII header file describes the number of pixels, bands and lines. BORIS found that CASI image files stored on tape with record sizes greater than 65,536 (64K) bytes could not be handled by some computer systems. This limited the number of users who would be able to read such tapes. A number of the 1996 CASI reflectance images extended beyond this 65,536 byte limit when all bands were written to a single record in BIL format. BORIS reformatted the 1996 CASI at-sensor radiance and reflectance data so that the record sizes were an even multiple of the number of pixels to reduce the record size. The 1994 data were written by BORIS with the following blocksize configurations: At-sensor radiance 7 band images, blocksize = (number of pixels) * 2 (bytes) * (number of bands) 15 band images, blocksize = (number of pixels) * 2 (bytes) Note that extra bytes were found in the at-sensor radiance image files, but this did not affected reading and importing of this data. In retrospect, this may have been due to problems noted in section 11.2). Reflectance blocksize = (number of pixels) * 2 (bytes) * 5 (bands) All of the 1994 CASI reflectance images contain 15 bands; thus, the reformatting to five bands per file record resulted in files that have three times as many records as there are lines in the image. 8.2.2 Compressed CD-ROM Files On the BOREAS CD-ROMs, the inventory files are stored as ASCII text files, as are the image header files (.hdr). However, the image data files 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 Radiance can be derived from the formula: Rad=DN/100 Reflectance can be derived from the formula: Ref(%) = (DN/500) 9.2 Data Processing Sequence 9.2.1 Processing Steps Radiance Imagery: 1. Instrument operator's flight logs entered into imagery data base. 2. Raw CASI data dumped from Exabyte tape to disc. 3. Graphic Interchange Format (GIF) quicklook imagery derived from raw data to allow imagery browsing. 4. GPS data extracted from CASI raw imagery. Imagery data base updated with GPS values for image acquisition time, altitude, heading, and speed. 5. CASI raw data calibrated, using radiance scale factors, to radiance. 6. Output file is in PCIDSK format. 7. Attitude data (Gyro) extracted from file. 8. Image geocorrected using GPS and attitude data. Resampled to desired grid size. 9. PCIDSK format rewritten to BIL binary format for BORIS submission. 10. ASCII header file created, one per imagery file. Reflectance Imagery: 1. Instrument operator's flight logs entered into imagery database. 2. Raw CASI data dumped from Exabyte tape to disc. 3. GIF quicklook imagery derived from raw data to allow imagery browsing. 4. GPS data extracted from CASI raw imagery. Imagery data base updated with GPS values for image acquisition time, altitude, heading, and speed. 5. CASI raw data calibrated, using radiance scale factors, to radiance. 6. Output file is in PCIDSK format. 7. Atmospheric correction control file created using sunphotometer data and sensor geometry information. 8. Radiance image (from step 5) corrected to at-ground modeled reflectance using CAM5S. 9. Attitude data (Gyro) extracted from file. 10. Image geocorrected using GPS and attitude data. Resampled to desired grid size. 11. PCIDSK format rewritten to BIL binary format for BORIS submission. 12. ASCII header file created, one per imagery file. 9.2.2 Processing Changes None. 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. 10. Errors 10.1 Sources of Error The absolute positional accuracy of the imagery should not be considered high because of limitations of the GPS and attitude data. 10.2 Quality Assessment All images submitted to BORIS have been checked to ensure that: • All channels are saved. • No obvious sensor anomalies exist. • The target has been acquired. 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 BORIS personnel reviewed a random sample of the images by reading them online and displaying the images on a terminal screen. No particularly anomalous items were noted in the visual review, however ORNL discovered the image size discrepancy noted in section 11.2. 