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ASC Data, No MERRA or MERRA2

LongName Description
ASTER Global Digital Elevation Model The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) was developed jointly by the U.S. National Aeronautics and Space Administration (NASA) and Japan’s Ministry of Economy, Trad, and Industry (METI). ASTER is capable of collecting in-track stereo usig nadir- and aft-looking near infrared cameras. Since 2001, these stereo pairs have been used to produce single-scene (60- x 60-kilomenter (km)) digital elevation models (DEM) having vertical (root-mean-squared-error) accuracies generally between 10- and 25-meters (m). The methodology used by Japan's Sensor Information Laboratory Corporation (SILC) to produce the ASTER GDEM involves automated processing of the entire ASTER Level-1A archive. Stereo-correlation is used to produce over one million individual scene-based ASTER DEMs, to which cloud masking is applied to remove cloudy pixels. All cloud-screened DEMS are stacked and residual bad values and outliers are removed. Selected data are averaged to create final pixel values, and residual anomalies are corrected before partitioning the data into 1 degree (°) x 1° tiles. The ASTER GDEM covers land surfaces between 83°N and 83°S and is comprised of 22,702 tiles. Tiles that con at least 0.01% land area included. The ASTER GDEM is distributed as Geographic Tagged Image File Format (GeoTIFF) files with geographic coordinates (latitude, longitude). The data are posted on a 1 arc-second (approximately 30–m at the equator) grid an referenced to the 1984 World Geodetic System (WGS84)/ 1996 Earth Gravitational Model (EGM96) eoid. While the ASTER GDEM 2 benefits from substantial improvements over GDEM 1, users are nonetheless advised that the products still may contain anomalies and artifacts that will reduce its usability for certain applications, because they can introduce large elevation errors on local scales. The data are provided “as is and neither NASA nor METI/ERSDAC will be responsible for any damages resulting from use o the data. V002 data set release date: 2009-06-28 Data Set Characteristics: Geographic Extent: Global between 83º latitude Scee Coverage: 1º x 1º tiles Image Dimensions: 3601 x 3601 Total Number Tiles: V001: 22,604; V002: 22,702 e Volume: ~25MB, 6.4 Mcompressed Compression Type: zip File Format: GEOTIFF Map Projection: Geographic Lat/Lon Datum: WGS84/EGM96 Resolution: 1 arcsecond (30-m horizontal posting at equator)
Circumpolar Vegetation Dynamics Product for Global Change Study Land surface phenology (LSP) and vegetation growth of the circumpolar north are changing in response to more pronounced warming in the region. The first phenology index (PI) based vegetation dynamics product, comprising start (SOS), end (EOS), length of growing season (LOS), and growing season integrated annual normalized difference vegetation index (NDVI), specifically designed for the entire circumpolar north (N45°N) using SPOT VGT data starting from 1999. PI combines the merits of NDVI and normalized difference infrared index (NDII) by taking the difference of squared greenness (from NDVI) and wetness (from NDII) to remove the soil and snow cover dynamics from key vegetation LSP cycles.
Decadal surface water maps 1991-2011 Maps of the location and extent of surface water for the ABoVE study region at decadal time step from 1991 - 2011.  Data are stored in raster files (geotiff) in the ABoVE tile grid.
Elevation Datasets in Alaska Intermap's DEM products are 3D raster datasets with elevations captured at 5-meter postings or every 5 meters. They are generated using Intermap's STAR technology (Interferometric Synthetic Aperture Radar), which is mounted to an aircraft. The Digital Terrain Model (DTM) data product represents the bare earth and is derived from the Digital Surface Model (DSM) using Intermap's proprietary algorithm and editing processes. Accuracy statements are based on unobstructed areas of moderately sloped terrain. Diminished accuracies are to be expected in areas of extreme terrain and dense vegetation. The DTM is stored as a contiguous dataset spanning continental land masses where we have captured data. It is available in specific areas of interest or in 15-minute by 15-minute tile areas. For more detailed information, refer to Intermap's Product Handbook
Fractional open water cover for the ABoVE domain & pan-Arctic region, 2002-2015 This data set provides land surface fractional open water (fw) inundation dynamics over the Arctic-Boreal Vulnerability Experiment (ABoVE) domain and pan-Arctic region for the period 2002-2015. The data were developed using high frequency (89 GHz) brightness temperatures (Tb) from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) and the Advanced Microwave Scanning Radiometer 2 (AMSR2), with other ancillary inputs from AMSR-E/AMSR2 25 km products and MODIS (Moderate Resolution Imaging Spectroradiometer). The data are at 10-day temporal fidelity and 5 km spatial resolution. 
