• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.197-198
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• 2001

일반적으로 해조류가 번무하고 있던 암초지대에서 무엇인가의 원인으로 해조류가 고사ㆍ소멸하고, 그 공간을 석회조류로 불리는 여러 종류의 산호말류 (coralline algae)이 점유하여 암반이 백색 또는 황색, 분홍색을 나타내는 현상을 ‘백화현상’ 이 라고 한다. 현재 추측되는 백화현상의 원인으로는 해양생태계 내에서의 환경변화 - 대기중 이산화탄소의 증가, 지구 온난화에 의한 수온상승, 그리고 연안역의 오염 -와 군집의 동태와 생물학적 작용-엽상형 해조류와 무절석회조류간의 경쟁과 성게를 포함한 초식동물의 초식작용, 질소, 인등의 결핍이 불러오는 빈(貧)영양화 - 에 의해 일어난다고 추측된다 (analysis.cheju.ac.kr.). (중략)

• Korean Journal of Remote Sensing
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• v.39 no.5_1
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• pp.467-479
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• 2023

Satellite altimeters have continuously observed sea surface height (SSH) in the global ocean for the past 30 years, providing clear evidence of the rise in global mean sea level based on observational data. Accurate altimeter-observed SSH is essential to study the spatial and temporal variability of SSH in regional seas. In this study, we used measurements from the Ieodo Ocean Research Station (IORS) and validate SSHs observed by satellite altimeters (Envisat, Jason-1, Jason-2, SARAL, Jason-3, and Sentinel-3A/B). Bias and root mean square error of SSH for each satellite ranged from 1.58 to 4.69 cm and 6.33 to 9.67 cm, respectively. As the matchup distance between satellite ground tracks and the IORS increased, the error of satellite SSHs significantly amplified. In order to validate the correction of the tide and atmospheric effect of the satellite data, the tide was estimated using harmonic analysis, and inverse barometer effect was calculated using atmospheric pressure data at the IORS. To achieve accurate tidal corrections for satellite SSH data in the seas around the Korean Peninsula, it was confirmed that improving the accuracy of tide data used in satellites is necessary.

• Journal of the Korean Geographical Society
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• v.43 no.1
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• pp.1-19
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• 2008

This study intends to clarify the characteristics and causes of current changes in wintertime precipitation in Korea and to predict the future directions based on surface observational $(1973/04\sim2006/07)$ and modeled (GFDL 2.1) climate data. Analyses of surface observation data demonstrate that without changes in the total amount of precipitation, snowfall in winter (November-April) has reduced by 4.3cm/decade over the $1973\sim2007$ period. Moreover, the frequency and intensity of snowfall have decreased; the duration of snow season has shortened; and the snow-to-rain day ratio (STDR) has decreased. These patterns indicate that the type of wintertime precipitation has changed from snow to rain in recent decades. The snow-to-rain change in winter is associated with the increases of air temperature (AT) over South Korea. Analyses of synoptic charts reveal that the warming pattern is associated with the formation of a positive pressure anomaly core over northeast Asia by a hemispheric positive winter Arctic Oscillation (AO) mode. Moreover, the differentiated warming of AT versus sea surface temperature (SST) under the high pressure anomaly core reduces the air-sea temperature gradient, and subsequently it increases the atmospheric stability above oceans, which is associated with less formation of snow cloud. Comparisons of modeled data between torrent $(1981\sim2000)$ and future $(2081\sim2100)$ periods suggest that the intensified warming with larger anthropogenic greenhouse gas emission in the $21^{st}$ century will amplify the magnitude of these changes. More reduction of snow impossible days as well as more abbreviation of snow seasons is predicted in the $21^{st}$ century.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.180-183
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• 2011

Recently, environmental problems have been deteriorating rapidly. Therefore, there is an urgent need to establish policies and research in the conservation of the global environment. Many researchers are studied in environment systems to prevent and reduce pollution of water, air and soil actively. In this paper, several parameters such as temperature, humidity, illumination, barometric pressure, dew point, water quality data, and air conditions are collected and transmitted thorough wireless sensor network. The field server is located in the coastal and marine area so that any abrupt changes can be detected quickly. In addition, WSN based flooding routing protocol for efficient data transmission is designed to support and monitor information of climate and marin factors.

