Climatic change of frost in Shihezi in recent 50a

Based on daily meteorological observational data of frost in Shihezi from 1964 to 2011,the climatic change of frost season,free frost season,the first and last dates of frost were mainly analyzed. The results show that the first dates of frost occurred later and the last dates of frost occurred earlier gradually,which led to the shortening of frost season and the increasing of free frost season,especially after the end of 1980s. The climate change trends had a significant cooperativity with the change trend of free frost season and the first dates of frost and had a strong negative correlation with frost season and the last dates of frost. The annual changing trend consisted with the trends of yearly variation,and the days of frost season reducing and free frost season increasing went to equal at the first of 20 century. Shihezi,Ulamwusu,Mosuowan and Paotai had consistent change trends overall,but the shortened mutation years in Mosuowan were earlier and that in Ulamwusu later. Comparing with the trend of the first frost date and the last frost date,the first frost date in Ulamwusu and Paotai appeared to have a marked change than the last frost date,which may have a very close relationship with the different variation of seasonal temperature.