| Jilin Province is located in northeastern China, which belongs to the monsoonclimate zone, is an important grain production base in China. With global warming,climate change and other global climate anomalies, Jilin Province is facing the threatof drought and flood–prone and it has a devastating impact on crop growth, people’slivelihood and economic development. Therefore, the study of spatial and temporalcharacteristics of the drought and flood in summer in Jilin Province has a veryimportant practical significance.With the development of remote sensing technology, remote sensing data whichhas advantage of better spatial coverage, spatial and temporal distribution ofcontinuous precipitation has become an important source of rainfall data. Amongthem, due to the three-dimensional information of precipitation, the Tropical RainfallMeasurement Mission data has been widely used.Drought/flood indicators of various disciplines and sectors defined differently.Where, because of its ease of access to information, the simple calculation, therealistic results, the Z index method is widely used in the analysis of thecharacteristics of drought and flood. This paper, by using TRMM summerprecipitation data from1998to2012, based on Z index method, accomplished thespace-time characteristics analysis of drought and flood in summer in Jilin province.The main findings are as follows:1. TRMM precipitation data availability verification.Based on correlation analysis and scatter slope method, the study associatedground-based meteorological observation data and corresponding site TRMM rainfalldata. In the summer months (from June to August) TRMM precipitation data is lowerthan the ground meteorological data as awhole. The R2of summer months and thewhole summer is0.63,0.63,0.67and0.64, the relative error were5.84%,7.80%,10.44%,8.17%, respectively.The results indicated that the discrete degree betweenTRMM precipitation and site measured is small and the TRMM precipitation is closeto the gauged precipitation.2. The spatial distribution of summer drought/flood in Jilin ProvinceJilin province change relatively frequent flood and drought in summer and thesame area has large change of the drought and flood in different summer months. Inaddition to features in July, during the fifteen years, the years in which the droughtand flood in June and August occurred in the same period in different areas are less.In Jilin province, drought and flood has characteristics of the consistent changes andcentralized occurrence.The drought and flood frequency analysis in the summer months in Jilin province shows that in June、July and the whole summer the drought frequency higher areasare concentrated in the northwest region of Jilin province; in August it is in thesoutheastern region of Jilin province;the flood high frequency areas in June、July、August、the whole summer is in southern、in eastern、in the north、 in the central andeastern of Jilin province，respectively.Z Index trend analysis of Jilin shows the development trend of flood and drought.The values of Z index in June have a rising trend in southern of Jilin province, whilethe most areas of the northern bureau have a tendency to reduce on the contrary. InJuly, the Z value has a lower trend in the mid-east regions of Jilin province, but thewest has a rising trend. August is just the reverse of July. From the west to east in Jilinprovince shows low-high-low trends in the whole summer.3. Drought and flood time series characteristics in summer in Jilin provinceThe past15years, the drought frequencies in summer months were all over35%,Jilin province over the summer is the season of frequent drought and flood, theoverall performance for the flood frequency is greater than the drought frequency, lessnormal years.The drought and flood level time series of Jilin province in June show thefour-year cycle, and since1998, drought and flood level of one cycle performancecharacteristics for the combination of flood-drought-flood. The drought and floodlevel time series of Jilin province in July performance cycles for three years. Droughtand flood in July has certain periodic change, from2000to2005, this stage is mainlycharacterized by partial waterlogging, while the value of2006to2012show thealternation frequent flood and drought.August Jilin drought/flood level time series showed no obvious cyclecharacteristics, but from1998to2000,2010to2012showed the same two timeperiods of floods and droughts and the variation is more frequent droughts and floodsalternating phase, from2001to2004and from2005to2009showed similarvariations, and the performance of the main stage to drought.Throughout the summer drought and flood level time series showed a three-yearcycle, and a cycle of alternating droughts and floods more frequently. |
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