Changes of annual accumulated temperature over Southern China during 1960-2011

The spatial and temporal variations of a parts per thousand yen10A degrees C annual accumulated temperature (AAT10) were analyzed by using the linear trend line method, cumulative anomaly method and the multiple linear regression model (MLRM) interpolation method based on the daily meteorological observation data from 104 meteorological stations in Southern China and surrounding 39 meteorological stations from 1960 to 2011. The results show that: (1) From time scale point of view, the climatic trend of the AAT10 increased with an average of 7.54A degrees C/decade in Southern China since 1960. The area of AAT10 < 6000A degrees C decreased from 1960 to 2011, and the area of 6000A degrees C < AAT10 < 8000A degrees C decreased from 1960 to 1979 and increased from 1980 to 2011, and the area of AAT10 > 8000A degrees C increased from 1960 to 2011. (2) From spatial scale point of view, the AAT10 in Southern China reduced with increasing latitude and reduced with increasing altitude. The proportion of the area with 5000A degrees C < AAT10 < 8000A degrees C accounted for 70% of the study area, followed by the area of 4000A degrees C < AAT10 < 5000A degrees C; and the area of AAT10 < 4000A degrees C and AAT10 > 8000A degrees C was the least. Climate trend rate of the AAT10 at 99% of the meteorological stations was greater than zero, which indicated that the AAT10 increased significantly in the central Yunnan province, southern Guangdong province as well as Hainan Island. (3) Comparison of period A (1960-1989) and period B (1980-2011) with the change of temperature zones shows that the boundaries of cool temperate zone, mid-temperate zone and warm temperate zone shifted northward and shrank westward. The northern boundary of north subtropical zone and mid-subtropical zone shifted northward gradually by over 0.5A degrees and 0.5A degrees latitude, respectively. The western part of northern boundary of south subtropical zone and marginal tropical zone shifted northward by 0.2A degrees and 0.4A degrees latitude, respectively. The change of temperature zones was expanded to high altitude and latitude. (4) The increase of the AAT10 is conducive to the production of tropical crops planted, which will increase the planting area that was suitable for tropical crops, and expand the planting boundaries to high latitude and high altitude.