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The O-B bias analysis scheme enables evaluation of spectral radiometric bias of SmallSat infared (IR) and microwave (MW) sensors w.r.t. atmospheric reanalysis background data through comparison with the Community Radiative Transfer Model (CRTM)-modeled brightness temperature (BT) using the global atmosphere reanalysis data from European Centre for Medium-Range Weather Forecasts (ECMWF). Table below summarizes the setup of the simulation model for radiative transfer modeling (RTM). In the case of cross-instrument (IR/MW vs. RO) temperature bias evaluation, the temperature and humidity profile data retrieved from radio occultation (RO) sensor measurements are used as input to the CRTM simulation. The CRTM-simulated BT from RO, e.g. COSMIC-2 or MetOp-A/B, measurements and observed BT by IR/MW sensors are compared for cross-instrument bias evaluation.

Input Variables and Parameters for RTM Simulation with CRTM.

image: Image acquired by SmallSat

In the figure below, NPP and NOAA-20 ATMS MW sensor data are used to demonstrate the O-B and cross-instrument (MW vs. RO) bias evaluation through CRTM modelling.

Example of O-B and Cross-instrument (MW vs. RO) Bias Evaluation through CRTM Modelling

image: Image acquired by SmallSat