• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.170-170
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• 2018

In some case studies, the heavy precipitation events and rapid cyclogenesis in the extratropics can be caused by moist and warm tropical air masses. Tropical Moisture Exports (TME) correspond to the meridional transport of moist air masses, primarily born in tropical oceanic areas, to higher latitudes; and are closely related to flood events, especially in the mid-latitudes. The TME for the region of interest is mostly estimated by the back tracking approach using Lagrangian Analysis Tools (LAGRANTO) from ECMWF Re-Analysis (ERA) data. In this study, we aim to estimate the TME that are related to rainfall in Korea. The major moisture sources of the TME that contribute to heavy rainfall and extreme floods in Korea are identified. The TME is found to have significant connection with extreme events in Korea such as heavy rainfall and extreme flood events. The results show the most of the moisture sources comes from the west Pacific during the warm half of the year and it contributes significantly to the annual TME and is linked to the East Asian monsoon.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.615-617
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• 2003

Carbon monoxide (CO) is one of the important trace gases because its concentration in the troposphere directly influences the concentrations of tropospheric hydroxyl (OH), which controls the lifetimes of tropospheric trace gases. CO traces the transport of global and regional pollutants from industrial activities and large scale biomass burning. The distributions of CO were analyzed using the MOPITT data for East Asia, which were compared with the ozone distributions. In general, seasonal CO variations are characterized by a peak in the spring, which decrease in the summer. The monthly average for CO shows a similar profile to that for O$_3$. This fact clearly indicates that the high concentration of CO in the spring is possibly due to one of two causes: the photochemical production of CO in the troposphere, or the transport of the CO into East Asia. The seasonal cycles for CO and O$_3$ in East Asia are extensively influenced by the seasonal exchanges of different air mass types due to the Asian monsoon. The continental air masses contain high concentrations of O$_3$ and CO, due to the higher continental background concentrations, and sometimes to the contribution from regional pollution. In summer this transport pattern is reversed, where the Pacific marine air masses that prevail over Korea bring low concentrations of CO and O$_3$, which tend to give the apparent summer minimums.

• 대기
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• 제30권3호
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• pp.311-318
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• 2020

Impacts on the atmospheric circulation and ocean system over the Mediterranean during boreal summer are investigated using Coupled Model Intercomparison Project Phase 5 (CMIP5) historical simulations (from 1911 to 2005). As the climate warms, global and remote effects lead to a strengthening in descending motion, an increase in sea surface temperature (SST) and surface dryness, but a decrease in marine primary production over the Western Mediterranean. The global effect is estimated from interannual variability over the global mean SST and the remote effect is driven by diabatic forcing generated from the South and East Asian summer monsoons. On the other hand, a local contribution leads to the strengthened descending motion and increased surface dryness over the Eastern Mediterranean, whereas the marine primary production over this region tends to increase due to possibly the urban wastewater and sewage. Our result suggests that particular attention needs to be paid to conserve the marine ecosystem over the Mediterranean.

• 한국지구과학회지
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• 제44권1호
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• pp.1-12
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• 2023

해양의 파랑은 지구온난화 및 기후변화의 중요한 지표 중 하나로 인식되고 있다. 기후변화와 동아시아 몬순의 영향을 직접적으로 받는 황해 및 동중국해역에서의 유의파고 및 파향의 시공간 변동성 연구가 필요하다. 본 연구에서는 유럽중기예보센터(European Centre for Medium-Range Weather Forecasts; ECMWF)에서 제공하고 있는 5세대 모델 재분석장 (ECMWF Reanalysis 5, ERA5) 자료를 활용하여 황해 및 동중국해역에서의 유의파고와 파향의 공간분포와 계절 및 경년변동을 포함하는 시공간 변동성을 분석하였다. 모델 재분석자료를 활용한 유의파고와 파향의 변동성 분석에 앞서 이어도 해양과학기지 관측 자료와의 비교를 통하여 정확도를 검증하였다. 평균 유의파고는 0.3-1.6 m의 범위를 보였으며 북쪽에 비해 남쪽이 높고 연안에 비해 황해 중심부에서 높은 공간분포 특성을 보였다. 유의파고의 표준편차 또한 평균과 유사한 양상을 나타내었다. 황해에서 유의파고와 파향은 뚜렷한 계절변동성을 보였다. 유의파고의 경우 전반적으로 겨울철에 가장 높았으며 늦봄 또는 초여름에 가장 낮았다. 파향은 계절풍의 영향으로 겨울철에는 주로 남쪽으로 전파되었으며 여름철에는 북쪽으로 전파되는 특성이 나타났다. 유의파고의 계절변동은 여름철 태풍 등의 영향으로 해마다 연 진폭의 큰 변화를 가진 강한 경년변동성을 보였다.

