• Journal of the Korean earth science society
• /
• v.29 no.7
• /
• pp.567-578
• /
• 2008

The extratropically transitioning cyclones have been shown to have a large effect on weather system in the midlatitues and cause sometimes the severe weather phenomena. However, both operational forecasting and research aspect of ET remain a significant challenge. Because it is difficult to distinguish ET stage due to obscure configuration of the cyclone itself. Furthermore, any definition of ET should not only be precise enough to satisfy the needs of the operational and research communities. Therefore, the "operational deterministic process for ET" was proposed and has been used to diagnose both structure and subsequent process of ET in 2007. In this study, it has been examined the maximum wind and SST in the 1st step, satellite image in the 2nd step, sounding in the 3rd step, surface weather chart analysis in the final step. This operational manual has allowed better monitoring and understanding of the changes in the structure as ET occurs.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.118-118
• /
• 2023

물순환 과정의 구성요소 중 하나인 증발산(증발과 증산)은 각종 수자원시설물의 운영관리, 수자원계획 수립, 농업용 시설의 개발 및 운영관리 등에 필요한 매우 중요한 요소이다. 한편, 기후변화 등으로 '14~'19년 장기간 가뭄, '17년 가뭄상황에서도 태풍 '차바'에 의한 국지적 홍수, '20년 역대 최장기간 장마에 의한 대규모 홍수, '22년 태풍 '힌남노' 이후 남부지역 극심한 가뭄 등 가뭄과 홍수가 반복되어 물관리 여건이 매우 어려운 상황이다. 이러한 홍수/가뭄에 효과적으로 대응하기 위해 강우-유출 모형을 사용한다. 신뢰적인 예측결과를 얻기 위해서는 상세하고 정밀한 증발산량 추정이 필요하다. Penman-Monteith(PM) 기법으로 기준 증발산량을 산정하기 위해서는 최고·최저기온, 이슬점온도, 풍속, 일조시간 등의 기상자료가 필요하다. 이러한 자료는 전국 95개 ASOS 지점에만 얻을 수 있다. 계산된 95개 지점의 기준 증발산량은 티센망 등 방법으로 공간평균하여 활용한다. 95개 지점 자료만으로는 지역적 기상 특성을 반영하여 기준 증발산량을 산정하는데 한계가 있으며, 결국 강우-유출분석의 신뢰도 저하로 귀결된다. 본 연구는 기상청 ASOS 지점 외 AWS 590개 지점을 추가하여 기준 증발산량을 산정하여 공간적으로 상세화하였다. ASOS 지점들에 대해 PM 기법과 Hargreaves(HS) 기법으로 22년간의 일단위 기준 증발산량을 각각 계산하였다. 이들의 상관계수는 평균 0.85로 매우 높아, HS 기법으로 산정된 AWS 지점 결과의 추가사용이 적정하였다. 기온만을 사용하는 HS 기법, PM과 HS의 상관성 및 풍속을 반영한 2가지 보정 HS 기법으로 기준 증발산량을 계산하여 비교·분석하였다. 보정된 HS의 결과가 기존 HS 기법에 비해 오차가 적고, 자료의 편향성이 줄어드는 등 더 좋은 결과를 나타내었다. 따라서, 각종 수문분석에 보정 HS 기법을 AWS 지점에 확대·적용하고, ASOS 관측소의 PM 기법과 병행해 상세화하여 활용하면 수문분석의 신뢰성을 더욱 높일 수 있을 것이다.

• Journal of Navigation and Port Research
• /
• v.33 no.8
• /
• pp.549-554
• /
• 2009

Wind velocity and wind direction are very important in the viewpoint of ship's safety and stability of port structure. The characteristics of wind distribution in the coast of Busan are analyzed for 10 years from 1997 to 2006 using AWS(Automatic Weather System) data. The characteristics of wind distribution of Miryang, is not affected by the land and sea breeze are also examined to understand clearly the characteristics of wind distribution in the coast of Busan. The mean wind velocity in the coast of Busan is stronger than that of Miryang. The mean wind velocitie at Youngdo and Gadukdo stations of Busan are stronger about 2.0 times than those at IlGwang, Haeundae and Daeyeon stations. The correlation a states show that the variation tendencies of monthly mean wind velocitie in the coast of Busan are very similar. The maximum monthly mean velocitie in the coast of Busan are recorded in September. This re ult is closely related to the influence of typhoon. The maximum instantaneous wind velocitie are also strong at Youngdo and Gadukdo stations and the peaks of maximum instantaneous wind $velocit^9$ are observed mainly from August to September. In the coast of Busan, the SW'ly-NNE'ly wind are prevailing in the winter and the SW'ly and NE'ly wind are predomi snt in the spring. w that the vs of wind direction in the summer and athumn are similar with those in the spring and winter, respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.4
• /
• pp.235-246
• /
• 2012

