• 한국대기환경학회지
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• 제27권6호
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• pp.791-804
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• 2011

Numerical simulations were carried out to investigate the impact of PBL (Planetary boundary layer) scheme implemented in WRF on the result of meteorological fields and CMAQ modeling. 25-day period, representing high ozone concentration, was selected for the simulations. The three WRF domains covered East Asia region, Korean Peninsula and Seoul metropolitan area. The sensitivity of WRF-CMAQ modeling to the various PBL schemes was assessed and quantified by comparing model output and against observation from the meteorological and the air quality monitoring network within the domain. The meteorological variables evaluated included temperature, wind speed and direction over surface sites and upper air sounding sites. The CMAQ variables included gaseous species $O_3$ and $NO_x$ over monitoring stations. Although difference of PBL schemes implemented in WRF, they did not appreciably affect the WRF and CMAQ performance. There are partially differences between non-local and local mixing scheme, but are not distinct differences for the results of weather and air quality. It is suggested that impact of parameterization of vertical eddy diffusivity scheme in CMAQ also need to be researched in the future study.

• 한국지리정보학회지
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• 제15권4호
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• pp.124-137
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• 2012

기후분석은 도시 쾌적도를 고려하는 도시계획에 있어 중요한 요소 중 하나이다. 도시지역의 기후는 종관규모보다 작은 국지규모의 기후 영향을 받는데, 본 연구에서는 도시 안에서의 야간 지면냉각과 찬공기 생성 및 유입의 효과를 분석함으로써 도시지역의 국지기후에 대한 영향을 정량화 하고자 하였다. 서울관측소 풍속에 미치는 종관 기상의 영향은 30%정도인 반면, 관측소 주변의 지형 건물 열적 현상의 영향은 70%정도인 것으로 나타났다. 또한 서울 은평구 뉴타운의 연구지역에 대하여 서울기후분석(CAS, Climate Analysis Seoul) 모델로 분석한 결과, 국지영향 기온편차 분포에서 토지피복률에 따라 도시 및 도시외곽 지역의 기온 특성이 함께 존재하고 있음을 보여주었다. 또한 고밀도 관측 자료로부터 각 지점들의 시간대별 열적반응이 국지영향 기온편차 분포와 일치함을 알 수 있었다. 관측지점들 중 실개천을 따라 설치된 지점들의 일변동은 유사하게 나타났는데, 인근 산으로부터 경사면을 따라 유입된 찬공기의 생성, 이동, 정체는 관측된 수직기온경도를 이용하여 표현되었다. 실개천의 입구에서 관측된 수직기온경도는 지면 냉각에 의한 것과 외부로부터의 찬공기 유입이라는 두 가지로 설명될 수 있다. 지면냉각은 풍속과 관계없이 존재하지만, 찬공기 유입에 의한 냉각효과는 풍속이 낮을 때만 일어났다. 풍속의 강약에 따른 회귀분석식을 이용하여, 찬공기 유입 냉각효과는 국지적인 지면 냉각의 84%였다는 것을 밝혔다. 본 연구를 통해 지역특성이 국지기후에 미치는 영향의 크기를 기존의 정적인 기온영향 분석에서 동적인 찬공기 유입분석으로 확장하였다. 이 연구를 바탕으로 앞으로의 기후분석에서는 도시민의 쾌적도를 지원하기 위한 도시개발계획의 찬공기 특성 변화를 분석할 수 있게 될 것이다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.134-139
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• 2012

This study observed downward long and short-wave radiant environment with selecting 4 areas which have different height in downtown and 1 suburban area to figure out the characteristic of radiant environment in each altitude. The purpose of this study is to collect the preliminary data for interpreting urban thermal environment in summer season by analyzing thermal characteristic of atmosphere in the upper of downtown. The results of this study are as follows. 1) The higher altitude has the lower temperature, and temperature difference was more huge in day time than night time. 2) The short wave radiation according to altitude was higher as altitude was high. 3) Generally, the higher altitude has the lower air temperature, and also the higher altitude has the lower downward long wave radiation by the atmospheric radiation. 4) The ratio short wave radiation of long wave radiation was lower as altitude was high. And the urbanization effect was higher as the ratio was low.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.33-36
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• 2007

We have persistently constructed gridded products of surface wind/wind stress over the world ocean using satellite scatterometer (ERS and Qscat). They are available for users as the Japanese Ocean Flux data sets with Use of Remote sensing Observation (J-OFURO) data together with heat flux components. Recently, a new version data of the Qscat/SeaWinds based on improved algorithm for rain flag and high wind-speed range have been delivered, and allowed us to reconstruct gridded product with higher spatial resolution. These products are validated by comparisons with in-situ measurement data by mooring buoys such as TAO/TRITON, NDBC and the Kuroshio Extension Observation (KEO) buoys, together with numerical weather prediction model products such as the NCEP-1 and 2. Results reveal that the new product has almost the same magnitude in mean difference as the previous version of Qscat product and much smaller than the NCEP-1 and 2. On the other hand, it is slightly larger root-mean-square (RMS) difference than the previous one and NCEPs for the comparison using the KEO buoy data. This may be due to the deficit of high wind speed data in the buoy measurement. The high resolution product, together with sea surface temperature (SST) one, is used to examine a new type of relationship between the lower atmosphere and upper ocean in the Kuroshio Extension region.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.795-800
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• 2000