11. Notes 11.1 Limitations of the Data The imagery has been geocorrected and resampled to aid in the interpretation of the imagery. The absolute positional accuracy of the imagery should not be considered high because of limitations of the GPS and attitude data. 11.2 Known Problems with the Data Check image comments for notes about conditions that may affect data. Data / Documentation problems: A. Four data files have fewer bytes than required by the number of rows and columns ("lines" and "pixels") listed in the header files. These are: (1) SSA-FEN radiance image from 13-Sep-1994, 18:01 GMT Header lists 1603 rows, 1072 columns. Correct values are 1063 rows, 1072 columns. (2) NSA-OJP radiance image from 10-Feb-1994, 20:32 GMT Header lists 611 rows, 621 columns. Correct values are 606 rows, 610 columns. (3) NSA-YJP radiance image from 11-Feb-1994, 20:27 GMT Header lists 808 rows, 649 columns. Correct values are 546 rows, 558 columns. (4) NSA-OJP reflectance image from 07-Sep-1994, 20:59 GMT Header lists 2965 rows, 2693 columns. Correct values are UNKNOWN. The pattern of non-zero bytes in the binary data combined with the file size suggest 2694 rows and 2693 columns, but using values close to these proved unsuccessful. B. NSA-OA reflectance image from 06-Jun-1994, 18:52 GMT, lists the reflectance scaling factor as 100. The data values suggest that the header value should be corrected to 50000 in agreement with that of other reflectance images. 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 given. 12. Application of the Data Set The CASI images can be used for detailed spectral analysis of the various boreal vegetation types and for characterizing the BOREAS site for modeling purposes. 13. Future Modifications and Plans None given. 14. Software 14.1 Software Description Software exists at CRESTech to manipulate and analyze the CASI data in the PCIDSK format. Software has been developed at CRESTech to calibrate the CASI imagery from its native tape format to calibrated radiance and then to modeled at-ground reflectance. Additional software modules can generate a "red edge" image from the reflectance. Other image map products are being developed. While the software works on the PCIDSK file format, the PCI EASI/PACE product is not required. Gzip (GNU zip) uses the Lempel-Ziv algorithm (Welch, 1994) used in the zip and PKZIP commands. 14.2 Software Access For information about available software, please contact the individuals named in Section 2. Gzip is available from many WWW-sites 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 for Data Center/Data Access Information These BOREAS 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 Oak Ridge, TN (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 15.2 Procedures for Obtaining Data BOREAS data may be obtained through the ORNL DAAC World Wide Web site at http://www-eosdis.ornl.gov/ or users may place requests for data by telephone, electronic mail, or fax. 15.3 Output Products and Availability Requested data can be provided electronically on the ORNL DAAC's anonymous FTP site or on various media including, CD-ROMs, 8-MM tapes, or diskettes. The complete set of BOREAS data CD-ROMs, entitled "Collected Data of the Boreal Ecosystem-Atmosphere Study", edited by Newcomer, J., et al., NASA, 1999, are also available. 16. Output Products and Availability 16.1 Tape Products CASI image data are available on 8-mm tape media. 16.2 Film Products None. 16.3 Other Products Although the inventory is contained on the BOREAS CD-ROM set, the actual CASI images are not. See Section 15 for information about how to obtain the data. Color GIF images of the BORIS subset are available and additional imagery can be viewed on the CRESTech World Wide Web (WWW) site (http://www.eol.crestech.ca). The following ancillary data may be of interest: • GPS data. • Gyro data. • Upwelling and downwelling light probe data, which may become available. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Dunlop, J.D. and P. Shepherd. 