Climate Change in China

Changes in the Frequencies of Record-breaking Temperature Events in China and Its Association with East Asian Winter Monsoon Variability

Authors:

Kuang et al

Abstract:

The daily maximum and minimum temperatures observed at the 1897 meteorological stations of China over the past 60 years (1951-2010) are analyzed in this study to examine the interdecadal variation of frequency for record-breaking event (RBE) of temperature in the context of global warming. The results indicate that the frequency of record-breaking high temperature in the first decade of the 21th century is the highest in the three decades from the 1980s to the 2000s, implying a distinct warming trend. Meanwhile, frequencies of record-breaking low temperature in the 1990s and the beginning of the 21th century are also significant. In particular, the RBEs of low temperature occurred over most of China in the 1990s but concentrated in northern China during the 2000s. To understand why the record-low temperatures in northern China are repeatedly broken in the 2000s, the related East Asian Winter Monsoon (EAWM) variability is investigated. The EOF analysis of surface air temperature reveals that the northern mode of the EAWM variability, which is highly associated with the Arctic Oscillation (AO) activities at both interdecadal and interannual timescales, has been intensifying since late 1990s. Corresponding to the intensification of the northern mode of the EAWM variability and the negative phase of AO in the 2000s, the Siberian High and East Asian trough intensify while the polar-front jet stream strengthens and the subtropical westerly jet stream abnormally shifts northward. As a result, anomalously strong cold air masses, originated from Siberia, intrude into East Asia, but are blocked by the enhanced northward subtropical westerly jet and cannot reach low latitudes area. Therefore the extremely strong cold air masses are amassed in mid-high latitudes of East Asia, resulting in RBEs of low temperature in this area.