Factors behind the rare winter Asian sand and dust storm in December 2022

In December 2022, Japan experienced its first rare winter sand and dust storm (SDS) in 10 years. In this study, the structure and mechanism of dust generation in December 2022 were clarified based on the dust prediction model, ground-based dust observations, satellite data, and atmospheric reanalysis data. The winter SDS was caused by strong surface winds associated with an extratropical cyclone passing over the Gobi Desert on December 11, 2022; the meteorological mechanism was the same as that for spring SDSs. The negative snow cover anomaly over the source region and the synoptic factors causing the unusual winter SDS were identified by using the satellite data and the European Center for Medium-Range Weather Forecasts fifth-generation global climate reanalysis (ERA5). Usually, the strong wind frequency in the Gobi Desert in December is low because of a stable cold winter high, whereas in 2022, the frequency was clearly increased. Based on the anomaly and composite analysis of the geopotential height at 500 hPa, the characteristics of the winter SDS years were identified as westward displacement of the Siberian High and the weakening of Aleutian Low over the North Pacific Ocean. The negative phase of the Pacific Decadal Oscillation and the Arctic Oscillation corresponded well with winter SDS years, especially since 2000, suggesting that favorable synoptic conditions for winter SDSs were formed during this negative phase.