Landsat 4-5 Thematic Mapper The Landsat Thematic Mapper (TM) is a sensor carried onboard Landsats 4 and 5 and has acquired images of the Earth nearly continuously from July 1982 to the present, with a 16-day repeat cycle. Landsat TM image data consist of seven spectral bands (band designations) with a spatial resolution of 30 meters for bands 1 to 5 and band 7. Spatial resolution for band 6 (thermal infrared) is 120 meters, but band 6 data are oversampled to 30 meter pixel size. Approximate scene size is 170 km north-south by 183 km east-west (106 mi by 114 mi). Systematic Correction (Level 1G) includes both radiometric and geometric correction. The scene will be rotated, aligned, and georeferenced to a user-specified map projection. Absolute geometric accuracy of the systematically corrected Landsat TM product can vary, depending on the accuracy of the predicted ephemeris that is used for processing. Please be aware that TM Level 1G products may require additional image geometric correction and/or co-registration to known ground control points (GCPs). Precision Correction (Level 1P) includes radiometric and geometric correction, as well as the use of ground control points (GCPs) to improve geometric accuracy. For locations outside the United States, accuracy of the precision-corrected product will depend on the availability of local GCPs. Terrain Correction (Level 1T) includes radiometric and geometric precision correction, as well as the use of a digital elevation model (DEM) to improve the satellite model and to correct for relief displacement caused by local terrain. For locations outside the United States, the accuracy of a terrain-corrected product will depend on the availability of local ground control points (GCPs), as well as the quality of the best available DEM.
Landsat 7 Enhanced Thematic Mapper Plus (ETM+) The Landsat Enhanced Thematic Mapper Plus (ETM+) is a sensor carried onboard the Landsat 7 satellite and has acquired images of the Earth nearly continuously since July 1999, with a 16-day repeat cycle. Landsat ETM+ image data consist of eight spectral bands (band designations), with a spatial resolution of 30 meters for bands 1 to 5 and band 7. Resolution for band 6 (thermal infrared) is 60 meters and resolution for band 8 (panchromatic) is 15 meters. Approximate scene size is 170 km north-south by 183 km east-west (106 mi by 114 mi). The Level 0R data product is reformatted raw data. Reformatting involves shiftin pixels by integer amounts to correct for three effects: 1) the alternating forward-reverse scanning pattern of the Landsat ETM+ sensor; 2) the odd-even detector arrangement within each band; and 3) the detector offsets inherent in engineering design of the focal plane array. Pixels in L0R images are not resampled, nor are they geometrically corrected or registered, which means that the pixels are NOT aligned per scan line. The Level 1T (L1T) data product provides systematic radiometric accuracy, geometric accuracy by incorporating ground control points, while also employing a Digital Elevation Model (DEM) for topographic accuracy. Geodetic accuracy of the product depends on the accuracy of the ground control points and the resolution of the DEM used.
MODIS-derived Snow Metrics The National Park Service and Geographic Information Network of Alaska (GINA) are developing an algorithm to derive snow cover climatology for Alaska using the Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover daily product. The algorithm is two-fold and involves both data processing and the derivation of snow cover metrics. Terra MODIS snow cover daily 500m grid data (MOD10A1) are processed to reduce cloud obscuration through iterations of cloud reduction methods that include spatial, temporal, and snow cycle filtering. MRT tool is used to mosaic daily tile files and re-sample the data. A total of 12 metrics (e.g. date of first snow, date of persistent snow cover) for each pixel are calculated. IDL with ENVI subroutines were used to develop the algorithm.
MODIS/Aqua Surface Reflectance 8-Day L3 Global 500m SIN Grid MODIS/Terra Surface Reflectance 8-Day L3 Global 500m SIN Grid
MODIS/Aqua Surface Reflectance Daily L2G Global 1km and 500m SIN Grid MODIS/Aqua Surface Reflectance Daily L2G Global 1km and 500m SIN Grid
MODIS/Terra Gross Primary Productivity 8-Day L4 Global 500m SIN Grid The MOD17A2H version 6 Gross Primary Productivity (GPP) product is a cumulative 8-day composite of values with 500 meter pixel size based on the radiation-use efficiency concept that can be potentially used as inputs to data models to calculate terrestrial energy, carbon, water cycle processes, and biogeochemistry of vegetation. The data product includes information about Gross Primary Productivity (GPP) and Net Photosynthesis (PSN). The PSN band values are the GPP minus the Maintenance Respiration (MR). The data product also contains a PSN Quality Control layer. The quality layer contains quality information for both the GPP and the PSN. Stage 3 validation has been achieved for MOD17 products.
 
