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This description was generated automatically using input from the Planetary Data System.

Data Set Overview

This volume contains portions of the CRISM Multispectral Reduced Data Record (MRDR) Archive, a collection of multiband images from the Compact Reconnaissance Imaging Spectrometer for Mars on the Mars Reconnaissance Orbiter spacecraft. Images consist of map-projected data calibrated to units of corrected I/F plus a text file listing the wavelengths present. Additional image data have had further corrections applied. Each image or text file is stored with a PDS label. This volume also contains an index file ('') that tabulates the contents of the volume, ancillary data files, and documentation files. It may also contain browse images in PNG or IMG format, and HTML documents that support a web browser interface to the volume. For more information on the contents and organization of the volume set refer to the aareadme.txt file located in the root directory of the data volumes.


CRISM observing scenarios are constructed using a set of key variables ('configurations') which include the following. (All are selectable separately for the VNIR and IR detectors. Only a subset of the configurations are used to generate MRDRs.) Image source: Image data may be generated using digitized output from the detector, or using one of up to seven test patterns. Only data from the detector are processed to a TRDR. Pixel binning: Pixels can be saved unbinned or binned 2x, 5x, or 10x in the spatial direction. No pixel binning in the spectral direction is supported. Data with 10x pixel binning are used in the generation of MRDRs. Row selection: All detector rows having useful signal can be saved, or alternatively an arbitrary, commandable subset of rows can be saved. The number of rows with useful signal is 545, 107 in the VNIR and 438 in the IR. The nominal number of rows for multispectral mode was 73, 18 in the VNIR and 55 in the IR prior to 10 Dec 2006. On that date an extra channel was added to the VNIR for a total of 19. One row in each detector is for calibration Purposes. Mapping data have also been collected with extended wavelength sets, all 107 VNIR channels and 155 IR channels, for a partially hyperspectral equivalent of the multispectral data. Those data are included in the MRDRs by extracting the wavelengths that are common to multispectral operating mode. Calibration lamps: 4095 levels are commandable in each of two lamps at each focal plane, and in two lamps in the integrating sphere. All lamps can be commanded open-loop, meaning that current is commanded directly. For the integrating sphere only, closed loop control is available at 4095 settings. For closed loop control, the setting refers to output from a photodiode viewing the interior of the integrating sphere; current is adjusted dynamically to attain the commanded photodiode output. Note: lamps reach maximum current at open- or closed-loop settings <4095. Only data for which the calibration lamps are off may be processed to an MRDR. Focal plane lamps are not used as part of the calibration process, but the integrating sphere lamp controlled by the IR focal plane is. Shutter position: Open, closed, or viewing the integrating sphere. The shutter is actually commandable directly to position 0 through 32. In software, open=3, sphere=17, closed=32. NOTE: during integration and testing, it was discovered that at positions <3 the hinge end of the shutter is directly illuminated and creates scattered light. Position 3 does not cause this effect, but the other end of the shutter slightly vignettes incoming light. Only data in which the shutter is open, and at position 3, may be processed to an MRDR. Pointing: CRISM has two basic gimbal pointing configurations and two basic superimposed scan patterns. Pointing can be (1) fixed (nadir-pointed in the primary science orbit) or (2) dynamic, tracking a target point on the surface of Mars and taking out ground track motion. Two types of superimposed scans are supported: (1) a short, 4-second duration fixed-rate ('EPF-type') scan which superimposes a constant angular velocity scan on either of the basic pointing profiles, or (2) a long, minutes-duration fixed-rate ('target swath-type') scan. Only fixed nadir-pointed data are processed to an MRDR.


