We focused on effects on data assimilation of simulated wind fields by using upper-air observations (wind profiler and sonde data). Local Analysis Prediction System (LAPS), a type of data assimilation system, was used for wind field modeling. Five cases of simulation experiments for sensitivity analysis were performed : which are EXP0) non data assimilation, EXP1) surface data, EXP2) surface data and sonde data, EXP3) surface data and wind profiler data, EXP4) surface data, sonde data and wind profiler data. These were compared with observation data. The result showed that the effects of data assimilation with wind profiler data were found to be greater than sonde data. The delicate wind fields in complex coastal area were simulated well in EXP3. EXP3 and EXP4 using wind profiler data with vertically high resolution represented well sophisticated differences of wind speed compared with EXP1 and EXP2, this is because the effects of wind profiler data assimilation were sensitively adjusted to first guess field than those of sonde observations.

The research was conducted to simulate and interpret the change of PM10 profile by Asian dust using the CALPUFF modeling system for the period April 6 through 18, 2001. The results, which are represented a daily variation of PM10 concentration before and after Asian dust, was located between a minimum concentration of 50 μg/㎥ and a maximum concentration of 100 μg/㎥. Most concentration peaks in the PM10 profile were shown within a level below 500 m and had a pattern that rapidly increased up the peak and decreased after the peak to 1000 m. Even though the shapes of the vertical profile during Asian dust days were similar to non-Asian dust days, no rapid change vertically was observed. In particular, the vertical profile on 1200 LST and 1800 LST was noticeably shifted to the higher concentrations, which means PM10 in the atmosphere was changed into a vertically and horizontally heterogeneous form under the Asian dust event. Finally, it is confirmed that the simulation result from CALPUFF might schematically sketched atmospheric PM10 profiles and their change by Asian dust throughout the comparison with profiles of aerosol extinction coefficients, which were acquired from Lidar measurement at KGAWO.

The characteristics of meteorological conditions relevant to Asian dust (AD) outbreaks and their occurrence frequencies were analyzed in four source regions (R1 to R4) during spring months (March to May) of 1998-2002. Moreover, the concentration variations of AD (e.g., PM10) observed in Korea were investigated during the study period. In the relationship between AD outbreaks and three meteorological parameters (i.e., air temperature, wind speed, and aridity), the largest AD outbreaks in April (～250 observations) mostly occurred in R2 when air temperature ranging from 10.0 to 15.0℃ and surface wind speed from 7 to 9 m s-1 were recorded. Moreover, the aridity (≥ 4) in April was significantly high in R2 with the maximum frequency of AD outbreaks (i.e., 206 observations). On the other hand, the number (percentage) of days belonging to AD events observed in five Korean cities were found to be 116 (44%), 121 (46%), and 26 days (10%) in March, April, and May, respectively. The mean PM10 concentrations were found to range from 150 to 220, 150 to 200, and 95 to 120 ㎍ m-3 in March, April, and May, respectively. Consequently, this implied that the AD events in Korea were found to be gradually frequent in early spring and to be affected from the large AD outbreaks observed in the source regions.

We employed two data assimilation techniques including MM5 Four Dimensional Data Asssimilation (FDDA) and Local Analysis and Prediction System (LAPS) to find out the effects of the changed initial conditions on the wind fields simulation according to the objective analysis methods. We designed 5 different modeling cases. EXP B used no data assimilation system. Both EXP F1 using surface observations and EXP F2 with surface and upper-air observations employed MM5 FDDA. EXP L1 using surface observations and EXP L2 with surface and upper-air observations used LAPS. As results of, simulated wind fields using MM5 FDDA showed locally characterized wind features due to objective analysis techniques in FDDA which is forcefully interpolating simulated results into observations. EXP F1 represented a large difference in comparison of wind speed with EXP B. In case of LAPS, simulated horizontal distribution of wind fields showed a good agreement with the patterns of initial condition and EXP L1 showed comparably lesser effects of data assimilation of surface observations than EXP F1. When upper-air observations are applied to the simulations, while MM5 FDDA could hardly have important effects on the wind fields simulation and showed little differences with simulations with merely surface observations (EXP F1), LAPS played a key role in simulating wind fields accurately and it could contribute to alleviate the overestimated winds in EXP L1 simulations.

We focus on the improvement of accuracy of sea surface wind over complex coastal area during the warm season. Local Analysis Prediction System (LAPS) was used to improve the initial values in Mesoscale Meteorological model (MM5). During the clear summer days with weak wind speed, sea surface wind simulated with LAPS was compared with the case without LAPS. The results of modeling with LAPS has a good agreement mesoscale circulation such as mountain and valley winds on land and in case of modeling without LAPS, wind speed overestimated over the sea in the daytime. And the results of simulation with LAPS indicated similar wind speed values to observational data over the sea under influence of data assimilation using BUOY, QuikSCAT, and AMEDAS. The present study suggests that MM5 modelling with LAPS showed more improved results than that of without LAPS to simulate sea surface wind over the complex coastal area.

