• Atmosphere
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• v.29 no.2
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• pp.131-147
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• 2019

On the urban scale, Micro-climate analysis models for urban scale have been developed to investigate the atmospheric characteristics in urban surface in detail and to predict the micro-climate change due to the changes in urban structure. BioCAS (Biometeorological Climate Impact Assessment System) is a system that combines such analysis models and has been implemented internally in the Korea Meteorological Administration. One of role in this system is the analysis of the health impact by heat waves in urban area. In this study, the vegetation cooling models A and B were developed and linked with BioCAS and evaluated by the temperature drop at the vegetation areas during ten selected heat-wave days. Smaller prediction errors were found as a result of applying the vegetation cooling models to the heat-wave days. In addition, it was found that the effects of the vegetation cooling models produced different results according to the distribution of vegetation area in land cover near each observation site - the improvement of the model performance on temperature analysis was different according to land use at each location. The model A was better fitted where the surrounding vegetation ratio was 50% or more, whereas the model B was better where the vegetation ratio was less than 50% (higher building and impervious areas). Through this study, it should be possible to select an appropriate vegetation cooling model according to its fraction coverage so that the temperature analysis around built-up areas would be improved.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.495-505
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• 2012

Modeling the effects of high-rise buildings on thermo-dynamic conditions and meteorological fields over a coastal urban area was conducted using the modified meso-urban meteorological model (Urbanized MM5; uMM5) with the urban canopy parameterization (UCP) and the high-resolution inputs (urban morphology, land-use/land-cover sub-grid distribution, and high-quality digital elevation model data sets). Sensitivity simulations was performed during a typical sea-breeze episode (4~8 August 2006). Comparison between simulations with real urban morphology and changed urban morphology (i.e. high-rise buildings to low residential houses) showed that high-rise buildings could play an important role in urban heat island and land-sea breeze circulation. The major changes in urban meteorologic conditions are followings: significant increase in daytime temperature nearly by $1.0^{\circ}C$ due to sensible heat flux emitted from high density residential houses, decrease in nighttime temperature nearly by $1.0^{\circ}C$ because of the reduction in the storage heat flux emitted from high-rise buildings, and large increase in wind speed (maximum 2 m $s^{-1}$) during the daytime due to lessen drag-force or increased gradient temperature over coastal area.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.5
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• pp.479-490
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• 1998

The concentrations of ten inorganic (sodium, chloride, sulfate, ammonia, etc.) and three organic (acetate, formate, and MSA) ions associated with airborne particulate matter were measured from Cheju Island, Korea during the three field intensive campaigns conducted in (1) Sept./oct. 1997 (fall), (2) Dec. 1997 (winter), and (3) April 1998 (spring). The results of our measurements indicated that the concentration levels of most ionic species were decreasing significantly across the three experimental periods. The patterns of concentration reduction were clear as the sum of all cation and anion species changed dramatically across those periods such as 294> 144 > 65 and 193 >96>74 nequiv/m3, respectively. The changes were best explained in terms of the wind rose patterns of the study site. Since our sampling spot is located on the western-end point of Cheju Island, it is likely to reflect the effects of diverse sources such as natural, marine processes during NW and local non-maritime ones during SE winds. .Hence, the periodical changes in ionic concentrations may be accounted for by the comparable changes in wind direction. To further investigate environmental characteristics of these ionic components, correlation analysis was conducted not only between meteorological and ion data but between different ion-pairs. The results of these analyses confirm that the concentration levels of ionic species are strongly affected by wind speed and temperature and that there are certain patterns between ion species to which such effects apply. In light of the significance of the wind rose patterns in the area, we further extended these analyses into four data groups that were divided on the basis of wind direction. The results of these analyses showed that the strength of correlations between important pairs (e.g.:. between windspeed and most of major inorganic species including sodium and chloride) can be ranked on the distribution of major ions are very diverse, depending on data grouping scheme for such analysis. The results of this study thus suggest that environmental behavior of chemical components be analyzed in various respects, rather than simple standard, especially if measurements are made in complex environmental condition under which both natural and anthropogenic effects are competing each other.

• Journal of Environmental Policy
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• v.14 no.2
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• pp.3-25
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• 2015

Our goal is to verify how changes in water's hydraulic characteristics after urban regeneration stream can affect any possible transformation of its thermal environment. To that end, we analyzed changes in numerous physical characteristics the subject stream along with the meteorological factors and thermal environment affected by it. Cheonggyecheon was selected as our subject as it is a great example of successful urban regeneration stream. As for physical characteristics, we allocated Type I (0.0%) and Type II (20.2%), depending on the green coverage ratio. As for numerical characteristics, at the point of Ba in which the riffle ends, the water temperature fell by $0.2^{\circ}C$ and the flow increased from 0.7m/s to 0.9 m/s with the dissolved oxygen increasing from 0.5mg/L to 0.6mg/L. As for meteorological factors surrounding the subject stream, the temperature dropped from $1.1^{\circ}C$ to $1.4^{\circ}C$ on average and relative humidity increased from 6.6% to 8.7%. Furthermore, there was an irregular change in wind velocity. According to the result of the Wet Bulb Globe Temperature (WBGT), the change in the values of Type I and II inside and on the surface of the subject stream was negligible. The downstream temperature in Type I fell from $0.3^{\circ}C$ to $0.6^{\circ}C$ and by $0.8^{\circ}C$ in Type II. As for vertical cooling effect, the change of water level was 120cm in Type I and 140cm in Type II. As for horizontal cooling effects, the value of Type I was increased from the point of Ba where the riffle ends and the value of Type II was on a steady decline.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.237-238
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• 2002

