Name: SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture, Version 5
Creator: National Snow and Ice Data Center
Keywords: BRIGHTNESS TEMPERATURE,SURFACE SOIL MOISTURE

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

Data set id:

SPL2SMP_E

DOI: 10.5067/LOT311EZHH8S

Data Citation and Acknowledgment
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O'Neill, P. E., Chan, S., Njoku, E. G., Jackson, T., Bindlish, R., Chaubell, J. & Colliander, A. (2021). SMAP Enhanced L2 Radiometer Half-Orbit 9 km EASE-Grid Soil Moisture. (SPL2SMP_E, Version 5). [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/LOT311EZHH8S. [describe subset used if applicable]. Date Accessed 11-15-2026.

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Literature references: Please include the following literature citations in addition to the data citation above:

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

There is a more 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.

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 TEMPERATURE

SURFACE SOIL MOISTURE

Platform(s):

SMAP

Sensor(s):

SMAP L-BAND RADIOMETER

Data Format(s):

HDF5

Temporal Coverage:

31 March 2015 to 4 December 2023

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:

Northern latitude
90
Southern latitude
-85.044
Eastern longitude
180
Western longitude
-180

Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.

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Data Access & Tools

This data set has been retired. There is a more recent version of these data.

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