SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture, Version 3
Data set id:
SPL2SMP_E
DOI: 10.5067/017XZSKMLTT2
There is a more recent version of these data.
Version Summary
For the full major and minor version history, go to https://nsidc.org/data/smap/version-history
Version Summary
Changes to this version include:
- The Dual Channel Algorithm (DCA) has been replaced by the Modified Dual Channel Algorithm (MDCA). MDCA achieves better retrieval performance through the modeling of polarization mixing between the vertically and horizontally polarized brightness temperature channels, as well as new estimates of single-scattering albedo and roughness coefficients. MDCA supersedes optional algorithms MPRA (option 4) and E-DCA (option 5).
- As part of the option algorithm changes, the following data fields were removed: soil_moisture_option4, vegetation_opacity_option4, retrieval_qual_flag_option4, soil_moisture_option5, vegetation_opacity_option5, retrieval_qual_flag_option5.
- As part of the option algorithm changes, the following data fields were added: albedo_option3, roughness_coefficient_option3, bulk_density, clay_fraction.
- The baseline algorithm (SCA-V) remains unchanged.
- Improved aggregation of values in input ancillary data, e.g. roughness, soil texture, NDVI. The fix has negligible impacts on retrievals estimated to be of recommended quality.
For the full major and minor version history, go to https://nsidc.org/data/smap/version-history
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.
Parameter(s):
BRIGHTNESS TEMPERATURESOIL MOISTURE
Platform(s):
SMAP
Sensor(s):
SMAP L-BAND RADIOMETER
Data Format(s):
HDF5
Temporal Coverage:
31 March 2015 to 27 August 2020
Temporal Resolution:
- 49 minute
Spatial Resolution:
- 9 km
- 9 km
Spatial Reference System(s):
WGS 84 / NSIDC EASE-Grid 2.0 Global
EPSG:6933
Spatial Coverage:
N:
85.044
S:
-85.044
E:
180
W:
-180
Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.
Data Access & Tools
This data set has been retired. There is a more recent version of these data.
Documentation
User Guide
ATBDs
General Resources
Quality Assessment Reports
Product Specification Documents
Help Articles
General Questions & FAQs
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.
How to Articles
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
Harmony API Quickstart Guide: Customizing NASA NSIDC DAAC data in Earthdata Cloud
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.
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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All data from the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) is directly accessible through our HTTPS file system using Wget or curl. This article provides basic command line instructions for accessing data using this method.
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