• Korean Journal of Remote Sensing
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• v.25 no.1
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• pp.1-10
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• 2009

We studied on the relationship between oceanic variation in the offshore and abnormal sea surface temperature rise in the coastal area of the Yellow Sea using a variety of satellite and in-situ data during winter 2004. In results of the satellite data, the average value of sea surface temperature in the Yellow Sea for 2003 was $10^{\circ}C$, and the average value of sea surface temperature for 2004 was $13^{\circ}C$. It was higher than those of the last year about $3^{\circ}C$. In results of the in-situ data, the average value of surface layer temperature in the Yellow Sea for 2003 was $9.85^{\circ}C$, and the average value of surface layer temperature for 2004 was $12.17^{\circ}C$. In the same satellite data, it was higher than those of the last year about $3^{\circ}C$. In results of the T-S diagram, we divided definitely into water mass of the Yellow Sea and the East China Sea in 2003. But we didn't divide definitely into water mass of the Yellow Sea and the East China Sea in 2004. The average values of air temperature and wind speed for 2003 were $5.23^{\circ}C$ and 4.81 m/s, respectively. And, the average values of air temperature and wind speed for 2004 were $5.61^{\circ}C$ and 4.52 m/s, respectively. So, These were similar. But the wind directions for 2003 were superior northwestern wind, and the wind directions for 2004 were various northern wind. The wind directions were different from each other. Therefore, the abnormal sea surface temperature rise in the coastal area of the Yellow Sea during winter 2004 were better related to oceanic variation in the offshore than influences of atmosphere. In the future, We will do in-depth study for these.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.375-388
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• 2019

Accurate evaluation of sea-to-air $CO_2$ flux and its variability is crucial information to the understanding of global carbon cycle and the prediction of atmospheric $CO_2$ concentration. $fCO_2$ observations are sparse in space and time in the East Sea. In this study, we derived high resolution time series of surface $fCO_2$ values in the southwest East Sea, by feeding sea surface temperature (SST), salinity (SSS), chlorophyll-a (CHL), and mixed layer depth (MLD) values, from either satellite-observations or numerical model outputs, to three machine learning models. The root mean square error of the best performing model, a Random Forest (RF) model, was $7.1{\mu}atm$. Important parameters in predicting $fCO_2$ in the RF model were SST and SSS along with time information; CHL and MLD were much less important than the other parameters. The net $CO_2$ flux in the southwest East Sea, calculated from the $fCO_2$ predicted by the RF model, was $-0.76{\pm}1.15mol\;m^{-2}yr^{-1}$, close to the lower bound of the previous estimates in the range of $-0.66{\sim}-2.47mol\;m^{-2}yr^{-1}$. The time series of $fCO_2$ predicted by the RF model showed a significant variation even in a short time interval of a week. For accurate evaluation of the $CO_2$ flux in the Ulleung Basin, it is necessary to conduct high resolution in situ observations in spring when $fCO_2$ changes rapidly.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.617-629
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• 2020

Sea surface temperature (SST), which plays an important role in climate change and global environmental change, can be divided into skin sea surface temperature (SSST) observed by satellite infrared sensors and the bulk temperature of sea water (BSST) measured by instruments. As sea surface temperature products distributed by many overseas institutions represent temperatures at different depths, it is essential to understand the relationship between the SSST and the BSST. In this study, we constructed an observation system of infrared radiometer onboard a marine research vessel for the first time in Korea to measure the SSST. The calibration coefficients were prepared by performing the calibration procedure of the radiometer device in the laboratory prior to the shipborne observation. A series of processes were applied to calculate the temperature of the layer of radiance emitted from the sea surface as well as that from the sky. The differences in skin-bulk temperatures were investigated quantitatively and the characteristics of the vertical structure of temperatures in the upper ocean were understood through comparison with Himawari-8 geostationary satellite SSTs. Comparison of the skin-bulk temperature differences illustrated overall differences of about 0.76℃ at Jangmok port in the southern coast and the offshore region of the eastern coast of the Korean Peninsula from 21 April to May 6, 2020. In addition, the root-mean-square error of the skin-bulk temperature differences showed daily variation from 0.6℃ to 0.9℃, with the largest difference of 0.83-0.89℃ at 1-3 KST during the daytime and the smallest difference of 0.59℃ at 15 KST. The bias also revealed clear diurnal variation at a range of 0.47-0.75℃. The difference between the observed skin sea surface temperature and the satellite sea surface temperature showed a mean square error of approximately 0.74℃ and a bias of 0.37℃. The analysis of this study confirmed the difference in the skin-bulk temperatures according to the observation depth. This suggests that further ocean shipborne infrared radiometer observations should be carried out continuously in the offshore regions to understand diurnal variation as well as seasonal variations of the skin-bulk SSTs and their relations to potential causes.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.209-212
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• 2006

