• 한국환경과학회지
• /
• 제13권8호
• /
• pp.721-731
• /
• 2004

The dispersion of suspended particulates in the coastal complex terrain of mountain-inland basin (city)-sea, considering their recycling was investigated using three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). Convective boundary layer under synoptic scale westerly wind is developed with a thickness of about I km over the ground in the west of the mountain, while a thickness of thermal internal boundary layer (TIBL) is only confined to less than 200m along the eastern slope of the mountain, below an easterly sea breeze circulation. At the mid of the eastern slop of the mountain, westerly wind confronts easterly sea breeze, which goes to the height of 1700 m above sea level and is finally eastward return flow toward the sea. At this time, particulates floated from the ground surface of the city to the top of TIBL go along the eastern slope of the mountain in the passage of sea breeze, being away the TIBL and reach near the top of the mountain. Then those particulates disperse eastward below the height of sea-breeze circulation and widely spread out over the coastal sea. Total suspended particulate concentration near the ground surface of the city is very low. On the other hand, nighttime radiative cooling produces a shallow nocturnal surface inversion layer (NSIL) of 200 m thickness over the inland surface, but relatively thin thickness less than 100m is found near the mountain surface. As synoptic scale westerly wind should be intensified under the association of mountain wind along the eastern slope of mountain to inland plain and further combine with land-breeze from inland plain toward sea, resulting in strong wind as internal gravity waves with a hydraulic jump motion bounding up to about 1km upper level in the atmosphere in the west of the city and becoming a eastward return flow. Simultaneously, wind near the eastern coastal side of the city was moderate. Since the downward strong wind penetrated into the city, the particulate matters floated near the top of the mountain in the day also moved down along the eastern slope of the mountain, reaching the. downtown and merging in the ground surface inside the NSIL with a maximum ground level concentration of total suspended particulates (TSP) at 0300 LST. Some of them were bounded up from the ground surface to the 1km upper level and the others were forward to the coastal sea surface, showing their dispersions from the coastal NSIL toward the propagation area of internal gravity waves. On the next day at 0600 LST and 0900 LST, the dispersed particulates into the coastal sea could return to the coastal inland area under the influence of sea breeze and the recycled particulates combine with emitted ones from the ground surface, resulting in relatively high TSP concentration. Later, they float again up to the thermal internal boundary layer, following sea breeze circulation.

• 대한원격탐사학회지
• /
• 제34권6_1호
• /
• pp.879-891
• /
• 2018

본 연구에서는 GIS 자료와 CFD 모델을 이용하여, 도시 재개발 및 건물 신축이 부경대학교 주변의 상세 흐름 변화에 미치는 영향을 조사하였다. 건설 전 후에 대한 부경대학교 내부와 주변 지역의 상세 흐름을 분석하기 위해, 건설 전 후의 16방위 유입류에 대하여 수치 모의 실험을 수행하였다. 장애물에 의한 마찰이 반영되지 않은 관측 풍속을 유입 경계 조건으로 사용하기 위해, 광안 등표기상관측장비에서 관측한 풍속 자료를 사용하였다. 건물 신축에 의한 부경대학교 내부의 대기 흐름 변화를 분석하기 위해, 건물 신축 이후에 16방위 유입류에 따라 풍속이 변화한 영역을 분석하였다. 동남동풍과 남풍이 부는 경우에 풍속 변화 영역이 넓게 나타났는데, 이는 수치 영역의 동쪽에 건설된 고층 건물과 부경대학교 남쪽에 건설된 아파트 단지와 공학관에 의한 영향이 크게 나타났기 때문이다. 대연 AWS(AWS 942)에서 최대 관측 빈도로 나타난 동풍이 부는 경우, 건설 후에 풍속이 변화한 영역은 비교적 좁게 나타났다. 수치 모의 결과를 통해 도시 재개발 및 건물 신축이 건설 지역의 풍하측 방향으로 멀리 떨어진 지역에도 영향을 미치는 것을 확인하였다. 또한, GIS 자료와 CFD 모델이 도시 재개발 및 건물 신축 계획 단계에서 건물 신축 이후의 상세 흐름을 분석하는데 유용함을 확인하였다.

