• 대기
• /
• 제27권3호
• /
• pp.345-358
• /
• 2017

The decadal change in rainfall for Changma period over the South Korea in early-2000s is detected in this study. The Changma rainfall in P1 (1992~2002) decade is remarkably less than in P2 (2003~2013) decade. The much rainfall in P2 decade is associated with the increase of rainy day frequency during Changma period, including the frequent occurrences of rainy day with a intensity of 30 mm/day or more in P2 decade. This decadal change in the Changma rainfall is due to the decadal change of atmospheric circulation around the Korean Peninsula which affects the intensity and location of Changma rainfall. During P2 decade, the anomalous anti-cyclone over the south of the Korean Peninsula, which represents the expansion of the North Pacific high with warm and wet air mass toward East Asia, is stronger than in P1 decade. In addition, the upper level zonal wind and meridional gradient of low-level equivalent potential temperature in P2 decade is relatively strengthened over the northern part of the Korean Peninsula than in P1 decade, which corresponds with the intensification of meridional gradient between air mass related to the East Asian summer monsoon nearby the Korean Peninsula in P2 decade. The enhanced meridional gradient of atir mass during P2 decade is favorable condition for the intensification of Changma rainfall band and more Changma rainfall. The atmospheric conditions related to enhanced Changma rainfall during P2 decade is likely to be influenced by the teleconnection linked to the suppressed convection anomaly over the southern part of China and South China Sea in P2 decade.

• 한국물환경학회지
• /
• 제30권2호
• /
• pp.212-219
• /
• 2014

In this study, a land pollutant load calculation method in TMDLs was improved to consider climate change scenarios. In order to evaluate the new method, future change in rainfall patterns was predicted by using SRES A1B climate change scenarios and then post-processing methods such as change factor (CF) and quantile mapping (QM) were applied to correct the bias between the predicted and the observed rainfall patterns. Also, future land pollutant loads were estimated by using both the bias corrected rainfall patterns and the enhanced method. For the results of bias correction, both methods (CF and QM) predicted the temporal trend of the past rainfall patterns and QM method showed future daily average precipitation in the range of 1.1~7.5 mm and CF showed it in the range of 1.3~6.8 mm from 2014 to 2100. Also, in the result of the estimation of future land pollutant loads using the enhanced method (2020, 2040, 2100), TN loads were in the range of 4316.6~6138.6 kg/day and TP loads were in the range of 457.0~716.5 kg/day. However, each result of TN and TP loads in 2020, 2040, 2100 was the same with the original method. The enhanced method in this study will be useful to predict land pollutant loads under the influence of climate change because it can reflect future change in rainfall patterns. Also, it is expected that the results of this study are used as a base data of TMDLs in case of applying for climate change scenarios.

• 한국토양비료학회지
• /
• 제44권6호
• /
• pp.983-990
• /
• 2011

Universal Soil Loss Equation (USLE) has been used to estimate potential long-term soil erosion in the fields. However, the USLE does not estimate sediment yield due to lack of module considering sediment delivery ratio (SDR) for watershed application. For that reason, the Sediment Assessment Tool for Effective Erosion Control (SATEEC) system was developed and applied to compute the sediment yield at watershed scale. However, the R factor of current SATEEC Ver. 2.1 was estimated based on 5-day antecedent rainfall, it is not related with fundamental concept of R factor. To compute R factor accurately, the energy of rainfall strikes should be considered. In this study, the R module in the SATEEC system was enhanced using formulas of Williams, Foster, Cooley, CREAMS which could consider the energy of rainfall strikes. The enhanced SATEEC system ver. 2.2 was applied to the Imha watershed and monthly sediment yield was estimated. As a result of this study, the $R^2$ and NSE values are 0.591 and 0.573 for calibration period, and 0.927 and 0.911 for validation period, respectively. The results demonstrate the enhanced SATEEC System estimates the sediment yield suitably, and it could be used to establish the detailed environmental policy standard using USLE input dataset at watershed scale.

• 대한지리학회지
• /
• 제46권3호
• /
• pp.277-290
• /
• 2011

본 연구에서는 장기간의 관측 자료를 분석하여 레짐이동에 따른 우리나라 여름철 강수의 특성변화 및 그 원인을 파악하였다. 우리나라 여름철 강수량의 시간적 변동을 분석한 결과, 1998년 이후 강수량의 변동 폭이 크게 증가하였다. 이는 장마 후 기간인 8~9월 강수량의 변동성 증가가 기여한 것으로 보이며, 6~7월의 강수량 역시 점차적인 증가 경향을 보였다. 강수량의 레짐이동에 따른 공간 분포의 변화는 1998년 이후 동아시아 전체에 걸쳐 밴드 형태의 강수량 증가 구역이 나타났으며, 8~9월에는 동아시아 지역 내에서 우리나라가 유일하게 큰 증가를 보였다. 특히 서울 및 경기 지역은 130mm 이상으로 강수량이 가장 크게 증가했다. 이는 우리나라 북쪽과 동쪽에 위치한 고기압성 흐름의 강화로 북쪽의 찬 공기와 남동쪽에서 불어오는 따뜻하고 습윤한 공기가 우리나라에서 수렴하게 되어 강수시스템 발달에 좋은 조건이 되기 때문인 것으로 나타났다. 우리나라 동쪽의 상층까지 발달한 키 큰 순압고기압은 동아시아와 북태평양의 해수면온도 상승에도 기여하여 온난한 공기의 유입이 우리나라 쪽으로 강화되었다.

