On the usage of re-calibrated AMSU-A data in NASA reanalysis

Usage of re-calibrated data in reanalysis systems are quite common due to their uniform and continuous data distribution. Re-calibrated radiosonde temperature and SSU radiances have already shown positive impact in MERRA and MERRA2 reanalyses. In this study re-calibrated AMSU-A radiances are used to study sudden degradation of observation statistics which are noticed with the introduction of new AMSU-A radiances in MERRA2. In particular, the analysis temperature in the upper stratosphere showed large variability due to lack of viable observation at that height in the atmosphere. Our results show that the re-calibrated AMSU-A radiance in a system similar to MERRA2 is capable of mitigating the problem.