• 한국해양학회지:바다
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• 제24권4호
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• pp.509-518
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• 2019

다양한 표층 수온 자료를 통해 1979년부터 2018년 기간 동안의 가을철 동해 공간 평균 표층 수온이 태평양 순년 진동과 높은 상관관계를 나타내는 것을 확인하였다. 이 해역에서 제트류의 활동이 가장 강한 200 hPa에서의 바람과 동해 표층 수온의 회귀 분석 결과, 가을철 동해 표층 수온이 상승할 때 제트류의 중심축이 북상하면서 전반적으로 제트류가 약화하는 경향을 보이며, 동해 수온이 하강할 때는 제트류의 중심축이 남하하면서 제트류가 강화되는 경향을 보였다. 이러한 분석 결과는 제트류의 강도 변화와 중심축의 남북 진동이 동해 표층 수온과 태평양 순년 진동의 커플링과 관련되어 있음을 시사한다. 여름철의 약한 제트류와 겨울철 및 이른 봄철의 강한 동아시아 동계계절풍 효과는 동해와 태평양 순년 진동의 커플링이 가을철 외의 다른 계절에 잘 나타나지 않게 하는 이유로 생각해볼 수 있다.

• 생태와환경
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• 제35권3호통권99호
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• pp.160-171
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• 2002

본 연구는 낙동강 하류에서 장마 기간의 강우가 수질 변화에 미치는 영향을 평가하였다. 1997년 하절기 장마기간 주요 집수역의 강우상황을 분석하고 낙동강 하류역 (물금)에서 $1{\sim}3$일 간격으로 수질항목(수소이온농도,　탁도, 투명도, 엽록소-a, 용존산소, 전기전도도, 수온)과　영양염류 등(총질소, 총인, 질산성 질소, 암모니아성 질소, 인산 인, 규산)을 측정하였다. 또한 갈수기 이후 큰 강에서 최초 집중강우가 수질 변화에 미치는 영향을 평가하기 위하여 수질 자동측정장비(Hydrolab $Recorder^{TM}$)를　이용하여 장마 초기강우 전후에 1시간 간격으로 수질　및 수위변화를 모니터링하였다. 우리나라는 연간 강우의약 50%이상이 하절기 ($6{\sim}8$월)에 집중되며,　특히 장마는6월 하순경에 시작하여 7월 중순까지 약 한 달간 하천수환경에 크게 영향을 미친다. 1997년 장마기간동안 낙동강의 주요 집수역에서 50mm 이상의 강우가 내린 횟수는 총 5회였고,　여름기간 중 물금 지역에서 물리${\cdot}$화학적 환경요인에 급격한 변화가 일어난 시기는 장마 초기를 전후해서였다. 초기강우로 기초수질항목 중 수온, 수소이온농도, 전기전도도, 용존산소는 큰 폭으로 감소하였고 탁도, 영양염류 및 규산 등과 같은 항목은 증가하는 양상을 보였다. 하절기 엽록소-a 농도는 총인, 총질소의 높은 농도에도 불구하고 연중 최저치를 나타냈는데, 이는 장마 강우로 인한 탁도 증가와 수체의 체류시간감소 영향 등이 크게 작용한 것으로 사료된다. 장마 초기 강우 동안 영양염류의 농도는 크게 증가하는 양상을　보였으나 항목에 따라 그 패턴은 다소 상이했다. 장마는　몬순기후에 의해 발생하는 기상 현상으로,　연중 가장 두드러진 집중된 강우 및 급격한 유량변화를 유발함으로써 하천생태계에 큰 영향을 미치게 된다. 특히, 이 기간동안 강우의 빈도 및 강도는 하천의 육수학적 현상 변화와 패턴에 중요한 요소로서 작용하며, 이는 동아시아몬순기후대에 속하는 하천들에서 유사하게 발생하는 하천의 중요한 특성으로 사료된다.

