Temporal climate inhomogeneity in reanalyses and an ongoing effort on homogenization of MERRA reanalysis

The inhomogeneity in reanalyses is a compelling problem for research focused on climate change and trends. In this presentation, first, a general picture of the inhomogeneities in reanalyses will be shown. Then we will give a detailed description about the inhomogeneity in recent NASA reanalysis (MERRA) and the associated changes in the observing system. At last, we will discuss about the progress and challenge in an ongoing effort to homogenize MERRA reanalysis with multiple observing system experiments (OSE).