• 대기
• /
• 제26권1호
• /
• pp.141-158
• /
• 2016

The objective of this study is to examine the impact of urban canopy and the horizontal resolution on simulated meteorological variables such as 10-m wind speed, 2-m temperature and precipitation using WRF model for a local, convective rainfall case. We performed four sensitivity tests by varying the use of urban canopy model (UCM) and the horizontal resolution, then compared the model results with observations of AWS network. The focus of our study is over the Seoul metropolitan area for a convective rainfall that occurred on 16 August 16 2015. The analysis shows that mean diurnal variation of temperature is better simulated by the model runs with UCM before the convective rainfall. However, after rainfall, model shows significant difference in air temperature among sensitivity tests depending on the simulated rainfall amount. The rainfall amount is significantly underestimated in 0.5 km resolution model run compared to 1.5 km resolution, particularly over the urban areas. This is due to earlier occurrence of light rainfall in 0.5 km resolution model. Earlier light rainfall in the afternoon eliminates convective instability significantly, which prevents occurrence of rainfall later in the evening. The use of UCM results in a higher maximum rainfall in the domain, which is due to higher temperature in model runs with urban canopy. Earlier occurrence of rainfall in 0.5 km resolution model is related to rapid growth of PBL. Enhanced mixing and higher temperature result in rapid growth of PBL, which provides more favorable conditions for convection in the 0.5 km resolution run with urban canopy. All sensitivity tests show dry bias, which also contributes to the occurrence of light precipitation throughout the simulation period.

• 대기
• /
• 제18권4호
• /
• pp.317-338
• /
• 2008

Analyses of observational data and numerical simulations were performed to understand the mechanism of MCSs (Mesoscale Convective Systems) occurred on 13-14 July 2004 over Jindo area of the Korean Peninsula. Observations indicated that synoptic environment was favorable for the occurrence of heavy rainfall. This heavy rainfall appeared to have been enhanced by convergence around the Changma front and synoptic scale lifting. From the analyses of storm environment using Haenam upper-air observation data, it was confirmed that strong convective instability was present around the Jindo area. Instability indices such as K-index, SSI-index showed favorable condition for strong convection. In addition, warm advection in the lower troposphere and cold advection in the middle troposphere were detected from wind profiler data. The size of storm, that produced heavy rainfall over Jindo area, was smaller than $50{\times}50km^2$ according to radar observation. The storm developed more than 10 km in height, but high reflectivity (rain rate 30 mm/hr) was limited under 6 km. It can be judged that convection cells, which form cloud clusters, occurred on the inflow area of the Changma front. In numerical simulation, high CAPE (Convective Available Potential Energy) was found in the southwest of the Korean Peninsula. However, heavy rainfall was restricted to the Jindo area with high CIN (Convective INhibition) and high CAPE. From the observations of vertical drop size distribution from MRR (Micro Rain Radar) and the analyses of numerically simulated hydrometeors such as graupel etc., it can be inferred that melted graupels enhanced collision and coalescence process of heavy precipitation systems.

• 대한환경공학회지
• /
• 제33권6호
• /
• pp.439-446
• /
• 2011

본 연구에서는 도시 비점오염물질의 퇴적과 배출특성의 파악, 우수저류/침투 시설의 계획과 효율평가, 건전한 도시의 물환경관리 등의 관점에서, 고해상도 인공위성과 GIS를 병용한 도시내 상세 토지이용분류 방법을 제안하였다. 제안된 방법을 적용하여 도시유역을 네 종류의 지표면으로 분류하였으며, 기존의 실내조사방법이나 GIS만을 이용한 방법으로는 불투수면으로 파악되었던 전체 유역면적의 3%에 달하는 건물옥상이나 도로의 중앙분리대에 조성된 화단 등을 투수면으로 분류하였다. 강우유출모의의 정확도 향상에 있어서 토양피복별 분포 및 면적의 차이가 미치는 영향을 파악하기 위해, 추출된 각 토양피복에 강우손실 파라미터를 설정하여, 총강우량 7.1~15.0 mm의 강우사상에 대한 강우유출해석을 실시하였다. 기존의 10m 격자의 세밀토지이용 정보에 의한 토양피복 분류결과를 이용한 강우유출 해석에서는 관측유량과의 오차가 31~71%이었던 것이, 제안된 토양피복 분류기법을 이용한 강우유출 해석에서는 그 오차가 4~29%로 향상되었으며, 특히 강우규모가 적을 때의 유출수문곡선의 첨두유량과 유량증감부 등의 유출특성에 대한 재현성에 있어서 향상된 결과를 나타내었다.

