In this study, we investigated the optimal meteorological conditions for cloud seeding using aircraft over the Korean Peninsula. The weather conditions were analyzed using various data sources such as a weather chart, upper air observation, aircraft observation, and a numerical model for cloud seeding experiments conducted from 2018 to 2019 by the National Institute of Meteorological Sciences, Korea Meteorological Administration. Cloud seeding experiments were performed in the seasons of autumn (37.0%) and winter (40.7%) in the West Sea and Gangwon-do. Silver iodide (70.4%) and calcium chloride (29.6%) were used as cloud seeding materials for the experiments. The cloud seeding experiments used silver iodide in cold clouds. Aircraft observation revealed relatively low temperatures, low liquid water content, and strong wind speeds in clouds with a weak updraft. In warm clouds, the cloud seeding experiments used calcium chloride. Observations included relatively high temperatures, high liquid water content, and weak wind speeds in clouds with a weak updraft. Based upon these results, we determined the comprehensive meteorological conditions for cloud seeding experiments using aircraft over the Korean Peninsula. The understanding of optimal weather conditions for cloud seeding gained from this study provide information critical for performing successful cloud seeding and rain enhancement.

미국 9.11 사고 이후 테러는 과거에 비하여 다중이용시설 공격을 통한 불특정 다수의 공격이 증가하고 있다. 연이은 런던 폭탄테러, 파키스탄의 자폭 등은 사람들의 공포심 및 사회적 불안감을 증가시켰다. 최근 국내에서 다양한 국제행사가 개최되고 있어, 방사능테러 위협에 대비한 방사성물질의 국가 안보 의식이 증대되고 있다. 본 논문에서는 HotSpot Code를 사용하여 서로 상이한 기상조건에 따른 결과를 비교하였다. 국내에서 발생 가능한 테러 시나리오 작성 후, RDD(Radiological Dispersal Device) 및 더티밤에 사용될 가능성이 높은 선원을 조사하였다. 기상조건은 Pasquill-Gifford 안정도 등급에 따라 가장 안정된 조건의 F, 가장 불안정한 조건의 A를 선택하여 비교하였다. 시뮬레이션을 통한 A, F 등급 결괏값은 방사선학적 영향에 의해 시민들이 급성 영향으로 사망하는 경우는 없다고 판단하였다. 또한, 풍속 및 기상 안정도에 따라 방사능의 도달 정도가 서로 다르며, 기상 조건에 따라 방사능 희석정도가 서로 다름을 확인할 수 있다. 분석결과는 방사능테러 발생 시 초동 대응에 활용할 수 있을 것으로 예상된다.

Both the propagation velocity and the direction of atmospheric waves are important factors for analyzing and forecasting meteo-tsunami. In this study, a total of 14 events of meteo-tsunami over 11 years (2006-2016) are selected through analyzing sea-level data observed from tidal stations along the west coast of the Korean peninsula. The propagation velocity and direction are calculated by tracing the atmospheric disturbance of each meteo-tsunami event predicted by the WRF model. Then, the Froude number is calculated using the propagation velocity of atmospheric waves and oceanic long waves from bathymetry data. To derive the critical condition for the occurrence of meteo-tsunami, supervised learning using a logistic regression algorithm is conducted. It is concluded that the threshold distance of meteo-tsunami occurrence, from a propagation direction, can be calculated by the amplitude of air-pressure tendency and the resonance factor, which are found using the Froude number. According to the critical condition, the distance increases logarithmically with the ratio of the amplitude of air-pressure tendency and the square of the resonance factor, and meteo-tsunami do not occur when the ratio is less than 5.11 hPa/10 min.

The classification of airflow patterns during high ozone (O3) and PM10 episodes on Jeju Island in recent years (2009-2015), as well as their correlation with meteorological conditions according to classified airflow patterns were investigated in this study. The airflow patterns for O3 and PM10 were classified into four types (Types A-D) and three types (Types E-G), respectively, using the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and synoptic weather charts. Type A was the most dominant airflow pattern for O3 episodes, being characterized by the transport of airflows from urban and industrial areas in China with the highest frequency (about 69%, with a mean of 67 ppb). With regard to the PM10 episodes, Type E was the most dominant airflow pattern, and was mostly associated with long distance transport from Asian dust source regions along northwesterly winds, having the highest frequency (about 92%, with a mean of 136 μg/m3). The variations in the concentration of O3 and PM10 during the study period were clarified in correlation with two pollutant and meteorological variables; for example, the high (low) O3 and PM10 concentrations with high (low) air temperature and/or wind speed and vice versa for precipitation. The contribution of long-range transport to the observed PM10 levels in urban sites for different airflow patterns (Types E-F), if estimated in comparison to the data from the Gosan background site, was found to account for approximately 87-93% (on average) of its input. The overall results of the present study suggest that the variations in O3 and PM10 concentrations on Jeju Island are mainly influenced by the transport effect, as well as the contribution of local emissions.

