Abrupt change of winter temperature over the Mongolian Plateau during 1961–2017

Studying the abrupt change of winter temperature (ACWT) over the Mongolian Plateau (MP, including Inner Mongolia Autonomous Region and State of Mongolia) is of great significance for understanding the spatiotemporal distribution of temperature and the mechanism of global climate change. Monthly temperature data during 1961–2017 was collected, and the abrupt change point was determined by the Mann–Kendall test and sliding t-test, to analyze the characteristics and causes of ACWT. The results showed that (a) The winter temperature has rapidly increased with a trend of 0.41°C/10a, which was significantly higher than that of the rest area of Chinese mainland, indicating that climate change in the MP was more sensitive to global warming. (b) The abrupt change point occurred in 1988, with temperature of −15.5 °C and −14.1 °C before and after abrupt change, respectively. The ACWT in 50°N was 1–3 years later than that in 40°N, and the isotherms of different temperatures moved northward by 10–200 km, especially −16°C isotherms moved approximately 200 km northward after 1988. (c) The Arctic Oscillation (AO) and Mongolian High (MH) anomaly affects winter temperature over the MP. When the AO is unusually strong, the MH and East Asian winter monsoon are weak, and southerly winds prevail in most regions, which is not conducive to the cold air developing southward, leading to higher winter temperature in the MP. Overwise, abnormally northerly winds prevail and temperature is low. Meanwhile, the abrupt change time of AO occurred in 1987 before winter temperature. It shows that the AO indirectly causes winter temperatures to rise by influencing the MH and is also the main driving factor of ACWT.