MODIS/Terra Land Surface Temperature/Emissivity 8-Day L3 Global 1km SIN Grid The MOD11A2 version 6 product provides an average, 8-day, per-pixel land surface temperature (LST) in a 1200 x 1200 kilometer grid. Each pixel value in the MOD11A2 is a simple average of all the corresponding MOD11A1 LST pixels collected within that 8 day period. The 8 day compositing period was chosen because twice that period is the exact ground track repeat period of the Terra and Aqua platforms. In this product, along with both the day- and night-time surface temperature bands and their quality indicator (QC) layers, are also MODIS bands 31 and 32 and eight observation layers. Validation at stage 2 has been achieved for all MODIS LST/Emissivity products.
 
MODIS/Terra Land Surface Temperature/Emissivity Monthly L3 Global 0.05Deg CMG The MOD11C3 Version 6 product provides daily land surface temperature (LST) and emissivity values in a 0.05 (5600 m x 5600 m) degree latitude/longitude climate modeling grid (CMG). A CMG granule is a Geographic grid with 7200 columns and 3600 rows representing the entire globe. The LST and emissivity values in the MOD11C3 product are derived by compositing and averaging the values from the corresponding months MOD11C1 daily files. The MOD11C3 granule consists of 17 layers. These layers include day and night LST and their corresponding quality indicator (QC) layers, six Emissivity layers, and seven observation layers. Validation at stage 2 has been achieved for all MODIS LST/Emissivity products.
 
MODIS/Terra Leaf Area Index/FPAR 8-Day L4 Global 500m SIN Grid The MOD15A2H version 6 MODIS Level 4, Combined Fraction of Photosynthetically Active Radiation (FPAR), and Leaf Area Index (LAI) product is an 8-day composite data set with 500 meter pixel size. The algorithm chooses the “best” pixel available from all the acquisitions of the Terra sensor from within the 8- day period. LAI is defined as the one-sided green leaf area per unit ground area in broadleaf canopies and as one-half the total needle surface area per unit ground area in coniferous canopies. FPAR is defined as the fraction of incident photosynthetically active radiation (400-700nm) absorbed by the green elements of a vegetation canopy.The LAI product has attained stage 2 validation and the FPAR product has attained stage 1 Validation.
 
MODIS/Terra Surface Reflectance 8-Day L3 Global 500m SIN Grid MODIS/Terra Surface Reflectance 8-Day L3 Global 500m SIN Grid
MODIS/Terra Surface Reflectance Daily L2G Global 1km and 500m SIN Grid MODIS/Terra Surface Reflectance Daily L2G Global 1km and 500m SIN Grid
MODIS/Terra Surface Reflectance Daily L2G Global 250m SIN Grid The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric scattering or absorption. Low-level data are corrected for atmospheric gases and aerosols, yielding a level-2 basis for several higher-order gridded level-2 (L2G) and level-3 products.

MOD09GQ provides Bands 1 and 2 at a 250-meter resolution in a daily gridded L2G product in the Sinusoidal projection. Science Data Sets provided for this product include reflectance for Bands 1 and 2, a quality rating, observation coverage, and observation number. This product is meant to be used in conjunction with the MOD09GA, where important quality and viewing geometry information is stored.

Version-5 MODIS/Terra Surface Reflectance products are Validated Stage 2, meaning that accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts. 
MODIS/Terra Thermal Anomalies/Fire Daily L3 Global 1km SIN Grid MODIS Thermal Anomalies/Fire products are primarily derived from MODIS 4- and 11-micrometer radiances. The fire detection strategy is based on absolute detection of a fire (when the fire strength is sufficient to detect), and on detection relative to its background (to account for variability of the surface temperature and reflection by sunlight). Numerous tests are employed to reject typical false alarm sources like sun glint or an unmasked coastline.



MOD14A1 is produced every 8 days at 1-kilometer resolution as a gridded level-3 product in the Sinusoidal projection. This product is unique in that it has three dimensions: fire-mask (1D) and a maximum fire-radiative-power (2D) are provided for each day (3D) in the 8-day period. For example, the fire-mask contains eight, band sequential (day) 1200 x 1200 images of fire data representing consecutive days of data collection.



