| Drought, as one of the most severe and destructible meteorological disasters, has a most far-reaching side-effect on economic and social development. In recent decades the occurrence of droughts was more and more frequent under the background of the global climate warming. In order to ascertain the occurrence patterns of droughts in different regions,the drought index as a key paramenter of drought monitoring,forewarning and assessment play an important role in the prevention from drought and the mitgation of disaster loss. Therefore, this study was designed to seek some reliable indices for drought monitoring and forewarning in Jiangsu Province. The purpose was guiding the prevention from droughts, reducing the loss of droughts so as to ensure the safety of the industrial and agricultural production and provide scientific basis for the harmonious development of the society in Jiangsu Province.Based on the climate data of 54 meteorological stations in Jiangsu Province, the daily potential evapotranspiration (ET0) during 1960 to 2009 in the area was calculated by the Penman-Monteith formulation. According to the Chinese Meteorological Drought Grades in the National Standard BG/T20481-2006 in China, MI, a relative index of climate dryness and wetness, was used to evaluate the arid and moist conditions of the climates in different regions of Jiangsu Province. The analysis on the spatial-temporal distribution and variation pattern of MI in the province were displayed as follows:(1) In space, the relative dry and the relative wet climate area half of each in Jiangsu province. (2)Interannual variability:Annual fluctuations of PE was consistent with the change of the temperature.(3) Seasonal change:The MI was in turn increase from north to south in spring, the whole province belonged to wet period in summer, Autumn was semiarid area except a part of south Jiangsu, the MI was a significant zonally distribution in winter. (4) To the meteorological droughts of Jiangsu Province, in the decade scale, the droughts of the whole year and all seasons have been existing a obvious cycle of 10 to 12 years and the cycle of 2 to 4 years was most remarkable on the inter-annual variation. (5) The drought lasting days of different grades in Jiangsu Province were reducing from north to south in general. The drought lasting days of different grades were most in winter and least in summer.In this paper, the observed meteorological data of 54 meteorological stations from 1960 to 2009 in Jiangsu Province of China were collected and a composite index (CI) of meteorological drought was used to analyze the temporal and spatial characteristics of droughts in the province. Based on the daily CI values of each station in 50 years, the drought processes of each station was confirmed one by one and the occurred frequencies, scopes and severities of the meteorological droughts in the different regions of Jiangsu Province were computed and analyzed to reveal the temporal and spatial occurrence pattern of the meteorological droughts in Jiangsu Province. The results were showed as follows:(1) The annual and seasonal occurrence frequencies of the meteorological drought in Jiangsu Province transferred high to low from north to south. In all seasons, the occurred frequency of the winter droughts was highest, the summer droughts occurred least and the difference of the autumn droughts between the north part and south part of the Province was the least in the occurrence frequency. (2) The years of the drought occurred in a large scope (more than 90% of total area of the Province) was most in winter and least in summer. (3) In the recent 50 years, there was an notable inter-annual wave of the annual average lasting days and the annual average occurrence severities of meteorological droughts in the whole Province but their linear change tendencies were not obvious. (4) The drought lasting days of different grades in Jiangsu Province were reducing from north to south in general. The drought lasting days of different grades were most in winter and least in summer.In order to understand the engendering, disappearing and evolving pattern, in this paper, a serious autumn drought event when occurred in from October to November in 2006 and covered the whole Jiangsu Province was selected as a typical case and the daily composite meteorological drought index was calculated after the daily observed data of 54 meteorological stations were collected. Based on it, the beginning date, ending date, lasting days and daily drought severity for every station were determined and the drought engendering, disappearing and evolving characteristics of the whole province and each region in this drought event were discussed. A monitoring data production of MODIS Satellite remote sensing was merged into a vegetation water supply index and was used to reflect the evolving pattern of this drought process. The inverse distance weighted interpolation in ArcGIS9.3, a software of geographic information system, was applied in the temporary and spatial analysis of the drought development combined with the observed soil moisture data of 16 agro-meteorological observation stations in Jiangsu Province. The results were showed as follows:(1) In this typical autumn drought event, the engendering, disappearing and evolving pattern of the atmospheric, vegetation and soil drought reflected by the composite drought index, vegetation water supply index and soil moisture were consistent essentially. (2) The engendering of the drought event expanded and spread gradually from the northwestern part to the southeastern part of the province and its ending shrank and disappeared little by little from the southeastern part to the northwestern part of the province and the lasting days decreased successively from the northern part to the southern part of Jiangsu Province. (3) The drought severity in the northern part of the province was heavier than the southern part. Because of the different atmospheric backgrounds and natural geographic conditions, there was a obvious divergence of the evolving processes in the different regions. (4) Composite drought index, vegetation water supply index and soil moisture could be used to monitoring the engendering, developing, disappearing, and severity variations characteristics of a drought process in an all-round and systematic way. |
PDF Full Text Request