This Near Real-Time (NRT) data set corresponds to the standard SMAP L1B Radiometer Half-Orbit Time-Ordered Brightness Temperatures (SPL1BTB) product. The data provide calibrated estimates of time-ordered geolocated brightness temperature data measured by the Soil Moisture Active Passive (SMAP) passive microwave radiometer, the SMAP L-band radiometer. These Near Real-Time data are available within three hours of satellite observation. The data are created using the latest available ancillary data and spacecraft and antenna attitude data to reduce latency. The SMAP satellite orbits Earth every two to three days, providing half-orbit, ascending and descending, coverage from 86.4°S to 86.4°N in swaths 1000 km across. Data are stored for approximately two to three weeks. Thus, at any given time, users have access to at least fourteen consecutive days of Near Real-Time data through the NSIDC DAAC. Users deciding between the NRT and standard SMAP products should consider the immediacy of their needs versus the quality of the data required. Near real-time data are provided for operational needs whereas standard products meet the quality needs of scientific research. If latency is not a primary concern, users are encouraged to use the standard science product, SPL1BTB (https://doi.org/10.5067/ZHHBN1KQLI20).

The MODIS Near Real Time (NRT) Combined Aqua and Terra Nadir BRDF-Adjusted Reflectance, MCD43A4N, Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) dataset is produced daily using 16 days of Terra and Aqua MODIS data at 500 meter (m) resolution. This product in sinusoidal map projection that provides view angle corrected Nadir BRDF-Adjusted Reflectances (NBAR) at local solar noon for the 7 land bands, along with corresponding mandatory QA dataset.

There is a significant change in the science algorithm of the Collection 61 (C61) NRT BRDF/Albedo products and, therefore significant differences/discontinuities between the C6 and C61 products. C61 algorithm changes are intended to minimize the differences between the NRT and Standard BRDF. The C61 NRT BRDF code has been modified to allow for an extra round of magnitude inversion, following a full inversion using the full set of inputs. This extra magnitude inversion will only use the set of 9 days that are overlapping between standard and NRT, with the highest weight being assigned to the last day.

Additional information from MODIS Land Science Team at:
https://modis-land.gsfc.nasa.gov/brdf.html

The MODIS Near Real Time (NRT) Combined Aqua and Terra Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Quality, MCD43A2N is a L3 daily 16-day composite global gridded tiled product that provides full set of quality control flags for use in determining the quality of the retrievals at pixel level in the daily L3 BRDF/Albedo suite of products: BRDF/Albedo Model Parameters (MCD43A1N), Albedo (MCD43A3N) and the NBAR (MCD43A4N).

There is a significant change in the science algorithm of the Collection 61 (C61) NRT BRDF/Albedo products and, therefore significant differences/discontinuities between the C6 and C61 products. C61 algorithm changes are intended to minimize the differences between the NRT and Standard BRDF. The C61 NRT BRDF code has been modified to allow for an extra round of magnitude inversion, following a full inversion using the full set of inputs. This extra magnitude inversion will only use the set of 9 days that are overlapping between standard and NRT, with the highest weight being assigned to the last day.

Additional information from MODIS Land Science Team at https://modis-land.gsfc.nasa.gov/brdf.html

The MODIS Near Real Time (NRT) MCD43A1N, MODIS Combined Aqua and Terra Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameters is produced daily using 16 days of Terra and Aqua MODIS data. This global gridded tiled product provides model parameters/coefficients (isotropic, volume and surface) for characterizing the BRDF of each pixel at 500m resolution in the sinusoidal map projection. BRDF at each pixel for the current day is derived by inverting all available good quality corrected surface reflectance observations acquired by Terra and Aqua MODIS from the 16-day period ending with the current data day. The daily observation are weighed as a function of quality, observation coverage and temporal distance from the current data date. Model parameters are stored as 3D datasets for each of the 7 land bands, visible, near-infrared and shortwave bands along with corresponding mandatory QA flags.
There is a significant change in the science algorithm of the Collection 61 (C61) NRT BRDF/Albedo products and, therefore significant differences/discontinuities between the C6 and C61 products. C61 algorithm changes are intended to minimize the differences between the NRT and Standard BRDF. The C61 NRT BRDF code has been modified to allow for an extra round of magnitude inversion, following a full inversion using the full set of inputs. This extra magnitude inversion will only use the set of 9 days that are overlapping between standard and NRT, with the highest weight being assigned to the last day.

