Availability of global satellite based Soil Moisture (SM) data has promoted the emergence
of many applications in climate studies, agricultural water resource management and hydrology.
In this context, validation of the global data set is of substance. Remote sensing measurements
which are representative of an area covering 100 m2 to tens of km2 rarely match with in situ SM
measurements at point scale due to scale difference. In this paper we present the new Indian Cosmic
Ray Network (ICON) and compare it’s data with remotely sensed SM at different depths. ICON is
the first network in India of the kind. It is operational since 2016 and consist of seven sites equipped
with the COSMOS instrument. This instrument is based on the Cosmic Ray Neutron Probe (CRNP)
technique which uses non-invasive neutron counts as a measure of soil moisture. It provides in
situ measurements over an area with a radius of 150–250 m. This intermediate scale soil moisture
is of interest for the validation of satellite SM. We compare the COSMOS derived soil moisture to
surface soil moisture (SSM) and root zone soil moisture (RZSM) derived from SMOS, SMAP and
GLDAS_Noah. The comparison with surface soil moisture products yield that the SMAP_L4_SSM
showed best performance over all the sites with correlation (R) values ranging from 0.76 to 0.90.
RZSM on the other hand from all products showed lesser performances. RZSM for GLDAS and
SMAP_L4 products show that the results are better for the top layer R = 0.75 to 0.89 and 0.75 to 0.90
respectively than the deeper layers R = 0.26 to 0.92 and 0.6 to 0.8 respectively in all sites in India.
The ICON network will be a useful tool for the calibration and validation activities for future SM
missions like the NASA-ISRO Synthetic Aperture Radar (NISAR).