• 한국지구과학회지
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• 제40권1호
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• pp.1-8
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• 2019

Although recent reports suggest that the negative correlation between the Arctic Oscillation (AO) and the East Asian winter monsoon (EAWM) has been strengthened, it is not clear whether this intermittent relationship is an intrinsic oscillation in the climate system. We investigate the oscillating behavior of the AO-EAWM relationship at decadal time scales using the long-term (500-yr) climate model simulation. The results show that ice cover over the East Siberian Seas is responsible for the change in the coupling strength between AO and EAWM. We found that increased ice cover over these seas strengthens the AO-EAWM linkage, subsequently enhancing cold advection over the East Asia due to anomalous northerly flow via a weakened jet stream. Thus, this strengthened relationship favors more frequent occurrences of cold surges in the EAWM region. Results also indicate that the oscillating relationship between AO and EAWM is a natural variability without anthropogenic drivers, which may help us understand the AO-EAWM linkage under climate change.

• Ocean and Polar Research
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• 제27권3호
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• pp.237-250
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• 2005

To investigate the air mass modification related with Yeongdong Heavy snowfall events, we examined sensible and latent heat fluxes on the East Sea, the energy exchange between atmosphere and ocean in this study. Sensible and latent heats were calculated by a bulk aerodynamic method, in which NCEP/NCAR reanalysis data and NOAA/AVHRR weekly SST data with high resolution were used. Among winter precipitation events in the Yeongdong region, 19 heavy precipitation events $(1995{\sim}2001)$ were selected and classified into three types (mountain, cold-coastal, and warm types). Mountain-type precipitation shows highly positive anomalies of sensible and latent heats over the southwestern part of the East Set When separating them into the two components due to variability of wind and temperature/ specific Humidity, it is shown that the wind components are dominant. Cold-coastal-type precipitation also shows strong positive anomalies of sensible and latent heats over the northern part and over the central-northern part of the East Sea, respectively. It is shown that the sensible heat anomalies are caused mostly by the decrease of surface air temperature. So it can be explained that cold-coastal-type precipitation is closely related with the air mass modification due to cold air advection over warm ocean surface. But in warm-type precipitation, negative anomalies are found in the sensible and latent heat distributions. From this result, it may be postulated that warm-type precipitation is affected by the internal process of the atmosphere rather than the atmosphere-ocean interaction.

• 한국수산과학회지
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• 제25권1호
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• pp.1-14
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• 1992

국립수산진흥원의 16개년(1973-1988)의 해양 관측 자료와 1989년 11월 6-11일 동안 한국해양대학 실습선으로 관측한 CTD 자료를 사용하여 대한해협 서수도에 존재하는 저층 냉수의 유입 경로를 조사하였다. 대한해협 서수도의 저층 수온은 하계에 가장 낮으며, 해에 따라 변동이 큰 것으로 나타났다. 하계 대한해협 서수도에 저층 냉수가 존재하였던 해의 수온 분포에 의하면, 동해 남서부 해역에 있는 냉수가 울산 남동쪽 10-15마일 떨어진 해역을 거쳐 대한해협 서수도에 유입되며, 이 냉수는 이류하는 동안 그 특성이 다소 변하는 것으로 나타났다.

• 한국환경과학회지
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• 제18권11호
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• pp.1271-1281
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• 2009

The heavy snowfall event over the eastern part of Seoul, Korea on Mar. 04, 2008 has been abruptly occurred after the frontal system with the heavy snowfall event had been past over the Korean peninsula on Mar. 03, 2008. Therefore, this heavy snowfall event couldn't be predicted well by any means of theoretical knowledges and models. After the cold front passed by, the cold air mass was flown over the peninsula immediately and became clear expectedly except the eastern part and southwestern part of peninsula with some large amount of snowfall. Even though the wide and intense massive cold anticyclone was expanded and enhanced by the lowest tropospheric baroclinicity over the Yellow Sea, but the intrusion and eastward movement of cold air to Seoul was too slow than normally predicted. Using the data of numerical model, satellite and radar images, three dimensional analysis Products(KLAPS : Korea Local Analysis and Prediction System) of the environmental conditions of this event such as temperature, equivalent potential temperature, wind, vertical circulation, divergence, moisture flux divergence and relative vorticity could be analyzed precisely. Through the analysis of this event, the formation and westward advection of lower cyclonic circulation with continuously horizontal movement of air into the eastern part of Seoul by the analyses of KLAPS fields have been affected by occurring the heavy snowfall event. As the predictability of abrupt snowfall event was very hard and dependent on not only the synoptic atmospheric circulation but also for mesoscale atmospheric circulation, the forecaster can be predicted well this event which may be occurred and developed within the very short time period using sequential satellite images and KLAPS products.

