• Title/Summary/Keyword: Sea weather

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Reconstruction and Validation of Gridded Product of Wind/Wind-stress derived by Satellite Scatterometer Data over the World Ocean and its Impact for Air-Sea Interaction Study

  • Kutsuwada, Kunio;Koyama, Makoto;Morimoto, Naoki
    • Proceedings of the KSRS Conference
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    • 2007.10a
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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.

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Extraction and Analysis of Topographic Variables from DTM: A Case Study in Jeju Island (DTM으로부터 지형변수의 추출 및 분석: 제주도 사례연구)

  • Kim Seok Choong;Cho Sung Hyen;Kim Hyoung Chan
    • Journal of Soil and Groundwater Environment
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    • v.9 no.3
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    • pp.56-61
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    • 2004
  • The topographic variables, which influence the precipitation phenomena, are classified by elevation (ELEV), slope (SLOPE), distance to sea (SEA), obstruction (OBST), barrier (BAR), roughness (SHIELD), extracted and analysed according to resolutions. This study is performed through 100 m, 200 m, 400 m, 600 m, 800 m and 1,000 m based on 50 m DTM using TOVA (Topographic Variables Extraction Program). The result of a case study on Jeju weather station says that the variance according to resolution is generally less than that according to cardinal direction, but particularly SHIELD values and some cases for 600m resolution have a significant results.

A Study on Improvement Plan for LST-II LCM Cradle Damage (LST-II급 함정 함수 LCM 거치대 손상에 대한 개선방안 연구)

  • Choi, Sang-Min;Beak, Yong Kawn;Jung, Young In;Hwang, In Ha;Baek, Jae Sung
    • Journal of Korean Society for Quality Management
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    • v.47 no.1
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    • pp.139-150
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    • 2019
  • Purpose: LST-II is a special naval ship to carry out landing operations by transporting tanks, armored vehicles and military vehicles. Bad weather, maximum wave height of 4-5 m, caused damage to the LCM cradles while the LST-II No.O ship was moving to Thailand for training in February 2016. Methods: Based on the results of the field check, DTaQ conducted a study on the causes analysis and improvement measures. Results: The improvement plan that was derived was verified through a structural analysis and the improvement plan was applied to the follow-up ships. Conclusion: The improvement of LCM cradle has increased the safety of the crew and landing forces, and improved the operational efficiency.

Relationship between the Tropical Sea Surface Temperature Distribution and Initiation Timing of the Typhoon Season in the Northwestern Pacific (열대 해수면 온도 분포와 북서태평양 태풍의 계절적 활동 시작일 변동 사이의 관련성)

  • Kim, Donghee;Kim, Hyeong-Seog
    • Journal of Climate Change Research
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    • v.8 no.1
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    • pp.11-19
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    • 2017
  • This study examined the relationship between the initiation timing typhoon season in the Northwestern Pacific and the tropical sea surface temperature (SST) using a numerical simulation. The initiation timing of the typhoon season is closely associated with SSTs over the Indian Ocean (IO) and the eastern Pacific (EP) in the preceding winter and early-spring. The experiment based on the Weather and Research Forecast (WRF) model showed that the start date of the typhoon season is delayed for about one month when the SSTs over the IO and the EP increase in the preceding winter. The forced tropical SST pattern induces anticyclonic anomalies in the Northwestern Pacific, which is an unfavorable condition for typhoon development, and hence it could delay the initiation of the typhoon season.

Impact of Tidal Effects on Fog Events in the Western Coast of Korea (서해 연안 해역에서의 조석현상이 안개에 미치는 영향)

  • An, Hye Yeon;Jeong, Ju-Hee;Kim, Yoo-Keun
    • Journal of Environmental Science International
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    • v.30 no.11
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    • pp.925-936
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    • 2021
  • The study was aimed to investigate the correlation between tidal effects and fog occurrence in Incheon and Mokpo, which are located in the middle and southern coasts of the West Sea of Korea, respectively. The investigation used meteorological data obtained from the automated synoptic observing systems and automatic weather stations and ocean data from tide stations from 2010 to 2019. Fog occurrence frequency was highest at high tide (Incheon, 41%; Mokpo, 45%). During fog event days at high tide, the dew-point depression was low (Incheon, 0.5℃; Mokpo, 0.4℃) and the relative humidity was high (Incheon, 97%; Mokpo, 98%). The wind speed was 2.4 m/s in Incheon and 2.0 m/s in Mokpo, and the main wind directions were west-southwesterly from Incheon and southwesterly from Mokpo. In the fog case study, tidal flats were covered with water before and after the fog started. During the fog period, both stations experienced negative air-sea temperature differences, low dew-point depression, and high relative humidity were maintained, with weak winds forming from the tidal flats to the shore.

Relationship between Some Weather Conditions and Immigration of the Brown Planthopper, Nilaparvata lugens Stal (벼멸구의 비래와 기상과의 관계)

  • 엄기백;박중수;이영인;최궤문;이문호;이정운
    • Korean journal of applied entomology
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    • v.27 no.4
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    • pp.200-210
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    • 1988
  • ABSTRACT Brown planthopper collection data by 151 light traps located throughout the southern part of Korean peninsula for 7 years from 1981 thru 1987 were analysed with each immigration wave in relation to daily weather charts when the immigration occurred, and summarized as below. 1) Most of the main immigration took place during the mid and late July, though there were some variations from year to year. 2) Number of the BPH collected at one time, and the number of the area where those immigrants where collected were increased when it occurred closer to the end of July. 3) Weather conditions when the immigration took place were divided into 4 types; (a) depression with stationary front passed over the central peninsula (A type, 12 times); (b) depression with stationary front passed over the southern sea (B type, 5 times); (c) stationary front passed over the central peninsula(C type, 7 times); (d) without depression and stationary front (D type, 2 times). 4) Whatever the types of the weather, those immigrations started to land from south-west part of the peninsula, and those numbers of immigrants were also grater at those south-western areas. 5) When common weather factors were counted from each weather chart of the days when thcse immigrations took place, presence of wind from south-west was 26 times, presence of stationary front was 24 times, and presence of depression was 17 times out of all 26 cases of immigration. 6) Therefore, it could be concluded that the immigration of the BPH into Korea is simply accompanied by the north$.$easterly flowing air currents, connected from south-east part of China through Korean peninsula. And other factors seem to be related with inducing their landing.anding.

