Response of Frost to Temperature and Precipitation Changes in Recent 30 Years in Qinghai Province

The frost phenophase was anaylysed with linear trend and single correlation method by using meteorological data from 33 weather stations in Qinghai Plateau. Results show that the variation trends of first frost and latest frost present regional features of delay and ahead of schedule, respectively. On the interdecadal scale, first frost was delayed while latest frost was advanced and frostfree period was extended obviously in most regions. In a few areas, a negative correlation existed between latest frost with air temperature, and a positive correlation with precipitation. In some areas, a positive correlation existed between first frost with air temperature, and had no obvious responses to precipitation. In most areas, a positive correlation existed between frostfree period with air temperature and precipitation. The comprehensive response of first frost and latest frost to climate change showed that the extened variation trends have obvious regional differences.