• 한국환경과학회지
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• 제23권10호
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• pp.1719-1729
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• 2014

This study is carried out in order to bridge the gap to understand the relationships between South Asian and East Asian monsoon systems by comparing the summer (June-September) precipitation of Nepal and South Korea. Summer monsoon precipitation data from Nepal and South Korea during 30 years (1981-2010) are used in this research to investigate the association. NCEP/NCAR reanalysis data are also used to see the nature of large scale phenomena. Statistical applications are used to analyze these data. The analyzed results show that summer monsoon precipitation is higher over Nepal ($1513.98{\pm}159.29mm\;y^{-1}$) than that of South Korea ($907.80{\pm}204.71mm\;y^{-1}$) and the wettest period in both the countries is July. However, the coefficient of variation shows that amplitude of interannual variation of summer monsoon over South Korea (22.55%) is larger in comparison to that of Nepal (10.52%). Summer monsoon precipitation of Nepal is found to be significantly correlated to that of South Korea with a correlation coefficient of 0.52 (99% confidence level). Large-scale circulations are studied to further investigate the relationship between the two countries. wind and specific humidity at 850 hPa show a strong westerly from Arabian Sea to BOB and from BOB, wind moves towards Nepal in a northwestward direction during the positive rainfall years. In case of East Asia, strong northward displacement of wind can be observed from Pacific to South Korea and strong anticyclone over the northwestern Pacific Ocean. However, during the negative rainfall years, in the South Asian region we can find weak westerly from the Arabian Sea to BOB, wind is blowing in a southerly direction from Nepal and Bangladesh to BOB.

• 대한원격탐사학회지
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• 제14권2호
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• pp.165-174
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• 1998

구름 속의 수액량 분포와 인공강우에 의한 잠재적 증우 가능성을 조사하기 위해 1797년 7월부터 1998년 2월가지 이중채널 마이크로웨이브 레디오메타를 사용하여 안동 지방에서 관측을 실시하였다. 안동 지방의 수액량은 대부분의 시간대에서 0.1mm 이하로 매우 작은 값을 보였다. 계절적 특성을 살펴보면 여름철에 수액량이 가장 풍부하였으며, 봄, 가을, 겨을 순이었다. 수액량의 일변화 양상은 여름철을 제외한 계절에서 12시부터 17시까지 비교적 높은 수액량을 보였으며, 강수량이 많은 여름철에는 수액량의 시간 변동이 심한 것으로 조사되었다 풍향에 따른 수액량의 분포는 소백산맥을 넘어오는 기류인 서풍과 남서풍 계열의 바람에서 수액이 풍부하게 존재하는 것으로 조사되었다. 수평 수액량 플럭스와 연직 강수량의 비인 잠재적 증우 가능량(P$_{en}$)은 대부분 0.5 이하였으며, 계절적으로는 봄철에 0.5, 여름과 가을철에 0.2, 그리고 겨울철에 0.1 이었다. 결과적으로 안동지역에서 인공강우에 의한 최대 증우 가능성은 봄철 서풍계열의 바람에서 높은 것으로 조사되었다. .

• 한국환경과학회지
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• 제24권5호
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• pp.615-622
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• 2015

East Asia is characterized by anthropogenic emissions resulting from the large population and fast economic growth of this region. Since the prevailing wind is westerly and northwesterly, emissions from Ul-jin can be expected to contribute to acidic deposition increase in downwind direction. Aerosols collected at the near coast site, Uljin geun, gyungbook and were analyzed for $NH_4{^+}$, $Mg^{2+}$, $Na^+$, $Ca^{2+}$, $Cl^-$, $SO_4{^{2-}}$, and $NO_3{^-}$ from Aug. 2012 to Feb. 2013. The seasonal averaged aerosol concentration showed the highest potassium and calcium ion in winter and the highest ammonium ion due to a meadow and high solar intensity in summer. Sodium and chloride ion showed the same ratio all seasons and sulfate and nitrate species showed the maximum value in winter Chemical components of aerosols collected at the near coast site, Uljin geun, gyungbook were lower by 16 to 73% than those collected at other similar environment site such as kanghwa, yangyang. Comparing air quality data at the near coast site, Uljin geun, gyungbook, There was found that Uljin coast site is less influenced by the sea salts(potassium, magnesium, calcium) and nss-$SO_4{^{2-}}$ percentage is 3~13% higher than similar condition site.