• 지구물리
• /
• 제8권3호
• /
• pp.159-167
• /
• 2005

Turbulent fluxes of sensible heat and latent heat were analyzed at King Sejong station in the austral summer of 2002 (December) and 2003 (January and February). Monthly mean air temperatures of January and February (2.2oC) were similar to those averaged over 1988 to 2001. Precipitation was less in January and greater in February than those averaged over last 14 years. In December of 2002 and January, there was precipitation primarily when easterly wind blew usually. The frequency of snowfall was equal to or larger than that of rainfall. In the mean while, precipitation primarily in forms of rainfall occurred with westerly wind in February. In addition, while for easterly wind, temperature and humidity was low, temperature and humidity were high in case of westerly wind. Based on flux footprint, measured flux mainly came from within 300 m with maximum of 40 m upwind, indicating the insignificant role of the sea around the study site. Half-hourly downward short wave radiation amounted up to ∼ 1000 Wm-2 and net radiation ranged from -50 to 600 Wm-2. Half-hourly sensible heat flux was positive at daytime with maximum of ∼ 400 Wm-2, except the 27th and 28th in February of 2003 when it was negative all day despite of positive net radiation at short daytime. Latent heat flux was positive with maximum of ∼ 130 Wm-2. Depending on wind direction, the partitioning of net radiation into the sum of sensible heat flux and latent heat flux was larger than 0.8, indicating the strong source of the land surface for the atmospheric heating. The daytime averaged Bowen ratio (=sensible heat flux /latent heat flux) was significantly greater than 1, indicating that sensible heat flux was the main source to heat the atmosphere over the site.

• Ocean Science Journal
• /
• 제42권2호
• /
• pp.89-102
• /
• 2007

The surface circulation of northern South China Sea (hereafter SCS) for the period 1987-2005 was studied using the data of more than 500 satellite-tracked drifters and wind data from QuikSCAT. The mean flow directions in the northern SCS except the Luzon Strait (here after LS) during the periods October_March was southwestward, and $April{\sim}September$ northeastward. A strong northwestward intrusion of the Kuroshio through the LS appears during the $October{\sim}March$ period of northeasterly wind, but the intrusion became weak between April and September. When the strong intrusion occurred, the eddy kinetic energy (EKE) in the LS was $388cm^2/s^2$ which was almost 2 times higher than that during the weak-intrusion season. The volume transport of the Kuroshio in the east of the Philippines shows an inverse relationship to that of the LS. There is a six-month phase shift between the two seasonal phenomena. The volume transport in the east of the Philippines shows its peak sis-month earlier faster than that of the LS. The strong Kuroshio intrusion is found to be also related to the seasonal variation of the wind stress curl generated by the north easterly wind. The negative wind stress curl in the northern part of LS induces an anticyclonic flow, while the positive wind stress curl in the southern part of LS induces a cyclonic flow. The northwestward Kuroshio intrusion in the northern part of LS happened with larger negative wind stress curl, while the westward intrusion along $20.5^{\circ}N$ in the center of the LS occurred with weaker negative wind stress curl.

• 통합자연과학논문집
• /
• 제7권3호
• /
• pp.214-218
• /
• 2014

The main objective of this study is to analyse the influence factors of snowfall enhancement by glaciogenic seeding in a mountainous area. Twenty-five seeding experiments have been conducted during the period of February to April 2010. To use two rates seeding experiments (SR1: $1.04g\;min^{-1}$, SR2: $2.08g\;min^{-1}$) have been tested to get an appropriate ratio for snowfall enhancement at Daegwallyeong area. The conditions of seeding are able as followings: surface temperature <$0^{\circ}C$, wind speed <5 m/s, wind direction between 0 and $130^{\circ}$. The experiment results indicated that in the case of SR1 was more effective than SR2. The number of small ice particles below 1.0 mm was increased during seeding period measured by PARSIVEL disdrometer near generator. Most of snowfall enhancement by seeding was observed the inflow of the easterly wind blew in toward Gangwon regions from the East Sea and the supersaturated supercooled liquid water due to orographic effect.

• 대기
• /
• 제17권4호
• /
• pp.393-405
• /
• 2007

Simulation results of WRF for the case of typhoon 'Rusa' were analyzed, comparing with observed data especially forjavascript:confirm_mark('abe', '1'); the Gangneung area around to examine its ability in numerical simulation. From the hourly precipitation time series, two peaks were found at Gangneung and Daegwallyeong, while only one peak was found from those of inland regions else. Especially, for the Yeongdong region, the first peak was directly related to spiral bands generated in front of the typhoon. Convective cells that were developed within the spiral bands moved to the eastern coastal area from the sea so that local heavy rainfall occurred in the Yeongdong region. The second peak was mainly related to the accompanying rain band of typhoon itself, topographic effect and the convergence near Gangneung area. Precipitation in Gangneung was simulated as much as about 30% of observed one. The main reason of this result came from a poor representation of wind directions in Gangneung area of WRF model. Observed wind direction was northwesterly but simulated one was nearly easterly in the area. This might shift a local heavy rainfall area downstream to the mountain area rather than the coastal area.

