Variation Characteristics of Thermal Resource in Korla from 1961 to 2015

Climate warming results in changes of heat resources，which influences on spatial distribution of agricultural production.It is instructive to study change of heat resources to rationally utilize heat resources and adjust agricultural climate index and planting structure.Variation characteristics of Korla temperature and beginning date，ending date and duration of ≥0、3、5、10、15 and 20 ℃ and frost-free beginning date，ending date and duration were studied by using daily air temperature data of Korla from 1961 to 2015，through climate tendency rate and Mann-Kendall mutation method.Results showed that mutation of Korla temperature occur in 1998，annual average temperature rise rate was 0.29 ℃/10 a（P＜0.01），1.0 ℃ warmer after mutation than before；average temperature increased by the largest in winter；beginning date of ≥0、3、5、10、15 and 20 ℃ advanced，ending date delayed，crop growing season significantly extended；accumulated temperature of ≥0、3、5、10、15 and 20 ℃ increased significantly，change rates were 80.7、80.2、85.1、69.0、75.6和103.4 d·℃/10 a；non-frost beginning date significantly increased by 4.0 d，ending date significantly delayed by 4.3 d，and number of continuous days significantly increased by 8.4 d.In the past 55 years，temperature in Korla has increased，accumulated temperature has increased，and growth season and frost-free period have been delayed.It has a positive effect on agricultural introduction and variety promotion.It is necessary to re-determine appropriate agricultural climate index and planting zoning according to status of heat resources.