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Verification of precipitation enhancement by weather modification experiments using radar data (레이더 자료를 이용한 기상조절 실험에 의한 강수 증가 검증 연구)

  • Ro, Yonghun;Cha, Joo-Wan;Chae, Sanghee
    • Journal of Korea Water Resources Association
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    • v.53 no.11
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    • pp.999-1013
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    • 2020
  • Weather modification research has been actively performed worldwide, but a technology that can more quantitatively prove the research effects are needed. In this study, the seeding effect, the efficiency of precipitation enhancement in weather modification experiment, was verified using the radar data. Also, the effects of seeding material on hydrometeor change was analyzed. For this, radar data, weather conditions, and numerical simulation data for diffusion were applied. First, a method to analyze the seeding effect in three steps was proposed: before seeding, during seeding, and after seeding. The proposed method was applied to three cases of weather modification experiments conducted in Gangwon-do and the West Sea regions. As a result, when there is no natural precipitation, the radar reflectivity detected in the area where precipitation change is expected was determined as the seeding effect. When natural precipitation occurs, the seeding effect was determined by excluding the effect of natural precipitation from the maximum reflectivity detected. For the application results, it was found that the precipitation intensity increased by 0.1 mm/h through the seeding effect. In addition, it was confirmed that ice crystals, supercooled water droplets, and mixed-phase precipitation were distributed in the seeding cloud. The results of these weather modification research can be used to secure water resources as well as for future study of cloud physics.

A Study on the Maneuvering Area of Ship in Moving at Single Point Mooring (SPM 이안 선박의 조종영역에 관한 기초 연구)

  • Kim Jin-Soo;Jong Jae-Yong;Kim Kung-Tae;Kim Jong-Rok
    • Proceedings of KOSOMES biannual meeting
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    • 2005.11a
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    • pp.21-26
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    • 2005
  • The work of VLCC SPM mainly is accomplished on the open sea On the open sea as a result of meteorological condition and the ocean wave influence, When the weather condition is get bed, peremptorily moving to the safety place, because of the gale and the billow, almost happened frequently, the pilot is unable to go on board and the tug is also unable to be used Now bemuse of the bad weather the VLCC SPM moving to the other safety place frequently happened in the ulsan port. the construction of new harbor, it constructed many break water around SPM. So that it is necessary to propose the new standard about how to maneuvering area actually. Now our country is at the blank stage about the establishment of SPM research Most of the situations are refer to overseas standard But these standards lack of consistency and clarity. So when moving to the other safety place from SPM, we must carry through the researching and study on the ships using by sailing data of AIS. we must put forward a new standard about maneuvering area of ship in moving at SPM.

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A Study on the Frequency and Intensity Variations of Okhotsk High: Focused on the Korean Peninsula (오호츠크해고기압의 출현일과 강도의 변동에 관한 연구 -한반도에 영향을 미친 날을 중심으로-)

  • Cho, Li-Na;Lee, Seung-Ho
    • Journal of the Korean Geographical Society
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    • v.46 no.1
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    • pp.36-49
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    • 2011
  • This paper aims to investigate the frequency and intensity variations of Okhotsk high pressure system focused on the Korean Peninsula. Weather chart (00UTC), daily weather data and reanalysis data were used. The first occurrence date of Okhotsk high pressure system tends to be earlier in those years that surrounding land air temperature in April is high. The frequency of Okhotsk high has recently decreased, and its intensity tends to be stronger when the difference between sea surface temperature and surrounding land air temperature is big. The frequency of Okhotsk high in April, May, June and July increases when surrounding land air temperature is high, and its intensity grows when the difference between surrounding land air temperature and sea surface temperature is big. The frequency of Okhotsk high may increase and its intensity may increase when the first occurrence date comes earlier. In June, however, the reverse may apply.

A Study on the Maneuvering Area of Ship in Moving at Single Point Mooring (SPM 이안 선박의 조종영역에 관한 기초 연구)

  • Kim Jin-Soo;Jong Jae-Yong;Kim Kyung-Tae
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.11 no.2 s.23
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    • pp.19-25
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    • 2005
  • The work of VLCC SPM mainly is accomplished on the open sea. On the open sea as a result of meteorological condition and the ocean wave influence, When the weather condition is get bed, peremptorily moving to the safety place, bemuse of the gale and the billow, almost happened frequently, the pilot is unable to go on board and the tug is also unable to be used Now bemuse of the bad weather the VLCC SPM moving to the other safety place frequently happened in the ulsan port. the construction of new harbor, it constructed many break water around SPM. So that it is necessary to propose the new standard about how to maneuvering area actually. Now our country is at the blank stage about the establishment of SPM research Most of the situations refer to overseas standards. But these standards lack consistency and clarity. So when moving to the another safe place from SPM, we must Carry through the research and study on the ships using sailing through AIS Data We must put forward a new standard about maneuvering area of ships moving at SPM.

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