Typhoon induced surge simulations are done to make an establishment of coastal disaster prevention plan. To apply efficient run-up and overtopping on vertical harbor docks, in which prevailing wet-dry scheme cannot be satisfied due to infinite steepness, an imaginary internal barrier concept introduced and analyzed. Before real application on the Mokpo harbor area, feasibility tests are done on an idealized simple geometry and as a result it is found that the moderate width of the barrier might be 1 m. The threshold value of the minimum wet depth $H_{min}$ for land area, which behaves sensitive role in inundation area and depth, depends on grid size. However it is revealed that 0.01 m is adequate value in this fine finite element with 10 m spacing. A hypothetical typhoon of 100 years return period in central pressure and maximum velocity is generated based on historical tracks. Simulation of possible inundation on Mokpo area is performed with asymmetrical vortex of hypothetical typhoon and wave coupling. Model results show general agreement in pattern compared to other's prediction, however possibility of inundation enlargement is expected in harbor area.

• Journal of the Korea Institute of Building Construction
• /
• v.19 no.6
• /
• pp.529-538
• /
• 2019

Typhoons can cause significant financial damage worldwide. For this reason, states, local governments and insurance companies attempt to quantify and mitigate the financial risks related to these natural disasters by developing a typhoon risk assessment model. As such, the importance of typhoon risk assessment models is increasing, and it is also important to reflect local vulnerabilities to enable sophisticated assessments. Although a practical study of economic losses associated with natural disasters has identified essential risk indicators, comprehensive studies covering the correlation between vulnerability and economic loss are still needed. The purpose of this study is to identify typhoon damage indicators and to develop evaluation indicators for typhoon damage prediction functions, utilizing the loses from Typhoon Maemi as data. This study analyzes actual loss records of Typhoon Maemi provided by local insurance companies to prepare for a scenario of maximum losses. To create a vulnerability function, the authors used the wind speed and distance from the coast and the total value of property, construction type, floors, and underground floor indicators. The results and metrics of this study provide practical guidelines for government agencies and insurance companies in developing vulnerability functions that reflect the actual financial losses and regional vulnerabilities of buildings.

• Journal of the Korean earth science society
• /
• v.42 no.3
• /
• pp.264-277
• /
• 2021

This study analyzed the relationship between the total precipitable water vapor in the atmosphere and the moving speed of recent typhoons. This study used ground observation data of air temperature, precipitation, and wind speed from the Korea Meteorological Administration (KMA) as well as total rainfall data and Red-Green-Blue (RGB) composite images from the U.S. Meteorological and Satellite Research Institute and the KMA's Cheollian Satellite 2A (GEO-KOMPSAT-2A). Using the typhoon location and moving speed data provided by the KMA, we compared the moving speeds of typhoon Bavi, Maysak, and Haishen from 2020, typhoon Tapah from 2019, and typhoon Kong-rey from 2018 with the average typhoon speed by latitude. Tapah and Kong-rey moved at average speed with changing latitude, while Bavi and Maysak showed a significant decrease in moving speed between approximately 25°N and 30°N. This is because a water vapor band in the atmosphere in front of these two typhoons induced frontogenesis and prevented their movement. In other words, when the water vapor band generated by the low-level jet causes frontogenesis in front of the moving typhoon, the high pressure area located between the site of frontogenesis and the typhoon develops further, inducing as a blocking effect. Together with the tropical night phenomenon, this slows the typhoon. Bavi and Maysak were accompanied by copious atmospheric water vapor; consequently, a water vapor band along the low-level jet induced frontogenesis. Then, the downdraft of the high pressure between the frontogenesis and the typhoon caused the tropical night phenomenon. Finally, strong winds and heavy rains occurred in succession once the typhoon landed.