The Terra MODIS instrument acquires data twice daily (10:30 AM and PM), as does the Aqua MODIS (2:30 PM and AM). These four daily MODIS fire observations serve to advance global monitoring of the fire process and its effects on ecosystems, the atmosphere, and climate.



Version-5 MODIS Thermal Anomalies & Fire products have attained Validation Stage 3, which was completed using active fire reference data that were derived from ASTER and Landsat-5 TM (30 m resolution) data sources.
MODIS/Terra Vegetation Indices 16-Day L3 Global 250m SIN Grid The MOD13Q1 Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The first is the Normalized Difference Vegetation Index (NDVI) which is referred to as the continuity index to the existing National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer (NOAA-AVHRR) derived NDVI. The second vegetation layer is the Enhanced Vegetation Index (EVI), which has improved sensitivity over high biomass regions. The grid consists of 4,800 rows and 4,800 columns of 250 meter pixels. The algorithm chooses the best available pixel value from all the acquisitions from the 16 day period. The criteria used is low clouds, low view angle and the highest NDVI/EVI value. Along with the Vegetation layers and the two QA layers the HDF file will have MODIS Reflectance bands 1 (Red), 2 (NIR), 3 (Blue), and 7 (MIR), as well as four observation layers. Validation at stage 3 has been achieved for all MODIS MOD/MYD13 vegetation products.
 
MODIS/Terra Vegetation Indices Monthly L3 Global 1km SIN Grid The MOD13A3 Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The algorithm for this product chooses the best available pixel value from all the acquisitions from the 16 day period. The criteria used is low clouds, low view angle and the highest NDVI/EVI value. The first is the Normalized Difference Vegetation Index (NDVI), which is referred to as the continuity index to the existing National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer (NOAA-AVHRR) derived NDVI. The second vegetation layer is the Enhanced Vegetation Index (EVI), which has improved sensitivity over high biomass regions. Provided along with the Vegetation layers and the two Quality Assurance (QA) layers and Reflectance bands 1 (Red), 2 (Near-Infrared), 3 (Blue), and 7 (Mid-Infrared), as well as four observation layers. Validation at stage 3 has been achieved for all MODIS MOD/MYD13 vegetation products.
 
Pre-ABoVE: Remotely Sensed Active Layer Thickness, Barrow, Alaska, 2006-2011 Active layer thickness (ALT) is a critical parameter for monitoring the status of permafrost that is typically measured at specific locations using probing, in situ temperature sensors, or other ground-based observations. The thickness of the active layer is the average annual thaw depth, in permafrost areas, due to solar heating of the surface. This data set includes the mean Remotely Sensed Active Layer Thickness (ReSALT) over years 2006 to 2011 for the region near Barrow, Alaska. The data were produced by an Interferometric Synthetic Aperture Radar (InSAR) technique that measures seasonal surface subsidence and infers ALT. ReSALT estimates were validated by comparison with ground-based ALT obtained using probing and Ground Penetrating Radar at multiple sites. These results indicate remote sensing techniques based on InSAR could be an effective way to measure and monitor ALT over large areas on the Arctic coastal plain. These data provide gridded (30-m) estimates of active layer thickness (cm; ALT) and seasonal subsidence (cm), as well as calculated uncertainty in each of these parameters. This data set was developed in support  of NASA's Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign.
Pre-ABoVE: Remotely Sensed Active Layer Thickness, Prudhoe Bay, Alaska, 1992-2000 Active layer thickness (ALT) is a critical parameter for monitoring the status of permafrost that is typically measured at specific locations using probing, in situ temperature sensors, or other ground-based observations. The thickness of the active layer is the average annual thaw depth, in permafrost areas, due to solar heating of the surface. This data set includes the mean Remotely Sensed Active Layer Thickness (ReSALT) over years 1992 to 2000 for an area near Prudhoe Bay, Alaska. The data were produced by an Interferometric Synthetic Aperture Radar (InSAR) technique that measures seasonal surface subsidence and infers ALT. ReSALT estimates were validated by comparison with ground-based ALT measurements at multiple sites. These results indicate remote sensing techniques based on InSAR could be an effective way to measure and monitor ALT over large areas on the Arctic coastal plain.These data provide gridded (100-m) estimates of active layer thickness (cm; ALT), seasonal subsidence (cm) and subsidence trend (mm/yr), as well as calculated uncertainty in each of these parameters. This data set was developed in support  of NASA's Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign.The data are presented in one netCDF (*.nc) file. .