Hwa Woon Lee

Characteristics of Asian dust transport based on synoptic meteorological analysis over Korea.

Classification of synoptic patterns and their correlation with dust events over East Asia were performed by means of cluster analysis. The average linkage and K-means clustering techniques were used to identify two major weather types during Asian dust events (ADEs; total 26 ADEs with 47 dusty days) of six spring seasons from 1996 to 2001. The first weather type mainly influenced neighboring Asian countries and frequently occurred with ADEs (∼23% of ADE cases). It mostly occurred under a surface high (low)-pressure system over the west (east) of the Korean peninsula coupled with an upper-level trough and cutoff low passage over the center of the Korean peninsula. It showed strong advection in the middle/upper troposphere with both a high aerosol index and enhanced coarse particulate matter (PM) loading over Korea. In contrast, the second weather type was mostly associated with long distance or continental-scale transport and occurred less frequently with ADEs (∼15%). It appeared with an upper-level trough and a cutoff low vertically connected with a surface low system that was formed by a strong cyclonic vortex over the north of the Korean peninsula. There were weak advection, low aerosol index, and low coarse PM concentration over the Korean peninsula during the second weather type. In addition, it was found to be mostly associated with the trans-Pacific transport of Asian dust to the western coast of North America.

Identification and Interpretation of Representative Ozone Distributions in Association with the Sea Breeze from Different Synoptic Winds over the Coastal Urban Area in Korea

Abstract To aid the studies of long-term impact assessment of cumulative ozone (O3) exposures, the representative 8-hr O3 pollution patterns have been identified over the Greater Seoul Area (GSA) in Korea. Principal component analysis and two-stage clustering techniques were used to identify the representative O3 patterns, and numerical and observational analyses were also used to interpret the identified horizontal distribution patterns. The results yielded three major O3 distribution patterns, and each of the three patterns was found to have strong correlations with local and synoptic meteorological conditions over the GSA. For example, pattern 1, accounting for 46% of O3 concentration distributions, mostly occurred under relatively weak westerly synoptic winds. The predominant features of this pattern were infrequent high O3 levels but a distinct gradient of O3 concentration from the western coastal area to the eastern inland area that was mainly induced by the local sea breeze. Pattern 2, accounting for 31% of O3 concentration distributions, was found with higher O3 levels in the western coastal area but lower in the eastern inland area. This is due to the modified sea breeze under the relatively stronger easterly opposing synoptic wind, affecting the high O3 occurrence in the western coastal area only. However, pattern 3, accounting for 21% of O3 concentration distributions, showed significantly higher O3 concentrations over the whole GSA mainly due to the retarded and slow-moving sea-breeze front under the weak opposing synoptic flow. Modeling study also indicated that local and synoptic meteorological processes play a major role in determining the high O3 concentration distribution patterns over the GSA.

Satellite-based assessment of the impact of sea-surface winds on regional atmospheric circulations over the Korean Peninsula

In order to clarify the impact of sea‐wind satellite‐data assimilation under fair and calm weather conditions over the Korean Peninsula, several numerical experiments were carried out. The numerical model used in this study was the Fifth Mesoscale Model (MM5), verified by many previous studies; satellite data of sea winds were gathered by the QuikSCAT sensor launched on ADEOS II. During the daytime, the change in mesoscale circulations according to the assimilation of sea‐wind data increased in the coastal area and decreased deep inland. Although variations in mesoscale circulations due to satellite‐based sea‐wind data assimilation occurred near the coastal area, the mixing height far inland over the Korean Peninsula often changed according to the intensity of inflow from the surrounding seas and that of the topographic effect. In this study, a lower mixing height inland was generated by a numerical simulation using QuikSCAT sea‐wind data assimilation. The lower mixing height was caused by strong westerly and weak easterly winds from the Yellow Sea and the East Sea, respectively. The validation of the sea‐wind influence was verified quantitatively by RMSD and IOA analyses. The accuracy of weather forecasting increased at the East Sea and Korea Strait and decreased at the Yellow Sea. These different accuracy levels were caused by the inhomogeneity of sea‐wind data quality. The maintenance of the uniform quality of satellite‐based data on sea wind is an important factor in the reasonable forecasting of mesoscale circulations.

Spatial and Temporal Features of PM 10 Evolution Cycle in the Korean Peninsula

【Power spectral analysis for

An Analysis of Wind Field around the Air Quality Monitoring Station in the Urban Area by Using the Envi-met Model

PM_{10}

부산지역 미세먼지 농도 분포에 따른 기상요소 분석

observed at 10 cities in the Korean Peninsula from 2004 to 2010 was carried out to examine the spatial and temporal features of

Impact of future urban growth on regional climate changes in the Seoul Metropolitan Area, Korea

PM_{10}

Numerical Study on the Characteristics of High PM 2.5 Episodes in Anmyeondo Area in 2009

evolution cycle. The power spectrum analysis proposed 9 typical cycles (0.5 day, 1day, 5.4day, 8~10day, 19~21day, 26day, 56day, 180day and 365day) for

Identification of chemical fingerprints in long-range transport of burning induced upper tropospheric ozone from Colorado to the North Atlantic Ocean

PM_{10}

A Case Study on Sea Breeze Circulation and Ozone Concentration due to the Effect of Cold Water in the Southeastern Coastal Area of Korea

evolution and the cycles are strongly associated with dilution and transportation due to the meterological influence. The spectrum intensity of 5.4day and 26day