SMAP Data Products
The SMAP baseline science-data products will be publicly available through two NASA-designated data centers, the Alaska Satellite Facility (ASF) and the National Snow and Ice Data Center (NSIDC) DAAC. ASF will distribute the Level 1 radar products and NSIDC will distribute the radiometer and Level 2-4 products. All products will conform to the HDF-5 standard.
SMAP synthetic aperture radar (SAR) data have a spatial resolution of 1-3 km over the outer 70% of the swath (L1C_S0_HiRes product). The low-resolution radar data are ‘slices’ of resolution approximately 5 km x 30 km (L1B_S0_LoRes product). The radiometer data have a spatial resolution (IFOV) of 39 km x 47 km, nominally referred to as 40-km resolution (L1B_TB product). The L1C_TB data products are resampled TB data on a 36-km Earth grid and will have spatial resolution ~10% greater than the L1B_TB data (depending on the resampling method).
SMAP science-data products will be generated on the Science-Data System production system using science software developed on the SDS Testbed. The science software is based on algorithms for each product described in the Algorithm Theoretical Basis Documents (ATBDs).
(Beta Level 1 radar products now available for download)
| Short Name | Description | Gridding (km) | Latency* | ATBD** | Product Spec Doc | Source |
|---|---|---|---|---|---|---|
| L1A_Radar | Raw radar data in time order (half orbit) | - | 12 hrs | n/a | View | ASF |
| L1A_Radiometer | Radiometer raw data in time order | - | 12 hrs | n/a | NSIDC | |
| L1B_S0_LoRes | Low-resolution radar σ ο in time order (half orbit) Backscatter analysis document | 5x30 | 12 hrs | View | View | ASF |
| L1B_TB | Radiometer TB in time order | 36x47 | 12 hrs | View | NSIDC | |
| L1C_S0_HiRes | High-resolution radar σ ο (half orbit gridded) Backscatter analysis document | 1 (1-3)*** | 12 hrs | View | View | ASF |
| L1C_TB | Radiometer T B (half orbit, gridded) | 36 | 12 hrs | View | NSIDC | |
| L2_SM_A | Soil moisture (radar, half orbit) | 3 | 24 hrs | View | NSIDC | |
| L2_SM_P | Soil moisture (radiometer, half orbit) | 36 | 24 hrs | View | NSIDC | |
| L2_SM_A/P | Soil moisture (radar/radiometer, half orbit) | 9 | 24 hrs | View | NSIDC | |
| L3_F/T_A | Freeze-thaw state (radar, daily composite) | 3 | 50 hrs | View | NSIDC | |
| L3_SM_A | Soil moisture (radar, daily composite) | 3 | 50 hrs | View | NSIDC | |
| L3_SM_P | Soil moisture (radiometer, daily composite) | 36 | 50 hrs | View | NSIDC | |
| L3_SM_A/P | Soil moisture (radar/radiometer, daily composite) | 9 | 50 hrs | View | NSIDC | |
| L4_SM | Soil moisture (surface and root zone) | 9 | 7 days | View | NSIDC | |
| L4_C | Carbon net ecosystem exchange (NEE) | 9 | 14 days | View | NSIDC |
*Mean latency under normal operating conditions (defined as time from data acquisition by the observatory to availability to the public data archive).
**Algorithm Theoretical Basis Documents (ATBDs) provide the physical and mathematical descriptions of the algorithms used in the generation of science-data products. The ATBDs include a description of variance and uncertainty estimates and considerations of calibration and validation, exception control, and diagnostics. Internal and external data flows are also described.
***Over outer 70% of swath
Ancillary Data Reports
The SMAP Ancillary Data Reports below hold application-related descriptions of datasets used with science-algorithm software in generating SMAP science-data products, as well as links to EASE grid information relevant to SMAP products.
These reports may undergo additional updates as new ancillary datasets or processing methods become available.
| Data Reports | Ancillary Data Examples | Main Ancillary Data Cited |
|---|---|---|
| Crop Type |  | USDA Cropland Data ECOCLIMAP (global database of land surface parameters) |
| Landcover |  | MODIS Land Cover Type (NASA Moderate Resolution Imaging Spectroradiometer) |
| Digital Elevation Model |  | JPL Global Digital Elevation Model |
| Soil Attributes |  | Harmonized World Soil Database |
| Static Water Fraction |  | MODIS Water Mask |
| Urban Area |  | Gridded Population of the World (GRUMP) |
| Vegetation Water Content |  | Normalized Difference Vegetation Index (NDVI) |
| Permanent Ice |  | MODIS Products Table |
| Precipitation |  | ECMWF (European Centre for Medium-Range Weather Forecasts) |