• Journal of Korean Society of Forest Science
• /
• v.100 no.2
• /
• pp.246-255
• /
• 2011

This study was carried out to investigate the characteristics of wind damaged trees in the Hongneung Arboretumin Korea. Many trees in the Hongneung Arboretum were damaged by the 'Kompasu', the seventh typhoon in the year of 2010 having strong impacts on the central region of Korea. Damaged trees were divided into 3 damage types: windthrow, slanted and broken trees. Most of damaged trees (97.3%) were found at low slope (below 15 degree) or medium slope (15~20 degree). The 45.3% of damaged trees were coniferous and 54.7% were deciduous trees. The wind speed was recorded for the duration of the typhoon from 04:00 AM to 12:00 PM on September 2. The average wind speed and the maximum instantaneous wind speed inside the forest were 1.4 m/sec and 3.5 m/sec, respectively. The highest peak of the average and the maximum instantaneous wind speed inside of forest, 3.4 m/sec and 8.7 m/sec respectively, were recorded at 06:10 AM on September 2. To analyze relationship between wind characteristics and the damage types, the average wind speed and the frequency of wind wave was compared to those of pre-typhoon period (Feb. 13, Feb. 20, Apr. 21, Oct. 16, 2009 and Mar. 20, 2010). The results indicated that the damaged trees were affected by frequent wind wave rather than the wind speed itself. Also average wind direction inside the forest was analyzed to investigate the impact of wind direction on the damaged trees. The wind had mainly blown from SE and SW, and the maximum instantaneous wind direction was SE direction overall. Most of the damaged trees (84.0%) had fallen down to the NW or NE direction. This result showed that the fallen direction of the damaged trees and wind direction was highly related. Therefore, we found that the frequency of wind wave was the main factor of wind damages during the typhoon 'Kompasu' and wind direction was highly related to the fallen direction.

• Journal of the Korean Institute of Rural Architecture
• /
• v.14 no.4
• /
• pp.117-124
• /
• 2012

The purpose of this study is the impact of the typhoon damage to housing and facilities in rural areas. House of damage, as well as the only including damage of facilities in rural areas, particularly greenhouse(Glass greenhouse, Plastic greenhouse, Vinyl greenhouse) leads to damage of crops the scale of the damage increases. In this study, focused on Jeollabuk-do area, accompanying him, the number of gale damage and evaluate the extent of the damage to the typhoon. And aims to provide basic data for the rural areas of strong winds and typhoons preparedness and facility design based on the results. Judging from the results of the analysis of natural disasters caused by typhoons and strong winds, the city formed mainly in the area than in the plains or coastal rural areas compared to other areas more damage can appear. In recent years, many design maximum wind speed of 40m/s wind over because disaster type, even if the standard installation, preferably determined through a precise structural analysis to ensure the structural history of acting urgently.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.1 s.74
• /
• pp.1-6
• /
• 2007

While a typhoon is traveling, characteristics of its wind fields are continuously changing, producing severe changes in local water level and wave conditions, especially, when a typhoon comes into shallow water. However, there have not been many studies related to local typhoon effects, especially, considering real time changes of wind direction related to the coastal topography. In the study, the characteristics of the wind field by typhoon and topographical characteristics in shallow water are considered, as well as conditions of wave climate estimation. These are performed by the SWAN (Simulating waves nearshore) model, in order to estimate the growth of wave energy due to the wind field. It can be strongly suggested that the wave energy of theof an inner bay should be estimated when the direction of the bay entrance and the wind direction of the typhoon are identical. The result of the numerical calculations is in better agreement with the observed data than the result of the conventional estimation techniques.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.25 no.3
• /
• pp.55-66
• /
• 2020

Near-inertial waves (NIW) which are primarily generated by wind can contribute to vertical mixing in the ocean. The energetic NIW can be generated by typhoon due to its strong wind and preferable wind direction changes especially on the right-hand side of the typhoon. Here we investigate the generation and distribution of NIW using the output of a real-time ocean forecasting system. Five-year model outputs during 2013-2017 are analyzed with a focus on cases of energetic NIW generation by the passage of three typhoons (Halong, Goni, and Chaba) over the East Sea. Calculations of wind energy input (${\bar{W}}_I$), and horizontal kinetic energy in the mixed layer (${\bar{HKE}}_{MLD}$) reveal that the spatial distribution of ${\bar{HKE}}_{MLD}$, which is strengthened at the right-hand side of typhoon tracks, is closely related with ${\bar{W}}_I$. Horizontal kinetic energy in the deep layer (${\bar{HKE}}_{DEEP}$) shows patch-shaped distribution mainly located at the southern side of the East Sea. Spatial distribution of ${\bar{HKE}}_{DEEP}$ shows a close relationship with negative relative vorticity regions caused by warm eddies in the upper layer. Monthly-mean ${\bar{HKE}}_{MLD}$ and ${\bar{HKE}}_{DEEP}$ during a typhoon passing over the East Sea shows about 2.5-5.7 times and 1.2-1.6 times larger values than those during summer with no typhoons, respectively. In addition, their magnitudes are respectively about 0.4-1.0 and 0.8-1.0 times from those during winter, suggesting that the typhoon-induced NIW can provide a significant energy to enhance vertical mixing at both the mixed and deep layers during summer.