1995. Building a Boreal Forest Virtual Library. DSS Technical Report (Design Document). Itres Research Ltd. 1992. Compact Airborne Spectrographic Imager (CASI) User Manual Revision 2.1. 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 Achal, S. 1991. Personal Communication. Anger, C.D., S. Mah, and S. K. Babey. 1994. Technological enhancements to the Compact Airborne Spectrographic Imager (CASI). Proceedings of the First International Airborne Remote Sensing Conference and Exhibition, Vol. II, pp. 205-213. Anger, C.D., S.K. Babey, and R.J. Adamson. 1990. A new approach to imaging spectroscopy. Imaging Spectroscopy of the Terrestrial Environment, G. Vane, Editor. Proc. SPIE 1298. pp. 72-86. Babey, S. and R.J. Soffer. 1992. Radiometric calibration of the Compact Airborne Spectrographic Imager (CASI). Canadian Journal of Remote Sensing (Special issue on Imaging Spectrometry), Vol. 18, No. 4, Oct. 1992, pp. 233-242. Freemantle, J.R., J.R. Miller, and A.B. Hollinger. 1991. Improvements in spectral feature extraction after image based refinement of spectral calibration of imaging spectrometer data. Proceedings of the 14th Canadian Symposium on Remote Sensing. Calgary, Alberta. pp. 347-349. Gray, L.H., J.R. Freemantle, P.R. Shepherd, J.R. Miller, J.W. Harron, and C.H. Hersom. 1997. Characterization and calibration of the CASI airborne imaging spectrometer for BOREAS. Canadian Journal of Remote Sensing (Special issue on BOREAS), Vol. 23, No. 2, June 1997, pp. 188-195. Harron, J.W., J.R. Freemantle, A.B. Hollinger, and J.R. Miller. 1992. Methodologies and errors in the calibration of a Compact Airborne Spectrographic Imager. Canadian Journal of Remote Sensing (Special issue on Imaging Spectrometry), Vol. 18, No. 4, Oct. 1992, pp. 243-249. Harron, J.W., J.R. Freemantle, L.H. Gray, P.R. Shepherd, C.H. Hersom, J.R. Miller, and A.B. Hollinger. 1995. Radiometric calibration measures for the multi-temporal BOREAS projects: results of the inter-agency cross calibration and temporal stability of CASI responsivity. Proceedings of the 17th Canadian Symposium on Remote Sensing, 13-16 June, Saskatoon, Saskatchewan, p. 202-207. Li, X.W. and A.H. Strahler. 1992. Geometrical-optical bidirectional reflectance modeling of the discrete crown vegetation canopy: effect of crown shape and mutual shadowing. IEEE Transactions on Geoscience and Remote Sensing, Vol. GE- 30, 276-291. Matson, P., L. Johnson, C. Billow, J.R. Miller, and R. Pu. 1994. Seasonal patterns and remote spectral estimation of canopy chemistry across the Oregon Transect. Ecological Applications, Vol. 4, pp. 280-298. Miller, J.R., J.R. Freemantle, P.R. Shepherd, L. Gray, N. O'Neill, A. Royer, and E. Senese. 1995. Deployment of CASI to meet the Needs of BOREAS Science. Proceedings of the 17th Canadian Symposium on Remote Sensing, 13-16 June, Saskatoon, Saskatchewan, pp. 169-175. Newcomer, J., D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp, A. Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F. Hall, and P. Sellers, eds. 2000. Collected Data of The Boreal Ecosystem-Atmosphere Study. NASA. CD- ROM. O'Neill, N.T., F. Zagolski, M. Bergeron, A. Royer, J. Miller, and J. Freemantle. 1997. Atmospheric Correction Validation of CASI Images Acquired over the BOREAS Southern Study Area. Canadian Journal of Remote Sensing (Special issue on BOREAS), Vol. 23, No. 2, June 1997, pp. 143-162. Schafer, J. 1994. Personal Communication. 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. 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. 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. Journal of Geophysical Research 102(D24): 28,731-28,770. Shepherd, P.R., N.T. O'Neill, and T. Piekutowski. 1995. Analysis of downwelling and up-welling diffuser probe data to determine at-sensor irradiance fluxes. Proceedings of the 17th Canadian Symposium on Remote Sensing, 13-16 June, Saskatoon, Saskatchewan, pp. 337-342. Soffer, R.J., W. Wanner, J.R. Miller, and A.H. Strahler. 1995. Winter boreal forest canopy BRF results: comparisons between airborne data, laboratory simulations, and geometrical-optical model data. Proceedings of IGARSS'95, 10-14 July, Firenze, Italy. Thomas, P.J., A.B. Hollinger, K.M. Chu, and J.W. Harron. 