The Changing Law Of Rainfall In Lanzhou And Its Distribution Characteristics

The long-term rainfall time series data can directly display the local climate change process and has good utilization value.This paper hopes to reveal the change law of rainfall in Lanzhou City from important nodes and the whole time period by studying the long-term daily meteorological data of Lanzhou rainfall,so that people have a deeper understanding of rainfall and can assist the meteorological department to improve the accuracy of rainfall prediction.It also provides reference value for local agricultural development,tourism travel,and urban water supply.The paper analyzes the rainfall over time from Mann-Kendall trend test,MK mutation test,wavelet analysis and descriptive statistics from the annual rainfall data of Lanzhou City from 1951 to 2016 from three time scales: interannual,quarterly and monthly.The changing laws and distribution characteristics,including the characteristics of rainfall distribution,trend and periodicity,etc.,in addition to the conversion of rainfall into frequency,further understanding the characteristics of rainfall days,and according to the size of rainfall,will The rainfall is divided into different grades.On the important nodes,the change of the first rainfall in Lanzhou City is analyzed from the rainfall and rainfall.The relationship between the 24 solar terms and the rainfall is also studied.The law of change in the day's rainfall.Through analysis,Lanzhou has a significant downward trend in August every year,and in 2019,the spring will enter the dry season,and summer,autumn and winter will enter the flood season,which will drive the whole year.During the flood season.In the days and grades of rainfall,the number of interannual rainfall days showed a significant downward trend,which means that in the future,when Lanzhou enters the flood season,the rainfall will increase,and the number of rain days will decrease,indicating that the future rainfall characteristics of Lanzhou City are mainly characterized by Centralized,high-intensity rainfall;on a quarterly scale,the number of light rain days in spring showed a significant downward trend,while the spring was mostly dominated by light rain,indicating that the rainfall in the next spring will decrease,which coincides with the conclusion that the spring will enter the dry season.It is necessary to do a good job in Lanzhou's entry into the flood season,and to prevent and warn of concentrated heavy rainfall.At the important nodes,there was no significant trend change in the first rain and the rainfall in Lanzhou.In the analysis of the 24 solar terms rainfall,the most rainfall is the summer heat season.The most frequent rainfall is the autumn season.From the perspective of rainfall level,the rainfall level of Xiaoshu is mostly medium to light rain,while the heavy rain in the autumn is more,so Take precautions at the relevant time.