• Journal of the Korean earth science society
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• v.42 no.5
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• pp.536-555
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• 2021

Sea-surface wind is an important variable in ocean-atmosphere interactions, leading to the changes in ocean surface currents and circulation, mixed layers, and heat flux. With the development of satellite technology, sea-surface winds data retrieved from scatterometer observation data have been used for various purposes. In a complex marine environment such as the Korean Peninsula coast, scatterometer-observed sea-surface wind is an important factor for analyzing ocean and atmospheric phenomena. Therefore, the validation results of wind accuracy can be used for diverse applications. In this study, the sea-surface winds derived from ASCAT (Advanced SCATterometer) mounted on MetOp-A/B (METeorological Operational Satellite-A/B) were validated compared to in-situ wind measurements at 16 marine buoy stations around the Korean Peninsula from January to December 2020. The buoy winds measured at a height of 4-5 m from the sea surface were converted to 10-m neutral winds using the LKB (Liu-Katsaros-Businger) model. The matchup procedure produced 5,544 and 10,051 collocation points for MetOp-A and MetOp-B, respectively. The root mean square errors (RMSE) were 1.36 and 1.28 m s^-1, and bias errors amounted to 0.44 and 0.65 m s^-1 for MetOp-A and MetOp-B, respectively. The wind directions of both scatterometers exhibited negative biases of -8.03° and -6.97° and RMSE values of 32.46° and 36.06° for MetOp-A and MetOp-B, respectively. These errors were likely associated with the stratification and dynamics of the marine-atmospheric boundary layer. In the seas around the Korean Peninsula, the sea-surface winds of the ASCAT tended to be more overestimated than the in-situ wind speeds, particularly at weak wind speeds. In addition, the closer the distance from the coast, the more the amplification of error. The present results could contribute to the development of a prediction model as improved input data and the understanding of air-sea interaction and impact of typhoons in the coastal regions around the Korean Peninsula.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.1
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• pp.11-36
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• 2021

The solar annual (Sa) and semiannual (Ssa) tides account for much of the non-uniform annual and seasonal variability observed in sea levels. These non-equilibrium tides depend on atmospheric variations, forced by changes in the Sun's distance and declination, as well as on hydrographic conditions. Here we employ tidal harmonic analyses to calculate Sa and Ssa harmonic constants for 21 Korean coastal tidal stations (TS), operated by the Korea Hydrographic and Oceanographic Agency. We used 19 year-long (1999 to 2017) 1 hr-interval sea level records from each site, and used two conventional harmonic analysis (HA) programs (Task2K and UTide). The stability of Sa harmonic constants was estimated with respect to starting date and record length of the data, and we examined the spatial distribution of the calculated Sa and Ssa harmonic constants. HA was performed on Incheon TS (ITS) records using 369-day subsets; the first start date was January 1, 1999, the subsequent data subset starting 24 hours later, and so on up until the final start date was December 27, 2017. Variations in the Sa constants produced by the two HA packages had similar magnitudes and start date sensitivity. Results from the two HA packages had a large difference in phase lag (about 78°) but relatively small amplitude (<1 cm) difference. The phase lag difference occurred in large part since Task2K excludes the perihelion astronomical variable. Sensitivity of the ITS Sa constants to data record length (i.e., 1, 2, 3, 5, 9, and 19 years) was also tested to determine the data length needed to yield stable Sa results. HA results revealed that 5 to 9 year sea level records could estimate Sa harmonic constants with relatively small error, while the best results are produced using 19 year-long records. As noted earlier, Sa amplitudes vary with regional hydrographic and atmospheric conditions. Sa amplitudes at the twenty one TS ranged from 15.0 to 18.6 cm, 10.7 to 17.5 cm, and 10.5 to 13.0 cm, along the west coast, south coast including Jejudo, and east coast including Ulleungdo, respectively. Except at Ulleungdo, it was found that the Ssa constituent contributes to produce asymmetric seasonal sea level variation and it delays (hastens) the highest (lowest) sea levels. Comparisons between monthly mean, air-pressure adjusted, and steric sea level variations revealed that year-to-year and asymmetric seasonal variations in sea levels were largely produced by steric sea level variation and inverted barometer effect.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.33-35
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• 2020

