• 한국지구과학회지
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• 제34권4호
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• pp.303-312
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• 2013

중위도 기압골과 태풍 이동속도와의 상호작용에 대한 예측에서 한국기상청 전구자료동화예측시스템(GDAPS) 모델 바이어스 경향을 알아보기 위해 태풍 산바 사례가 선정되었다. 이 연구는 태풍 분석 및 예측 시스템(TAPS) 및 기상정보시스템-3(COMIS-3)에 저장된 태풍자료로부터 2012년 9월 15일 00UTC로 초기화 된 한국 기상청 GDAPS 분석장과 예측장을 사용하였다. 먼저 해면기압장은 500 hPa 제트구역과 연관하여 중위도 하층 저기압이 발생됨을 보여주었다. 이후 태풍 산바가 중위도 지역으로 들어온 후, 태풍의 이동속도가 증가될 것이라 예측되었다. 특히, 태풍 산바가 9월 17일 00UTC와 06UTC에 전향을 할 시점에 태풍 산바는 중위도 기압골 전면에서 중위도 서풍대와 상호작용을 하였다. 반면, 기상청 GDAPS 해면기압 예측장은 하층 중위도 저기압의 강도를 분석장보다 약하게 예측하였다. 결국 태풍 산바의 이동속도에 영향을 주는 중위도 순환은 분석장보다 느리게 나타났다. 이 순환은 500 hPa에서 제트가 약화됨으로서 증명되었다. 이런 이유로, 기상청 GDAPS 예측장은 태풍 산바가 중위도 기압골과 상호작용함으로써 느린 이동속도의 바이어스를 나타내었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.153-155
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• 2007

Korea Meteorological Administration (KMA) has operationally produced Atmospheric Motion Vector (AMV) from the consecutive MTSAT-1R satellite image dataset. Comparing with radiosonde data, our current AMV scheme shows more than 10 m/s RMSE. Therefore we need to improve continuously its accuracy. Many AMV producers have stated that the bad performance of the Height Assignment (HA) algorithm is the main reason of degrading the accuracy of AMV. The uncertainties in AMV HA can occur in the algorithm itself, used NWP profiles, and the performance of Radiative Transfer Model (RTM) etc. This study introduces currently operated AMV HA schemes and the impacts of NWP profile data and RTM that these schemes use were investigated. Finally we analyzed the relationship between vectors by vector tracking and heights assigned to each vector by using collocated wind profile dataset with radiosonde data. This study is a preliminary work to improve the accuracy of AMV by removing or decreasing the uncertainties in AMV estimation.

• 대기
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• 제21권1호
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• pp.17-33
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• 2011

A dynamical downscaling system for seasonal forecast has been constructed based on a regional climate model, and its predictability was investigated for 10 years' wintertime (December-January-February; DJF) climatology in East Asia. Initial and lateral boundary conditions were obtained from the operational seasonal forecasting data, which are realtime output of the Global Data Assimilation and Prediction System (GDAPS) at Korea Meteorological Administration (KMA). Sea surface temperature was also obtained from the operational forecasts, i.e., KMA El-Nino and Global Sea Surface Temperature Forecast System. In order to determine the better configuration of the regional climate model for East Asian regions, two sensitivity experiments were carried out for one winter season (97/98 DJF): One is for the topography blending and the other is for the cumulus parameterization scheme. After determining the proper configuration, the predictability of the regional forecasting system was validated with respect to 850 hPa temperature and precipitation. The results showed that mean fields error and other verification statistics were generally decreased compared to GDAPS, most evident in 500 hPa geopotential heights. These improved simulation affected season prediction, and then HSS was better 36% and 11% about 850 hPa temperature and precipitation, respectively.

