吉林省东南部山区气温客观订正方法研究

利用吉林省智能网格2020年72 h日最高、最低气温格点气温指导预报产品、2020年地面2 m实况日最高、最低气温数据,采用小波分析方法、准对称混合滑动训练方法、最优融合方法对吉林省东南部山区72 h最高、最低气温进行产品检验及订正研究。结果表明:72 h日最高、最低气温预报随时间延长,准确率和误差均增加;客观模式在东南部山区气温预报中存在局地小气候特征,高寒山区预报准确率及误差较其他地区明显偏大;72 h日最高气温预报准确率均较最低气温高且误差小;客观方法空间区域上预报性能存在差别,在高寒山区预报性能较其他地区较差,沿鸭绿江流域相关区域预报稳定性较好,且准确率高,同时高温预报准确率仍高于低温预报准确率;最优融合方法在72 h日最高、最低气温订正中普遍高于其他订正方法,特别是在最低气温预报和48—72 h预报时效上优于其他预报产品。

Interpretation of 850 hPa Temperature in Temperature Forecast of Jiamusi Area

Based on the initial field temperature data of ECMWF 850 hPa from Jan- uary 2012 to December 2015, linear interpolation method of ECMWF was employed to calculate the 850 hPa temperature values at 8：00 and 20：00 of 7 stations （Jiamusi, Tangyuan, Huachuan, Huanan, Fujin, Tongjiang, Fuyuan）. Combined with the observed daily minimum and maximum air temperatures at the same time of the 7 stations, the correlations of the 850 hPa temperature values at 8：00 and 20：00 with the daily maximum or minimum air temperature of the ground meteorological obser- vation stations were established, and the ground observation data in accordance with the relevant analysis and correlation test principle of the prediction equation for factor were primarily selected. Regression method was used to establish forecast e- quation dividing into counties, month by month. The results showed that the 850 hPa temperature values at 8：00 and 20：00 were significantly correlated with the daily maximum or minimum air temperature, and the established temperature fore- cast equation was of certain guiding significance for the forecast of daily minimum and maximum temperature, which could help to improve the forecast accuracy.

Change in Extreme Climate Events over China Based on CMIP5

The changes in a selection of extreme climate indices(maximum of daily maximum temperature(TXx),minimum of daily minimum temperature(TNn),annual total precipitation when the daily precipitation exceeds the 95th percentile of wet-day precipitation(very wet days,R95p),and the maximum number of consecutive days with less than 1 mm of precipitation(consecutive dry days,CDD))were projected using multi-model results from phase 5 of the Coupled Model Intercomparison Project in the early,middle,and latter parts of the 21st century under different Representative Concentration Pathway(RCP)emissions scenarios.The results suggest that TXx and TNn will increase in the future and,moreover,the increases of TNn under all RCPs are larger than those of TXx.R95p is projected to increase and CDD to decrease significantly.The changes in TXx,TNn,R95p,and CDD in eight sub-regions of China are different in the three periods of the 21st century,and the ranges of change for the four indices under the higher emissions scenario are projected to be larger than those under the lower emissions scenario.The multi-model simulations show remarkable consistency in their projection of the extreme temperature indices,but poor consistency with respect to the extreme precipitation indices.More substantial inconsistency is found in those regions where high and low temperatures are likely to happen for TXx and TNn,respectively.For extreme precipitation events(R95p),greater uncertainty appears in most of the southern regions,while for drought events(CDD)it appears in the basins of Xinjiang.The uncertainty in the future changes of the extreme climate indices increases with the increasing severity of the emissions scenario.