| Dry and hot wind is a kind of agrometeorological disaster in extreme weather,which is sensitive to global warming.When the dry and hot wind is high,it is the period from wheat flowering and grouting to maturity.When wheat encounters the dry and hot wind,its root system activity decreases,water balance is out of balance,and aging and death are accelerated.In agricultural production,it is easy to cause crop yield reduction,and it is one of the main factors leading to crop yield reduction.Mastering the spatio-temporal characteristics and occurrence rules of dry-hot wind disasters has an important impact on preventing dry-hot wind disasters,improving disaster prevention and reduction capacity,and ensuring the stable development of agriculture and food security.Therefore,it is of great significance for regional agricultural management,production,people’s life and food security to study the spatial and temporal characteristics and risk zoning of dry-hot wind disasters.Gansu,Gansu and Xinjiang provinces are located in the arid and semi-arid areas in northwest China.The frequent occurrence of dry-hot wind disasters leads to the instability of wheat planting and production,and is the main agrometeorological disaster affecting the high and stable yield of wheat.Therefore,this paper uses the daily climate data of73 meteorological stations in the spring wheat area of the three provinces of Gansu and Qinghai for nearly 57 years,and uses the linear trend method and inverse distance weighting(IDW)interpolation method to analyze the spatial and temporal variation characteristics of the hot and dry wind in the study area.Principal component analysis and linear regression were used to analyze the influence factors of dry and hot air in three provinces.Finally,combined with relevant statistical data,risk regionalization of hot and dry wind disaster was conducted from the aspects of risk factors,environmental sensitivity and disaster prevention and reduction ability.The main conclusions of this paper are as follows:(1)In recent 57 years,Qinghai province dry-hot wind days showed a trend of decrease,the change tendency rate for-0.267d/10a(α≥0.1).Dry-hot wind days change trend of the provinces exist obvious difference,among them,Gansu and Xinjiang dry-hot wind days all showed a trend of decrease,change trend raterespectively-0.231d/10 a and-0.29d/10a(α≥0.05),and the dry-hot wind days of Qinghai province increased,change tendency rate is 0.4d/10a(α≥0.01).(2)The spatial distribution of dry-hot wind disaster in the whole region is obviously regional,with the Hexi corridor in Gansu province,the tu-ha basin in Xinjiang,the eastern tarim basin and the junggar basin as the center and decreasing to the surrounding areas.In June,the Hexi corridor,tu-ha basin and the eastern tarim basin are the hot and dry areas.In July,the east of tarim basin and hexi corridor are the hot and dry areas.In August,the dry and hot wind disaster decreased from southwest to northeast.(3)According to the analysis of influencing factors,the regional dry and hot air is mainly affected by the relative humidity and total precipitation in June and August;The main influencing factors of dry and hot wind in Gansu province are latitude and total sunshine hours from June to August.From June to August,relative humidity,total precipitation and total sunshine hours are the main factors affecting the dry-hot wind in Qinghai province.The dry and hot winds in Xinjiang are mainly affected by the average temperature and total precipitation from June to August.For each 100 m rise in altitude,the average total number of dry and hot air days in each station in the study area for 57 years decreased by 7.7d,among which,the number decreased by32 d in Gansu province,5.4d in Qinghai province and 13 d in Xinjiang.In addition,the three provinces of Qinghai new dry-hot wind also affected by the northern subtropical high area index and the impact of Asian zonal circulation index,among them,in June by the index of the Tibet plateau and the Asian zonal circulation index had the greatest influence,mainly by the northern hemisphere subtropical high area index in July,the northern hemisphere subtropical high strength index,the northern hemisphere polar vortex intensity index and Asian zonal circulation index,the influence of August by the northern subtropical high area index,the northern hemisphere subtropical high strength index and has the greatest effect in the northern hemisphere polar vortex area index,and through the significance test of 0.01.(4)The results of comprehensive risk regionalization analysis of dry-hot wind show that the high-risk areas are mainly concentrated in Hexi corridor of Gansuprovince,northwest of tu-ha basin of Xinjiang,west and north of tarim basin and northwest of junggar basin,and southeast of Gansu province,southeast of Qinghai province and the belt from altay to balikun are dry-hot wind low-risk areas. |
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