The CRISM data stream downlinked by the spacecraft unpacks into a succession of compressed image frames with binary headers containing housekeeping. In each image, one direction is spatial and one is spectral. There is one image for the VNIR focal plane and one image for the IR focal plane. The image from each focal plane has a header with 220 housekeeping items that contain full status of the instrument hardware, including data configuration, lamp and shutter status, gimbal position, a time stamp, and the target ID and macro within which the frame of data was taken. These parameters are stored as part of an Experiment Data Record (EDR), which consists of raw data. The data in one EDR represents a series of image frames acquired with a consistent instrument configuration (shutter position, frame rate, pixel binning, compression, exposure time, on/off status and setting of different lamps). Once data are assembled into EDRs, they are calibrated into TRDRs. Image data are converted to units of radiance using level-4 and level-6 CDRs, and analog housekeeping items in the text file (voltages, currents, and temperatures) have been converted into physical units using a level-6 CDR. Both files share a common label. The calibration algorithms are discussed at length in the CRISM Data Products SIS. A TRDR may also contain separately labeled multiband images in which radiance has been processed to one of the following: radiance in units of (W / (m^2 sr micron)) I/F (radiance divided by (pi * solar flux at 1 AU * heliocentric distance^2)), During construction of MRDRs, additional values generated from I/F include: Lambert albedo, or a set of derived spectral parameters (summary products) that provide an overview of the data set. The summary products include Lambert albedo at key wavelengths, or key band depths or spectral reflectance ratios. To create Lambert albedo or most summary products, estimated corrections for atmospheric and photometric effects are applied to the I/F data. Information on physical properties and illumination conditions of the site observed in the EDR or TRDR is maintained in a Derived Data Record or DDR. There are 14 layers in each DDR: Solar incidence angle relative to areoid, at the same planetary radius as surface projection of pixel, units degrees. Emission angle relative to areoid, at the same planetary radius as surface projection of pixel, units degrees. Solar phase angle, units degrees. Areocentric latitude, units degrees N. Areocentric longitude, units degrees E. Solar incidence angle relative to planetary surface as estimated using MOLA shape model, units degrees. Emission angle relative to planetary surface as estimated using MOLA shape model, units degrees. Slope magnitude, using MOLA shape model and reference ellipsoid, units degrees. Slope azimuth, using MOLA shape model and reference ellipsoid, units degrees clockwise from N. Elevation relative to MOLA datum, units meters. TES thermal inertia, units J m^-2 K^-1 s^-0.5. TES bolometric albedo, unitless. Spare. Spare. The TES data are in support for a correction for thermal emission which is not included as part of MRDR processing. The sequence of processing that creates an MRDR from the above products is as follows: (a) EDRs are assembled from raw data. (b) The radiance multiple band images in TRDRs are created from EDRs and Calibration Data Records, or CDRs, using a calibration algorithm discussed at length in an Appendix in the CRISM Data Products SIS. Briefly, a measurement of bias is subtracted from shutter-closed dark measurements, images of the interior of the integrating sphere taken with the shutter in an intermediate position, and scene data taken in the appropriate open position. Electronics artifacts are removed as detailed in the Data Product SIS, and the data are linearized. Dark measurements accompanying each the sphere and scene data are averaged by wavelength to improve signal-to-noise ratio, and scaled spatially to the dimensions of the scene and sphere data. Dark measurements are subtracted from both the scene and sphere measurements. The sphere measurements are averaged by wavelength to improve signalto-noise ratio, and scaled spatially to the dimensions of the scene data. The scene and sphere measurements are divided by their respective exposure times. The scene data are divided by the sphere data, both now in units of corrected DN per second, to yield a unitless result, which is multiplied by a ground-calibration-derived model of integrating sphere spectral radiance, to yield scene spectral radiance. (c) Gimbal positions are extracted from the EDR housekeeping and formatted as a gimbal C kernel. (d) Using the gimbal C kernel and other SPICE kernels, DDRs are created. The surface intercept on the MOLA shape model is calculated for each spatial pixel (sample at the reference detector row). The angles of this pixel relative to the equatorial plane and reference longitude constitute the latitude and longitude of the pixel. For that latitude and longitude, solar incidence, emission, and phase angles are determined at a surface parallel to the areoid but having a radius from planetary center equivalent to that of the surface intercept of the shape model. Solar incidence and emission are also determined relative to the shape model itself. Using the latitude and longitude of