해양 및 대기 오염 방지를 위한 친환경선박에 대한 관심이 고조되고 있고 특히 LNG를 연료로 하는 LNG 연료추진선이 확대되고 있다. 그리고 국내에서도 LNG Bunkering 선박 건조에 지속적으로 추진되고 있다. LNG Bunkering의 안전한 운용을 위해서는 여러 위험요소를 분석해야한다. 그 중에도 LNG Bunkering 작업 중 주변 선박 통항에 따른 안전한 이격거리의 확보 또한 중요한 사항이지만 이에 대한 연구는 미진한 형태이다. 이에 안전한 이격거리에 대해서 외국 및 국내규정을 검토하였으나 명확한 규정이 없어 이에 대한 분석을 통한 안전하고, 경제적인 이격거리에 대한 연구가 필요하다. 안전한 이격거리에 대해 분석하기 위한 우선적으로 안전한 이격거리에 영향을 미칠 요소에 대해 검토한다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.4
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• pp.291-306
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• 2021

From the climate change scenario experiments of 21 models participating in Coupled Climate Model Inter-comparison Project Phase 6, future changes of sea surface temperature (SST) and Kuroshio in the Northwest Pacific were analyzed. The spatial feature of SST change was found to be related to the change of the current speed and spatial distribution of Kuroshio. To investigate the relationship between the change in latitude of the Kuroshio extension region, which flows along the boundary between the subtropical gyre and the subarctic gyre in the North Pacific, and the large-scale atmospheric circulation due to global warming, the zero-windstress curl line for each climate change experiment from 9 out of 21 models were compared. As the atmospheric radiative forcing increases due to the increase of greenhouse gases, it was confirmed that the zero-windstress curl line moves northward, which is consistent with the observation. These results indicate that as the Hadley Circulation expands to the north due to global warming, the warming of the mid-latitudes to which the Korean Peninsula belongs may be accelerated. The volume transport and temperature of the Tsushima Warm Current flowing into the East Sea through the Korea Strait also increased as the atmospheric radiative forcing increased.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.118-124
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• 2007

The oceans could absorb almost all the anthropogenic carbon dioxide the mankind has been producing eventually, but in the nature the air-sea $CO_2$ exchange occurs very slowly and to lower the atmospheric $CO_2$ concentration substantially $CO_2$ must be injected to the interior of the ocean directly. If we inject $CO_2$ collected at the major $CO_2$ sources into the international waters in the Philippine Sea or east of Japan, we could store the $CO_2$ in the oceans effectively for a few hundred years. When $CO_2$ is dissolved into the water, PH drops. The creatures adapted to the deep oceans where environment is very stable could be affected by even a small change in pH significantly. If, therefore, we are to inject $CO_2$ into the oceans, we must assess the effect of $CO_2$ injection in the marine ecosystem beforehand. Only when the damage to the marine ecosystem is smaller than the benefit from the $CO_2$ injection, $CO_2$ injection is effective.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.221-226
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• 2008

Air pollution associated with the SOx emission from the shipboard propulsion and generation engines is becoming one of the major environmental concerns these days. Lead by the international organizations including IMO and European Union, a significantly strengthened air pollution related regulations have been introduced and they are becoming in practice as scheduled. Such rules are basically giving the guidelines for permissible SOx emission which can be only met by using high quality fuel oils with less sulfur content or operating scrubbing systems aiming at reducing SOx at the engine exhaust. Since both countermeasures can lead to the cost increase in ship building and operation, Korean shipbuilding industries, leading the world's market, need to be well aware of the ever changing regulations and be prepared with proper solutions. Here, we briefly summarize such latest rules and regulations on the air pollution at sea, and review some technical issues on the scrubbing systems available with some suggestions.