1991. The ISTS Array Detector Test Facility. Proceedings of the Society of Photo-Optical Instrumentation Engineers, 834, pp. 91-105. Zarco, P. 1998. Correlations between CO2 fluxes and high spatial resolution reflectance imagery. Master of Science thesis submitted to the University of Dundee. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms AC - Alternating Current AFM - Airborne Fluxes and Meteorology AGL - Above Ground Level AOCI - Airborne Ocean Color Imager ASAS - Advanced Solid-state Array Spectroradiometer ASCII - American Standard Code for Information Interchange AVHRR - Advanced Very High Resolution Radiometer AVIRIS - Airborne Visible and Infrared Imaging Spectroradiometer B/GHRIS - BOREAS Global Hypermedia Research Information System BIL - Band Interleaved by Line BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System BRDF - Bidirectional Reflectance Distribution Function BSQ - Band Sequential CARTEL - Centre d'Applications et de Recherches en Teledetection CASI - Compact Airborne Spectrographic Imager CCD - Charge-Coupled Device CCRS - Canada Centre for Remote Sensing CD-ROM - Compact Disk-Read-Only Memory CRESTech - Centre for Research in Earth and Space Technology DC - Direct Current EOL - Earth Observations Laboratory EOS - Earth Observing System EOSDIS - EOS Data and Information System FFC-T - Focused Field Campaign - Thaw FFC-W - Focused Field Campaign - Winter FOV - Field of View FWHM - Full Width, Half Maximum GIF - Graphic Interchange Format GIS - Geographic Information System GMT - Greenwich Mean Time GOES - Geostationary Operational Environmental Satellite GPS - Global Positioning System GSFC - Goddard Space Flight Center HYD - Hydrology IFC - Intensive Field Campaign ILP - Incident Light Probe ISTS - Institute for Space and Terrestrial Science JPL - Jet Propulsion Laboratory LAI - Leaf Area Index MAS - MODIS Airborne Simulator MERIS - Medium Resolution Imaging Spectrometer MODIS - Moderate Resolution Imaging Spectrometer NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NRC - National Research Council NSERC - Natural Sciences and Engineering Research Council 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 PARABOLA - Portable Apparatus for Rapid Acquisition of Bidirectional Observations of Land and Atmosphere PI - Principal Investigator PRSO - Provincial Remote Sensing Office RSS - Remote Sensing Science SeaWiFS - Sea-viewing Wide Field-of-View Sensor SPOT - Satellite Pur l'Observation de la Terre SSA - Southern Study Area SSM/I - Special Sensor Microwave/Imager TE - Terrestrial Ecology TF - Tower Flux TGB - Trace Gas Biogeochemistry TM - Thematic Mapper TMS - Thematic Mapper Simulator URL - Uniform Resource Locator UTM - Universal Transverse Mercator VIS/NIR - Visible/Near-Infrared WWW - World Wide Web YJP - Young Jack Pine 20. Document Information 20.1 Document Revision Date Written: 07-May-1996 Last Updated: 04-Apr-2001 20.2 Document Review Date BORIS Review: 15-Sep-1997 Science Review: 12-Feb-1998 20.3 Document ID 20.4 Citation The CASI instrument was not supported as a facility sensor at BOREAS. The preparation, deployment, and analysis of CASI data were made possible through Natural Sciences and Engineering Research Council (NSERC) funding to the PI and funding from the Ontario Government through the Institute for Space and Terrestrial Science (ISTS), now renamed CRESTech. Users of CASI data are requested to make contact with the PI to discuss a mutually acceptable form of acknowledgment or collaboration. Acknowledgments should also include citations of relevant papers in Section 17.2. Also, cite the BOREAS CD-ROM set as: Newcomer, J., D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp, A. Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F. Hall, and P. Sellers, eds. Collected Data of The Boreal Ecosystem-Atmosphere Study. NASA. CD-ROM. NASA, 2000. 20.5 Document Curator 20.6 Document URL Keywords: Radiance BRDF Aircraft Sensors Remote Sensing Multispectral Hyperspectral Boreal Forest RSS19_CASI_1994.doc 11/22/99