This study is analysed on corelation between topographical conditions around 36 weather stations and climate data in South Korea. As a result of analysis, the altitude above sea level shows linear negative corelation with temperature. The low relative height sites appear that sunshine duration and temperature are the lowest and precipitation and precipitation duration are bigger than average by influences of surrounding landform. The relief amount shows high positive corelation with precipitation phenomena such as precipitation, precipitation duration and cloud amount. In terms of the aspect, southern slope sites show the highest daily minimum temperature and sunshine duration, and western slope sites show daily mean and maximum temperatures. The eastern close sites appear the lowest temperature and the highest humidity. The distance from coastline shows linear negative corelation with temperature data. The far distance sites from coastline appear that temperature, precipitation and precipitation duration are the lowest. In respect of landform structures, the piedmont areas show the highest moisture related indicators. The hill areas show the lowest humidity and cloud amount and the longest sunshine duration. Temperature and wind speed are low in basin areas.

본 연구에서는 우리나라 주요 해변관광지인 강릉지역 고속도로 톨게이트를 대상으로 기상상황의 변화가 고속도로 일별 유입교통량에 미치는 영향을 분석한다. 기상청이 운용하는 ASOS 및 AWS 관측자료를 이용하여 일별 기상상황을 파악하고 호우 및 폭설 등 일별 기상상황의 변화가 강릉지역 톨게이트 유입교통량에 미치는 영향을 회귀분석을 통해 파악한다.

목재칩과 우레탄 수지를 결합한 혼합물을 보도포장의 표층재료로서 사용하였을 때, 기상조건에 따른 물성 변화를 알아보기 위한 실험을 실시하였다. 시험체는 다짐기구의 종류에 따라 다짐횟수 및 가압시간을 변화시켜 폭 410mm, 길이 670mm, 두께 40mm의 크기로 제작하였으며, 7일 양생 후 단위용적질량을 측정한 다음 폭 30mm의 크기로 절단하여 인장강도 시험을 실시하였다. 기상조건에 따른 물성 변화를 알아보기 위한 실험은 강우 환경과 해수 환경에서의 실험, 동결융해실험 및 내후성 실험으로 구분하여 실시하였다. 목재칩과 우레탄 수지를 결합한 혼합물에 대한 실험결과, 인장강도는 강우 환경에서 상당한 감소를 나타냈으나 이러한 강도 저하는 해수 환경 및 동결융해 시에 더욱 심화되지는 않는 것으로 나타났다. 또한 제논 아크에 노출시킨 경우 시험체의 인장강도가 변화하였는데 이는 목재칩과 우레탄 수지의 혼합물이 햇빛에 의해 다소 열화될 수 있음을 나타낸 결과로 판단된다.

아스팔트 콘크리트 포장 도로의 온도 분포 특성과 경계 조건을 분석하기 위하여 경상도 지역에 구축된 현장계측시스템으로부터 계측된 현장 온도를 활용하여 대기의 기상조건 및 온도가 포장체 내부의 온도 분포에 미치는 영향에 대하여 분석하였다. 아스팔트 콘크리트 포장의 깊이별 온도 분포를 분석한 결과 깊이별 온도가 동일한 시점인 교차시간은 여름보다 겨울이 상대적으로 늦게 나타나는 것을 확인하였다. 아스팔트 콘크리트 포장체의 온도 분포는 구름양과 강우의 영향을 모두 받으며, 동일 구름양량의 경우 강우량의 크기에 따라 포장체의 온도 분포가 달라지는 것을 확인하였다. 강설 및 포장면 적설의 영향으로 아스팔트 콘크리트 층의 온도 변동폭이 감소하며, 차량 운행에 의해 쌓인 눈이 녹는 구간은 적설량에 따른 영향이 적은 것으로 나타났다.

The effects of meteorological and reclaiming conditions on the reduction of suspended particles are investigated using a computational fluid dynamics (CFD) model with the k-ε turbulence closure scheme based on the renormalization group (RNG) theory. Twelve numerical experiments with different meteorological and reclaiming conditions are performed. For identifying the meteorological characteristics of the target area and providing the inflow conditions of the CFD model, the observed data from the automatic weather station (AWS) near the target area is analyzed. Complicated flow patterns such as flow distortion, horse-shoe vortex, recirculation zone, and channeling flow appeared due to the topography and buildings in the domain. Specially, the flow characteristics around the reclamation area are affected by the reclaiming height, reclaiming size and windbreak height. Reclaiming height affected the wind speed above the reclaiming area. Windbreak induces more complicated flow patterns around the reclaiming area as well as within the reclaiming area. In front of the windbreak, flow is distorted as it impinges on the windbreak. As a result, upward flow is generated there. Behind the windbreak, a secondary circulation, so called, a recirculation zone is generated and flow is reattached at the end of the recirculation zone (reattachment point). At the lower part of the recirculation zone, there is a reverse flow toward the windbreak. Flow passing to the reattachment point starts to be recovered. Total amounts of suspended particles are calculated using the frictional and threshold frictional velocities, erosion potential function, and the number of surface disturbance. In the case of a 10 m-reclaiming and northerly wind, the amount of suspended particles is largest. In the presence of 5 m windbreak, the friction velocity above the reclaiming area is largely reduced. As a result, the total amount of the suspended particles largely decreases, compared to the case with the same reclaiming and meteorological conditions except for the windbreak The calculated suspended particle amounts are used as the emission rate of the dispersion model simulations and the dispersion characteristics of the suspended particles are analyzed.

