SPL3SMP_E.006 SMAP L3 Radiometer Global Daily 9 km Soil Moisture

NASA/SMAP/SPL3SMP_E/006
Dataset Availability
2023-12-04T12:00:00Z–2024-04-10T00:00:00Z
Dataset Provider
Earth Engine Snippet
ee.ImageCollection("NASA/SMAP/SPL3SMP_E/006")
Tags
drought nasa smap soil-moisture surface weather

Description

Data prior from 2023-12-04 are available in the older NASA/SMAP/SPL3SMP_E/005 collection. They will eventually be reprocessed and added to this collection.

This Level-3 (L3) soil moisture product provides a daily composite of global land surface conditions retrieved by the Soil Moisture Active Passive (SMAP) L-Band radiometer. The daily data here were collected from the descending (local solar time of 6 am) and ascending (local solar time of 6 pm) passes.

The SMAP mission is an orbiting observatory that measures the amount of water in the surface soil everywhere on Earth. A detailed description can be found in the SMAP Handbook. It was launched in January 2015 and started operation in April 2015. The radar instrument, ceasing operation in early 2015 due to failure of radar power supply, collected close to 3 months of science data. The prime mission phase of three years was completed in 2018, and since then SMAP has been in extended operation phase.

SMAP measures soil moisture every 2-3 days. This permits changes around the world to be observed over time scales ranging from major storms to repeated measurements of changes over the seasons.

Everywhere on Earth not covered with water or not frozen, SMAP measures how much water is in the top layer of soil. It also distinguishes between ground that is frozen or thawed. Where the ground is not frozen, SMAP measures the amount of water found between the minerals, rocky material, and organic particles found in soil everywhere in the world (SMAP measures liquid water in the top layer of ground but is not able to measure the ice.)

SPL3SMP_E data are transformed to geographic coordinates using GDAL libraries before the data are ingested into Google Earth Engine.

See the SMAP L3 Soil Moisture User Guide and references therein for additional documentation and algorithm details.

See basic and advanced tutorials to learn how to use SMAP data in Earth Engine.

Bands

Resolution
9000 meters

Bands

Name Units Min Max Description
soil_moisture_am Volume fraction

Retrieved soil moisture estimate from the disaggregated/downscaled vertical polarization brightness temperature at 9-km grid cell; AM overpass

tb_h_corrected_am K 0 330

Weighted average of horizontally polarized brightness temperatures. This value represents the corrected land brightness temperature if the water fraction is lower than 0.9 (otherwise no correction is applied) or represents the corrected water brightness temperature if the water fraction is greater than 0.1 (otherwise no correction is applied); AM overpass

tb_v_corrected_am K 0 330

Weighted average of vertically polarized brightness temperatures. This value represents the corrected land brightness temperature if the water fraction is lower than 0.9 (otherwise no correction is applied) or represents the corrected water brightness temperature if the water fraction is greater than 0.1 (otherwise no correction is applied); AM overpass

vegetation_water_content_am kg/m^2 0 30

Vegetation water content at 9-km spatial scale. This parameter is used as input ancillary data parameter to the SPL2SMAP processing software when the baseline algorithm is used. The valid minimum and maximum below are subject to further analysis. AM overpass

retrieval_qual_flag_am 0 65536

0 = Pass: Soil moisture with acceptable quality; 1 = Fail: Soil moisture does with unacceptable quality; AM overpass

tb_qual_flag_h_am 0 65536

0= brightness temperatures with unacceptable quality; 1= brightness temperatures with acceptable quality; AM overpass

tb_qual_flag_v_am 0 65536

0= brightness temperatures with unacceptable quality; 1= brightness temperatures with acceptable quality; AM overpass

soil_moisture_pm Volume fraction

Retrieved soil moisture estimate from the disaggregated/downscaled vertical polarization brightness temperature at 9-km grid cell; PM overpass

tb_h_corrected_pm K 0 330

Weighted average of horizontally polarized brightness temperatures. This value represents the corrected land brightness temperature if the water fraction is lower than 0.9 (otherwise no correction is applied) or represents the corrected water brightness temperature if the water fraction is greater than 0.1 (otherwise no correction is applied); PM overpass

tb_v_corrected_pm K 0 330

Weighted average of vertically polarized brightness temperatures. This value represents the corrected land brightness temperature if the water fraction is lower than 0.9 (otherwise no correction is applied) or represents the corrected water brightness temperature if the water fraction is greater than 0.1 (otherwise no correction is applied); PM overpass