• 한국환경과학회지
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• 제11권6호
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• pp.507-517
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• 2002

Cheeka Peak is a unique site for monitoring the background chemistry and aerosol contents of pristine marine air at mid-latitude. During long-range onshore winds that occur frequently throughout the year, it is predicted to have the cleanest air in the northern hemisphere. Measurements of CO and O$_3$were conducted at Cheeka Peak Observatory(CPO) on the northwestern tip of Washington state, USA during March 6 ∼May 29, 2001. The data have been segregated to quantify the mixing ratio of these species in the Pacific marine atmosphere. Also the marine air masses were further classified into four categories based on 10-day backward isentropic trajectories; high, mid, and low latitude and those which had crossed over the Asian industrial region. The diurnal variation of CO and O$_3$at CPO showed a similar to tendency of background measurement site. When marine air mass flowed to CPO, CO concentration was lower and O$_3$was similar or higher than those of total data. The westerly flow from ocean, not easterly from continent occurred the high concentration of CO and O$_3$at CPO. Using the trajectory segregation of marine air mass, the comparison of concentration according to latitude calculated. the CO concentration of Asian trajectory was lower than other latitudes, O$_3$concentration was higher.

• Journal of Korean Society for Atmospheric Environment
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• 제20권E1호
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• pp.1-14
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• 2004

Meteorological mechanisms in association with long-range transport of Asian dust in April 2001 have been investigated using weather maps, satellite images, TOMS and surface $PM_{10}$ data, backward trajectories, plus modeling output results (geopotential heights, horizontal wind vectors, potential temperatures, and streamlines). The results indicated that long -range transport of Asian dust to the west coast of North America was associated with strong westerlies between the Aleutian low and the Pacific high acting as a conveyor belt. Accelerating westerly flows due to cyclogenesis at the source regions over East Asia transported pollution from the continent to the central Pacific. When the system reached the Aleutian Islands, the intensity of troughs and the westerlies were amplified in the North Pacific. Thereafter the winds between the Aleutian Islands and the Pacific Ocean were more intensified from the air flow transport of the conveyor belt. Consequently, the strong wind in the conveyor belt enhanced the dust transport from the Pacific Ocean to the west coast of North America. This was evidenced by $PM_{10}$ concentration (maximum of about $100{\mu}g\;m^{-3}$) observed In California. Further evidence of the dust transport was found through the observation of satellite images, the distribution of TOMS aerosol index, and the analyses of streamlines and backward trajectories.

• 한국환경과학회지
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• 제5권4호
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• pp.411-427
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• 1996

A Lagrangian dispersion model has been developed to study the transport of atmospheric pollutants over the southern Korean peninsula on sunny summer days. A mesoscale atmospheric model has been employed to provide the wind fields and information for turbulent diffusion for the calculation of trajectories using a conditioned particle technique. The model has been applied to the simulation of the transport of atmospheric pollutants emitted from five sources in the coastal locations under various synoptic scale winds. Under calm synoptic scale condition, the particles emitted during daytime are mixed vertically and transported toward inland by sea-breeze, according to the model simulation. The particles are then transported upward at she sea-breeze front or by the upward motion over the mountain, and some particles show tendency of returning toward the coast by the return flow of the sea-breeze circulation. The particles are found to remain over the peninsula throughout the integration period under calm synoptic scale condition. When there is westerly synoptic scale winds the particles emitted in the west coast can reach the east coast within a day of faster depending on the speed. With a synoptic scale southerly wind of 5 m/s, most of the particles from the fine sources are advected toward inland during daytime. During nighttime, significant portion of particles released in the west coast remains over the land, while most particles released in the east coast move toward the sea to the east of the middle peninsula.

