Analysis Of Thermal And Precipitation Resources In Northeast China Under Greenhouse Gas Emission Scenarios

The impact of climate change on agriculture has become a hot issue in the world,especially in Northeast China as the main producing area of food,which is particularly affected by climate warming.Based on the regional climate model,Providing Regional Climates for Impacts Studies(PRECIS),annual mean temperature(Tmean),minimum temperature(Tmin),maximum temperature(Tmax),annual precipitation and related agro-climatic indices are projected in the future under RCP4.5 and RCP8.5 scenarios in Northeast China.The period of 1961-1990 is selected as baseline period to verify the performance of simulations and calculate the potential changes during 21 st century compared to the baseline.For 21 st century,it is divided to three periods,i.e.,initial period(2011-2040,2020s),mid period(2041-2070,2050s)and last period(2071-2100,2080s).Daily outputs have been corrected by using mapping quantile method;the distributed features of temperature and precipitation are shown in Probability Distribution Function;agricultural climate resource indices are quantified by five-day moving average method.In the future periods,the average temperature,annual rainfall and climatic indices are projected to reveal potential changes.The main conclusions are followed:(1)PRECIS is good at simulating temperature and precipitation in Northeast China,and the performance of temperature is better than precipitation.Regards the distribution of temperature,it decrease from south area to north area,and the bias has been offset after bias correction.The increments of temperature decrease from north to south during 21 st century,Tmean,Tmin and Tmax will increase by above 4.4?,4.6? and 4.2? in 2080 s under RCP4.5 scenario,with a less increment relative to mid period,which is in keeping with the emission pathway of RCP4.5.Temperature will continue to increase during the 21 st century under RCP8.5 scenario,and Tmean,Tmin,and Tmax will increase by 7 ?,7.2 ? and 6.8 ? in 2080 s,which is consistent with the pathway of RCP8.5 scenario.(2)The special distribution features of precipitation(P)and wet days(WD)can be well reproduced by PRECIS,which illustrate a decreasing trend for P from southeast to northwest in Northeast China,and larger increment of WD in Changbai mountain areas.Under RCP4.5scenario,annual precipitation will increase by 80~100mm at the end of 21 st century,and more than 180 mm at Changbai mountain and source area of Liaoning province;in themeanwhile,WD will increase by 9~25 days at the end of 21 st century,and the increment will be over 25 days at the southwest part of Jilin province.Under RCP8.5 scenario,there is a general increment of 160~200mm in precipitation and 15~25 days in WD,at the end of 21 st century.In comparison with RCP4.5 scenario,the region in a over 200 mm increment will expand.increase days of WD will be larger.(3)Trends of agriculture thermal indices are identical to the concentration of CO2 under RCP4.5 and RCP8.5.Increment of accumulated temperature with ?10?(AT10)will be larger than that with ?0?(AT0)at the end of 21 st century,with 1200~1700?·d and 600~1700?·d,respectively.At the spatial scale,there is an increase trend from south to north.Under RCP4.5scenario,the number of risen days of potential growing season are projected to be larger than frost free period,but it is opposite under RCP8.5 scenario,with a increment of 40~65 days and 45~55 days,respectively.The most increased days are appeared at Sanjiang Plain,followed by Songneng and Liaohe Plain.Therefore,it is identified that warmer trend tends to be faster in colder regions.(4)As the main producing area of crop in China,crop growing is closely related to climate change in Northeast China.Changing trend of temperature during growing(Tmon)season of crop is identical with annual average temperature.Under RCP4.5 and RCP8.5scenarios,Tmon will increase by a magnitude of more than 3.6 ? and 6.3 ?,with a increment of more than 4? and 6? in Sanjiang Plain,respectively.At the same time,changing trend of precipitation during grow season of crop(Pmon)is similar to annual rainfall.At the end of 21 st century,the increment of precipitation will be 40~100mm,60~120mm and 100~140mm at Sanjiang,Songneng and Liaohe Plains,respectively.It is thus seen that warming areas are not consistent with wet-indreasing areas in future.In this paper,the temporal and spatial changes of the main agricultural climate resource indicators are systematically evaluated in Northeast China in the future.Based on these results,scientific basis can be provided for agricultural adjustment of crop planting structure and crop varieties,and corresponding measures and scientific support can be proposed to increase crop yield.