Research On The Spatio-Temporal Characteristics Of Drought-Flood As Well As Cold-Warm Of Northern China During Qing Dynasty

Historical literature includes large amount of meteorological information,it is an important proxy data for climate change study on long time scale.For studying the drought and flood as well as cold and warm condition in historic period,explore the change trend and evolution rule deeply on long time scale,in this paper,drought and flood as well as cold and warm condition was excavated and researched using time series analysis methods and GIS,which aimed at exploring the spatio-temporal evolution and the impact factors with multi-method,multi-scale,and kinds of data sources,and analyze the physical mechanism in depth.The main conclusions are:(1)Wavelet analysis of the drought and flood grade series of Northern China from 1644 to 1911 shows that the period changes obviously in the characteristic time scale of 10-lla,20-22a,45-50a,90-100a.Do mutual test on the series,it is found that the 10a jump point is 7and the 30a jump point number is 4.Analyze the spatial distribution of the drought and flood grade series of Northern China,it presents a decrease trend from the east to the west,the precipitation of Shandong Province is obvious higher than other areas,it is related with the plentiful moisture of Shandong as it is a coastal area.(2)Do cross wavelet power spectrum analysis and wavelet coherency spectrumanalysis between drought and flood grade series of Northern China and Nino3 SSTindex、sunspot number seriesseparately,it is found that drought and flood grade series of Northern China and Nino3 SSTindex have strong relationship on the scale of 2-4a and 8-12a,the phase difference are different on different timescales;drought and flood grade series and sunspot number series are closely related on 8-14a.(3)Set the grade standard of the cold and warm,then reconstruct the grade index series of cold and warm in Northern China from 1644 to1911,the results show that the cold and warm change can be devided into two cold periods and one warm period,the cold period focused on 1644-1690 year and 1810-1911 year,the warm period focused on 1691-1809 year.Do mutual test on the series,8 jump points are found,among them,5 points are on 10a timescale,3 points are on 30a timescales.(4)Do wavelet transform on the reconstructed grade index series of cold and warm in Northern China from 1644 to 1911,the results show that the series has period of 11-15a、22-30a、38-45a、80-90a,power spectrum analysis shows the most significant periods are 2a、4a、8a and 14a.Do cross wavelet power spectrum analysis between the reconstructed grade index series of cold and warm in Northern China and sunspot numbers series from 1700 to 1911,the two series are found closely related on 4-12a timescale,wavelet coherency spectrum analysis reveals they have strong coherence resonance period of 60-70a.(5)The frequency of frost and snow disasters which happens in Northern China from 1644to 1911 are counted,there are 1982 frost and snow disasters in this area,mild、moderate and serious disasters are 1132、708 and 142 respectively,among it,the frequency of autumn are the highest,spring is second to it,then comes to winter,summer is the least.According to the frequency,the frost and snow disasters in Northern China can be devided into four stages,the first stage is 1644-1703,the second stage is 1704-1803,the third stage is 1804-1903,the fourth stage is 1904-1911,the second and fourth stages are high in the frequency of which disasters happen,the first and the third stages are low in the frequency.(6)The complete ensemble empirical mode decomposition of the annual frequency of frost and snow disasters in Northern China from 1644 to 1911 shows:Inter-annualperiodic changes are mainly found for 2.8a、5.3a;Inter-decadal periodic fluctuations are mainly found for 11.3a、22.6a、45.2a、52.0a;And the centurial periods are mainly found for 119.4a.The spatial distribution of frequency shows the frost and snow disasters in Northern China is distributed unevenly in Qing Dynasty,the frequency of Henan and Hebei is smaller than that of Shandong and Shanxi,among them Shanxi is higher.The spatial distribution of grades presents a certain degree of consistency with the distribution of frequency,the disasters of Shandong、Henan and Hebei are more mild and moderate,the disasters of Shanxi are more severe,it presents the distribution of sheet.