One of the main purposes of the International Soil Moisture Network is to serve calibration and validation of satellite observed soil moisture products. This has become an increasingly important task given the large number of global soil moisture datasets that have become available in recent years from microwave radiometers (SMOS, AMSR-E, Windsat, TRMM, SMMR) and scatterometers (ERS SCAT, ASCAT). In addition, NASA prepares for the launch of Soil Moisture Active/Passive (SMAP) mission foreseen to be launched in 2014 while the ESA Sentinel-1 mission is expected to provide soil moisture products at a very fine spatial scale


Satellite: SMOS
Sensor: L-band radiometer with aperture synthesis (MIRAS)
Agency: ESA
Operations: launch in 2009
Resolution: 30
Revisit time: 1-2 days


Satellite: SMAP
Sensor: Active and passive microwave instrument in L-band
Agency: NASA
Operations: launch in 2013
Resolution: 10 km (active) 40 km (passive)
Revisit time: 1-2 days


Satellite: METOP (three satellites)
Sensor: C-Band Scatterometer (ASCAT)
Agency: EUMETSAT in cooperation with ESA
Operations: 2006-2020
Resolution: 25/50 km
Revisit time: 1-2 days


Satellite: ERS-1 and ERS-2
Sensor: C-Band Scatterometer (SCAT)
Agency: ESA
Operations: 1991-2010
Resolution: 25/50 km
Revisit time: 2-7 days


Satellite: AQUA
Sensor: Multi-frequency radiometer (AMSR-E)
Agency: NASA in cooperation with JAXA
Operations: 2002-2011, followed up by GCOM-W1 AMSR-B in 2012
Resolution: 50 km
Revisit time: 1-2 days


Satellite: Coriolis WindSat
Sensor: Multi-frequency polarimetric radiometer (WindSat)
Agency: US Naval and Air Force Research Laboratories
Operations: since 2003
Resolution: 50 km
Revisit time: 1-2 days