Reconstruction And Analysis Of Climate Change Series In Beijing Region During The 1820-2020 Period

High-resolution historical climate change series reconstruction is an important element of past global change research,and it is important for deeper understanding of long-term climate change patterns and prediction of future climate change.Using 33,604 records of daily weather phenomena in Beijing from private diaries of the Qing Dynasty,and modern instrument observations data,the winter half-year temperature series,annual and four seasons precipitation series and sunshine duration series in Beijing during 1820-2020 were reconstructed,the climate change characteristics of Beijing in the past 200 years were analyzed,and the future climate change trend of Beijing was predicted.The research results not only help to reveal the law of climate change in Beijing,but also provide basic data,regional cases and historical similarities for adaptation to future climate change.The main conclusions are as follows:(1)The winter half-year temperature in the Beijing area from 1820 to 2020 shows a multi-decadal fluctuation of "cold-warm-cold-warm",with a significant warming trend at a rate of 0.104±0.020 ℃/10a(p< 0.001),and there are several significant warming and cooling trends on the interdecadal scale;since 1820,there are 39 a,15 a and 27 a quasiperiodic changes in the winter half-year temperature in Beijing,and a sudden change occurred in 1986.(2)The annual and seasonal precipitation in Beijing from 1820 to 2020 showed several alternating wet and dry processes.In the past 200 years,annual,spring,summer and winter precipitation in Beijing showed a decreasing trend,while autumn precipitation showed an increasing trend,and there were several significant increasing and decreasing phases of annual and seasonal precipitation on interdecadal scales.There are seasonal differences in the cycles and abrupt changes.(3)The annual sunshine duration in Beijing from 1820 to 2020 showed two more periods and two less periods.The rate of 3.221±3.998 h/10 a showed an insignificant decreasing trend(p>0.05).There were several rapid increasing and decreasing processes in multiple years and scales,and the maximum decreasing rate was concentrated in the middle and late 20 th century.The maximum rate of increase began in the late 19 th century;The annual sunshine duration had a main cycle variation of 113 a,88 a and 59 a,with abrupt changes in 1886,1904,1925 and 1987.There are seasonal differences in the variation rate,cycle and mutation of sunshine duration.(4)In different time scales,the changes of temperature,annual precipitation and annual sunshine duration in the future winter in Beijing will be continuous,and the climate change will be "warm and dry" and "dark".On the seasonal scale,the future change trend of autumn precipitation is contrary to the past change trend,while the change sequence of spring,summer and winter temperature,precipitation and sunshine duration is continuous and will continue the past change trend in the future.