Cool island intensity urban green space was investigated based in Dalsung Park, that is one of the largest parks in Daegu. Cool island intensity(CII), which is defined as the temperature difference between the green space and its surrounding built-up areas, shows time variations. A through-year measurement(2008-2009) of ground level air temperature revealed seasonal variation and relationship to the atmospheric condition of CII. The temperature variation in the park and the reference downtown Daegu was as same order as CII. The noontime CII is larger in summer than that in winter due to the leaf fall of the park trees. On the other hand, seasonal variation of nighttime CII is not so clear. The nighttime CII was larger under the stable atmosphere.

The chemical and meteorological effects on the concentration variations of air pollutants (O3 and its precursors) were evaluated based on ground observation data in coastal and inland regions, Busan during springs and summers of 2005-2006. For the purpose of this study, study areas were classified into 5 categories: coastal area (CA), industrial area (IA), downtown area (DA), residential area (RA), and suburban area (SA). Two sites of Dongsam (DS) and Yeonsan (YS) were selected for the comparison purpose between the coastal and inland regions. O3 concentrations in CA and SA were observed to be highest during spring (e.g., 40 ppb), whereas those in DA and RA were relatively low during summer (e.g., 22～24 ppb). It was found that O3 concentrations in IA were not significantly high although high VOCs (especially toluene of about 40 ppb) and NOx (≥ 35 ppb) were observed. On the other hand, the concentration levels of O3 and PM10 at the DS site were significantly higher than those at the YS site, but NOx was slightly lower than that at the YS site. This might be caused by the photochemical activity and meteorological conditions (e.g., sea-land breeze and atmospheric stagnance). When maximum O3 (an index of photochemical activity) exceeds 100 ppb, the contribution of secondary PM10 ((PM10)SEC) to total observed PM10 concentrations was estimated up to 32% and 17% at the DS and YS sites, respectively. In addition, the diurnal variations of (PM10)SEC at the DS site were similar to those of O3 regardless of season, which suggests that they are mostly secondary PM10 produced from photochemical reactions.

The purpose of this study is to clarify the characteristic of urban heat island intensity in urban area formed at a basin. Thermal environments for basin-type cities are influenced by significant topographic relief winds. In this study, we analyzed the diurnal variations of the heat island intensity according to meteorological condition and season using AWS(Automatic Weather observation System) data in Daegu Metropolitan area for 1 year(3/April, 2003 ～ 2/April, 2004). In this study, we defined the urban heat island intensity as the air temperature difference between two points, the downtown and the suburban area. The suburban area is located at valley mouth around the western tip of Daegu. The results are summarized as follows; 1. The maximum heat island intensity was recorded at early morning under the meteorological conditions, calm and clear 2. The heat island intensity was strong in the order of winter, fall, spring and summer. 3. The heat island intensity came out minus values in the afternoon. This phenomenon is known as a common for basin-type cities. 4. The heat island intensity was twice or more in clear and calm than not so.

Several samplers using gravimetric methods such as high-volume air sampler, MiniVol portable sampler, personal environmental monitor(PEM) and cyclone were applied to determine the concentrations of fine particles in atmospheric condition. Comparative evaluation between high-volume air sampler and MiniVol portable sampler for PM10, and between MiniVol portable sampler and PEM was undertaken from June, 2003 to January 2004. Simultaneously, meteorological conditions such as wind speed, wind direction, relative humidity and temperature was measured to check the factors affecting the concentrations of fine particles. In addition, particle concentrations by cyclone with an aerodynamic diameter of 4 ㎛ were measured. Correlation coefficient between high- volume air sampler and portable air sampler for PM10 was 0.79 (p<0.001). However, the mean concentration for PM10 by high-volume air sampler was significantly higher than that by MiniVol portable sampler (p=0.018). Correlation coefficient between Minivol portable sampler and PEM for PM2.5 was 0.74 (p<0.001), and the measured mean concentrations for PM2.5 did not show significant difference. Difference of the measured concentrations of fine particle might be explained by wind speed and humidity among meteorological conditions. Particle concentration differences by measurement samplers were proportional to the wind speed, but inversely proportional to the relative humidity, though it was not a significant correlation.