the surface intercept of each spatial pixel, MOLA elevation is retrieved from a global elevation map and resampled into CRISM sensor space using nearest neighbor resampling. (e) Radiance is converted to I/F by dividing by (pi * solar flux at 1 AU * heliocentricdistance^2)). Solar flux is maintained in a level 4 CDR, and solar distance is written in the label to the radiance image. (f) I/F is converted to Lambert albedo to allow rapid identification of new ROIs and to quickly assess the information content of targeted observations. Some or all of the following corrections may be made: I/F is divided by cosine of the solar incidence angle The estimated contribution to and attenuation of the signal by atmospheric aerosols is removed. The estimated attenuation of the signal by atmospheric dust and ice aerosols is corrected to a target value. (g) After the corrections discussed below are performed, multispectral TRDRs are map projected into MRDRs using the latitude and longitude information in the DDRs. Because of the mosaicked nature of an MRDR, the following protocol was used in MRDR versions 1 and 3 to select between overlapping TRDRs for inclusion in the MRDR: If I/F is available but not Lambert albedo, the TRDR with the lower incidence angle at the areoid is used If Lambert albedo is available, then: If both TRDRs have incidence angles >70 degrees, the one with the lower incidence angle is used. If one incidence angle is >70 degrees and one is <70, the TRDR with i < 70 degrees is used. If both incidence angles are <70 degrees, then the TRDR with the lower 440-nm Lambert albedo is used. For version 4, strips of mapping data are placed into the Lambert albedo multiple band images such that the strip acquired under the conditions of highest atmospheric opacity from [MONTABONEETAL2015] data is placed first, and strips are then placed in order of decreasing atmospheric opacity with the strip acquired under the lowest atmospheric opacity is placed 'on top'. Only data acquired during periods of atmospheric opacity <1.0 from [MONTABONEETAL2015] are included, to limit the opacity whose Effects are to be corrected as described below. TIME DEPENDENCY OF THE APPROACH TO ATMOSPHERIC CORRECTION: There are two alternative paths for correction of atmospheric and photometric effects (the second path only applies to version 4 MRDRs): Mapping data acquired prior to May 2012 fall within the time range of acquisition of gimbaled CRISM Emission Phase Functions, from which retrievals provide a record of atmospheric dust opacity sampled at CRISM's wavelength sampling and resolution as a function of latitude, longitude, solar longitude, and Mars year. MRO MARCI data provide retrievals of atmospheric water-ice opacity also as a function of latitude, longitude, Ls, and Mars year. For times when these opacities are present, using the procedures described by [MCGUIREETAL2013], a full radiative transfer model is used to correct I/F to a standard reference photometric geometry with atmospheric contributions to I/F normalized to a nadir geometry with a dust opacity of 0.2 and an ice opacity of 0.0. Information on latitude, longitude, Ls, and altitude are extracted from the header of the TRDR containing the I/F data and the companion DDR. These data are used to extrapolate to the best estimate of the atmospheric opacites from CRISM and MARCI data. Then the photometric angles, altitude, Ls, and wavelength plus the opacities extracted from CRISM and MARCI data are used to interpolate wavelength-bywavelength to correct from I/F to Lambert albedo at i=30 degrees, e=0, g=30, dust opacity=0.2, and ice opacity=0.0 with no absorptions due to atmospheric gases. The Lambert albedo becomes the basis to which mapping strips acquired after May 2012 (when EPFs were no longer acquired) are corrected. For mapping data acquired after May 2012, a two-step correction is used that does normalize out atmospheric gas absorptions and correct for photometric effects, but does not attempt to correct for aerosol effects. This processing closely follows that applied to CRISM TERs and MTRDRs. The first step is the volcano scan atmospheric correction uses empirically derived Mars atmospheric transmission spectra to correct CRISM IR (L-detector) spectral reflectance data for atmospheric gas absorptions (due primarily to CO2, H2O, and CO) [MURCHIEETAL2009, MORGANETAL2011]. There are no significant atmospheric gas absorptions over the CRISM VNIR wavelength range, so this correction is not applied to VNIR (S-detector) data. Detector column-specific reference atmospheric transmission spectra (to accommodate spectral smile) are derived from a suite of push-broom hyperspectral Flat Field Calibration (FFC) scans over Olympus Mons and are matched to a given observation to minimize high frequency residual spectral structure due to sub-nm wavelength calibration variability across the wavelengths affected by the 2000 nm CO2 absorption (1947 - 2066 nm). The depth of the 2000 nm CO2 absorption is determined for the spectrum of each spatial pixel in the image cube under consideration, the selected reference transmission spectrum is scaled to match according to the Beer-Lambert Law, and the resulting model transmission spectrum is ratioed out of the I/F data. The MRDR pipeline implementation of the volcano also includes a CRISM-specific