• 대기
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• 제20권4호
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• pp.505-518
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• 2010

We investigated the impacts of the diabatic heating location, vertical profile and basic state on the Rossby wave propagation. To examine the dynamical process of individual responses on the regional heat source, a dry version of the linear baroclinic model was used with climatological summertime (JJA) mean basic state and vertical structure of the diabatic heating for 1979-2008. Two sets of diabatic heating were constructed of those positioned in the mid-latitudes (Tibetan Plateau, eastern Mediterranean Sea, and the west-central Asia) and the tropics (the southern India, Bay of Bengal, and western Pacific). It was found that using the principal component analysis, atmospheric response to diabatic heating reaches to the steady state in 19th days in time. The prescribed mid-latitude forcing forms equivalent barotropic Rossby wave propagation along the westerly Asia jets, whereas the tropical forcing generates the Rossby wave train extending from the tropics to mid-latitudes. In relation to the maximum vertical profile, the mid-level forcing reveals a stronger response than the lower-level forcing, which may be caused by more effective Rossby wave response by the upper-level divergent flow. Under the different sub-seasonal mean state, both of the tropical and mid-latitude forcing induce the different sub-seasonal response intensity, due to the different basic-state wind.

• 대기
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• 제17권1호
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• pp.1-15
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• 2007

A constraint based on climatology is introduced to the cost function of the three-dimensional variational assimilation (3dVar) to correct the error of the zonal mean wind structure in the global data assimilation system at Korea Meteorological Administration (KMA). The revised cost function compels the analysis fit to the chosen climatology while keeping the balance between the variables in the course of analysis. The constraint varies selectively with the vertical level and the horizontal scale of the motion. The zonally averaged wind field from European Centre for Medium-Range Weather Forecasts Re-Analysis 40 (ERA-40) is used as a climatology field in the constraint. The constraint controls only the zonally averaged stratospheric long waves with total wave number less than 20 to fix the error of the large scale wind field in the stratosphere. The constrained 3dVar successfully suppresses the erroneous westerly in the stratospheric analysis promptly, and has been applied on the operational global 3dVar system at KMA.

• 한국대기환경학회지
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• 제9권3호
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• pp.200-206
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• 1993

Since November 1990, observations of carbon monoxide(CO) levels have been carried out at Tat-ahn Peninsula(TAP) in Korea. Analysis on atmospheric data, obtained in the period from November 1990 to February 1992, is carried out and the results are included in this study. It is observed that variations of monthly average level on CO are in the range of 141.61-516.06ppb(amplitude 374.45 ppb). An average level in 1991 is 308.18 ppb. CO observed at TAP has a larger seasonal variation. One of reasons appears that CO of TAP is strongly influenced by local sources and westerly airflows. When this gas of TAP is compared with data observed at Korea National University of Education(KNU) and in Seoul, we learn that CO values of KNU are higher(in average 2.15 times) than those of TAP; CO value observed in Seoul are 7 times higher than those of TAP. We interprete that air samples taken both at KNU and in Seoul are influenced strongly by local sources than those at TAP. According to analysis of trajectories and air flows, the CO value is higher with NW airflows than the value with SW airflows.

• 한국대기환경학회지
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• 제27권5호
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• pp.494-503
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• 2011

Fine particles ($PM_{2.5}$) were collected and analyzed from December 2005 through December 2009 in Chuncheon, Korea to investigate the long-term trend of $PM_{2.5}$ concentrations. Also $PM_{10}$ concentrations were collected from Environmental Monitoring System operated by Ministry of Environment. Average concentrations of $PM_{2.5}$ and $PM_{10}$ were 30.5 and 58.2 ${\mu}g/m^3$, respectively. Both $PM_{2.5}$ and $PM_{10}$ were significantly affected by meteorological factors including wind speed, wind direction and precipitation. They generally decreased as wind speed increased (p=0.000), and increased when there was a prevailing westerly wind. Low concentrations of $PM_{2.5}$ were observed during rainy days while high concentrations were shown when fog, mist and/or haze occurred.