| The wind erosion in the wind erosion area in northern China is serious,the Gobi desert is widespread,and the dust source is extremely rich.Wind as a driving force for soil wind erosion plays a vital role in the occurrence and movement of soil wind erosion.In this study,the observation data of 186 ground meteorological observatories in the northern wind erosion area from 1970 to 2017 were used to analyze the spatial and multivariate time scale changes of the average wind speed in the region using methods such as climatic erosivity,spatial interpolation,bfast mutation analysis and wavelet analysis.Characteristics and trends,periodic characteristics and abrupt changes;statistics of different levels of wind speed days,analysis of temporal and spatial characteristics of wind speed days of each level,and temporal and spatial correlation between different levels of wind speed days and average wind speed;using wind erosion climatic factor index to calculate wind erosion climate in the region Erosion,analyze the temporal and spatial distribution and variation characteristics of wind erosion climatic erosivity,and use the methods of time-space correlation and sensitivity analysis to focus on the driving force analysis of wind erosion climatic force in wind erosion area in northern China.The main conclusions are as follows:(1)During the period from 1970 to 2017,the average annual wind speed in the wind erosion area of northern China was 2.66 m/s,showing a significant downward trend,and the rate of decline was 0.016 m/(s·a).There were significant differences in wind speed variations in different seasons.The annual average wind speed tendency rate in the northern wind erosion area ranges from-0.084 to 0.104 m/(s·a),and there is a spatial difference in wind speed variation.In the north wind erosion area,northwestern and southeastern Xinjiang,Qinghai,central Inner Mongolia and northeastern part Heilongjiang and Jilin are the regions with faster wind speed reduction.The southeastern part of Gansu,Ningxia,Shanxi and northwestern Shaanxi,Liaoning,Xinjiang,and the northwestern part of Xinjiang are areas where wind speed is not significantly reduced.There are multiple time-scale periodic structures of wind speed change.Characteristics,the 28-year time scale is the main period of the wind speed period change,and the average change period is 19 years;the BFAST algorithm deals with the monthly average wind speed in the northern wind erosion area.The results show that there are two sudden changes in the trend component,and the time nodes are 1988.Month and March 2011.(2)The number of wind speed days in grade I(0-5 m/s)of wind erosion area in northern China shows an increasing trend.The grades of wind speed II(5-10 m/s)and III grade(above 10 m/s)show a decreasing trend.The trend of the four seasons is consistent with the annual trend,and the rate of change is significantly different between the four seasons;the spatial distribution of the number of wind speed days of the I grade has a good high and low correspondence with the grade II and III;in the past 48 years,with the wind speed grade When the annual wind speed decreases,the change speed slows down,the inter-annual difference narrows,and the difference between seasons and regions decreases.The three-level wind speed days change have periodic characteristics of multiple time scales,and the I-level wind speed days change.The main cycle is a 30-year time scale,and the main periods of the change of the number of days of the II and III are 29-year time scales;the results of the BFAST algorithm show that the mutation points are detected in the trend component in the three-level wind speed days,and the mutation occurs.The rate of change in the number of days after the wind speed becomes slower.There is only one mutation point in the seasonal component of the II grade wind speed day,and the seasonal variation of the wind speed day of the grade is reduced after the mutation.(3)From 1970 to 2017,the weather erosion climatic erosion in the wind erosion area of northern China showed a significant downward trend,with a rate of decline of 0.745 per year.The trend of the year shows that from January onwards,the weather erosion of wind erosion gradually increased,reaching the highest in April,and then gradually decreased;the annual average wind erosion of the northern wind erosion area varies between 2-698 and climatic erosivity.The slope rate is between-11.78 and 32.05.Although most of the annual average climate wind erosion rate is less than zero,there is a significant spatial difference in the extent of wind erosion climatic erosion;wind erosion climatic change varies for 10-14 years.25-32 and three change cycles in 15-24;the main cycle around the 29-year time scale,the average change period is 19 years;the bfast algorithm deals with the monthly wind erosion climatic erosivity in the northern wind erosion area,showing no mutations in the seasonal components Point,there was a mutation point in the trend component in August 1993,and the 95% confidence interval for the mutation occurred between May 1993 and April 1994.(4)Both the average wind speed and the I-level wind speed days show a good correlation between time and space.The temporal and spatial changes of the I-level wind speed days can basically reflect the change of the average wind speed.The correlation analysis between wind erosion climatic erosivity and meteorological elements in wind erosion area of northern China shows that wind speed is an important factor affecting the evolution of wind erosion climatic erosivity.The decrease of average wind speed directly leads to the reduction of wind erosion climatic force in northern wind erosion area.trend.From the internal structure of wind speed,wind is the most important driving factor for wind erosion climatic erosion.The cumulative number of days with wind speed above 10m/s is the best and better than the average wind speed. |
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