A CCFL(Counter Current Flow Limit) test have been performed in narrow annular gaps with large diameter, because it has been confirmed that the CCFL phenomena affected the critical power in hemispherical narrow gap geometries from the SONATA(Simulation Of Naturally Arrested Thermal Attack)-IV (In-Vessel)/VISU(Visualization)-II experiments. The objectives of the CCFL experiments are to investigate the small gap sizes(1, 2mm) effect on CCFL under the large diameter condition and to confirm the findings of the VISU-II study that global dryout in hemispherical narrow gaps was induced by the CCFL. The test section was made of acrylic resin to allow visual observation on the two-phase flow behaviors inside annular gaps. It was observed from visualization that a part of water supplied was accumulated in the upper plenum and a significant increase in the differential pressure across the gap was occurred, which was the definition of the CCFL occurrence in this experimental study. From the experimental results in annular gap with large diameter it can be known that an increase in the differential pressure was not big at small air flow-rates. When the CCFL was occurred, the differential pressure across gaps was increased significantly and a water accumulated in the upper plenum. The occurrence of CCFL was correlated using the Wallis parameter.

• 대기
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• 제17권3호
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• pp.281-289
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• 2007

Micrometeorlogical and upper air observation have been conducted in order to determine the atmospheric boundary layer depth based on data from satellite and automatic weather systems. Terra/MODIS temperature profiles and sensible heat fluxes from the gradient method were used to estimate the mixed layer height over a coastal region. Results of the integral model were in good agreement with the mixed layer height observed using GPS radiosonde at Wolsung ($35.72^{\circ}N$, $129.48^{\circ}E$). Since the variation of the mixed layer height depends on the surface sensible heat flux, the integral model estimated properly the mixed layer height in the daytime. The buoyant heat flux, which is more important than the sensible heat flux in the coastal region, must be taken into consideration to improve the integral model. The vertical structure of atmospheric boundary layer can be analyzed only with the routine data and the satellite data.

• Journal of Astronomy and Space Sciences
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• 제27권3호
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• pp.213-220
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• 2010

As an observation instrument of the longest record of tropospheric water vapor, radiosonde data provide upper-air pressure (geopotential height), temperature, humidity and wind. However, the data have some well-known elements related to inaccuracy. In this article, radiosonde precipitable water vapor (PWV) at Sokcho observatory was compared with global positioning system (GPS) PWV during each summertime of year 2007 and 2008 and the biases were calculated. As a result, the mean bias showed negative values regardless of the rainfall occurrence. In addition, on the basis of GPS PWV, the maximum root mean square error (RMSE) was 5.67 mm over the radiosonde PWV.

• 대기
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• 제21권1호
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• pp.1-16
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• 2011

Numerical prediction capability has been improved over the decades, but progress of prediction for high-impact weather (HIW) was unsatisfactory. One reason of low predictability for HIW is lack of observation data. The National Institute of Meteorological Research (NIMR) has been performed observation program for improvement of predictability, and reduction in social and economical cost for HIW. As part of this observation program, summer intensive observation program (ProbeX-2009) was performed at the observation-gap areas from 25 August to 6 September 2009. Sounding observations using radiosonde were conducted in the Gisang2000 research vessel (R/V) from the Korea Meteorological Administration (KMA) over the West Sea and the Eardo R/V from the Korea Ocean Research and Development Institute (KORDI) over the South Sea. Observation System Experiment (OSE) is carried out to examine the effect of ProbeX-2009 data. OSEs using Korea Local Analysis and Prediction System (KLAPS) and Weather Research and Forecasting (WRF) Model are conducted to investigate the predictability for a short time forecast. And, OSEs using WRF/3DVAR system and WRF forecast model are conducted to study the predictability for an extended time. Control experiment (K_CTL and CNTL) used only GTS observation and experiment (K_EXP and SWEXP) used ProbeX-2009 data from two system are performed. ETS for 3hr accumulated rainfall simulated by KLAPS-WRF shows that K_EXP is higher than K_CTL. Also, ETS for 12hr accumulated rainfall of SWEXP from 3DVAR-WRF is higher than CNTL. The results indicate that observation over the ocean has positive impact on HIW prediction.

• 대한원격탐사학회지
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• 제16권1호
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• pp.47-54
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• 2000

한반도 기후 분석에 마이크로파 위성자료의 이용을 위해 1981년에서 1998년까지 18년간 한반도 4개의 고층 관측 지점에서 얻어진 온도자료와 위성자료를 비교하였다. 위성자료로 극궤도 위성인 NOAA위성에 탑재되어 있는 MSU(Microwave Sounding Unit) 채널 2와 채널 4 휘도온도를 이용하였다. 고층 관측소의 라디오존데 자료는 MSU 휘도온도와 비교하기위해 MSU 가중함수를 이용하여 고도마다 가중을 두어 월평균 온도 값을 만들어내었다. 월평균 기후값 비교에서 여름철에 라디오존데 온도가 MSU 휘도온도보다 높은 온도를 보였다. 두 온도사이의 상관에서는 채널2의 경우 0.72 - 0.76, 채널 4에서는 0.73 - 0.81정도를 보였다 18년 동안의 온도경향은 채널 2의 경우는 0.04$^{\circ}C$/year의 증가가 있었고, 채널 4의 경우는 -0.07$^{\circ}C$/year의 감소가 보였다.

• 한국환경과학회지
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• 제30권12호
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• pp.1027-1039
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• 2021

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.