• 수산해양기술연구
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• 제18권2호
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• pp.91-96
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• 1982

1965년부터 1979년까지의 해양관측자료를 사용하여 우리나라 서해에서 일어나는 수온역전 현상을 조사하였다. 그 결과는 다음과 같다. (1) 겨울의 수온역전 현상은 전 해역과 모든 수심에 걸쳐서 일어난다. (2) 여름은 제주도 서방 해역에서만 비교적 많이 일어난다. 이와 같은 수온역전 현상은 겨울의 경우는 현열손실, 잠열손실 및 남하 Ekman 수송 등에 의한 표면 냉각효과 때문으로 생각된다. 여름의 경우는 온도와 염분의 성질이 서로 다른 황해 저층수와 황해 난류가 제주도 서방 해역에서 경계를 이루고, 서로 혼합되는 과정에서 생기는 것으로 보여진다.

• 한국해양학회지
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• 제17권2호
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• pp.51-58
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• 1982

1965년 부터 1979년 까지 한국 동해에서 관측된 온도 및 염분 자료를 이용하여 밀도역전 현상을 조사하였다.그 결과 밀도역전 여름보다 겨울에 많은 것으로 나타났다.겨울에는 동해 전 해역의 절반정도에서 역전층이 형성되며,여름에는 대한해엽의 일부해협에서만 일어난다.또한 역전층의 깊이는 보통 표층에서 수십 m까지이다.이와같은 역전현상은 표층 Ekman수송에 의한 냉수의 이류로 설명 할 수 있다. 즉,겨울에는 북서 계절풍에 의한 표층 냉수의 남하로 인하여 생기며,여름에는 남서퓽에 의해서 연안 근처에서 용승된 저층 냉수가 대한해협 쪽으로 공급되어 일어난다고 생각된다.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.65-68
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• 2003

A quantitative study of the amount of air transported between the boundary layer and the free atmosphere is important for understanding air quality and upper tropospheric ozone, which is a greenhouse gas. Frontal systems are known to be an effective mechanism for the vertical transport of pollutants. Numerical experiments have been performed with a simple two-dimensional front model to simulate vertical transport of trace gases within developing cold fronts. Three different trace gases experiments have been done numerically according to the different initial fields of trace gases such as aerosol, ozone and $H_2O_2$. Trace gas field tilts to the east while the front tilts to the west. Aerosol simulation shows that pollutants can be transported out of the boundary to altitudes of about 10 km. The stratospheric ozone is brought downwards in a tropopause fold behind of the frontal surface. The meridional gradient in trace gas ($H_2O_2$) can cause a complicate structure in the trace field by the meridional advection.

• 대기
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• 제18권4호
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• pp.317-338
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• 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.

• 한국환경과학회지
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• 제11권2호
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• pp.111-120
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• 2002

Asian dust(or yellow sand) occurs mainly in spring and occasionally in winter in east Asia, when the weather conditions are under an upper trough/cut-off low and surface high/low pressure system during blocking episode days associated with the stationary patterns of the upper level jet stream. The transport mechanism for Asian dust during the blocking episode days in spring 2001 was analyzed using the TOMS aerosol index and meteorological mesoscale model 5(MM5). Based on the E vector, an extension of an Eliassen-Palm flux, the blocking episode days were found to be associated with the development of an upper cut-off low and surface cyclones. Concurrently, the occurrence of dust storms was also determined by strong cold advection at the rear of a jet streak, which exhibited a maximum wind speed within the upper jet stream. As such, the transport mechanism for Asian dust from China was due to advection of the isentropic potential vorticity(IPV) and isentropic surfaces associated with tropopause folding. The transport heights for Asian dust during the blocking episode days were found to be associated with the distribution of the isentropes below the IPV At the same time, lee waves propagated by topography affected the downward motion and blocking of Asian dust in China. The Asian dust transported from the dust source regions was deposited by fallout and rain-out with a reinforcing frontogenesis within a surface cyclone, as determined from satellite images using TOMS and GMS5. Accordingly, these results emphasize the importance of forecasting jet streaks, the IPV, and isentropes with geopotential heights in east Asia.

• 한국수산과학회지
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• 제16권2호
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• pp.111-116
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• 1983

1965년부터 1979년까지의 해양관측자료를 사용하여 우리나라 남해에서 일어나는 수온역전현상을 조사하였다. 그 결과를 요약하면 다음과 같다. 1) 역전현상은 여름보다 겨울에 6배정도 많이 일어난다. 2) 겨울의 경우, 남해 서부해역에서는 수온역전이 모든 수심에서 골고루 일어나는 반면, 동부해역에서는 주로 표층에서 일어난다. 3) 여름의 경우, 서부해역에서는 역전층이 주로 수온약층 아래에 형성되는 반면, 동부해역에서는 주로 표층에 형성된다. 겨울의 역전현상은 기본적으로는 표면 냉각효과에 의해서 생기는 것으로 생각된다. 다만, 서부와 동부해역에서 역전층이 형성되는 수심에 차이가 있는 것은 쓰시마난류 영향의 정도가 양해역에서 크게 다르기 때문이라고 보여진다. 여름의 경우 서부해역에서는 쓰시마난류와 황해 저층냉수가 수온약층 밑에서 혼합되는 과정에서 생기는 것으로 보이고, 동부해역에서는 보다 수온이 낮은 물이 표층을 따라 유입하기 때문에 일어나는 것으로 생각된다.