• International Journal of Contents
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• 제15권4호
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• pp.65-73
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• 2019

Social media is a massive dataset in which individuals' thoughts are freely recorded. So there have been a variety of efforts to analyze it and to understand the social phenomenon. In this study, Twitter was used to define the moments when negative perceptions of the Korean Meteorological Administration (KMA) were displayed and the reasons people were dissatisfied with the KMA. Machine learning methods were used for sentiment analysis to automatically train the implied awareness on Twitter which mentioned the KMA July-October 2011-2014. The trained models were used to validate sentiments on Twitter 2015-2016, and the frequency of negative sentiments was compared with the satisfaction of forecast users. It was found that the frequency of the negative sentiments increased before satisfaction decreased sharply. And the tweet keywords and the news headlines were qualitatively compared to analyze the cause of negative sentiments. As a result, it was revealed that the individual caused the increase in the monthly negative sentiments increase in 2016. This study represents the value of sentiment analysis that can complement user satisfaction surveys. Also, combining Twitter and news headlines provided the idea of analyzing the causes of dissatisfaction that are difficult to identify with only satisfaction surveys. The results contribute to improving user satisfaction with weather services by efficiently managing changes in satisfaction.

• 한국지리정보학회지
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• 제20권3호
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• pp.42-51
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• 2017

대설은 우리나라의 법적 자연재해 중 하나이다. 최근 기상현상에 의한 사회경제적 영향력을 함께 예보하는 영향예보가 부각되고 있으며, 이를 위해서는 먼저 각 지역의 기후적 특징을 분석할 필요가 있다. 본 연구에서는 영향예보의 기반마련을 위해 자기조직화지도를 활용하여 적설동질지역을 구분하여 지역별 적설 특징을 분석했다. 연구결과 적설동질지역은 7개 군집으로 나타났으며, 강설량 및 관측일수, 최대강설량을 이용하여 각 그룹의 특징을 구분했다. 대관령, 강릉시, 정읍시는 강설량이 많은 지역으로, 경상도는 강설량이 적은 지역으로 구분되었다. 선행연구와 비교결과 대표적인 지역이 잘 구분되었으나 강설의 특징은 차이가 있는 것으로 나타났다. 본 연구의 결과는 각 지역의 영향예보를 위한 정책결정에 기초자료로 활용될 수 있다.

• 대기
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• 제17권1호
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• pp.1-15
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• 2007

A constraint based on climatology is introduced to the cost function of the three-dimensional variational assimilation (3dVar) to correct the error of the zonal mean wind structure in the global data assimilation system at Korea Meteorological Administration (KMA). The revised cost function compels the analysis fit to the chosen climatology while keeping the balance between the variables in the course of analysis. The constraint varies selectively with the vertical level and the horizontal scale of the motion. The zonally averaged wind field from European Centre for Medium-Range Weather Forecasts Re-Analysis 40 (ERA-40) is used as a climatology field in the constraint. The constraint controls only the zonally averaged stratospheric long waves with total wave number less than 20 to fix the error of the large scale wind field in the stratosphere. The constrained 3dVar successfully suppresses the erroneous westerly in the stratospheric analysis promptly, and has been applied on the operational global 3dVar system at KMA.

• 대기
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• 제28권2호
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• pp.163-174
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• 2018

In order to assimilate MHS satellite data into the convective scale model at KMA, ATOVS data are reprocessed to utilize the original high-resolution data. And then to improve the preprocessing experiments for cloud detection were performed and optimized to convective-scale model. The experiment which is land scattering index technique added to Observational Processing System to remove contaminated data showed the best result. The analysis fields with assimilation of MHS are verified against with ECMWF analysis fields and fit to other observations including Sonde, which shows improved results on relative humidity fields at sensitive level (850-300 hPa). As the relative humidity of upper troposphere increases, the bias and RMSE of geopotential height are decreased. This improved initial field has a very positive effect on the forecast performance of the model. According to improvement of model field, the Equitable Threat Score (ETS) of precipitation prediction of $1{\sim}20mm\;hr^{-1}$ was increased and this impact was maintained for 27 hours during experiment periods.