The average ratio of the daily UV-B to total solar (75) irradiance at Busan (35.23˚N, 129.07˚E) in Korea is found as 0.11%. There is also a high exponential relationship between hourly UV-B and total solar irradiance: UV-B=exp (a× (75-b))(R2=0.9 0.93). The daily variation of total ozone is compared with the UV-B irradiance at Pohang (36.03˚N, 129.40˚E) in Korea using the Total Ozone Mapping Spectrometer (TOMS) data during the period of May to July in 2005. The total ozone (TO) has been maintained to a decreasing trend since 1979, which leading to a negative correlation with the ground-level UV-B irradiance doting the given period of cloudless day: UV-B=239.23-0.056 TO (R2=0.5 0.52). The statistical predictions of daily total ozone are analyzed by using the data of the Brewer spectrophotometer and TOMS in East Asia including the Korean peninsula. The long-term monthly averages of total ozone using the multiplicative seasonal AutoRegressive Integrated Moving Average (ARIMA) model are used to predict the hourly mean UV-B irradiance by interpolating the daily mean total ozone far the predicting period. We also can predict the next day's total ozone by using regression models based on the present day's total ozone by TOMS and the next day's predicted maximum air temperature by the Meteorological Mesoscale Model 5 (MM5). These predicted and observed total ozone amounts are used to input data of the parameterization model (PM) of hourly UV-B irradiance. The PM of UV-B irradiance is based on the main parameters such as cloudiness, solar zenith angle, total ozone, opacity of aerosols, altitude, and surface albedo. The input data for the model requires daily total ozone, hourly amount and type of cloud, visibility and air pressure. To simplify cloud effects in the model, the constant cloud transmittance are used. For example, the correlation coefficient of the PM using these cloud transmissivities is shown high in more than 0.91 for cloudy days in Busan, and the relative mean bias error (RMBE) and the relative root mean square error (RRMSE) are less than 21% and 27%, respectively. In this study, the daily variations of calculated and predicted UV-B irradiance are presented in high correlation coefficients of more than 0.86 at each monitoring site of the Korean peninsula as well as East Asia. The RMBE is within 10% of the mean measured hourly irradiance, and the RRMSE is within 15% for hourly irradiance, respectively. Although errors are present in cloud amounts and total ozone, the results are still acceptable.

We focused on improvement in simulation of wind fields for the complex coastal area. Local Analysis and Prediction System(LAPS) was used as a data assimilation method to improve initial conditions. Case studies of different LAPS inputs were performed to compare improvement of wind fields. Five cases have been employed : Ⅰ) non data assimilation, Ⅱ) all available data, Ⅲ) AWS, buoy, QuikSCAT, Ⅳ) AWS, buoy, wind profiler, Ⅴ) AWS, buoy, AMEDAS. Data assimilation can supplement insufficiency of the mesoscale model which does not represent detailed terrain effect and small scale atmospheric flow fields. Result assimilated all available data showed a good agreement to the observations rather than other cases and estimated well the local meteorological characteristics including sea breeze and up-slope winds. Result using wind profiler data was the next best thing. This implies that data assimilation with many high-resolution sounding data could contribute to the improvements of good initial condition in the complex coastal area. As a result, these indicated that effective data assimilation process and application of the selective LAPS inputs played an important role in simulating wind fields accurately in a complex area.

In predicting oxidants concentration, the most important fact is to select a suitable photochemical reaction mechanism. Sensitivity analysis of O3 and other important photochemical oxidants concentrations was conducted by using CBM-IV model. The predicted oxidants concentration was considerably related with the initial concentration of formaldehyde, [NO2]/[NO],NOx, RH and RCHO. As the initial concentration of formaldehyde increased, concentration of NO2 increased. O3 concentration was proportional to the [NO2]/[NO] ratio. When the initial concentrations of RH and RCHO were high, photochemical reaction was more reactive, including more rapid conversion of NO to NO2 and increased oxidants. Also, the sensitivities of ozone formation to rate constants, Kl,K2andK3 in the NO2 photolysis were studied.

