• Ocean and Polar Research
• /
• v.31 no.4
• /
• pp.297-304
• /
• 2009

We investigated the response of the westerly winds over the Southern Ocean (SO) to glacial boundary conditions for the Last Glacial Maximum using the CCM3 atmospheric general circulation model. In response to glacial boundary conditions, the zonally averaged maximum SO westerly winds weakened 20-35% and were displaced toward the equator by 3-4 degrees. This weakening of the SO westerly winds arose from a substantial increase in mean sea level pressure (MSLP) in the southern part of the SO around Antarctica relative to the northern part. The increase in MSLP around Antarctica is associated with a marked temperature reduction caused by an increase in sea ice cover and ice albedo feedback during the glacial time. The weakened westerly winds in the SO and their equator-ward displacement might play a role in reducing the atmospheric $CO_2$ concentration by reducing upwelling of the carbon rich deep water during the glacial time.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
• /
• v.24 no.1
• /
• pp.29-45
• /
• 1996

Before (March 26, 1994) or after the occurrence of a downslope windstorm (March 29), the NO, $NO_2$, and $SO_2$ at the ground level of Kangnung city were monitored with high concentrations in the afternoon, due to a large amount of gases emitted from combustion of motor vehicle and heating apparatus, especially near 1600-1800 LST and 2000-2100 LST, but at night, they had low concentrations, resulting from small consumptions of vehicle and heating fuels. When both moderate westerly synoptic-scale winds flow over Mt. Taegwallyang and easterly meso-scale sea breeze during the day, atmospheric pollutants should be trapped by two different wind systems, resulting in higher concentration at Kangnung city in the afternoon. At night, the association of westerly synoptic wind and land breeze can produce relatively strong winds and the dissipation by the winds cause these low concentrations to lower and lower, as nightime goes on. From March 27 through 28, an enforced localized windstorm could be produced along the lee side of the mountain near Kangnung, generating westerly internal gravity waves with hydraulic jump motions. Sea breeze toward inland appartantly confines to the bottom of the eastern side of the mountain, due to the interruption of eastward violent internal gravity waves. As the windstorm moves down toward the ground, an encountering point of two opposite winds approaches Kangnung, and a great amount of NO and $NO_2$ were removed by the strong surface winds. Thus, their maximum concentrations are found to be near 18 and 20 LST, 17 and 21 LST. In the nighttime, the more developed storm should produce very strong surface winds and the NO and $NO_2$ could be easily dissipated into other place. The $SO_2$ concentration had no maximum value, that is, almost constant one all day long, due to its removal by the strong surface winds. Especially, the CO concentrations were slightly lower during the strom period than both before or after the strom, but they were nearly constant without much changes during the during the daytime and nighttime.

• Journal of Environmental Science International
• /
• v.5 no.2
• /
• pp.131-140
• /
• 1996

Analysis of hourly variations of sulfur dioxide ($SO_2$) concentrations affected by regional climates for the period of yellow sandy dusts was carried out from March 31 through April 9, 1993. The concentration of 50, at a coastal city, Kangnung city, was much higher than that at an inland city Wonju in the west, but the hourly distrbutions of $SO_2$ concentrations show a similar tendency at both cities. Under the prevailing synoptic-scale westerly winds blowing over a high Mt. Taegualyang in the west toward Kangnung city in the eastern coastal region, the $SO_2$ at Kangnung is trapped by an easterly sea-breeze during the day and under prevailing easterly winds, it is also isolated by the high wall of Mt. Taegualyang, with its high concentration from 14 to 16 LST. Furthermore, when the westerly winds were dominent all day long the high $SO_2$ concentrations at Kangnung were produced by its intrusion from a urban city, Wonju or China in the west into a mountainous coastal city, Kangnung, to some extent, and when the air becomes rapidly cooled down at the clear daytime or the nighttime, their concentrations are also increased by a great amount of heating fuel combustion. Especilly, its maximum concentrations were shown in Wonju and Kangnung from 08 LST through 10 LST, due to the increase of auto vehicles near the beginning time of office hour and were detected again after sunset due to both increases of vehicles at the end of office hour and heating fuel combustion. During the period of Yellow Sandy Dusts which are transported from China into Korea, the $SO_2$ concentrations on rainy days at Wonju and Kangnung were much lower than the monthly mean values of $SO_2$, and their low concentrations could be caused by the scavenging process of rain.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
• /
• v.23 no.1
• /
• pp.18-33
• /
• 1995

