关键词: 极端高温阈值, 极端低温阈值, 北极涛动, 相关分析

Abstract:

Based on the daily maximum and minimum temperature data of 1959~2009 at ten meteorological stations in Ningxia Hui Autonomous Region, and using percentile method defined extreme high and low temperature threshold of different stations year by year, this paper studied nearly 51 years extreme temperature variation features in Ningxia Hui Autonomous Region, obtained temperature mutated years in the meteorological stations by Mann-Kendall test, and then applied Pearson correlation coefficient to analyze the correlation between the extreme temperature threshold and the AO index. The result showed that: (1) Both extreme high temperature threshold and extreme low temperature threshold in Ningxia showed very significant upward trend. The increase amplitudes were 0.199℃/10a and 0.62℃/10a for the extreme high and low temperature threshold respectively and the upward trend of extreme low temperature threshold was more significant, so the upward of extreme low temperature was the main character and trend of the temperature change in the nearly 51 years in Ningxia Hui Autonomous Region. (2) Extreme high temperature threshold was high in north and low in south while extreme low temperature threshold was low in north and high in south of Ningxia Hui Autonomous Region. The difference value between the extreme high temperature and the extreme low temperature showed that the temperature changing range of temperature was high in north and low in south of Ningxia Hui Autonomous Region. (3) The mutation time of extreme low temperature threshold in Ningxia Hui Autonomous Region concentrated in the 1980s or so, and the mutation time of extreme high temperature threshold relatively late. The mutation time of the extreme temperature showed that the global climate change had the more influence on the low temperature. The mutation time of Guyuan was large far later than other regions, and the result meant that the mountains around Guyuan would block the cold and warm atmosphere and reduce the global climate change influence on the extreme temperature. (4) From 1959 to 2009, the annual average values, the summer average values and the winter average values of the AO index had rising trend, and the maximum increase amplitudes of the AO index appeared in the winter. The correlation of extreme high temperature threshold and the summer AO index was not significant in Ningxia Hui Autonomous Region, and there had significant positive correlation between the extreme low temperature threshold of the north, centre and the whole area of Ningxia Hui Autonomous Region and the winter AO index. The Arctic Oscillation had little influence on the extreme high temperature while had great impact on winter low temperature in Ningxia Hui Autonomous Region. The high mountains reduced the influence of the Arctic Oscillation on the south of Ningxia Hui Autonomous Region by the block of cold atmosphere, so there had no significant correlation between the extreme low temperature of south of Ningxia Hui Autonomous Region and the AO index.

Key words: extreme high temperature threshold, extreme low temperature threshold, Arctic Oscillation, correlation analysis