1071 Merged-field Analysis considering the Atmospheric-Oceanic Factors for the Meteorological Drought Analysis in South Korea

Wednesday, 25 January 2017
4E (Washington State Convention Center )
Ae-sook Suh, Korea Water Resources Corporation, Gwacheon-si, Korea, Republic of (South); and J. B. Ahn

Drought is generally defined as the natural hazard by the deficit of rainfall or water supply. In addition, the damage of drought are slowly occurred in the wide ranges. Therefore, the comprehensive analysis for various causes and status of drought is needed to manage the drought risk. In this study, the merged-field analysis for seasonal drought events of South Korea was performed considering the atmospheric-oceanic factors and identified the meteorological causes of drought events.
The seasonal precipitations such as spring (March-April-May, MAM), summer (June-July-August, JJA), autumn (September-October-November, SON), and winter (December-January-February, DJF) recorded from 1975 to 2015 were considered for drought analysis. In addition, the drought event was defined as the event with seasonal precipitation below the value of “-1úIstandard deviation” in a normal year. Especially, the summer precipitations were divided as the monsoon season (June and July, JJ) and season after monsoon (August) because the monsoon influences on the precipitations of June and July and the local convection and typhoon effect on one of August.
In the case of spring drought, the northerly wind by low pressure anomaly in the east of South Korea was stronger and the weakening of the North Pacific anticyclone was showed. In addition, a jet stream shifted southward. For the summer drought, the North Pacific anticyclone was not extended into South Korea because of the low pressure anomaly in the South sea of Japan. Therefore, the supply of water vapor into South Korea was difficult and a jet stream shifted southward compared to a normal year. For autumn drought, the northwesterly wind was stronger and the north part of northwest Pacific anticyclone was weakening because of the low pressure anomaly in the east of Japan. The patterns of 500 hPa geopotential height were similar to Western Pacific Pattern and it was the appearance of Rossby wave from North East Asia to Greenland. In the case of winter drought, northwesterly wind was stronger compared to a normal year because of the northwesterly wind anomalous in the west of South Korea. Thus, the dry air from the continent entered into South Korea.
As the results, the complex factors of meteorological phenomena influence on the occurrence of seasonal droughts in South Korea. Thus, it is needed that the information systems is developed for the proper respond and public share of drought in the climate change as well as the causes and characteristics of current drought are investigated.

This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KIMPA 2015-6190.

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