In cold season, the developed extratropical cyclones and associated cold fronts, and NW winter monsoon are encountered very frequently in the North Pacific, especially in the northwest part of it. The two sea areas, namely, the northwest part of North Pacific, especially the eastern area far off Japan east coast, and Burmuda Triangle in the North Atlantic are generally known as two of the most dangerous areas in the world because of high incidence of sea casualties. Even large ocean going vessels were sunk frequently due to strong winds and very high seas caused by NW monsoon or developed cyclones during the winter months. The purpose of this paper is to analyse the real state of heavy weather and high sea phenomena on the vesscls at sea, thus helping mariners operate in such conditions.

In cold season, ice accretion on ship, drift ice, NW winter monsoon, developed extratropical cyclones and associated cold fronts, in warm season, tropical cyclones and dense sea fogs, are encountered very frequently in the North Pacific, especially in the northwest part of it. The two areas, namely, the northwest part of the North Pacific and Burmuda Triangle in the North Atlantic are generally known as most dangerous areas in the world because its high incidence of sea cascualities. In recent years, the small fisherboats operating in the northern seas were frequently sunk in a group as they encountered ice accretion or drift ice. And ocean going vessels were also sunk frequently due to strong winds and very high seas in winter monsoon or developed cyclones and cold fronts. The purpose of this paper is to analyze the real state of heavy weather conditions such as ice accretion on ship drift, ice, typhoons and sea fogs, and also to analyse the effect of these heavy weather phenomena on the vessels at sea, thus helping mariners operate in such heavy weather conditions.

이앙기에 따른 등숙기상조건의 차이가 수도의 탈립성에 미치는 영향을 구명하기 위하여 탈립성이 큰 태백벼와 비탈립성인 진흥을 재료로 40일 묘를 5월 11일부터 15일 간격으로 4회 이앙하고 출수 후 40일 및 55일의 시기에 각각 벼알의 인장강도를 측정하였으며 작기 및 수확시기의 영향, 그리고 기상요인들과 탈립성과의 관계를 분석하였다. 1. 벼알의 인장강도는 각 처리를 통틀어 진흥의 경우 214-251g의 변이폭을 보였고 이 범위의 인장강도는 벼의 포장손실에 무관하나 태백벼의 경우 인장강도는 127.5-204g의 변이폭을 보였고 이앙기 및 수확시기가 탈립성 및 벼의 포장손실에 미치는 영향은 매우 컸다. 2. 벼알의 인장강도에 미치는 영향은 태백벼의 경우 수확시기, 이앙기 및 이앙기와 수확시기와의 상호작용이 모두 컸으며, 특히 이앙기가 6월 25일 경우 현저히 탈립성이 커졌다. 진흥의 경우에는 이앙기의 영향은 유의하지 않았고 수확시기가 늦을수록, 즉 벼알이 건조될수록 인장강도가 다소간 커지는 경향이었다. 3. 기상요인들의 탈립성에 미치는 영향은 일평균, 최저, 최고기온 및 일기온교차가 컸고, 특히 수확전 30일간의 이들의 영향이 컸으며, 태백벼의 경우 일사량과 대기온도가 영향하지 않았지만 진흥의 경우에는 수확전 10일간의 일사량과 수확전 30일간의 대기온도가 영향하였다.

재배 환경 조건이 주요 밀 품종의 품질에 미치는 영향을 보기 위하여 조광을 포함한 9개 품종을 8개 지역에 재배하여 지역별 기상인자와 소맥분 단백질함량 및 침전가와의 관계를 검토한 결과는 다음과 같다. 1. 소맥 재배기간중의 기온이 낮은 북부 일수록 단백질 함량과 침전가는 품종에 관계없이 높은 경향을 보였다. 2. 소맥분의 단백질 함량 및 침전가에 미치는 가장 큰 기상요소는 등숙기간중의 평균 기온이었다. 3. 기온이 낮은 북부지역일수록 출수일이 늦어져서 등숙기간의 기온이 높아진다. 등숙기간의 평균기온이 높은 지방일수록 소맥분의 단백질 함량 및 침전가는 높아졌다. 4. 소맥의 단백질 함량에 미치는 온도반응은 품종에 따라 차이가 있었으며 온도반응이 예민한 품종은 Altas 66, Kitakamikomugi 및 영광이었고 둔감한 품종은 원광, Centurk 및 Bezostaya 이었다. 5. 소맥분의 침전가에 미치는 온도반응은 침전가가 높은 Atlas 66, Centurk, NE 701132, 품종들에서 높았고 침전가가 낮은 Roussalka 및 국내 품종들에서는 둔감하였다.