Spatial-temporal Characteristics And Influencing Factors Of Climate Growth Period Of Chimonophilous Crop In North China From 1960 To 2016

Agricultural production is a process that is highly dependent on natural conditions,especially climate conditions,and the change of climate resources must have a significant impact on it.Heat resource is an important part of agricultural production,and the accumulated temperature,the onset and upset date and continuous days are also indicators of the quantity and availability of heat resources.Under the background of global warming,climate change will inevitably cause is closely related to the crop growing period of the change of the heat resource in time and space,which has aroused widespread attention of scholars both at home and abroad at present.As a transition zone and sensitive area in different climatic regions,north China is also an important production base of grain,cotton and oil in China,and its climate change often has a great impact on crop growth.Therefore,based on the daily average temperature of 137 meteorological stations in north China of the distribution area of chimonophilous crop,we analyzed spatial and temporal variation characteristics and the impact factors of the onset and upset date,growing period and effective accumulated temperature during growth of chimonophilous crop,with the aid of methods including a climatic tendency rate,IDW under the ArcGIS software,Mann-Kendall mutation test,Morlet wavelet analysis,two element linear regression model,principal component analysis and correlation analysis.The main conclusions are as follows:(1)In the past 57 years,the start date of climate growth period of chimonophilous crop in north China has advanced and the end date has postponed;the dates of the growing period have gradually prolonged,the effective accumulated temperature during growth have gradually increased,with the trend rates being-1.389d/10a?1.223d/10a?2.612d/10a?75.346?/10 a,respectively.Moreover,in the 1970 s,in Norh China,the start date of climate growth period of chimonophilous crop exhibited the most significant trend towards a advancement,the end date towards a postponement,growing period towards a prolongation,the effective accumulated temperature during growth towards a increase.In the 1990 s,in Northeast China,the start date of climate growth period of chimonophilous crop exhibited the most significant trend towards a postponement,the end date towards a advancement,growing period towards a shortage,the effective accumulated temperature during growth towards a increase.(2)Although spatial disparity in onset and upset dates,growing period,as well as the effective accumulated temperature during growth of chimonophilous crop exhibit significant regional differences,the characteristics of spatial variation remain consistent.In general,the growing period and effective accumulated temperature during growth of chimonophilous crop have tended to be shorten and reduced over time;specifically,start dates have tended to be delayed while end dates have advanced from south to north over north China.Among them,in Norh China,the start date of climate growth period of chimonophilous crop exhibited the most significant trend towards a advancement,while the trend of the end date towards a postponement,growing period towards a prolongation,the effective accumulated temperature during growth towards a increase are the highest in Northwest China.(3)The Mann-Kendall mutation analysis showed that mutation points of the onset and upset date,growing period and effective accumulated temperature during growth of chimonophilous crop were respectively observed in 1993,1989,1993 and 1995.The onset and upset date,growing period and effective accumulated temperature during growth of chimonophilous crop were about 11 a mesoscale and 2a short time scale dominant period,coinciding with 2~4a general atmospheric circumfluence and 11 a sunspot activity cycle;in addition,climate growth period short cycles for chimonophilous crop are 4a,5a,6a,and 8a,consistent with the periodicity of El Ni?o period of 2-7 years.(4)The influence factors analysis showed that the main driving factor of climate growth period of chimonophilous crop in north China was the average temperatures in March,altitude and latitude;while the number of days that comprise the growing season was more significantly perturbed by latitude and altitude than the start and end date;the Arctic Oscillation(AO),the Asian polar vortex area index(APVAI),the Asia polar vortex intensity index(APVII),the intensity of East Asian Trough(EAT),and the westerly circulation index(WCI)were the main factors affecting the onset and upset date,growing period and effective accumulated temperature during growth of chimonophilous crop in Northeast,North and Northwest China.This result is consistent with the periodic outcomes of Morlet wavelet analysis.