On The Climate Change Over China: A Study Based On Climate Memory And External Forcing

The characteristics of memory and influences of external forcing on climate system have attracted much attention in the study of global climate change.The representation of multi-scale interactions of climate between subsystems is climatic memory,and the response to adjusted forcing but do not changing the initial condition on climate system is external forcing.Complexity of interactions between inner and external factor take vastly challenges to predict the future climate change.For better understanding the earth climat system,establishing state-of-the-art coupling climatic model and improving capacity of predicting,this article base on detecting the characteristics of memory from surface air temperature(SAT)and precipitation,using the Fractional Integrated-Stochastic Model(FISM)to correct the memory of reconstructional precipitation over China,evaluate model ability of simulating memory and forcing part,and investigate quantified connection between modeling temperature and radiative forcing.The results are shown as follows:There are significantly long-term memory(LTM)in detecting some of temperature records but do no in precipitation form nearly 70 years observational station data in China.Analysing the nearly 50 years observational grid data in China,higher memory values of temperature are found in the northeast and southwest of China and lower values are found in the south of the Yangtze River,but there are not significant memory in most region of China.Detecting the nearly 30 years global observation data,the air temperature over the ocean have strong memory and weaker over the land,however,the memory of precipitation are found weaker all over the world.Diagnosis the reconstruction precipitation data over the past 530 years in China,the LTM values are found significantly overestimated in the western china and others regional.Comparing with memory values of proxy data,the sources of overestimation of reconstruction are from tree-ring records.Using FISM to correct the memory part of reconstruction,correction grid precipitation performance well in western China,but regional averaged precipitation time-series is still overestimated memory values.Analysing difference of network degrees and locating distribution of the tree rings,the sources of overestimated LTM of regionally averaged time-series also come from the tree rings.Evaluating the decadal hindcast experiments of 11 models in phase 5 of the Coupled Model Intercomparison Project(CMIP5),poor skills in simulating the memory part of SAT are found in all the considered models.In the northwest and northeast,the LTM of 4 and 6 models is overestimated,while the LTM of 11 models is signifcantly underestimated in the southwest.After removing the biased memory part from the simulations using FISM,the remaining forcing part,however,is found reasonably simulated in the CCSM4?Can ESM2 and MPI-ESM-LR,especially in multimodel means.The decadal hindcast experiments of models have potential predictability for SAT forcing term.Investigating quantified connection between modeling SAT and different radiative forcing experiments,nature radiative forcing influence the short-term global averaged temperature and its forcing term,there is not obviously warming or cooling trend in the century scale.From forcing term of global averaged temperature in well-mixed greenhouse gases and anthropogenic aerosols forcing experiments,the ratio of warming and cooling trend in past 155 years is from 1.1 to 1.6 times,however,considering the model simulating memory by itself,the ratio is larger from 1.6 to 3 times.And from forcing term of chinese averaged temperature in the same experiments,the ratio is nearly 2 times,but the uncertainty of trend in past 155 years become larger,the ratio change from 1.5 to 2.6 times when investigating chinese averaged temperature.