Additional information at MODIS Land Science Team website at https://modis-land.gsfc.nasa.gov/brdf.html

The MODIS Near Real Time (NRT) Combined Aqua and Terra Albedo, MCD43A3N is the daily L3 16-day composite global gridded tiled product that provides the black-sky albedo and the white-sky albedo at local solar noon for each of the 7 land bands, visible, near infra-red and the short wave bands. The albedo is retrieved for the current data day as identified in the product granule id using the BRDF/Albedo model parameters provided in the daily MCD43A1N product. The product also contains the mandatory QA dataset for each of the spectral albedo dataset in the file.

The C61 NRT BRDF code has been modified to allow for an extra round of magnitude inversion, following a full inversion using the full set of inputs. This extra magnitude inversion will only use the set of 9 days that are overlapping between standard and NRT, with the highest weight being assigned to the last day.

Additional information from MODIS Land Science Team website at:
https://modis-land.gsfc.nasa.gov/brdf.html

This global Level-3 (L3) data set provides monthly mean snow cover extent within 0.05° (approx. 5 km) MODIS Climate Modeling Grid (CMG) cells. This data set is derived from snow cover observations in the 'MODIS/Terra Snow Cover Daily L3 Global 0.05Deg CMG’ data set (DOI:10.5067/MODIS/MOD10C1.061).

The terms "Version 61" and "Collection 6.1" are used interchangeably in reference to this release of MODIS data.

This global Level-3 (L3) data set provides the maximum snow cover extent observed over an eight-day period within 10° x 10° MODIS sinusoidal grid tiles. Tiles are generated by compositing 500 m observations from the 'MODIS/Terra Snow Cover Daily L3 Global 500m Grid' data set (DOI:10.5067/MODIS/MOD10A1.061). A bit flag index is used to track the eight-day snow/no-snow chronology for each 500 m cell.

The terms "Version 61" and "Collection 6.1" are used interchangeably in reference to this release of MODIS data.

This global level-3 (L3) data set provides the maximum percentage of snow-covered land and persistent cloud-covered land observed over eight-days, within 0.05° (approx. 5 km) MODIS climate modeling grid (CMG) cells. Percentages are computed from snow cover observations in the 'MODIS/Terra Snow Cover 8-Day L3 Global 500m SIN Grid' data set (DOI:10.5067/MODIS/MOD10A2.061).

The terms "Version 61" and "Collection 6.1" are used interchangeably in reference to this release of MODIS data.

This global Level-2 (L2) data set provides daily snow cover detected using the Normalized Difference Snow Index (NDSI) and a series of screens designed to alleviate errors and flag uncertain snow cover detections. The NDSI is derived from radiance data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra satellite: DOI:10.5067/MODIS/MOD02HKM.061 and DOI:10.5067/MODIS/MOD021KM.061. Each data granule contains 5 minutes of swath data observed at a resolution of 500 m.

The terms "Version 61" and "Collection 6.1" are used interchangeably in reference to this release of MODIS data.

The MODIS/Terra Clear Sky Radiance 8-Day Composite Daily L3 Global 25km Equal Area (MODCSR_8) product is created from composited MODCSR_D files. Nine clear-sky radiance and reflectance statistics (bands 1-7 and 17-36, see description of the MODCSR_G product for description of statistics) are produced for day and night separately, for every calendar day from the previous eight days (eight MODCSR_D files). There must be valid clear-sky data from at least four of the eight days in order to generate a MODCSR_8 output file. The statistics include observed minus calculated data from bands 20, 22-25, and 27-36 and numbers of land vs. water observations. The data is global in extent at 25-km resolution. MODCSR_8 files are in Hierarchical Data Format (HDF).