近50年淮河流域气温时空变化及其与PDO的关系

气温的变化是造成自然景观和生态环境改变的主要因素之一。利用淮河流域1965-2016年67个数据序列完整的气象站日平均气温、最高气温、最低气温数据，采用线性倾向估计、Mann-Kendall检验、皮尔逊相关系数、连续小波（CWT）、交叉小波变换（XWT）和小波相干谱（WTC）等方法分析了流域气温时空变化特征以及流域年平均气温和PDO（太平洋年代际涛动）的周期特征。结果表明:在时间尺度上，淮河流域年平均气温、最高气温和最低气温在1965-2016年均存在不同程度的上升，年平均最低气温增幅最为明显；空间上流域气温从南向北呈现递减趋势，不同地区的增温趋势略有不同，东部沿海地区平均气温的升温幅度高于西部内陆地区，流域西南部年平均最高气温的升温趋势比较明显，西北部年平均最低气温升温趋势比较明显，年平均气温的突变主要发生在1996年，而年平均最高气温和年平均最低气温的突变时间则略早于年平均气温（1992年）。淮河流域年平均气温存在1.3~5.5 a尺度的年际振荡周期，与PDO指数的振荡变化相似。淮河流域气温也随着PDO冷暖相位的转变发生了相应的变化。

Temporal and Spatial Change of Temperature in the Huaihe River Basin During the Past 50 Years and Its Relationship with PDO

Temperature change is one of the main factors which cause the changes of natural landscape and eco-environment. Based on the complete data of daily mean temperature, maximum temperature and minimum temperature of meteorological stations in the Huaihe River Basin from 1965 to 2016, the temporal and spatial variation and periodic characteristics of temperature of the annual mean temperature as well as PDO (Pacific Decadal Oscillation) were quantitatively analyzed by using the linear trend estimation, Mann-Kendall non-parametric test method, continuous wavelet (CWT), cross wavelet Transform (XWT), and wavelet coherence spectrum (WTC) in this study. The results indicate that the annual average temperature, maximum temperature and minimum temperature in the basin increased at different levels during the period 1965-2016, and the increase of annual average minimum temperature was obvious; spatially, the temperature showed the decreasing trend from the south to the north of the basin. The warming trend in different regions of the study area was slightly different. The average temperature in the eastern coastal region of the basin was warmer than that in the western inland area. The increase of the annual average maximum temperature in the southwestern part of the basin was relatively obvious, and the increase of the annual average minimum temperature in the northwest was more obvious. The annual average temperature mutations mainly occurred in 1996, but the abrupt time of annual average maximum temperature and annual average minimum temperature was slightly earlier than that the annual average temperature (1992). The average temperature of the Huaihe River Basin had an interannual oscillation period of 1.3~5.5 years, showing similar characteristic to the PDO index. The cold and warm phase transitions of PDO have also the significant impact on temperature changes in the study area.