SNO-Based Radiometric Bias Evaluation for Emulated Small Satellite Microwave Sensors

In the era of increasing demand for timely and accurate Numerical Weather Predictions (NWP), miniaturization of satellite components is making the use of small satellite data in NWP increasingly more promising. This paper addresses the initiative of inter-calibration/validation of microwave (MW) sensor on small satellite using Simultaneous Nadir Overpass (SNO) method. The SNO event selection criteria usually includes cloud screening, nadir view, and confined time and distance difference. Comparison of simultaneous measurements between two or more instruments at their orbital intersection under nearly identical viewing conditions makes this approach highly suitable for reducing the uncertainties associated with the atmospheric variability. This paper performs SNO-based radiometric bias evaluation among MW sensors such as Microwave Humidity Sounder (MHS) onboard MetOp-A and MetOp-B satellites and the Advanced Technology (ATMS) on NOAA-20 and NPP satellites for selected microwaves channels. These sensor data are emulated as proxy small satellite MW sensor. The radiometric performance among these MW sensors are inter-compared through SNO-Method. The impacts of the differences in channel frequency on the residual radiometric bias are studied. By using these legacy satellites as proxy small satellites, this approach provides assessment of challenges in calibration and validation of small satellite data.