황해와 동중국해의 해황 변동에 관한 연구는 현장관측을 중심으로 체계적으로 많이 수행되어 왔지만, 인공위성자료를 이용한 황해와 동중국해의 해황 변동 연구는 미비한 실정이다. 이것은 인공위성자료를 통해 얻을 수 있는 관측항목이 표층수온자료에 국한되어 있었기 때문이다. 그러나 SeaWiFS 해색위성과 같은 인공위성자료들을 이용하여 부유물 농도, 엽록소 농도 등이 원활하게 생산되고 있으며 최근 연구결과에 의해 염분과 유향성분 동도 추정 및 추출이 가능케 되었으므로 이들 인공위성자료를 이용한 황해와 동중국해의 해황 변동에 관한 연구를 수행하게 되었다. 특히 2004 년도는 계절변동에 있어서 이상기후의 해라고 점철되고 있다. 2004년 봄철의 폭설과 일시적인 고온현상, 여름철에는 10년만의 무더위, 겨울철에는 36년만에 가장 포근한 날씨가 지속되었다. 이러한 이상기후의 발생은 해양과 대기의 상호작용에 의해서 기인했을 것이라고 생각되어 한반도 주변 해역에서 황해와 동중국해의 해황변동이 연안해역의 해황변동과 어떠한 연관성이 존재하고, 이러한 요인들은 2004년도에 발생한 이상기후와 어떤 상관관계를 갖는지 연구하기 위한 기초연구를 진행하였다. 2003년 12월 - 2004년 2월과 2004년 12월 2005년 2월에 통일한 시기에 관측된 NOAA 표층수온 분포 영상자료들을 황해와 동중국해 해역을 중심으로 월별로 비교해보면 2003년 12월 - 2004년 1월에 관측된 표층수온 분포값보다 2004년 12월 - 2005년 1월에 관측된 표층수온 분포값이 상대적으로 높은 분포 특성을 나타내고 있었다. 이와 같은 현상은 국립수산과학원의 2004년 10월과 12월의 정선관측자료에서도 나타나고 있었다. 그러나 이와는 반대로 2004년 2 월에 관측된 표층수온 분포값보다 2005년 2월에 관측된 표층수온 분포값이 상대적으로 낮은 분포 특성을 나타내고 있었다. 따라서 인공위성자료를 이용한 황해의 2004년 해황 분석 결과는 이상수온 상승의 원인이 쿠로시오 해류의 변통과 관련성이 높다고 판단되며 이에 대한 지속적인 연구가 현재 진행중에 있다.

• 한국해양학회지
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• v.29 no.4
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• pp.325-337
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• 1994

The distributions of heat and momentum fluxes on the surface over the oceans around the Korean Peninsula are obtained based on the surface-layer flux model of Kim and Kang (1994), and their seasonal variations are examined in the present study. the input data of the model is the oceanatmosphere data with a grid interval of 2$^{\circ}$ in longitude and latitude. The atmosphere data, which are the pressure, temperature, and specific humidity on the 1000 mb level for 3 year period of 1985∼1987, are obtained from the European center for Medium Range Forecast. The sea surface temperature (SST) is obtained from National Meteorological Center (NMC). The solar insolation and longwave radiation on the ocean surface are obtained, respectively, from the NASA satellite data and based on an emprical formula. It is shown from the net heat flux that the oceans near Korea lose heat to the atmosphere in January and October with the rates of 200∼ 400 Wm/SUP -2/ and 100 Wm/SUP -2/, respectively. But the oceans are heated by the atmosphere in April and July with about the same rate of 100 Wm/SUP -2/. The annualmean net heat flux is negative over the entire domain except the northern part of the Yellow Sea. The largest annual-mean cooling rate of about 120 Wm/SUP -2/ is appeared off the southwest of Japan. In the East Sea, the annual-mean cooling rate is 60∼90 Wm/SUP -2/ in the southern and northern parts and about 30 Wm/SUP -2/ in the middle part. The magnitude of wind stress in january is 3∼ 5 times bigger than those of the other months. As a result, the spatial pattern of annual-mean wind stress is similar to that of January. It is also shown that the annual-mean wind stress curl is negative. in the East China Sea and the South Sea,but it is positive in the northern part of the Yellow Sea.In the East sea,the stress curl is positive in the southeast and northern parts and negative in the northwestern part.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.553-568
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• 2018

Chromophoric Dissolved Organic Matter (CDOM) plays a dominant role in absorbing UV-VIS light and is also important in the biogeochemical carbon cycle due to the production of carbon dioxide from photo-oxidation at the sea surface in marine environments. Since absorption by CDOM was recently found to be responsible for increasing the energy absorbed in the mixed layer by 40 % over pure seawater, the importance of CDOM absorption in seawater for increasing sea surface temperature has come to be well recognized. We measured aCDOM and the absorption characteristics of CDOM during spring 2012 and 2014 in the southwestern East Sea. Distribution of CDOM in spring 2012 and 2014 was compared and S value was used to find the source of CDOM in the study area. As a result, the average $a_{CDOM}$ was $0.237m^{-1}$ ($0.009{\sim}0.988m^{-1}$) and the average S value was $16{\mu}m^{-1}$,which shows coastal properties. Also a positive correlation between Chl a and CDOM was observed ($r^2=0.34$), with an especially strong correlation near coastal stations. aCDOM in 2014 was about 40 % higher than aCDOM in 2012 during spring in the study area. This difference in aCDOM concentration resulted not only from annual variation but also from stratification and photobleaching in late spring 2012. This observation implies the possibility of flux of carbon dioxide into the atmosphere as a result of photo-oxidation in the East Sea.

• Korean Journal of Remote Sensing
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• v.20 no.4
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• pp.245-252
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• 2004

The mechanism of cold core eddy formation was investigated using boundary conditions between the East China coastal cold water and the Kuroshio Warm Current, wind data related to the monsoon which was measured by QuikSCAT, and the bottom topography of the East China Sea. When winds blow from the southeast at an intensity comparable to that in the winter period in 1999 and 2003, the warm Kuroshio and Tsushima Current became stronger, and temperatures were considerably higher than those of the extended cold water of the coast of the East China. At that time, the cold water was captured by warm water from the Kuroshio and the Tsushima Current. This facilitated the formation of mesoscale cold core eddies with diameter of 150km in the East China Sea in May, 1999 and February, 2003. The cold core eddy which was detected by NOAA, SeaWiFS and QuikSCAT satellites. The East China Sea is considered to be important not only as a good fishing ground but also nursery and spawning area for many kinds of fishes. Therefore, it would be worth studying spatio-temporal variations of the cold core eddy in the environmental conditions of the northwestern East China Sea using systematic remote sensing techniques.