SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture, Version 5 (SPL2SMP_E)
Data set:
SPL2SMP_E
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This is the most recent version of these data.
Version Summary
Changes to this version include:
- Dual Channel Algorithm (DCA) replaces Single Channel Algorithm – Vertical (SCA-V) as baseline algorithm.
- Addition of north-polar grid soil moisture retrievals which are intended to mitigate the distortion of global-grid cells at high northern latitudes (> 50N). These are presented in the products in the new Soil_Moisture_Retrieval_Data_Polar data group.
- Addition of the soil texture elements organic_content and sand_fraction in both global and polar grid groups.
- Bulk_density maximum value changed from 1 to 2.65.

Overview

This enhanced Level-2 (L2) product contains calibrated, geolocated, brightness temperatures acquired by the Soil Moisture Active Passive (SMAP) radiometer during 6:00 a.m. descending and 6:00 p.m. ascending half-orbit passes. This product is derived from SMAP Level-1B (L1B) interpolated antenna temperatures. Backus-Gilbert optimal interpolation techniques are used to extract maximum information from SMAP antenna temperatures and convert them to brightness temperatures, which are posted to the 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) in a global cylindrical projection [available as the SPl1CTB_E product]. As of 2021, the data are also posted to the Northern Hemisphere EASE-Grid 2.0, an azimuthal equal-area projection. These 9-km brightness temperatures are then used to retrieve surface soil moisture posted on the 9-km grid [this SPL2SMP_E product].
Parameter(s):
BRIGHTNESS TEMPERATURE SURFACE SOIL MOISTURE
Platform(s):
SMAP
Sensor(s):
SMAP L-BAND RADIOMETER
Data Format(s):
HDF5
Temporal Coverage:
31 March 2015 to present
Temporal Resolution:
49 minute
Spatial Resolution:
9 km
9 km
Spatial Coverage:
N:
90
S:
-85.044
E:
180
W:
-180

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Many NSIDC DAAC data sets can be accessed using the NSIDC DAAC's Data Access Tool. This tool provides the ability to search and filter data with spatial and temporal constraints using a map-based interface. Users have the option to
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The following are instructions on how to import and geolocate SMAP Level-1C HDF5 data in ENVI. Testing notes Software: ENVI Software version: 5.3 and above. If using version 5.3, service pack 5.3.1 is needed.  Platform: Windows 7
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Getting started

There is considerable overlap of the SMAP radiometer footprints, or Instantaneous Fields of View (IFOVs), which are defined by the contours where the sensitivity of the antenna has fallen by 3db from its maximum.
SMAP data files contain rich quality information that can be useful for many data users. The retrieval quality flag and surface flag bit values and interpretations are documented in the respective product Data Fields pages of the user guides for these data products
The following table describes both the required and actual latencies for the different SMAP radiometer data sets. Latency is defined as the time (# days, hh:mm:ss) from data acquisition to product generation.
This short article describes the customization services available for SMAP data using Earthdata Search.
While the standard SMAP Level-2 and -3 radiometer soil moisture products contain landcover_class and landcover_class_fraction in the data files, the enhanced soil moisture products do not.