[Objective] The aim was to study the reasons of low temperature and characteristics of weather in Yuxi City.[Method] The reasons of low temperature in Yuxi City were expounded.The types of low temperature and their in...[Objective] The aim was to study the reasons of low temperature and characteristics of weather in Yuxi City.[Method] The reasons of low temperature in Yuxi City were expounded.The types of low temperature and their influences on agricultural crops were introduced.The route of cold air and the typical circulation characteristics of low temperature were analyzed.[Result] The low temperature in Yuxi City was formed because of the influence of its topography and climate.The low temperature and cold disaster included frost,low temperature in spring and autumn;the influencing path of cold air in Yuxi City had four paths:northeast,north,northwest and east path.The circulation characteristics of snowing included southerly trough,strong and cold air,and cold front shear;under the long-term control of cold advection of upper air and cold high pressure in the low layer,the radiation,cooling and temperature reducing were the main circulation characteristics of heavy frost;the circulation background of low temperature in August was conductive to the strong cold air intruding the upper air circulation of Yuxi City.The cold trough in the north and low pressure in the south influenced the circulation in Yuxi City.[Conclusion] The study provided reference for the weather report and relevant professionals.展开更多
Based on data of daily average temperature observed during maize growing period as well as data of different growing periods of maize at 24 meteorological stations in Heilongjiang Province from 1980 to 2010, changes i...Based on data of daily average temperature observed during maize growing period as well as data of different growing periods of maize at 24 meteorological stations in Heilongjiang Province from 1980 to 2010, changes in risk of chilling damage to maize since 1980 were analyzed. Initially, the risk of the hazard factor was calculated by adopting the criterion of "Comprehensive Decision System of Chilling Damage to Maize in Heilongjiang Province". Then, choosing the planting area of maize at 75 stations as the exposure degree index, risk zones of exposure degree were concluded. Afterwards, risk zones of maize sensitivity to chilling damage were outlined based on maize yield per unit area. At last, a comprehensive evaluation model of chilling damage to maize in Heilongjiang Province was established, and Heilongjiang Province was divided into 5 grades of risk zones according to the model. The results showed that compared with the period before 1995, the risk of chilling damage to maize was severer in the west area of Songnen Plain, and previous sub-low or medium risk of chilling damage to maize in the west of Sanjiang Plain changed into subhigh or hi qh risk since the middle 1980s.展开更多
Low temperature chilling damage is one of the most serious disasters in maize production,which is a typical non-linear complex issue with numerous influencing factors and strong uncertainty.How to predict it is not on...Low temperature chilling damage is one of the most serious disasters in maize production,which is a typical non-linear complex issue with numerous influencing factors and strong uncertainty.How to predict it is not only a hot theoretical research topic,but also an urgent practical problem to be solved.However,most of the current researches are focusing on post-disaster static descriptive assessment rather than pre-disaster dynamic predictive analysis,resulting in the problems such as no indicative result and low accuracy.In this study,the satisfaction rate of environmental accumulated temperature for maize production was used to measure the chilling damage risk,and a model for maize chilling damage risk prediction based on probabilistic neural network was constructed.The model was composed of input layer,pattern layer,summation layer and output layer.The obtained results showed that the prediction accuracy for the most serious risk level was as high as 0.91,and the rates of the Type I Error and Type II Error made by the model were 0.1 and 0.09,respectively.This indicated that the model employed was promising with good performance.The results of this research are of both theoretical significance for providing a new reference method of pre-disaster prediction to study maize chilling disaster risk and practical significance for reducing maize production risk and ensuring yield safety.展开更多
文摘[Objective] The aim was to study the reasons of low temperature and characteristics of weather in Yuxi City.[Method] The reasons of low temperature in Yuxi City were expounded.The types of low temperature and their influences on agricultural crops were introduced.The route of cold air and the typical circulation characteristics of low temperature were analyzed.[Result] The low temperature in Yuxi City was formed because of the influence of its topography and climate.The low temperature and cold disaster included frost,low temperature in spring and autumn;the influencing path of cold air in Yuxi City had four paths:northeast,north,northwest and east path.The circulation characteristics of snowing included southerly trough,strong and cold air,and cold front shear;under the long-term control of cold advection of upper air and cold high pressure in the low layer,the radiation,cooling and temperature reducing were the main circulation characteristics of heavy frost;the circulation background of low temperature in August was conductive to the strong cold air intruding the upper air circulation of Yuxi City.The cold trough in the north and low pressure in the south influenced the circulation in Yuxi City.[Conclusion] The study provided reference for the weather report and relevant professionals.
基金Supported by the Scientific Research Project of Public Welfare Industry of China(GYHY201306036)
文摘Based on data of daily average temperature observed during maize growing period as well as data of different growing periods of maize at 24 meteorological stations in Heilongjiang Province from 1980 to 2010, changes in risk of chilling damage to maize since 1980 were analyzed. Initially, the risk of the hazard factor was calculated by adopting the criterion of "Comprehensive Decision System of Chilling Damage to Maize in Heilongjiang Province". Then, choosing the planting area of maize at 75 stations as the exposure degree index, risk zones of exposure degree were concluded. Afterwards, risk zones of maize sensitivity to chilling damage were outlined based on maize yield per unit area. At last, a comprehensive evaluation model of chilling damage to maize in Heilongjiang Province was established, and Heilongjiang Province was divided into 5 grades of risk zones according to the model. The results showed that compared with the period before 1995, the risk of chilling damage to maize was severer in the west area of Songnen Plain, and previous sub-low or medium risk of chilling damage to maize in the west of Sanjiang Plain changed into subhigh or hi qh risk since the middle 1980s.
基金This study is supported by the general program of Humanities and Social Sciences Research of the Ministry of Education of China(Grant No.19YJC880064)the Hunan Provincial Education Department(Grant No.19B447)+1 种基金the Hunan Provincial Natural Science Foundation(Grant No.2017JJ3252)This work is also supported in part by the Huaihua University Double First-Class initiative Applied Characteristic Discipline of Control Science and Engineering.
文摘Low temperature chilling damage is one of the most serious disasters in maize production,which is a typical non-linear complex issue with numerous influencing factors and strong uncertainty.How to predict it is not only a hot theoretical research topic,but also an urgent practical problem to be solved.However,most of the current researches are focusing on post-disaster static descriptive assessment rather than pre-disaster dynamic predictive analysis,resulting in the problems such as no indicative result and low accuracy.In this study,the satisfaction rate of environmental accumulated temperature for maize production was used to measure the chilling damage risk,and a model for maize chilling damage risk prediction based on probabilistic neural network was constructed.The model was composed of input layer,pattern layer,summation layer and output layer.The obtained results showed that the prediction accuracy for the most serious risk level was as high as 0.91,and the rates of the Type I Error and Type II Error made by the model were 0.1 and 0.09,respectively.This indicated that the model employed was promising with good performance.The results of this research are of both theoretical significance for providing a new reference method of pre-disaster prediction to study maize chilling disaster risk and practical significance for reducing maize production risk and ensuring yield safety.