Particle - bound water changes the physical and chemical properties of aerosol particles, such as size and light scattering properties. Consequently, it is necessary to remove water vapor from ambient aerosols before aerosol particles are sized and counted. Silicon gel diffusion dryer is commonly employed for this purpose. However, it can not be operated continuously While in operation, silicon gel becomes progressively more loaded with water and must periodically be regenerated by drying off the water. (omitted)

• Journal of the Korean earth science society
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• v.32 no.5
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• pp.453-460
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• 2011

By performing a statistical change-point analysis of activities of the tropical cyclones (TCs) that have affected Korea (K-TCs), it was found that there was a significant change between 1983 and 1984. During the period of 1984-2004 (P2), more TCs migrated toward the west, recurved in the southwest, and affected Korea, compared to the period of 1965-1983 (P1). These changes for P2 were related to the southwestward expansion of the subtropical western North Pacific high (SWNPH) and simultaneously elongation of its elliptical shape toward Korea. Because of these changes, the central pressure and lifetime of K-TC during P2 were deeper and longer, respectively, than figures for P1. This stronger K-TC intensity for P2 was related to the more southwestward genesis due to the southwestward expansion of the SWNPH. The weaker vertical wind shear environment during P2 was more favorable for K-TC to maintain a strong intensity in the mid-latitudes of East Asia.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.927-932
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• 2022

Instrument drift is caused by the passage of time, environmental changes, normal wear and tear, debris buildup, sudden shock, vibrations, electromagnetic fields, and improper use. Since it is inappropriate to directly determine the change of the output value as drift during the limited test period, a new algorithm that reflects both zero drift and span drift by giving changes over time to the calibration method of the instrument was proposed. The temperature drift was calculated to be 0.49% for about 60 minutes at 1-minute intervals in the nine-step constant temperature environment through the warming and cooling process.

• Atmosphere
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• v.15 no.1
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• pp.69-74
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• 2005

In this short article, oceanic processes that could have strong effect on the climate have been explained while focusing on the oceanic thermohaline circulation (THC). First, the structure of THC is explained using a simple scaling law. Then, the thermohaline catastrophe, which is believed to be a cause of a rapid climate changes observed in paleoclimate records, and interdecadal variations in THC are explained. The interactions between the oceans and $CO_2$ are also mentioned briefly.

• Korean Journal of Remote Sensing
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• v.32 no.4
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• pp.365-382
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• 2016

The results from the Global Positioning System (GPS) measurements of the Mobile Observation Vehicle (MOVE) on the eastern coast of Korea have been compared with REFerence (REF) values from the fixed GPS sites to assess the performance of Precipitable Water Vapor (PWV) retrievals in a kinematic environment. MOVE-PWV retrievals had comparatively similar trends and fairly good agreements with REF-PWV with a Root-Mean-Square Error (RMSE) of 7.4 mm and $R^2$ of 0.61, indicating statistical significance with a p-value of 0.01. PWV retrievals from the June cases showed better agreement than those of the other month cases, with a mean bias of 2.1 mm and RMSE of 3.8 mm. We further investigated the relationships of the determinant factors of GPS signals with the PWV retrievals for detailed error analysis. As a result, both MultiPath (MP) errors of L1 and L2 pseudo-range had the best indices for the June cases, 0.75-0.99 m. We also found that both Position Dilution Of Precision (PDOP) and Signal to Noise Ratio (SNR) values in the June cases were better than those in other cases. That is, the analytical results of the key factors such as MP errors, PDOP, and SNR that can affect GPS signals should be considered for obtaining more stable performance. The data of MOVE can be used to provide water vapor information with high spatial and temporal resolutions in the case of dramatic changes of severe weather such as those frequently occurring in the Korean Peninsula.

• Atmosphere
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• v.21 no.4
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• pp.405-414
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• 2011

In this study, the influence of a change in land use on the local weather fields is investigated around the Lake Shihwa area using synthetic land cover data and a high-resolution mesoscale model - the Weather Research and Forecasting (WRF). The default land cover data generally used in the WRF is based on the land use category of the United States Geological Survey (USGS), which erroneously presents most land areas of the Korean Peninsula as savannas. To revise such a fault, a multi-temporal land cover data, provided by the Ministry of Environment of Korea, was employed to generate a land cover map of 2005 subject to the land use in Korea at that time. A new land cover map of 1989, before the construction of the Lake Shihwa, was made based on the 2005 map and the Landsat 4-5 TM satellite images of two years. Over the areas where the land use had been changed (e.g., from sea to wetlands, towns, etc.) due to the Lake Shihwa development project, the skin temperature decreased by up to $8^{\circ}C$ in the winter case while increased by as much as $14^{\circ}C$ in the summer case. Changes in the water vapor mixing ratio were mostly affected by advection and topography in both seasons, with considerable increase in the summer case due to continuous sea breeze. Local decrease in water vapor occurred over high land use change areas and/or over downstream of such areas where alteration in wind fields were induced by changes in skin temperature and surface roughness at the areas of land use changes. The albedo increased by about 0.1% in the regions where sea was converted into wetland. In the regions where urban areas were developed, such as Songdo New Town and Incheon International Airport, the albedo increased by up to 0.16%.