SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture, Version 5
Data set id:
SPL2SMP_E
DOI: 10.5067/LOT311EZHH8S
There is a more recent version of these data.
Version Summary
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.
- 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 TEMPERATURESURFACE 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 Reference System(s):
WGS 84 / NSIDC EASE-Grid 2.0 North
EPSG:6931
WGS 84 / NSIDC EASE-Grid 2.0 Global
EPSG:6933
Spatial Coverage:
N:
90
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
A free NASA Earthdata Login account is required to access these data. Learn More
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
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
Data subscriptions are available for select NSIDC DAAC data collections. Once signed up, the subscription service automatically sends you new data as they are delivered from active NASA satellite missions.
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.
This article highlights the NSIDC DAAC data sets available with customization options and outlines a workflow for searching, ordering, and customizing data in NASA Earthdata Search. This approach is ideal for users who want to download data to their local machine.
NASA Worldview is a map interface that allows users to interactively browse imagery, create visualizations, and download the underlying data.
NASA's Global Imagery Browse Services (GIBS) provides up to date, full resolution imagery for selected NSIDC DAAC data sets.