Dear Adugnaw,

Soil moisture is notoriously difficult to measure, but multiple attempts have been made in the past to retrieve at least rough estimates of this important geophysical variable from space, using a variety of techniques. The most promising approach currently being pursued is by using microwaves.

The SMOS mission of the European Space Agency (ESA), launched in November 2009, is a good example of a successful mission with a long track record. Note, however, that this technology generates estimates at a fairly broad spatial resolution (35-50 km). Hence, if you plan to compare such values to field observations, you will need to elaborate a sophisticated sampling scheme in order to generate meaningful comparisons. In any case, look at the following web sites as a start:

https://earth.esa.int/eogateway/missions/smos

http://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate/Nearly_four_decades_of_soil_moisture_data_now_available

Next, consider also learning about NASA's SMAP mission, launched in January 2015, which started operation in April 2015:

https://smap.jpl.nasa.gov/

I hope this may help you. Regards, Michel.

There can be multiple satellite data products depending on spatial and temporal resolution. You can get the 10-km spatial resolution NASA-USDA Enhanced SMAP Global soil moisture data from Google Earth Engine.

For a more specific area, I would suggest going to the following two websites, specify your spatial range, go through the data products available for your intended region and choose according to your requirements.

https://giovanni.gsfc.nasa.gov/giovanni/

https://disc.gsfc.nasa.gov/

https://earth.gsfc.nasa.gov/hydro/data/nasa-usda-global-soil-moisture-data