• 대기
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• 제17권4호
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• pp.471-481
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• 2007

전국 (60개 지점 평균)과 서울의 온도 및 강수를 분석하였다. 분석된 기간은 전국의 경우 1973-2007 년 기간 중 8월과 여름 및 서울의 경우 1908-2007년 기간 중 8월과 여름 이다. 금년 8월과 여름은 전국과 서울 모두 기온 (평균, 최고, 최저)이 평년에 비해 높았다. 전국의 경우 1973년부터 서울의 경우 1908년부터 8월과 여름 모두 최저기온이 꾸준히 증가하는 경향을 보인다. 최저 기온의 상승률은 평균 및 최고기온에 비하여 높다. 이러한 최저기온의 상승은 현재 전 지구적인 추세이며 전지구 온난화에 따른 증발량의 증가로 구름의 양이 증가하게 되어 최저기온이 상승한 것으로 해석하고 있다. 열대야라 불리는 최저기온 $25^{\circ}C$ 이상인 날은 8월과 여름 모두 1973년부터 2007년 현재까지 꾸준히 증가한다. 이는 전 지구 온난화와 도시화의 효과가 복합적으로 작용한 결과이다. 금년 8월의 전국 강수량 (60개 지점 평균)은 330.9mm 로 평년 (265.0 mm)보다 65.9 mm 많았다. 하지만 서울의 금년 8월 강수량은 237.6 mm 로 평년 (348.0mm)에 비해 110.4 mm 적었다. 전국의 금년 여름 강수량은 676.3 mm로 평년 (699.9 mm)과 비슷하였으며 서울은 566.2 mm 로 평년 (809.2 mm)모다 243.0 mm 적었다. 1973년부터 2007년까지 8월과 여름의 강수량을 분석한 결과 비록 변동 폭은 크나 1973년부터 (서울의 경우 1908년부터) 8월과 여름 모두 강수량은 증가하는 경향을 보인다. 전국 60개 지점의 8월 및 여름의 호우 일수 (120 mm 이상/일, 80 mm이상/일, 1시간 최다 30 mm 이상, 10분간 최다 10 mm 이상)는 1973년부터 꾸준히 증가하는 경향을 보였으나 금년에는 예외적으로 집중호우 현상이 일반적으로 오히려 감소한 것으로 분석되었다.

• 대기
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• 제15권3호
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• pp.179-186
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• 2005

Due to several difficulties, a number of Automatic Weather Systems (AWS) operated by Korea Meteorological Administration (KMA) are located on the rooftop so that the forming of standard observation environment to obtain the accuracy is needed. Therefore, the air temperature of AWSs on the synthetic lawn and the concrete of the rooftop is compared with the standard observation temperature. The hourly mean temperature is obtained by monthly and hourly mean value and the difference of temperature is calculated according to the location, the weather phenomenon, and cloud amount. The maximum and the minimum temperatures are compared by the conditions, such as cloud amount, the existence of precipitation or not. Consequently, the temperature on the synthetic lawn is higher than it on the concrete so that it is difficult to obtain same effect from ASOS, on the contrary the installation of AWS on the synthetic lawn seem to be inadequate due to heat or cold source of the building.

• 대기
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• 제24권1호
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• pp.77-87
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• 2014

The radar reflectivity is significantly affected by ground clutter, beam blockage, anomalous propagation (AP), birds, insects, chaff, etc. The quality of radar reflectivity is very important in quantitative precipitation estimation. Therefore, Weather Radar Center (WRC) of Korea Meteorological Administration (KMA) employed two quality control algorithms: 1) Open Radar Product Generator (ORPG) and 2) fuzzy quality control algorithm to improve quality of radar reflectivity. In this study, an occurrence of AP echoes and the performance of both quality control algorithms are investigated. Consequently, AP echoes frequently occur during the spring and fall seasons. Moreover, while the ORPG QC algorithm has the merit of removing non-precipitation echoes, such as AP echoes, it also removes weak rain echoes and snow echoes. In contrast, the fuzzy QC algorithm has the advantage of preserving snow echoes and weak rain echoes, but it eliminates the partial area of the contaminated echo, including the AP echoes.