A case of air pollution study of estimation of emission rate for source to railroad rolling stock and emissive character about is unusual. Recent emission rate of railroad rolling stock was estimated with emission factor of EPA in three region(Seoul, Incheon, and Gyeonggido). But this EPA factor could be incorrect because Korea and America have a different railroad environment in the variety of fuel and character of railroad rolling stock. In this study, emission rate of each line, car and region(district) with emission factor of Korean case(National Railroad Administration, 1997) was estimated. In Busan Metropolitan City, railroad rolling stocks were divided accoding to, each line, car and service. Particularly, the idle fuel rate omitted in the preceding study was included in calculation fuel rate. Total emission rate of Busan Metropolitan City was 887.41t/year. Each emission rates of Kyeongbu line, Donghaenambu line, Gaya line, Uam line, Bujeon line, and idle was 489.15t, 196.46t, 33.94t, 12.66t, 6.47t, and 148.72t, respectively.

Dustfall particles were collected by the modified American dust jar (wide inlet bottle type) at 6 sampling sites in Pusan area from March, 1999 to February, 2000. Thirteen chemical species (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Si, and Zn) were analyzed by AAS and ICP. The purposes of this study were to estimate qualitatively various bulk deposition flux of dustfall and insoluble components by applying regional and seasonal distribution. Dustfall amount of regional variations were found in order of coastal zone, industrial zone, commercial zone, agricultural zone and residential zone, and seasonal total dustfall had higher concentrations during spring for 6.741 ton/㎢/season, lower concentrations during summer for 1.989 ton/㎢/season, and annual total concentration was 17.742 ton/㎢/year. The regional distributions of enrichment factor show well-defined anthropogenic metals (Cd, Cu, Pb, and Zn) at industrial and agricultural zone, and contribution rate of soil particles were found in order of summer, fall, winter and spring. Factor loading effects of chemical composition of dustfall were found in order of road traffic emission source and combustion processed source, industrial activity source, soil source and marine source.

For the purpose of predicting air pollutants concentration in Pusan coastal urban, we used an Eulerian model of flow and dispersion/chemistry/deposition process considering SST effects which estimate through POM. The results of air quality model including emission from various sources show that the seasonal variation pattern of respective pollutants was affected by the seasonal SST fields and local circulation. Horizontal deviation of diurnal SST was 2.5∼4K, especially large gradients in coastal region. Through numerical simulation of wind fields we predicted that local circulation prevailed during daytime in summer and nighttime in winter. So high concentration distribution showed toward inland in spring and summer seasons, while high concentration distribution showed at inland near coast in autumn and winter.

The atmospheric conditions and the transport mechanism of long-range transport of air pollutants from coastal area to inland area were investigated using regular meteorological data and air pollution data obtatined from the southeastern area of Korea. Daytime temperature over the inland area(Taegu) was higher than that over the coastal area(Pusan) and the temperature difference of about 5∼6℃ when the thermal low was most fully developed and the sea level pressure over Taegu was lower than that over Pusan by about 4∼5 hPa at that time. Therefore this low pressure appeared to the thermally induced low. Air mass polluted from the coastal area during the morning period was transported inland area, at first by the sea breeze and by the large scale wind system toward the thermal low generated in the mountainous inland region. This was explained by the fact that the concentration of air pollutants over Taegu increased throughtout the late afternoon.

In order to investigate horizontal wind field in the boundary layer around Pusan area, wind speed and wind direction measured at 14 AWS(Automatic Weather Station), 1997, was used. The wind direction at PRMO(Pusan Regional Meterological Office) was showed that southwest and northeast wind dominated for spring and summer, northeast wind for fall and northwest for winter. Anticline flow was showed at 'Gaekumm' which is located between Mt. Backyang(641 m) and Mt. Yumkwang(503 m) and affected on wind field at 'Pusanjin'. The low wind speed and various wind direction was represented at the basin topography, 'Buckgu', 'Jeasong', 'Ilkwang' and 'Kijang'. The annual mean wind speed at 14 sites, 2.5 ms-1, was lower than that measured at PRMO, 3.9 ms-1. The wind direction analysis showed that the case of same direction in compare with that measured at PRMO is about 54% and case of opposite direction is about 12%. Annual and seasonal mean windrose showed wind direction is affected by not only synoptic weather state but also topography.

Visibility reduction is a barometer of air pollution, which people can notice easily. First of all, we need to measure quantified visibility continuously in order to examine visibility reduction. Prevailing visibility is not practical to measure visibility depending on observer's expertness. Scattering visibility using Forward Scattering Meter (Belfort Visibility Sensor 6230) has been measured at Kwangan-Dong in Pusan and analysed since July, 1998. According to the analysis, the correlation coefficient(R) between prevailing visibility and scattering visibility was 0.7235. The visibility appeared that each frequency of poor visibility (under 6㎞) and good visibility(over 25㎞) was 10.6%, 9.7% on summertime in Pusan and the visibility range from 10km to 20km ranked high frequency as a half of whole ranges. The order of correlation coefficients between visibility and air pollutants are ranking CO, PM10 and NO2, that values are 0.5878, 0.5369, 0.5284 respectively. In meteorological factor, the case of poor visibility presented more weakly wind speed and higher relative humidity than the case of good visibility. The correlation coefficient between calculated visibility of multiple linear regression model and observed visibility was 0.7215. But the trend of calculated and observed visibility variation was similar with the exception of several good visibility cases.