vegetation_water_content_pm kg/m^2 0 30

Vegetation water content at 9-km spatial scale. This parameter is used as input ancillary data parameter to the SPL2SMAP processing software when the baseline algorithm is used. The valid minimum and maximum below are subject to further analysis. PM overpass

retrieval_qual_flag_pm 0 65536

0 = Pass: Soil moisture with acceptable quality; 1 = Fail: Soil moisture does with unacceptable quality; PM overpass

tb_qual_flag_h_pm 0 65536

0= brightness temperatures with unacceptable quality; 1= brightness temperatures with acceptable quality; PM overpass

tb_qual_flag_v_pm 0 65536

0= brightness temperatures with unacceptable quality; 1= brightness temperatures with acceptable quality; PM overpass

soil_moisture_am_anomaly

Experimental. Difference of the 30-day average of 'soil_moisture_am', centered on asset date, relative to the same 30-day period averaged across years from 2015 to present, excluding asset year.

See this script for anomaly computations.

soil_moisture_pm_anomaly

Experimental. Difference of the 30-day average of 'soil_moisture_pm', centered on asset date, relative to the same 30-day period averaged across years from 2015 to present, excluding asset year.

See this script for anomaly computations.

Terms of Use

Terms of Use

This dataset is in the public domain and is available without restriction on use and distribution. See NASA's Earth Science Data & Information Policy for additional information.

Citations

Citations:
  • **O'Neill, P. E., S. Chan, E. G. Njoku, T. Jackson, R. Bindlish, J. Chaubell, and A. Colliander. 2021. SMAP Enhanced L3 Radiometer Global and Polar Grid Daily 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:10.5067/4DQ54OUIJ9DL

  • Entekhabi et al., 2014 D. Entekhabi, S. Yueh, P. O'Neill, K. Kellogg et al. SMAP Handbook - Soil Moisture Active Passive: Mapping Soil Moisture and Freeze/thaw From Space. SMAP Project, Jet Propulsion Laboratory, Pasadena, CA (2014) SMAP Handbook

  • Chan, S. K., R. Bindlish, P. E. O'Neill, E. Njoku, T. Jackson, A. Colliander, F. Chen, M. Burgin, S. Dunbar, J. Piepmeier, S. Yueh, D. Entekhabi, M. H. Cosh, T. Caldwell, J. Walker, X. Wu, A. Berg, T. Rowlandson, A. Pacheco, H. McNairn, M. Thibeault, J. Martinez-Fernandez, A. Gonzalez-Zamora, M. Seyfried, D. Bosch, P. Starks, D. Goodrich, J. Prueger, M. Palecki, E. E. Small, M. Zreda, J.-C. Calvet, W. T. Crow, and Y. Kerr. 2016. "Assessment of the SMAP Passive Soil Moisture Product" IEEE Transactions on Geoscience and Remote Sensing, 54 (8): 4994-5007 10.1109/tgrs.2016.2561938

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

  • Chaubell, M. J., J. Asanuma, A. A. Berg, D. D. Bosch, T. Caldwell, M. H. Cosh, C. H. Collins, J. Martinez-Fernandez, M. Seyfried, P. J. Starks, Z. Su, S. H. Yueh, M. Thibeault, J. Walker, R. S. Dunbar, A. Colliander, F. Chen, S. K. Chan, D. Entekhabi, R. Bindlish, and P. E. O'Neill. 2020. "Improved SMAP Dual-Channel Algorithm for the Retrieval of Soil Moisture." IEEE Transactions on Geoscience and Remote Sensing, 1-12 10.1109/tgrs.2019.2959239

DOIs

Explore with Earth Engine

Code Editor (JavaScript)

var dataset = ee.ImageCollection('NASA/SMAP/SPL3SMP_E/006')
                  .filter(ee.Filter.date('2024-01-01', '2024-01-31'));

var soilMositureSurface = dataset.select('soil_moisture_am');
var soilMositureSurfaceVis = {
  min: 0.0,
  max: 0.5,
  palette: ['0300ff', '418504', 'efff07', 'efff07', 'ff0303'],
};
Map.setCenter(-6.746, 46.529, 2);
Map.addLayer(soilMositureSurface, soilMositureSurfaceVis, 'Soil Mositure');
Open in Code Editor