Temperature/absorption cross integrals and the validation of radiometric temperatures for space-based radiometers

In the frame of the MetOp-SG MWS microwave radiometer, we determine the expected radiometric calibration bias caused by temperature gradients in the blackbody target. The target consists of a pyramidal array of metal pyramids coated with microwave absorber. The temperature gradients within the absorber layers are simulated using the Ansys NLT software, and the microwave volume loss density using HFSS. The effective brightness temperature of the target is obtained by integrating the product of these two spatial-depend variables.