SMAP Measurements
The list of SMAP baseline data products is shown in the table below.
Level 1: Level 1 (L1) products are calibrated sensor outputs (radar backscatter and brightness temperature) available both in time order and gridded.
Level 3: The L1 radar and radiometer data are used to retrieve estimates of soil moisture and freeze/thaw state in the top 5-cm surface layer. These variables are output as Level 3 (L3) products mapped to an Earth-fixed grid.
Level 4: The L1 and/or L3 data are assimilated with observational data from other sources into land surface models to provide estimates of water and carbon fluxes at the surface and soil moisture in the root zone (to a depth of approximately 1 meter below the surface). These estimates are output as Level 4 (L4) data products.
Spatial Resolution
SMAP radar measurements have a spatial resolution of 1-3 km, versus 40 km for the radiometer measurements. The 40-km soil moisture product (L3_SM_40km) is derived from the radiometer measurements.
The high resolution of the radar is critical for accurate determination of freeze/thaw state (L3_F/T_HiRes) in the heterogeneous landscapes of the boreal forest region north of 45N latitude.
The radar and radiometer measurements are combined to generate an intermediate resolution 10-km product (L3_SM_A/P) that optimizes the resolution and accuracy attributes of the radar and radiometer.
Data Availability
The latencies shown for the data products are the average times, under normal operating conditions, between data acquisition by the SMAP observatory and availability of the data for distribution to public users. Data distribution to public users will begin after the calibration/validation (Cal/Val) phase of the mission is complete. The Cal/Val phase follows the 60-day post launch initial orbit checkout (IOC) phase. The duration of the Cal/Val phase is 6 months for Level 1 products and 12 months for Level 3 and Level 4 products.
