Studies Of Forecasting Methods On The Summer Drought And Flood In Chifeng Area Of Inner Mongolia

Researches on the evolution characteristics of summer precipitation,the developing characteristics and circulation pattern of summer drought and flood(SDF) have been made by using the data of meteorologic factors from ten weather stations in Chifeng area of Inner Mongolia Autonomous Region, the synoptic charts and other products disseminated by National Climate Center.The emphases were put on the main elements that were affected the summer precipitation,especially the SDF,such as factors of climate,sunspot and atmosphere general circulation.The relations between Mongolia cold vortex, sub-tropical high,mid-latitude circulation and SDF were studied in the atmosphere general circulation part.Selected elements integrated through different contributions and influence types were used to form a SDF prediction model in order to improve such extreme climate events prediction of SDF.Veracity of forecasting SDF was more than 75%from 1995to 2006.Analysis in power spectrum of the summer precipitation shows that it's cycles are mainly 2.6a and 3.2a,but ther are not prominent.Still,the summer precipitation there are 4 distinct dry and wet phases. low-grade drought and drought years often occurred during the dry phase of summer precipitation,on the contrary,natural and flood years often occurred during the wet phase.There are 6 phased drought characteristics of summer.In 48 years,the frequency is about 69%for all phased drought characteristics,it often occurred during the 1.5 years.Autumn drought and early summer and summer drought are the most frequently,summer drought is the least.The fact is climate warming up in chifeng area.1987 is the first year of climate warmming up. After 1987,summer precipitation abnormity is more,the frequency increases for SDF,summer drought, summer and autumn drought.The Mongolia cold vortex,the mid-latitude circulation and the sub-tropical high could affect on the SDE Above three weather systems favorabl tone,the summer flood years were often,on the contrary,the drought years were often.Relation of the summer precipitation and the sunspot is opposite.The drought years were often found in or near the sunspot cycle maximum years.The winter circulation index and polar vertex position in north hemisphere in Asia area can affect on the summer circulation pattern.The winter polar vertex and the circulation index factors conjunctly affected on summer precipitation.However,their effects are different,and the effects are variational with the facts,they dynamicly affect on summer precipitation.Hereby the winter circulation is divided intoⅠ～Ⅵmodels.By test,the effect of circulation models on forecasting SDF and summer precipitation is more better than the regress equation method.The circulation factor was the most important effect factor on SDF,climate fact and the sunspot factor were less than important.By conformity to above three style facts,to establish the prediction model on the SDF.The model is stability and higher exact.Based the summer precipitation forcasting regress equation of jun,july and august by widely researching relativity.On this condition,making sure types of phased drought.