volcano scan patch (included in the CRISM Analysis Toolkit v7.1+ available at the PDS Geosciences Node) that is applied after the initial correction to reduce the influence of varying path length and pressure broadening in the derivation of the reference transmission spectra. The second step for data corrected using the volcano scan is application of a photometric correction using a Lambert assumption: IOF_corrected = IOF_uncorrected / cos(theta) where theta is the solar incidence angle. The photometric correction is calculated for each spatial pixel and is applied uniformly to all spectral channels. The spatial pixel specific incidence angle information is derived from the 'INA at areoid' band (incidence angle with respect to the Mars areoid) in the CRISM DDR (Derived Data Record) associated with the observation and segment under consideration. FILTERING TO REDUCE NOISE (version 4 only): 72-channel I/F mapping strips are filtered for stochastic noise and systematic noise and artifacts in two steps, respectively. The first step to remediate stochastic noise is a simplified version of the Iterative Kernel Filter used for noise remediation in the I/F version of TRR3s. The second step to remediate systematic effects is the Ratio Shift Correction also applied during that filtering. The Iterative Kernel Filter (IKF) procedure as applied to multispectral data is a kernel based filtering algorithm that models the information content of a given two dimensional normalized data kernel as a multidimensional polynomial. The model residuals are treated as a sample set and examined for outliers using the Grubbs test. If an outlier is detected, the corresponding pixel is removed from consideration and the kernel model is iterated. Model iteration is terminated when no further outliers are detected. The filtered value for the target pixel at the center of the input kernel is then given by a proximity weighted model of the kernel elements that were not marked as outliers. The confidence level threshold for the Grubbs test is conservative so the filter retains some marginal noise. The IKF is applied primarily to IR data. The Ratio Shift Correction (RSC) procedure as applied to multispectral data is the primary filtering process for VNIR data. Within a given spectral band, a spatial column corresponds to a single detector element. The Ratio Shift Correction characterizes residual bias of each detector element through the evaluation of inter-column (or crosstrack shifted) ratio statistics relative to a cross track model. Modifying the complexity of the underlying cross track model allows the RSC procedure to address high frequency column striping or low frequency banding while retaining real scene cross-track variability. NORMALIZATION OF STRIP-TO-STRIP RESIDUALS (version 4 only): At this stage of processing there are significant residual differences in I/F between overlapping strips of mapping data due to several effects: systematic errors in radiometric calibration between strips; inaccuracy in the assumption of a wavelength-independent Lambert photometric function; for strips processed to Lambert albedo, differences between the modeled and actual atmospheric dust and ice opacities; for strips processed using the volcano scan correction, the presence of atmospheric dust and ice opacities different that the target values of dust opacity = 0.2, and ice opacity=0.0; and differences between the actual and modeled values of H2O vapor and CO due to seasonal or meteorological variations. The calibration residuals are only somewhat notable in I/F, but the magnitudes are in family with real spectral variations for many of the mineralogical spectral indices represented as summary products. To remediate these interstrip differences, an optimization procedure is performed in which derived values of surface reflectance are corrected to the values in the closest to ideal data among the mapping strips, using the millions of overlap and proximity relations among the approximately 83,000 strips of VNIR+IR data in the map. Prior to optimization, the millions of areas of intersection and close proximity are identified. The differences between each such pair of strips is analyzed using graph theory, and the best-fit gain and offset describing the differences are recorded. Of course, each such solution will have some systematic error. In the optimization procedure, overall error is minimized (and the data set is optimized) by applying the gains and offsets in a weighted fashion, anchoring the output values to that part of the data which is closest to ideal. Those 'anchor' strips have the following attributes: low IR detector temperature, as close as possible to the minimum value used in flight; low solar incidence angles; low dust opacity in the data as acquired as recorded in [MONTABONEETAL2015] data; and the atmospheric corrections were performed using the full radiometric model, not the volcano scan correction. Note that only mapping strips corrected to dust opacity=0.2 and ice opacity=0.0 using DISORT-traceable procedures populate the anchor strips. Provided that there are overlaps with such strips, the strips corrected with the volcano scan approach effectively have their dust and ice opacities also normalized to the target values. Thus correction to Lambert albedo is propagated among all strips.


