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SMAP/Sentinel-1 L2 Radiometer/Radar 30-Second Scene 3 km EASE-Grid Soil Moisture, Version 3 (SPL2SMAP_S)
Data set:
SPL2SMAP_S
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This is the most recent version of these data.
Version Summary
Changes to this version include:
- An improved calibration methodology was applied to the SMAP Level-1B brightness temperatures.
- Revised the coefficients in the land surface temperature computation to be consistent with the SMAP Level-2 soil moisture passive enhanced product. The new coefficients are C=0.246, K=1.007 for AM passes and C=1.0, K=1.007 for PM passes.
- Changed the omega parameter of the tau-omega model for forest landcover classes (1-5) from 0.05 to 0.07.
- Uses a new high-resolution soil database (SoilGrid250m; Hengl et al., 2017).
- Uses bulk density to set the upper limit of the soil moisture retrievals. Previous versions used a fixed value of 0.65 m3/m3.
- Enhanced documentation on Data Flags in the User Guide to help data users to better understand and use the flags.
- Added a bit in the TB Disaggregation QC flag to indicate (1) the use of SMAP AM or PM data; and (2) the time difference (greater or less than 36 hours) between the SMAP and Sentinel observations overlap.
- Fixed the EASE_[row/column]_index_apm_[1km/3km] data fields to make them 0-based.
- Fixed the range beginning and ending time in the file metadata.

For the full major and minor version history, go to https://nsidc.org/data/smap/data_versions.

Overview

This Level-2 (L2) soil moisture product provides estimates of land surface conditions retrieved by both the Soil Moisture Active Passive (SMAP) radiometer during 6:00 a.m. descending and 6:00 p.m. ascending half-orbit passes and the Sentinel-1A and -1B radar. SMAP L-band brightness temperatures and Copernicus Sentinel-1 C-band backscatter coefficients are used to derive soil moisture data, which are then resampled to an Earth-fixed, cylindrical 3 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0). Note: These data are Beta-release quality. Additional analyses of in situ soil moisture stations will be conducted over the next several months, which should move the data quality to the validated category.
Data Contributor(s):
Das, N., D. Entekhabi, R. S. Dunbar, S. Kim, S. Yueh, A. Colliander, P. E. O'Neill, T. Jackson, T. Jagdhuber, F. Chen, W. T. Crow, J. Walker, A. Berg, D. Bosch, T. Caldwell, and M. Cosh.
Parameter(s):
BRIGHTNESS TEMPERATURE SIGMA NAUGHT SURFACE SOIL MOISTURE
Platform(s):
SENTINEL-1A, SENTINEL-1B, SMAP
Sensor(s):
C-SAR, SMAP L-BAND RADIOMETER
Data Format(s):
HDF5
Temporal Coverage:
31 March 2015 to present
Temporal Resolution:
30 second
Spatial Resolution:
3 km
3 km
Spatial Coverage:
N:
60
S:
-60
E:
180
W:
-180

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Help Articles

How To

Many NSIDC data set web pages provide the ability to search and filter data with spatial and temporal contstraints using a map-based interface. This article outlines how to order NSIDC DAAC data using advanced searching and filtering. 
To convert HDF5 files into binary format you will need to use the h5dump utility, which is part of the HDF5 distribution available from the HDF Group. How you install HDF5 depends on your operating system.
Data subscriptions are available for select NSIDC DAAC data collections (found below). Our subscription service automatically sends you new data as they are delivered from active NASA satellite missions.
This articles provides an example MATLAB snippet to read and plot SMAP/Sentinel-1 L2 Radiometer/Radar 30-Second Scene 3 km EASE-Grid Soil Moisture HDF5 soil moisture and brightness temperature data, as well as the related surface and quality flags.
NASA Earthdata Search is a map-based interface where a user can search for Earth science data, filter results based on spatial and temporal constraints, and order data with customizations including re-formatting, re-projecting, and spatial and parameter subsetting.
NASA Worldview uses the Global Imagery Browse Service (GIBS) to provide up to date, full resolution imagery for select NSIDC DAAC data sets (see attachments below).
NASA's Global Imagery Browse Services (GIBS) provides up to date, full resolution imagery for selected NSIDC DAAC data sets. 

Getting started

The following table describes the data subsetting, reformatting, and reprojection services that are currently available for SMAP data via the NASA Earthdata Search, a Data Subscription, and Programmatic Access.