• 대기
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• 제21권1호
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• pp.109-121
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• 2011

This study revisits the definition of Changma, which is the major rainy season in Korea and corresponds to a regional component of the East Asian summer monsoon system. In spite of several decades of researches on Changma, questions still remain on many aspects of Changma that include its proper definition, determination of its onset and retreat, and relevant large-scale dynamical and thermodynamical features. Therefore, this study clarifies the definition of Changma (which is a starting point for the study of interannual and interdecadal variability) using a basic concept of air mass and front by calculating equivalent potential temperature (${\theta}_e$) that considers air temperature and humidity simultaneously. A negative peak in the meridional gradient of this quantity signifies the approximate location of Changma front. This front has previously been recognized as the boundary between the tropical North Pacific air mass and cold Okhotsk sea air mass. However, this study identifies three more important air masses affecting Changma: the tropical monsoon air mass related to the intertropical convergence zone over Southeast Asia and South China Sea, the tropical continental air mass over North China, and intermittently polar continental air mass. The variations of these five air masses lead to complicated evolution of Changma and modulate intensity, onset and withdrawal dates, and duration of Changma on the interannual time scale. Importantly, use of ${\theta}_e$, 500-hPa geopotential height and 200 hPa zonal wind fields for determining Changma onset and withdrawal dates results in a significant increase (up to~57%) in the hindcast skill compared to a previous study.

• 대기
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• 제25권3호
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• pp.435-447
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• 2015

This study explores the synoptic characteristics of cold days over South Korea and their relationship with large-scale climate variability. The cold day, which is different from cold surge, is defined when daily-mean surface air temperature, averaged over 11 KMA stations, is colder than 1-percentile temperature in each year by considering its long-term trend over 1960~2012. Such event is detected by quantile regression and the related synoptic patterns are identified in reanalysis data. Composite geopotential height anomalies at 500 hPa show that cold days are often preceded by positive anomalies in high latitudes and negative anomalies in midlatitudes on the west of Korea. While the formers are quasi-stationary and quasi-barotropic, and often qualified as blocking highs, the latters are associated with transient cyclones. At cold days, the north-south dipole in geopotential height anomalies becomes west-east dipole in the lower troposphere as high-latitude anticyclone expands equatorward to the Northern China and mid-latitude cyclone moves eastward and rapidly develops over the East Sea. The resulting northerlies cause cold days in Korea. By performing composite analyses of large-scale climate indices, it is further found that the occurrence of these cold days are preferable when the Arctic Oscillation is in its negative phase and/or East Asian monsoon circulation and Siberian high are anomalously strong.

• 대기
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• 제27권1호
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• pp.79-91
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• 2017

It is imperative to understand the characteristics of atmospheric circulation patterns under the climate system due to its impact on climatic factors. Thus this study focused on analyzing the impact of the atmospheric circulation on the relationship between precipitation and temperature regionally. Here we used monthly gridded observational data (i.e., CRU-TS3.2, NOAA-20CR V2c) and HadGEM2-AO climate model by RCP8.5, for the period of 1960~1999 and 2060~2099. The experiment results indicated that the negative relationship was presented over East Asia and Europe during summer. On the other hand, at around Korea (i.e. EA1: $31^{\circ}N{\sim}38^{\circ}N$, $126^{\circ}E{\sim}140^{\circ}E$) and Northwestern Europe (i.e. EU1: $48^{\circ}N{\sim}55^{\circ}N$, $0^{\circ}E{\sim}16^{\circ}E$) in winter, strong positive relationship dominate due to warm moist advection come from ocean related to intensity variation of the East Asian winter monsoon (EAWM) and North Atlantic Oscillation (NAO), respectively. It was found that values of positive relation in EA1 and EU1 at the end of the 21st century is regionally greater than at the end of 20th century during winter since magnitude of variation of the EAWM and NAO is projected to be greater in the future as result of simulation with RCP 8.5. Future summer, the negative correlations are weakened in EA1 region while strengthened in EU1 region. For better understanding of correlations with respect to RCP scenarios, a further study is required.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.373-377
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• 2002

The Measurement of Pollution in the Troposphere (MOPITT) instrument is an eight-channel gas correlation radiometer launched on the Earth Observing System (EOS) Terra spacecraft in 1999. Its main objectives are to measure carbon monoxide (CO) and methane (CH4) concentrations in the troposphere. This work analyzes tropospheric carbon monoxide distributions using MOPITT data in East Asia and compared ozone distributions. In general, seasonal CO variations are characterized by a spring peak and decreased in the summer. Also, this work revealed that the seasonal cycles of CO are spring maximum and summer minimum with averaged concentrations ranging from 118ppbv to 170ppbv. The CO monthly means show a similar profiles to those of O3. This fact clearly indicates that the high concentration of CO in spring is caused by two possible causes: the photochemical CO production in the troposphere, transport of the CO in the northeast Asia. The CO and O3 seasonal cycles in northeast Asia are influenced extensively by the seasonal exchange of the different types of air mass due to the Asian monsoon. The continental air masses contain high concentrations of O3 and CO due to higher continental background concentrations and sometimes due to the contribution of regional pollution. In summer the transport pattern is reversed. The Pacific marine air masses prevail over Korea, so that the marine air masses bring low concentrations of CO and O3, which tend to give the apparent minimum in summer.