DATA DESCRIPTION: There is only one data type associated with this volume, the Multispectral Reduced Data Records or MRDRs. An MRDR consists of mosaicked, map-projected multispectral TRDRs. All data are represented as 32-bit real numbers. The multispectral map RDR contains up to five multiple-band images at 256 pixels/degree (versions 1 and 3) or 327 pixels/degree (version 4) and one list file. The first multiple-band image is map-projected I/F without any further corrections applied, taken directly from the TRDR associated with a strip of multispectral data. Although in the TRDRs there are separate multiple-band images for the VNIR and IR detectors, in this case the data are merged. The size of the multiple-band image varies between map tiles. A typical multiple-band image might have 1280 pixels (versions 1 and 3) or 1635 pixels (version 4) in the latitude direction, a variable number of pixels in the longitude direction, and approximately 72 pixels in the wavelength dimension, representing each of the selected channels in multispectral mode. This type of multiple-band image is present in version 1 and 3 MRDRs. The second multiple-band image is geometrically identical to the map-projected I/F multiple-band image (if present), except that data have been processed to Lambert albedo. This type of multiple band image is present in version 1 and 4 MRDRs. The third multiple-band image contains map-projected data from DDRs associated with a strip of multispectral data, used to derive I/F from radiance. The file corresponds to mosaicked I/F. 11 additional layers that are specific to individual multispectral strips used to assemble the tile, and are thus not contained in the DDR. This additional information provides traceability back to the source TRDRs: Solar longitude, units degrees Solar distance at time of measurement, units AU (versions 1,3) VNIR observation ID of constituent measurement IR observation ID of constituent measurement The VNIR ordinal counter carried through from the source scene EDRs The IR ordinal counter carried through from the source scene EDRs The VNIR column number carried through from the TRDR used to populate the MRDR; this identifies the VNIR wavelength calibration at the spatial pixel of the MRDR The IR column number carried through from the TRDR used to populate the MRDR; this identifies the IR wavelength calibration at the spatial pixel of the MRDR The ordinal number of the frame from the source VNIR TRDR; this together with column number, observation ID, and ordinal counter provides traceability back to a spatial pixel in a source EDR The ordinal number of the frame from the source IR TRDR Time of day, This type of multiple-band image is present in version 1 and 3 MRDRs. The fourth multiple-band image contains map-projected data from DDRs associated with a strip of multispectral data, which has been processed to Lambert albedo. The files correspond to the mosaicked Lambert albedo. The same additional layers as in the third file are also present. This type of multiple-band image is present in version 1 and 4 MRDRs. The fifth multiple-band image contains map-projected summary products. The list file, in ASCII format, contains wavelengths of each layer in the I/F and Lambert albedo images. A suite of mineral indicators and other measures of spectral shape and reflectivity, collectively called spectral summary parameters, is calculated from the Lambert albedo or I/F data. Summary product multiple band images are included in version 1 and 4 MRDRs. Version 1 used formulations based upon the published formulations of [PELKEYETAL2007]. Version 4 MRDRs used the revised and expanded spectral summary parameter library of [VIVIANO-BECKETAL2014] which was developed to better detect the surprisingly large range of minerals found by CRISM and to reduce false positives. The bands in the SU image cube are given below along with a brief description of their significance. Users are referred to Table 3-12 of the CRISM Data Product SIS for detailed formulations and caveats. R770 (versions 1, 4) = 0.77-micron reflectance (higher value more dusty or icy) RBR (versions 1, 4) = Red/blue ratio (higher value indicates more nanophase iron oxide or sky illumination) BBD530 (version 1), BD530_2 (version 4) = 0.53-micron band depth (higher value has more fine-grained crystalline hematite) SH600 (version 1), SH600_2 (version 4) = 0.6-micron shoulder height (select ferric minerals esp. hematite, goethite, or a compacted texture) SH770 (version 4) = 0.77-micron shoulder height (select ferric minerals, less sensitive to LCP than SH600_2) BD640 (version 1), BD640_2 (version 4) = 0.64-micron band depth (select ferric minerals, esp. maghemite, but obscured by VNIR detector artifact) BD860 (version 1), BD860_2 (version 4) = 0.86-micron band depth (select crystalline ferric minerals, esp. hematite) BD920 (version 1), BD920_2 (version 4) = 0.92-micron band depth (crystalline ferric minerals and low-Ca pyroxene, or LCP) RPEAK1 (versions 1, 3, 