Comparative analysis of the extreme temperature event change over Northeast China and Hokkaido, Japan from 1951 to 2011

On the basis of the daily minimum (T (min)), mean (T (mean)), and maximum (T (max)) temperature records of 25 meteorological stations in Northeast China (NEC) and 10 weather stations in Hokkaido, Japan (HKD), from 1951 to 2011, we comparatively analyzed the change in extreme temperature events and the relationship of these events with the mean value. Results showed that for the extreme lowest temperature (ELT) frequency, approximately 96 % of the stations exhibited decreasing trends ranging from -0.63 to 0 days/decade in NEC, whereas all the stations in HKD showed decreasing trends ranging from -0.4 to 0 days/decade. However, the average decrease in amplitude of 0.24 days/decade in HKD was significantly less than the 0.27 days/decade average in NEC. The extreme highest temperature (EHT) frequency trends in the two regions showed insignificant increases. Notable decreasing trends for the ELT intensity were found at -0.9 to 0 %/decade in 92 % of the stations in NEC and -1.1 to 0 %/decade in 90 % of the stations in HKD. Inversely, increasing trends in EHT intensity were observed in 80 % of the stations over HKD, ranging from 0.06 to 0.32 %/decade, and the majority of the stations (64 %) showed increasing trends in NEC. T (mean) and T (min) had strong negative correlations with the ELT intensity in NEC, whereas T (mean) and T (min) had strong significant negative correlations with the ELT frequency in HKD. T (min), T (mean), and T (max) between NEC and HKD exhibited strong significant positive correlations. The frequency and intensity of the ELT in both regions showed significant positive correlations.