Temporal And Spatial Variations Of Temperature And Its Influencing Factors In The Lower Reaches Of The Pearl River Basin During The Past 60 Years

Global climate change has had a profound impact on ecosystem,hydrological cycle and agricultural production.Temperature change is an important part of climate change.Therefore,this paper explores the climate change in the lower reaches of the Pearl River Basin in recent 60 years from the perspective of temperature.This paper systematically analyzes the temporal and spatial evolution characteristics and main attribution of temperature in this region,in order to provide a theoretical basis for agricultural layout adjustment and regional sustainable development.This paper studies the daily meteorological observation data of 52 meteorological observation stations in the lower reaches of the Pearl River Basin from 1961 to 2020.The temporal and spatial distribution characteristics of temperature changes in the study area at different time scales are analyzed by means of climate tendency rate,moving average and spatialization of meteorological elements;Wavelet method is used to analyze the periodic variation of air temperature;M-K method and sliding t-test are used to analyze the abrupt change of temperature series under various meteorological elements and scales;The temporal and spatial distribution and characteristics of heat island intensity in the study area are analyzed by meteorological station method;Geographical detector,principal component analysis and wavelet coherence are used to study the relationship between different influencing factors such as meteorological elements and atmospheric circulation and temperature.The main conclusions are as follows:(1)The interannual variation of air temperature in the lower Reaches of the Pearl River Basin shows an increasing trend in the past 60 years,and the trend rate of air temperature is0.16℃/10a(positive correlation,R=0.4752;F>Fa,significant correlation).The interdecadal variation of temperature is that the linear warming trend of annual mean temperature in the first 40 years is significant.The distribution function is applied to study the interdecadal temperature,and the trend of annual mean temperature is generally increasing in the alternation of cold and warm.The variation characteristics of temperature from flood season to non-flood season are that the average temperature in flood season is higher than that in non-flood season,and the trend rate of temperature in non-flood season is higher than that in flood season.There is a significant correlation between temperature change in flood season and time,but there is no correlation between temperature change in non-flood season.The results of extraction and analysis of temperature series period show that the temperature has a frequency structure of multiple time scales,and the average annual temperature has a main period oscillation of 10-24 A.The probability of temperature anomaly is 10%-14%.Abnormal temperature occurred in flood season and non-flood season,but the frequency of the latter was less than the former.The abrupt change of air temperature in flood season occurred in 1997 in the lower reaches of the Pearl River Basin,but the abrupt change of air temperature in non-flood season occurred in 1972.(2)The interannual and interdecadal variation of HEAT island intensity is as follows:from 1992 to 2012,the growth rate of heat island intensity in the lower reaches of the Pearl River Basin firstly increased gently and then increased rapidly.The variation pattern of heat island intensity in flood season and non-flood season in the lower Reaches of the Pearl River Basin from 1961 to 2020 shows a u-shaped curve with a trend of increasing,decreasing and increasing,and the non-flood season heat island intensity decreases year by year and then increases year by year.(3)The relationship between air temperature change and meteorological factors is evaporation,and the interaction between evaporation and atmospheric pressure is the main influencing factor of air temperature change in the study area.The relationship between heat island intensity and meteorological factors shows that water is the key factor affecting the change of heat island intensity in the lower reaches of the Pearl River Basin.The results show that NAO has a significant influence on the air temperature in the lower reaches of the Pearl River Basin in the whole time domain.The results of heat island intensity and atmospheric circulation index factor show that NAO has significant influence on heat island intensity in flood season and non-flood season in the lower reaches of the Pearl River Basin in the whole time domain.