4) = Reflectance peak 1 near 0.77 microns (<0.75 suggests olivine, 0.75 pyroxene, >0.8 dust) BDI1000VIS (versions 1, 4) = 1-micron integrated band depth; VNIR wavelengths (olivine, pyroxene, or Fe-bearing glass) BDI1000IR (versions 1, 4) = 1-micron integrated band depth; IR wavelengths (crystalline Fe2+ silicates) IRA (version 1), R1330 (version 4) = IR albedo at 1.3 microns, near peak between pyroxene absorptions BD1300 (version 4) = 1.3-micron absorption associated with Fe2+ substitution in plagioclase OLINDEX (version 1), OLINDEX3 (version 4) = Broad absorption centered at 1 micron (olivine strongly >0, also detects Fe-phyllosilicate) LCPINDEX (version 1), LCPINDEX2 (version 4) = Broad absorption centered at 1.81 micron (pyroxene is strongly +; favors LCP) HCPINDEX (version 1), HCPINDEX2 (version 4) = Broad absorption centered at 2.12 microns (pyroxene is strongly +; favors HCP) VAR (versions 1, 4) = 1.0-2.3-micron spectral variance; Ol & Px will have high values; MGS/TES Type 2 areas will have low values BD1270O2 (version 1) = O2 emission; inversely correlated with high altitude water; signature of ozone ISLOPE1 (versions 1, 4) = Spectral slope 1 (from 1.185 to 2.530 microns; ferric coating on dark rock) BD1400H20 (version 1), BD1400 (version 4) = 1.4-micron H2O and -OH band depth (hydrated or hydroxylated minerals) BD1435 (versions 1, 4) = 1.435-micron CO2 ice band depth BD1500 (version 1), BD1500_2 (version 4) = 1.5-micron H2O ice band depth ICER1 (version 1), ICER1_2 (version 4) = CO2 and H2O ice band depth ratio at 1.43-1.5 microns BD1750 (version 1), BD1750_2 (version 4) = 1.75-micron H2O band depth (gypsum or alunite) BD1900 (version 1), BD1900_2 (version 4) = 1.9-micron H2O band depth (hydrated minerals except monohydrated sulfates) BD1900r2 (version 4) = 1.9-micron H2O band depth (hydrated minerals except monohydrated sulfates) BDI2000 (versions 1, 4) = 2-micron integrated band depth (pyroxene) BD2100 (version 1), BD2100_2 (version 4) = 2.1-micron shifted H2O band depth in monohydrated sulfates BD2165 (version 4) = 2.165-micron Al-OH band depth (pyrophyllite, kaolinite-group minerals) BD2190 (version 4) = 2.190-micron Al-OH band depth (beidellite, allophane, imogolite) MIN2200 (version 4) = 2.16-micron Si-OH band depth and 2.21-micron H-bound Si-OH band depth (doublet; kaolinite) BD2210 (version 1), BD2210_2 (version 4) = 2.21-micron Al-OH band depth (Al-OH minerals) D2200 (version 4) = 2.2-micron dropoff (Al-OH minerals) BD2230 (version 4) = 2.23-micron band depth (hydroxylated ferric sulfate) BD2250 (version 4) = 2.25-micron broad Al-OH and Si-OH band depth (opal, Al-OH minerals) MIN2250 (version 4) = 2.21-micron Si-OH band depth and 2.26-micron H-bound Si-OH band depth (opal) BD2265 (version 4) = 2.265-micron band depth (jarosite, gibbsite, acid-leached nontronite) BD2290 (versions 1, 4) = 2.29-micron Mg,Fe-OH band depth / 2.292-micron CO2 ice band depth (Mg-OH and Fe-OH minerals, Mg carbonate, and CO2 ice) D2300 (versions 1, 4) = 2.3-micron dropoff (hydroxylated Fe,Mg silicates strongly >0) BD2350 (version 1), BD2355 (version 4) = 2.35-micron band depth (chlorite, prehnite, pumpellyite, carbonate, serpentine) SINDEX (version 1), SINDEX2 (version 4) = Inverse lever rule to detect convexity at 2.29 microns due to 2.1- and 2.4-micron absorptions (hydrated sulfates strongly >0) ICER2 (version 1), ICER2_2 (version 4) = 2.7-micron CO2 ice band BDCARB (version 1) = 2.33, 2.53-micron Ca or Fe carbonate band MIN2295_2480 (version 4) = Mg Carbonate overtone band depth and metal-OH band MIN2345_2537 (version 4) = Ca/Fe Carbonate overtone band depth and metal-OH band BD2500_2 (version 4) = Mg Carbonate overtone band depth, or zeolite BD3000 (versions 1, 4) = 3-micron H2O band depth (adsorbed and bound H2O and ice) BD3100 (versions 1, 4) = 3.1-micron H2O ice band depth BD3200 (versions 1, 4) = 3.2-micron CO2 ice band depth BD3400 (version 1), BD3400_2 (version 4) = 3.4-micron carbonate band depth CINDEX (version 1), CINDEX2 (version 4) = Inverse lever rule to detect convexity at 3.6 micron due to 3.4- and 3.8-micron carbonate absorptions R440 (versions 1, 4) = 0.44-micron reflectance R530 (version 4) = 0.53-micron reflectance R600 (version 4) = 0.60-micron reflectance IRR1 (versions 1, 4) = IR ratio 1 (R880/R997; aphelion ice clouds >1, seasonal ice clouds and dust <1)) R1080 (version 4) = 1.08-micron reflectance R1506 (version 4) = 1.51-micron reflectance R2529 (version 4) = 2.53-micron reflectance BD2000CO2 (version 1) = 2-micron atmospheric CO2 band depth BD2600 (versions 1, 4) = 2.6-micron atmospheric H2O band depth BD2700 (version 1) = 2.7-micron atmospheric CO2 band depth IRR2 (versions 1, 4) = IR ratio 2 (R2530/R2210; aphelion ice clouds vs. seasonal ice clouds or dust) R2700 (version 1) = high clouds above most atmospheric CO2 IRR3 (versions 1, 4) = IR ratio 3 (R3500/R3390; aphelion ice clouds vs. seasonal ice clouds or dust) R3920 (version 4) = 3.92-micron reflectance, useful in detecting ice-free Regions at the poles.

