A 30-Year satellite based climatological dataset of Antarctic Cloud Mass Meridional Transport events

Abstract. Cloud Mass Meridional Transport events (CMMTs) are poleward propagating synoptic scale cloud masses that flux heat and moisture over the Antarctic continent for more than 48 consecutive hours. These events are vital for the surface mass balance and annual precipitation totals of the Antarctic Ice Sheet. Regardless of their shape and size, CMMTs are vertically developed, must penetrate more than 200 km onto the continent, and propagate southward for their entire duration. Presented here is a 30-year CMMT climatological dataset from November 1992 to December 2022 that uses infrared satellite composite imagery to manually identify and track landfalling CMMTs across seven regions around Antarctica. Previous climatologies built to study Antarctica’s atmosphere have been limited in time or are derived from reanalyses and algorithms instead of physical observations. The goal of this satellite-derived dataset is to supplement Antarctic forecasting operations and to ensure that reanalyses and weather forecasting models accurately resolve these high-impact events in both time and space. A total of 1,386 CMMTs were identified, lasting 2.81 days on average. Sixty percent of CMMTs occur over East Antarctica with heightened activity in austral winter. The longest event recorded in this time frame was 13 days long in May 1998, but events like this one are rare given that 91 % of CMMTs lasted less than four days. The satellite composite imagery, comma-separated value files, and monthly text documents defining the time and spatial distribution of each CMMT are publicly accessible at the Antarctic Meteorological Research and Data Center (AMRDC) Data Repository at the University of Wisconsin-Madison (AMRDC, 2022; Chambers, 2026; Chambers et al., 2026). Links to these data are listed in Sect. 6 on data availability.