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Data Set ID:
SPL2SMP_E

SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture, Version 5

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].

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.

COMPREHENSIVE Level of Service

Data: Data integrity and usability verified; data customization services available for select data

Documentation: Key metadata and comprehensive user guide available

User Support: Assistance with data access and usage; guidance on use of data in tools and data customization services

See All Level of Service Details

Parameter(s):
  • MICROWAVE > BRIGHTNESS TEMPERATURE
  • SOILS > SOIL MOISTURE/WATER CONTENT > SURFACE SOIL MOISTURE
Data Format(s):
  • HDF5
Spatial Coverage:
N: 90, 
S: -85.044, 
E: 180, 
W: -180
Platform(s):SMAP
Spatial Resolution:
  • 9 km x 9 km
Sensor(s):SMAP L-BAND RADIOMETER
Temporal Coverage:
  • 31 March 2015
Version(s):V5
Temporal Resolution49 minuteMetadata XML:View Metadata Record
Data Contributor(s):O'Neill, P. E., S. Chan, E. G. Njoku, T. Jackson, R. Bindlish, J. Chaubell, and A. Colliander.

Geographic Coverage
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As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

O'Neill, P. E., S. Chan, E. G. Njoku, T. Jackson, R. Bindlish, J. Chaubell, and A. Colliander. 2021. SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture, Version 5. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/LOT311EZHH8S. [Date Accessed].

Literature Citation

As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.

  • Chan, S., R. Bindlish, P. E. O'Neill, T. Jackson, E. G. Njoku, S. Dunbar, J. Chaubell, J. R. Piepmeier, S. Yueh, D. Entekhabi, A. Colliander, F. Chen, M. Cosh, T. Caldwell, J. Walker, A. Berg, H. McNairn, M. Thibeault, J. Martinez-Fernandez, F. Uldall, M. Seyfried, D. Bosch, P. Starks, C. Holifield -Collins, J. Prueger, R. Van der Velde, J. Asanuma, M. Palecki, E. E. Small, M. Zreda, J. Calvet, W. T. Crow, and Y. Kerr. 2018. Development and assessment of the SMAP enhanced passive soil moisture product, Remote Sensing of the Environment. 204. 931–941. https://doi.org/10.1016/j.rse.2017.08.025

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How To

Programmatic Data Access Guide
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 or through our Application Programming Interface (API). Our API offers you the ability to order data using specific temporal and spatial filters... read more
How to import and geolocate SMAP Level-1C and Level-2 data in ENVI
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 set: SMAP L1C... read more
How do I interpret the surface and quality flag information in the Level-2 and -3 passive soil moisture products?
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: Level-2 soil moisture product (SPL2SMP)... read more
Visualize NSIDC data as WMS layers with ArcGIS and Google Earth
NASA's Global Imagery Browse Services (GIBS) provides up to date, full resolution imagery for selected NSIDC DAAC data sets. ... read more
Search, order, and customize NSIDC DAAC data with NASA Earthdata Search
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. Thousands of Earth science data... read more
Filter and order from a data set web page
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.  Step 1: Go to a data set web page This article will use the... read more
How do I convert an HDF5/HDF-EOS5 file into binary format?
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. Full instructions for installing and using h5dump on Mac/Unix and... read more
Visualize and download NSIDC DAAC data with NASA Worldview
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). The map interface allows users to... read more
NSIDC DAAC Data Subscription Requests
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. The service cannot be applied to past data already archived at NSIDC. This service is... read more

FAQ

What are the latencies for SMAP radiometer data sets?
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. Short name Title Latency Required # days hh:mm:ss Actual (... read more
What data subsetting, reformatting, and reprojection services are available for SMAP data?
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. Short name Title Subsetting Reformatting... read more
Why don't the SMAP enhanced soil moisture products include landcover class?
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. This is because the landcover class ancillary data are not available at the 9 km grid posting that the... read more
How are the enhanced SMAP radiometer products generated and what are the benefits of using these products?
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. The IFOVs are spaced about 11 km apart in the along scan direction with scan lines... read more
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