Under the synoptic scale strong westerly winds flowing over the large steep mountains in the eastern coastal region, the strong downslope wind storms such as internal gravity waves should be generated in the lee-side of mountain. Int he daytime as sea breeze circulation induced by meso-scale thermal forcing from sea toward inland confines to the offshore side of coastal sites due to the eastward internal gravity waves. Thus, surface winds near the coastal seas were relatively weaker than those in the open sea or the inland sites. Evidently, two different kinds of atmospheric circulations such as an internal gravity wave circulation with westerly wind and a sea breeze circulation with both easterly wind near the sea surface and westerly in the upper level were apparently produced. Under this situation the atmospheric pollutants at Kangnung city should be trapped by two different circulations in the opposite directions and resulted in the high concentrations of Total Suspended Particles (TSP) and ozone (O3). At night a meso-scale land breeze from land toward the more intensification of westerly winds in the coastal regions. The concentrations of TSP controled by the strong surface winds blowing from the mountain side toward the coastal sea were relatively higher at night than those in the daytime case and the concentrations of O3 due to the downward transport of ozone from the upper atmosphere toward the surface were also much higher at night than during the day. Consequently, the atmospheric pollutant concentrations in the mountainous coastal region under the downslope wind storms were higher than those after and before the occurrences of wind storms.

• Journal of the Korean earth science society
• /
• v.35 no.2
• /
• pp.104-114
• /
• 2014

The variation of acidity, conductivity, and ion components in precipitation depending on the dominant wind direction was investigated from January, 2009 to December 2009 in Busan, Korea. Both southwesterly and northeasterly winds were dominant in Busan area. The volume-weighted mean acidity showed pH 7, and the high conductivity indicated 200 ${\mu}scm^{-1}$ in westerly wind. The volume-weighted mean equivalent concentration showed higher value of $K^+$ and $Cl^-$ in all wind directions. The composition ratio of $NO{_3}^-/SO{_4}^{2-}$ showed over 3 in northerly wind. The neutralization factors have been found to have higher value for potassium ion in northeasterly, easterly, southwesterly, and westerly winds compared with different wind directions, which indicated significant neutralization of acidic components over the region by potassium. Also, the concentration of sea salt has been found over 800 ${\mu}sm^{-3}$ in northeasterly and southwesterly winds. Air masses passing through Manchuria, Inner Mongolia plateau, China, and Russia in spring, autumn, and winter covered Busan, Korea in northerly, westerly, and northwesterly winds. However, air masses passing through the ocean in summer covered Busan, Korea in easterly, northeasterly, and southwesterly winds. Therefore, the variation of acidity, conductivity, and ionic components contained in precipitation shows each seasonal characteristics with prevailing wind systems between the continental and coastal area in Busan, Korea.

• Journal of the Korean earth science society
• /
• v.38 no.1
• /
• pp.24-34
• /
• 2017

The westerly waves generation is described in the advanced earth science textbook used at high school as follows: as westerly wind approaches and blows over large mountains, the air flow shows wave motions in downwind side, which can be explained by the conservation of potential vorticity. However, there has been no case study showing the phenomena of the mesoscale westerly waves with observational data in the area of small mountains in Korea. And thus the wind speed and time persistency of westerly winds along with the width and length of mountains have never been studied to explain the generation of the westerly waves. As a first step, we assured the westerly waves generated in the downwind side of Sobaek mountains based on surface station wind data nearby. Furthermore, the critical or minimum wind velocity of the westerly wind over Sobaek mountains to generate the downwind wave were derived and calcuated tobe about $0.6m\;s^{-1}$ for Sobaek mountains, which means that the westerly waves could be generated in most cases of westerly blowing over the mountains. Using surface station data and 4-dimensional assimilation data of RDAPS (Regional Data Assimilation and Prediction System) provided by Korea Meteorological Agency, we also analyzed cases of westerly waves occurrence and life cycle in the downwind side of Sobaek mountains for a year of 2014. The westerly waves occurred in meso-${\beta}$ or -${\gamma}$ scales. The westerly waves generated by the mountains disappeared gradually with wind speed decreasing. The occurrence frequency of the vorticity with meso-${\beta}$ scale got to be higher when the stronger westerly wind blew. When we extended the spatial range of the analysis, phenomena of westerly waves were also observed in the downwind side of Yensan mountains in Northeastern China. Our current work will be a study material to help students understand the atmospheric phenomena perturbed by mountains.

• Journal of Environmental Science International
• /
• v.24 no.3
• /
• pp.291-302
• /
• 2015

The seasonal variations of sea surface winds and significant wave heights were investigated using the data observed from the marine meteorological buoys (nine stations) and Automatic Weather Stations (AWSs) in lighthouse (nine stations) around the Korean Peninsula during 2010~2012. In summer, the prevailing sea surface winds over the East/West Sea and the South Sea were northerly/southerly and easterly/westerly winds due to both of southeast monsoon and the shape of Korean Peninsula. On the other hand, the strong northerly winds has been observed at most stations near Korean marginal seas under northwest monsoon in winter. However, the sea surface winds at some stations (e.g. Galmaeyeo, Haesuseo in the West Sea) have different characteristics due to topographic effects such as island or coastal line. The significant wave heights are the highest in winter and the lowest in summer at most stations. In case of some lighthouse AWSs surrounded by islands (e.g. Haesuseo, Seosudo) or close to coast (e.g. Gangan, Jigwido), very low significant wave heights (below 0.5 m) with low correlations between sea surface wind speeds and significant wave heights were observed.

