Additional NEDT requirement to constrain noise correlations of polar-orbiting microwave sounders

The current on-orbit polar-orbiting microwave sounder design (ATMS) shows spatially-correlated noise in brightness temperature measurements, manifested as cross-track (along-scan) striping. Current microwave radiometric sensitivity, or noise-equivalent delta temperature (NEDT), requirements do not fully address or constrain these excess noise characteristics in the sensor measurements. This paper proposes augmenting the current instrument NEDT requirement with an additional, along-track NEDT requirement. The additional requirement, if met, could lead to improved overall sensor performance impact in weather models through testable criteria in sensor component acquisition. An along-track NEDT requirement at the sensor system level is verifiable using data collected with existing sensor test procedures and would not overly constrain hardware implementation. This paper provides the necessary background and quantifies the proposed new requirement.