• 대한토목학회논문집
• /
• 제36권5호
• /
• pp.791-803
• /
• 2016

최근 기상변동성이 증가함에 따라 지난 30년 동안 극한강우의 발생 빈도는 점차 증가하고 있다. 우리나라는 지리적으로 단시간에 매우 높은 강우강도를 유발하는 강우사상이 빈번하게 발생하여 홍수사상이 유발되기 쉽다. 본 연구에서는 장기간의 강우자료를 활용하여 극치강우사상의 발생을 고려한 강우빈도해석을 수행하였다. 이를 위해 극치강우사상을 분석하는데 있어 서로 다른 절점기준을 사용하여 극치강우의 발생횟수를 반영한 포아송-GPD 강우빈도해석 기법을 개발하였다. 빈도해석을 수행함에 있어서 확률분포 매개변수의 불확실성을 보다 정량적으로 산정할 수 있는 Bayesian 기법을 적용하였으며, 또한 각각의 절점기준에 따라서 분류된 강우사상의 종관기후학적 분석을 수행하였다. 연구결과 우리나라의 극치강우 발생이 증가하는 지점에서 기존의 Gumbel 분포를 통한 확률강우량보다 상향된 결과를 도출하였다. 이는 포아송-GPD 모형이 치수안정성 측면에서 유리한 모형으로 판단된다. 또한 동중국해 지역의 저기압 특성과 북태평양 고기압 특성이 우리나라 극치강우현상에 주로 영향을 미치는 것을 확인하였다.

• 한국수자원학회논문집
• /
• 제50권1호
• /
• pp.17-28
• /
• 2017

최근 국지성 집중호우 및 돌발홍수와 같은 급격한 기상변화로 인한 기상재해의 발생빈도가 증가함에 따라 고해상도의 기상레이더 강우자료를 사용한 수공학 분야의 연구가 활발하게 진행되고 있다. 기상레이더는 넓은 지역에 걸쳐 실시간으로 강우현상 감시가 가능하며 지상우량계로는 파악이 불가능한 미계측유역을 통과하는 강우장의 이동 및 변동성 파악이 가능한 장점이 있지만 대기 중 존재하는 수상체로부터 반사되는 반사도를 사용하여 강우량을 산정하므로 시공간적 오차가 존재한다. 본 연구에서는 이러한 문제점을 해결하기 위하여 다변량 Copula 함수를 활용하여 레이더 강우에 존재하는 시공간적 오차를 규명하고 레이더 강우앙상블 생산기법을 개발하였다. 개발된 모형으로부터 생산된 레이더 강우앙상블은 통계적 효율기준 분석결과 우수한 모형성능을 확인하였으며 추가적으로 극치호우 및 강우시계열 패턴 분석결과 지상강우의 특성을 효과적으로 재현하는 것을 확인하였다.

• 한국지구과학회지
• /
• 제28권5호
• /
• pp.585-597
• /
• 2007

The characteristics of the rainfall events on the Korean peninsula have been investigated by means of regional and global observational data collected from 1954 to 2004 with an emphasis on extreme cases $80\;mm\;day^{-1}$. According to our analysis, long-term annual rainfall anomalies show an increasing trend. This trend is pronounced in the month of August, when both the amount of monthly rainfall and the frequency of extreme events increase significantly. Composite maps on August during the 8 wet years reveal warm SST anomalies over the eastern Philippine Sea which are associated with enhanced convection and vertical motion and intensified positive SLP over central Eurasia during August. The rainfall pattern suggests that the most significant increase in moisture supply over the southern parts of China and Korea in August is associated with positive SLP changes over Eurasia and negative SLP changes over the subtropical western Pacific off the east coast of south China. The frequent generation of typhoons over the warm eastern Philippine Sea and their tracks appear to influence the extreme rainfall events in Korea during the month of August. The typhoons in August mainly passed the western coast of Korea, resulting in the frequent occurrence of extreme rainfall events in this region. Furthermore, anomalous cyclonic circulations over the eastern Philippine Sea also promoted the generation of tropical cyclones. The position of pressure systems - positive SLP over Eurasia and negative SLP over the subtropical Pacific - in turn provided a pathway for typhoons. The moisture is then effectively transported further north toward Korea and east toward the southern parts of China during the extreme rainfall period.