Estimating dimensions of attractors are the most basic tools to analyze properties of chaotical dynamic systems. In this paper, we estimate correlation dimensions of meteorological variables, such as wind speed (v) and temperature (T) observed in Kimhae International Airport when the land-sea breeze circulation is appeared and find low non-integer values that reflect the deterministic chaos characterizing the dynamics. We compare the results with the correlation dimensions of 2-dimensional model that is calculated by finite element method. Though the correlation dimensions of the calculated wind speed (v) are less than those of the observed wind speed (v), we can suggest that the land-sea breeze circulation has not a unique mechanism. The land-sea breeze phenomenon is a complicated dynamics, which is constructed with various scale motions of atmosphere. In further research, we hope to find more accurate dynamics of land-sea breeze through wide observations and using of more sophisticated prediction models.

The flow of non-rotation atmosphere with uniform stratification and wind past an isolated three dimensional topography obstacle is investigated with three-dimensional hydrostatic and non- hydrostatic numerical model. The characteristic of turbulence created the back of topography obstacle is usually defined by Froude number which is the function of upstream wind speed, the height of topography obstacle, and atmospheric stability. Turbulence tends to be formed more easily at the non-hydrostatic model than hydrostatic model. Especially, the difference between flow patterns of two models generated by isolated obstacle is more clear under low Froude number. The difference of flow patterns can be only seen at relatively low altitude, but at high altitude the patterns of two models are almost same. In this research, wind velocity in the parameters related with Froude number have great sensitivity at responsibility of numerical models. and slop of obstacle is also important factor at the flow pattern regardless of the species of numerical model

After analyzing the correlation between air pollution and visibility, TSP and NO2 is responsible for poor visibility in Pusan. After analyzing the correlation between meteorological factors and visibility, general pattern of humidity has clear negative correlation. The variation of wind speed has a positive correlation. In order to investigate the cause of poor visibility in Pusan area, the Andersen sampler and PM-2.5 are used to collect and analyze aerosol. This study was carried out to monitor the visibility using Forward scattering meter and to find out the characteristics and the cause of good visibility case and poor visibility case by measuring and analyzing a variety of parameters, such as particle size distributions, chemical compositions, and meteorological conditions in Pusan. According to the analysis of intensive sampling, NO3-, NH4+ ion concentration increased together with the mass concentration around 0.5∼2.5㎛ approximately during the case of poor visibility. NH4NO3, NH4Cl, and NaCl were thought to be the major components of fine particles.

A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 ㎞, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind field should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.

The concentration of air pollution in a large city such as Pusan has been increased every years due to the increase on fuel consumption at factories and by vehicles as well as the gravitation of the population. In this study, we have analyzed NO2 concentration data and various data of meteorological factors during 1994-1997 to investigate the characteristics of NO2 concentration and how the high NO2 concentration is generated under the meteorological condition. According to the study, NO2 peak concentration at most sites occurred about 1h later after the rush hour. In the characteristics of emissions in sites, sinpyeong- dong was highly contributed to point source while the other sites were highly contributed to line source. The high NO2 concentration had high generation probability when temperature contained typical seasonal characteristics and wind speed was low. Using the relationship between meteorological factors and the daily average NO2 concentration, correlation analysis was practiced. The seasonal variation of the daily average NO2 concentration was correlated with air temperature, solar radiation and wind speed, but the correlation coefficient between meteorological factors and the daily average NO2 concentration was not so much high. Thus we have known that the daily average NO2 concentration is partially explained by meteorological factors.

Air quality modeling about coastal urban region such as Pusan shoud be consider shipping source emmited from ships anchoraging and running. It has been proved at our previous studies that the ratios of air pollutants emission amount in coastal area to inland are 12.2% for NO2 and 11.7% for SO2 and the air quality of coastal urban area consierably counts on ships. Also the dispersion pattern of the air pollutants followed local circulation system in this region. Therefore this study has been developed air quality model which can describe the formation, transport, transformation and deposition processes of air pollutants considering shipping source. Currently, restriction for emission amount of ships does not exist, so our study will be useful to set the emission standard and for devising air quality policy in coastal urban region.