• 대기
• /
• 제24권2호
• /
• pp.189-196
• /
• 2014

The definition of onset date of Changma is revisited in this study using a quality controlled Ieodo ocean research station data. The Ieodo station has great importance in terms of its southwest location from Korean Peninsula and, hence, makes it possible to predict Changma period in advance with less impact of continents. The onset date of Changma using the Ieodo station data is defined by the time that meridional wind direction changes and maintains from northerly to southerly, and then the zonal wind changes from easterly to westerly after first June. This definition comes from a recognition that the establishment and movement of the western North Pacific subtropical high (WNPSH) cause Changma through southwesterly flow. The onset data of Changma has been determined by large-scale dynamic-thermodynamic characteristics or various meteorological station data. However, even the definition based on circulation data at the Ieodo station has a potential for the improved prediction skill of the onset date of Changma. The differences between before and after Changma, defined as Ieodo station data, are also found in synoptic chart. The convective instability and conspicuous circulations, corresponding low-level southwesterly flow related to WNPSH and strong upper-level zonal wind, are represented during Changma.

• 한국환경과학회지
• /
• 제23권2호
• /
• pp.207-218
• /
• 2014

A ventilation model was developed for predicting the air change per hour(ACH) in buildings and the airflow rates between zones of a multi-room building. In this model, the important parameters used in the calculation of airflow are wind velocity, wind direction, terrain effect, shielding effect by surrounding buildings, the effect of the window type and insect screening, etc. Also, the resulting set of mass balance equations required for the process of calculation of airflow rates are solved using a Conte-De Boor method. When this model was applied to the building which had been tested by Chandra et al.(1983), the comparison of predicted results by this study with measured results by Chandra et al. indicated that their variations were within -10%~+12%. Also, this model was applied to a building with five zones. As a result, when the wind velocity and direction did not change, terrain characteristics influenced the largest and window types influenced the least on building ventilation among terrain characteristics, local shieldings, and window types. Except for easterly and westerly winds, the ACH increased depending on wind velocity. The wind direction had influence on the airflow rates and directions through openings in building. Thus, this model can be available for predicting the airflow rates within buildings, and the results of this study can be useful for the quantification of airflow that is essential to the research of indoor air quality(temperature, humidity, or contaminant concentration) as well as to the design of building with high energy efficiency.

• 대기
• /
• 제22권1호
• /
• pp.57-71
• /
• 2012

Influences of orographic and ocean effect, which depend on the detailed geographic characteristics, upon winter time (December-February) precipitation in the Yeongdong region are investigated. Most of precipitation events in the Yeongdong region during the wintertime are associated with moist northeasterly (coming from the northeast direction) winds and also the spatial distribution of precipitation shows a great difference between Mountain area (Daegwallyeong) and Coastal area (Gangneung). The linear correlation coefficient between the meteorological variables obtained from NCEP/NCAR Reanalysis Data and precipitation amount for each precipitation type is calculated. Mountain type precipitation is dominated by northeasterly wind speed of the low level (1000 hPa and 925 hPa) and characterized with more precipitation in mountain area than coastal area. However, Coastal type precipitation is affected by temperature difference between ocean and atmosphere, and characterized with more precipitation in coastal area than mountain area. The results are summarized as follows; In the case of mountain type precipitation, the correlation coefficient between wind speed at 1000 hPa (925 hPa) and precipitation amount at Daegwallyeong is 0.60 (0.61). The correlation is statistical significant at 1% level. In the case of coastal type precipitation, the correlation coefficient of temperature difference between ocean and 925 hPa (850 hPa) over the East sea area and precipitation amount at Gangneung is 0.33 (0.34). As for the mountain type precipitation, a detailed analysis was conducted in order to verify the relationship between precipitation amount at Daegwallyeong and low level wind speed data from wind profiler in Gangneung and Buoy in the East Sea. The results also show the similar behavior. This result indicates that mountain type precipitation in the Yeongdong region is closely related with easterly wind speed. Thus, the statistical analysis of the few selected meteorological variables can be a good indicator to estimate the precipitation totals in the Yeongdong region in winter time.

• 한국대기환경학회지
• /
• 제17권3호
• /
• pp.277-288
• /
• 2001

Continuous atmospheric CO$_2$measurements measured during the 1 year(1998.8∼1999.8) at Korea Global Atmosphere Watch Observatory (KGAWO) in Anmyeon-do are analyzed by the selecting method which is recommended by WDCGG to get background CO$_2$. This method can reject data based on two criteria: the instability of CO$_2$ concentration within 1 hour from hourly standard deviation (hourly variability$\leq$ 0.6 ppm first selection) and the large changes in the CO$_2$ concentration from one hour to the nex(∼$\leq$0.3 ppm, second selection). We could obtain hourly background CO$_2$ of 37% in first selection and 20% in second selection during the l year. That are a little less than those of Ryori station in Japan. especially, the cases of background CO$_2$ which is selected were few during the summer. That is caused by affection of vegetation and anthropogenic source. After the selecting methods are applied, the cases which is selected for easterly wind decrease remarkably according to the analysis of wind direction about continuous CO$_2$ .That was affected by anthropogenic source from the east area.