• Journal of Environmental Science International
• /
• v.25 no.7
• /
• pp.1017-1028
• /
• 2016

Wind information is one of the major inputs for the prediction of urban air flow using computational fluid dynamic (CFD) models. Therefore, the numerical characteristics of the wind data formed at their mother domains should be clarified to predict the urban air flow more precisely. In this study, the formation characteristics of the wind data in the Seoul region were used as the inlet wind information for a CFD based simulation and were analyzed using numerical weather prediction models for weather research and forecasting (WRF). Because air flow over the central part of the Korean peninsula is often controlled not only by synoptic scale westerly winds but also by the westerly sea breeze induced from the Yellow Sea, the westerly wind often dominates the entire Seoul region. Although simulations of wind speed and air temperature gave results that were slightly high and low, respectively, their temporal variation patterns agreed well with the observations. In the analysis of the vertical cross section, the variation of wind speed along the western boundary of Seoul is simpler in a large domain with the highest horizontal resolution as compared to a small domain with the same resolution. A strong convergence of the sea breeze due to precise topography leads to the simplification of the wind pattern. The same tendency was shown in the average vertical profiles of the wind speed. The difference in the simulated wind pattern of two different domains is greater during the night than in the daytime because of atmospheric stability and topographically induced mesoscale forcing.

• Journal of Environmental Science International
• /
• v.14 no.1
• /
• pp.41-51
• /
• 2005

Using three-dimensional non-hydrostatical numerical model with one way double nesting technique, atmo­spheric circulation in the mountainous coastal region in summer was investigated from August 13 through 15, 1995. During the day, synoptic westerly wind blows over Mt. Mishrung in the west of a coastal city, Sokcho toward the East Sea, while simultaneously, easterly upslope wind combined with both valley wind from plain (coast) toward mountain and sea-breeze from sea toward inland coast blows toward the top of the mountain. Two different directional wind systems confront each other in the mid of eastern slope of the mountain and the upslope wind goes up to the height over 2 km, becoming an easterly return flow in the upper level over the sea and making sea-breeze front with two kinds of sea-breeze circulations of a small one in the coast and a large one in the open sea. Convective boundary layer is developed with a thickness of about 1km over the ground in the upwind side of the mountain in the west and a thickness of thermal internal boundary layer from the coast along the eastern slope of the mountain is only confined to less than 200 m. On the other hand, after sunset, no prohibition of upslope wind generated during the day and downward wind combined with mountain wind from mountain towardplain and land-breeze from land toward under nocturnal radiative cooling of the ground surfaces should intensify westerly downslope wind, resulting in the formation of wind storm. As the wind storm moving down along the eastern slop causes the development of internal gravity waves with hydraulic jump motion in the coast, bounding up toward the upper level of the coastal sea, atmospheric circulation with both onshore and offshore winds like sea-breeze circulation forms in the coastal sea within 70 km until midnight and after that, westerly wind prevails in the coast and open seas.

• Atmosphere
• /
• v.21 no.2
• /
• pp.185-196
• /
• 2011

The performance assessment in radiosonde observation on the special observation program (ProbeX-2009) is performed and the characteristics of precipitation using Auto Weather System (AWS) and radiosonde data in 2009 at the Ulleungdo are investigated. The launching time, observation time, and maximum altitude of radiosonde are satisfied with the regulation from Korea Meteorological Administration (KMA) and World Meteorological Organization (WMO) but the duration of observational time of radiosonde is much shorter than that of the ProbeX-2007 because the altitude of launching site is higher than others in 2007. From the analysis of trajectories of radiosonde, most radiosondes at the Ulleungdo tend to move into the east because the westerly prevail at the middle latitude. However, when the Okhotsk high is expanded to the Korean peninsula and the north-westerly winds strengthen over the East Sea as the subtropical high is retreated, radiosonde tends to move into the south-west and south-east, respectively. Maximum distance appears at the end of observation level before May but the level of maximum distance is changed into 100 hPa after June because the prevailing wind direction is reversed from westerly to easterly at the stratosphere during summer time. The condition of precipitation was more correlated with the dynamic instability except Changma season. Precipitation in 2009 at the Ulleungdo occurred under the marine climate so that total precipitation amounts and precipitation intensity were increased and intensified during nighttime. The local environment favorable for the precipitation during nighttime was while the wind speed at the surface and the inflow from the shoreline were strengthened. Precipitation events also affected by synoptic condition but the localized effect induced by topography was more strengthened at the northern part of Ulleungdo.