Synthesis Reconstruction Precitipation Reconstruction Based On Centennial Resolution Since Holocene In China

Studying the ancient environment,especially the reconstruction of high resolution climate,is of great significance for understanding the evolution of the past climate and forecasting future climate change.China has a unique geographical location,a vast area,and diverse topography and landforms.It has a remarkable response to environmental changes.Integrating the paleo-precipitation series with100-year resolution since the Holocene,it provides a reference model and method for future paleoenvironment research,especially reconstruction work.It also has a certain significance for exploring the mechanism of future environmental changes.This research is based on a modern analogy method,using the climate parameters(average annual precipitation,average annual relative humidity,and annual average evaporation)from 1981 to 2009,surface soil pollen,fossil pollen,90*90m Chinese digital elevation model map,and domestic and international Published results of a study on the quantitative reconstruction of ancient precipitation.First,the ancient precipitation was reconstructed in Halin Lake in northern China.Afterwards combining ArcGis spatial analysis tools,R language programs,and SPSS statistical analysis tools,seven geographical factors affecting modern precipitation were selected and collinearity tests(tolerance and variance inflation factors)were performed.Then,a multiple linear regression model between geographic factors and multi-year average precipitation was established using the least squares method and add the influence factor in turn.The optimal result model showed an R~2 of 0.849.On this basis,the modern analogy method was used to explore the quantitative relationship between environmental proxy indicators sporopollen and climate parameters during regional paleoclimate reconstruction and collect ancient precipitation sequences for integrated reconstruction.The 1841 average annual precipitation values were extracted from 31 good paleo-precipitation series.Finally get the following conclusions:(1)Analyze the impact of various influencing factors on modern precipitation,use basic geographical factors to integrate paleosaid precipitation and analyze its dynamic changes.Finally,the four factors of longitude,latitude,altitude,and slope through the multicollinearity test are taken as the explanatory variables of modern precipitation reconstruction,and a multivariate regression model of modern precipitation is built using the least squares method.The result has a high correlation R~2=0.81 and can be used for ancient precipitation integration studies.(2)Quantitative reconstruction of paleoclimate using modern analogy based on pollen data.The average annual precipitation,relative humidity,and evaporation have a high correlation,and the most ideal parameter is the average annual precipitation,and the correlation coefficient R~2=0.894.Based on the fossil pollen records of Haring Lake in Jilin Province,the Holocene precipitation changes in the region were reconstructed.The precipitation sequence can be used as one of the integrated reconstruction data.(3)China's Holocene 100-year resolution precipitation sequence integration results can be broadly divided into early,middle,and late stages from time to time.The first stage:the early Holocene(early Holocene-8750 a BP),the gradual increase in precipitation is the humidification period,the precipitation is relatively low and then gradually increased,the average precipitation is 366.27 mm.The second stage:During the peak period of the Holocene(8650-5250 a BP),the precipitation increased rapidly,and the average annual precipitation reached the highest value of 681.29 mm at 5850 a BP.After reaching a maximum,it gradually showed a fluctuating downward trend,but the peak value of the fluctuations.The difference is lower than in the first phase.The third stage:the fluctuations of precipitation in the late Holocene(5150-50a BP)were relatively stable,and the precipitation changes were relatively stable.However,the amplitude of precipitation was relatively stable,but it was significantly reduced compared to the second stage.The mean value was 466.14 mm.The precipitation decreased gradually after 2650 a BP,and a precipitation peak reached570.56 mm before and after 1850 a BP.The precipitation before and after 450 a BP reached the lowest value of 381.15 mm during this period,which corresponds to the small ice age.