Ancillary Data

There is one type of ancillary data provided with this dataset: 1. The BROWSE directory contains browse images in PNG format. See BROWINFO.TXT for more details.

Coordinate System

Areocentric latitude and longitude, incidence, emission, and phase angles are derived from spacecraft attitude, gimbal position, pixel location, and MOLA shape model of Mars. The detailed procedure is described in the documentation on DDRs. The adopted projection convention is planetocentric, positive east, using the 2000 IAU prime meridian and pole of rotation. The projection varies in 5 degree latitude bands, using EQUIRECTANGULAR equatorward of 65 degrees latitude and POLAR STEREOGRAPHIC poleward of 65 degrees latitude. For the latitude band projected equirectangularly, the center latitude of projection is the equatorward boundary of each band to minimize distortion. For the latitude bands projected polar stereographically, the center of projection is the pole. In the north polar region, 0 longitude is down, and in the south polar region 0 longitude is up. The planet is divided into 1964 nonoverlapping tiles, 256 pixel/degree in versions 1 and 3, and 327 pixels/degree in version 4. Their longitude width increases poleward to keep tiles approximately the same in area.


The CRISM archive is made available online via Web and FTP servers. This is the primary means of distribution. Therefore the archive is organized as a set of virtual volumes, with each data set stored online as a single volume. As new data products are released they are added to the volume's data directory, and the volume's index table is updated accordingly. The size of the volume is not limited by the capacity of the physical media on which it is stored; hence the term virtual volume. When it is necessary to transfer all or part of a data set to other media such as DVD for distribution or for offline storage, the virtual volume's contents are written to the other media according to PDS policy, possibly dividing the contents among several physical volumes.

These data are available on-line from the Planetary Data System (PDS) at: in in subdirectories /mrocr_3001/, /mrocr_3002/, /mrocr_3101/, and /mrocr_3102/.

Alternate Names



  • Planetary Science: Geology and Geophysics

Additional Information



Questions and comments about this data collection can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Scott MurchieGeneral ContactApplied Physics
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