Research On The Relationships Between The Cold Wave In China And Northern Hemisphere Sea Level Pressure And Sea Surface Temperature

Based on 133 stations daily lowest temperature data in China and sea level pressure(SLP) and sea surface temperature(SST) data of the northern hemisphere from 1960 to 2010, this paper studies the temporal and spatial characteristics of cold wave and the relationship between these characteristics and the main circulation modes of SLP and SST, and the circulation background of the northern hemisphere using statistical analysis, wavelet analysis and composite analysis and so on. The main work and conclusions are the following several aspects:(1) Cold wave frequency has a decreasing trend in recent 51 years, the trend of regional cold wave and national cold wave is more obvious, and the frequency has apparent interannual and interdecadal variation characteristics with 3～5a and 10-15a. From north to south in china, the frequency of cold wave gradually reduce, regional cold wave mainly occurs in the north of china with sheet distributions, and regional cold wave in south of china is infrequently with zonal distributions, national cold wave can be divided into northwest and north cold wave according to the position where cold air enter into, the frequency of the two types of national cold wave is approximate in the 1960s and early 21st century, in the 1970s, north cold wave is more than northwest cold wave, and in the 1980s and 1990s, northwest cold wave is more than north cold wave.(2) AO, PDO and AMO are the main climate modes in northern hemisphere, and they all have the characteristics of 60yr timescale and 20-30yr timescale, on t60yr timescale, AO leads PDO by approximately 4 years with positive correlation, and lags AMO by 12 years with negative correlation, on 20-30yr timescale, AO leads PDO by 12 years with positive correlation, on 30yr timescale AO leads AMO by 8 years with positive correlation. Cold wave frequency has interannual and interdecadal characteristics, and on all timescale AO leads cold wave with positive correlation, PDO leads cold wave with negative correlation, but on 12yr and 4yr timescale AMO has negative correlation with cold wave, on 7yr timescale AMO has positive correlation with cold wave. On the spatial correlation, AO has positive correlation with most area of china, PDO has negative correlation with most area of china, and AMO has positive correlation with some area but some negative correlation.(3) From the relationship between cold wave and SLP and SST of the northen hemisphere, we can discover that:there is negative correlation between cold wave frequency and high latitudes air pressure anomaly and sea surface temperature anomaly, but cold wave intensity has positive correlation with high latitudes air pressure anomaly and negative correlation with sea surface temperature anomaly. When the sea level pressure positive anomalies in Siberian region, northwest cold wave frequency is more than north cold wave, and the sea level pressure negative anomalies in Siberian region, north cold wave frequency is more than northwest cold wave. The positive anomaly of sea surface temperature in east coasts and west coasts of Eurasia cause north cold wave frequency is more than northwest cold wave, and the negative anomaly cause northwest cold wave frequency is more than north cold wave.