A cold surge diagnostic for evaluating CMIP6 GCMs over the Maritime Continent

Abstract:

Cold surges are an important synoptic feature over the Maritime Continent (MC) during boreal winter. Besides playing a major role in extreme precipitation events, cold surges have been suggested to aid the MJO in its propagation across the MC. We have developed and utilized a cold surge diagnostic based on sea level pressure and 850 hPa winds, as part of a systematic evaluation of the ability of CMIP6 GCMs to simulate the climate over the MC. CMIP6 models are found to systematically underestimate surge frequency and exhibit wet bias over the eastern Maritime Continent. The diagnostics are performed in Python and CDO and is potentially suitable for inclusion into community packages such as ESMValTool.