Perspective Chapter: Validation of SMOS Satellite Soil Moisture Estimates Using Capacitance Probes over the Different Ecological Zones in Northern Ghana

Abstract

Researchers assessed the performance of L2 satellite soil moisture estimates from the European Space Agency’s SMOS satellite using in-situ data from capacitance SM probes. The in-situ measurements are from monitoring stations (at 10, 20, 30 cm depth) at two sites, Yendi and Jirapa in the Northern part of Ghana, West Africa. They are in two different sub-ecological zones of the Savanna in the North of Ghana. These sub-ecological zones are Western Sudan Savanna (Jirapa) and Open Guinea Savanna (Yendi). The correlation between SMOS SM estimates and the in-situ measurements was observed to improve with depth. In addition, the 10 cm depths capacitance probe SM measurements were observed to agree relatively better with the SMOS SM estimates. The L2 SMOS SM estimates performed much better in the dry season compared to the rainfall season for both ascending and descending orbital estimates. The 10 cm depth SM measurements recorded the best RMSE in both the dry and rainfall seasons. The descending dry season RMSE for the two sites ranging between 0.045 and 0.058 m3/m3 was relatively close to the SMOS expected accuracy. However, the RMSE and MBE were observed to deteriorate with depth.