• On Wednesday, May 29 from 9:00 a.m. to 11:00 a.m. (US Mountain Time), the following data collections may not be available due to a planned system maintenance: ASO, AMSR Unified, AMSR-E, Aquarius, High Mountain Asia, IceBridge, ICESat/GLAS, ICESat-2, LVIS, MEaSUREs, MODIS, Nimbus, SMAP, SnowEx, SSM/I-SSMIS and VIIRS. Users of the SMAP near real-time products should use the Persistent HTTPS File System for data access. 

SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data, Version 7
Data set id:
SPL4SMGP
DOI: 10.5067/EVKPQZ4AFC4D
This is the most recent version of these data.
Version Summary
Changes to this version include:
- The Catchment model now includes the PEATCLSM hydrology module for peatlands and uses an updated global map of peatland distribution.
- Revised parameters are used in the L-band radiative transfer model that converts the simulated soil moisture and temperature estimates into Tb predictions for the radiance-based L4_SM analysis. Specifically, the L-band parameters for scattering albedo climatology, soil roughness climatology, and (seasonally-varying) vegetation opacity climatology are obtained from the SPL2SMP_E, Version 5, dual-channel retrieval product (April 2015 - March 2022).
- The brightness temperature scaling parameters in the updated Level-4 soil moisture algorithm are based on seven years of SMAP observations and model simulations (April 2015 - March 2022).
- For peatlands, the EnKF state vector now additionally includes the "catchment deficit" model prognostic variable.

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

Overview

SMAP Level-4 (L4) surface and root zone soil moisture data are provided in three products: * SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data (SPL4SMGP, DOI: 10.5067/EVKPQZ4AFC4D) * SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU, DOI: 10.5067/LWJ6TF5SZRG3) * SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM, DOI: 10.5067/KN96XNPZM4EG). For each product, SMAP L-band brightness temperature data from descending and ascending half-orbit satellite passes (approximately 6:00 a.m. and 6:00 p.m. local solar time, respectively) are assimilated into a land surface model that is gridded using an Earth-fixed, global cylindrical 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) projection.
Parameter(s):
ROOT ZONE SOIL MOISTURESURFACE SOIL MOISTURE
Platform(s):
GEOS-5, SMAP
Sensor(s):
NOT APPLICABLE, SMAP L-BAND RADIOMETER
Data Format(s):
HDF5
Temporal Coverage:
31 March 2015 to present
Temporal Resolution:
  • 3 hour
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

A free NASA Earthdata Login account is required to access these data. Learn More

Help Articles

General Questions & FAQs

OPeNDAP, the Open-source Project for a Network Data Access Protocol, is a NASA community standard DAP that provides a simple way for researchers to access and work with data over the internet.
SMAP Ancillary data sets are used to produce SMAP Level-1, -2, -3, and -4 standard 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.
There are a few reasons that the soil moisture data values in SMAP Level-4 data products may vary from what you expect in a particular region. The first step a data user should take in investigating apparently anomalous values is to look at the rich quality information and other data flags c
The surface and root zone soil moisture estimates in the SMAP Level-4 soil moisture products are the outputs of a land surface model into which SMAP observations of brightness temperature have been assimilated.

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.
This step-by-step tutorial demonstrates how to access MODIS and SMAP data using the Application for Extracting and Exploring Analysis Ready Samples (AppEEARS). AppEEARS allows users to access, explore, and download point and area data with spatial, temporal, and parameter subsets.
The following are instructions on how to import and geolocate SMAP Level-3 Radiometer Soil Moisture HDF5 data in ENVI. Testing notes Software: ENVI Software version: 5.3 Platform: Windows 7
This How to guide outlines the steps for properly importing, projecting and visualizing HDF and NetCDF files in ArcMap. A couple of things to note before you start:
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) can be accessed directly from our HTTPS file system, using wget or curl. Basic command line instructions are provided in the article below. 
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 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.