Prediction Of Future Climate Change In The Kaidu-Kongqi River Basin Based On CMIP5 Model

The Kaidu-Kongqi River Basin is a key area of the Silk Road Economic Belt.Its development plays an important role in the construction of the “Belt and Road”.It is of significance to have a correct understanding of the future climate change of the Kaidu-Kongqi River Basin for the economic development of the basin,the construction of ecological civilization and water resource forecasting.Using CN05.1data and 21 CMIP5 downscaling daily maximum,minimum temperature and precipitation grid data provided by NEX-GDDP,firstly assess each model and EE,PM-EE,PLS and PM-PLS multi-model ensembles simulation results of historical climate change trends,sudden changes,and periodic changes,then predict climate change under the RCP4.5 and RCP8.5 scenarios for the Kaidu-Kongqi River Basin in2020-2050.The main results were as follows:(1)From 1961 to 2005,the multi-year average of the maximum temperature in the basin is between-0.9 and 21.5 °C,and the minimum temperature range from-13.5to 6.5.The spatial distribution law is that the temperature is high in the southeast and low in the northwest and it has been increasing significantly over the past 45 years.In the simulation of the maximum temperature,the growth rate of most model simulation results is higher than the observation result,and the minimum temperature.However,it is generally relatively small;for the sudden change,only a part could reasonably simulate the mutation year of the maximum and minimum temperature in the basin.Before and after the optimization,the mutation time of EE and PLS simulation are not much different;In the 1960 s,the maximum and minimum temperatures in the basin has a period of 2-3 years.In the periodic analysis of the single model,the simulation effect of the maximum temperature is better than that of the minimum temperature.(2)In the past 45 years,the multi-year average of precipitation in the basin range from 13 to 525 mm,it has been gradually increased from southeast to northwest.The simulation results has simulated the existing spatial characteristics;the precipitation has a rate of 6.53mm/10 a,which is significantly increased.The simulation results hasboth increasing trend and decreasing trend;for the sudden change of precipitation,only CNRM-CM5 and NorESM1-M can accurately simulate the sudden change of precipitation,PM-EE and PM-PLS can better simulate the sudden change year;most of the models can't simulate the periodic variation of the basin precipitation.(3)The maximum and minimum temperature show a significant increase under the two scenarios of 2020—2050,and greater rise rate of the RCP8.5 scenario than the RCP4.5 scenario.Under the two scenarios,the maximum temperature in plain area is higher than that in northwest mountainous area.But the largest increasing magnitude of the minimum temperature is mainly located in the central part of the basin,and RCP8.5 scenario show a greater temperature increase in the northwest and southeast regions.Under the RCP4.5 scenario,the maximum temperature in the basin will probably be abruptly changed in 2030.In 2040 s,there will probably be a period of 4 to 6 years.The minimum temperature will be 3 years later than the former,and in the 2040 s,there are periodic changes of about 4 to 5 years;In the RCP8.5 scenario,the abruptly change time of maximum and minimum temperature are the same,both in2033,the maximum temperature has a period of about 3 years,which occurred in the2020 s.The minimum temperature has a period of 3 to 4 years from 2030 s to 2040 s.(4)The precipitation in the basin show a decreasing trend under the two emission scenarios of 2020 — 2050,and show that the reduction trend under the RCP8.5scenario is greater than RCP4.5.Under the RCP4.5 scenario,the precipitation reduction rate decrease from the northwest mountainous area to the southeastern desert gradually,and the precipitation reduction rate in the northwest upstream area under the RCP8.5 scenario is relatively smaller than that in the RCP4.5 scenario.In the RCP4.5 scenario,the precipitation will probably be abruptly changed in 2022 and2045.The precipitation will probably have a change period of 2~3 years in the 30 s and 40 s of the 21 st century.Under the RCP8.5 scenario,the time of precipitation mutation will probably be 2022 and 2045.In the 20 s and 30 s of the 21 st century,there will probably be a periodic change of 3 to 4 years.