• Ocean and Polar Research
• /
• v.29 no.3
• /
• pp.193-204
• /
• 2007

In order to find out the annual variations in the marine ecosystem of the East China Sea, temperature, salinity, nutrients, chlorophyll-a, suspended solids, and suspended particulate organic carbon were extensively investigated in the northern East China Sea during the Summer of 2003 and 2006. During the Summer of 2003, the northern East China Sea was not significantly affected by the input of fresh waters from the Changjiang River. During the Summer of 2006, however, fresh waters of the Changjiang River intruded into the western part of the study area where temperature, nitrate, and phosphate in the surface waters were higher than in the other areas, and salinity, silicate, and suspended solids in the surface waters were lower. As a result of the increase in nitrate and phosphate concentrations, concentrations of chlorophyll-a and suspended particulate organic carbon increased in the western part compared with the other areas. However, the depth-integrated chlorophyll-a concentrations measured during the Summer of 2003 were rather similar to those during the Summer of 2006, and not considerably different from those measured in the East China sea during the Summer of 1994 and 1998. Therefore, the depth-integrated chlorophyll-a concentrations have not significantly changed in the East China Sea over the last 12 years. The lower concentrations of silicate and suspended solids in the western part may be related to construction of the Three-Gorges Dam since the concentrations of silicate and suspended solids in fresh waters of the Changjiang River have significantly decreased after construction of the Three-Gorges Dam in June 2003.

• Atmosphere
• /
• v.31 no.2
• /
• pp.215-227
• /
• 2021

The necessity of the prediction on the Seasonal-to-Subseasonal (S2S) timescale continues to rise. It led a series of studies on the S2S prediction models, including the Global Seasonal Forecasting System Version 5 (GloSea5) of the Korea Meteorological Administration. By extending previous studies, the present study documents sea surface temperature (SST) prediction skill around the Korean peninsula in the GloSea5 hindcast over the period of 1991~2010. The overall SST prediction skill is about a week except for the regions where SST is not well captured at the initialized date. This limited prediction skill is partly due to the model mean biases which vary substantially from season to season. When such biases are systematically removed on daily and seasonal time scales the SST prediction skill is improved to 15 days. This improvement is mostly due to the reduced error associated with internal SST variability during model integrations. This result suggests that SST around the Korean peninsula can be reliably predicted with appropriate post-processing.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.6
• /
• pp.974-983
• /
• 1997

The Okhotsk Sea is unique natural object with climatic peculiarities. The climate of the Okhotsk Sea results from the general distribution of solar radiation during a year, and the characteristics of the atmospheric circulation that varies through a year: In cold half year the main pressure formations are Siberian high and Aleutian low. Asian low centered on Afghanistan dominates over the Asian continent in summer. The North-Pacific sea surface is under effect of permanent North Pacific high. The changes in their position from year to year are very significant. The anticyclonic activity over the Far Eastern Seas is one of the main factors for the formation of weather anomalies over the adjacent territories. The analysis of summer weather characteristics over the coast of Okhotsk and East Sea using the data obtained from Hydrometeorological stations during $1949\~1990$ showed that, to a great extent, distribution of the air temperature depends on thermal state of the Okhotsk Sea and atmospheric circulation over it. We show some relations between weather characteristics and the intensity of atmospheric action center for the North Pacific high in summer when its ridge propagates to Okhotsk Sea. Correlation coefficients between air pressure over the Okhotsk Sea and air temperature for the coastal areas reach up to 0.7. Analysis of the spatial-temporal distribution of main meteorological values over the Okhotsk Sea such as air pressure, and air temperature are also performed.

• Proceedings of the KSRS Conference
• /
• v.2
• /
• pp.913-916
• /
• 2006

Spatial distribution, seasonal and interannual variability of chlorophyll a concentration in Okhotsk Sea from SeaWiFS data between 2001 and 2004 were describe. An Empirical Orthogonal Function method was applied for analysis data. The ten modes described about 85% of total variance. Two maxima were defined - more intensive in spring and weaker in autumn. The first mode showed zones with chlorophyll a concentration during maximum bloom. The second mode specified timing of spring bloom in various regions in Okhotsk Sea. Analysis of SeaWiFS data indicated connection between highest chlorophyll a concentration and sea surface temperature limits during spring bloom. Similar relation was not found during fall bloom.

• Ocean and Polar Research
• /
• v.38 no.2
• /
• pp.89-102
• /
• 2016

In this study, we evaluated the model performance with respect to Sea Surface Temperature (SST) and Net Heat Flux (NHF) by considering the characteristics of seasonal temperature variation and contributing factors and by analyzing heat budget terms in the Northwestern Pacific and East Asian Marginal Seas ($110^{\circ}E-160^{\circ}E$, $15^{\circ}N-60^{\circ}N$) using the HadGEM2-AO historical run. Annual mean SST of the HadGEM2-AO is about $0.065^{\circ}C$ higher than observations (EN3_v2a) from 1950 to 2000. Since 1960, the model has simulated well the long-term variation of SST and the increasing rate of SST in the model ($0.014^{\circ}C/year$) is comparable with observations ($0.013^{\circ}C/year$). Heat loss from the ocean to the atmosphere was simulated slightly higher in the HadGEM2-AO than that in the reanalysis data on the East Asian Marginal Seas and the Kuroshio region. We investigated the causes of temperature variation by calculating the heat budget equation in the two representative regions. In the central part of the Kuroshio axis ($125^{\circ}E-130^{\circ}E$, $25^{\circ}N-30^{\circ}N$: Region A), both heat loss in the upper mixed layer by surface heat flux and vertical heat advection mainly cause the decrease of heat storage in autumn and winter. Release of latent heat flux through the heat convergence brought about by the Kuroshio contributes to the large surface net heat flux. Positive heat storage rate is mainly determined by horizontal heat advection from March to April and surface net heat flux from May to July. In the central part of the subtropical gyre ($155^{\circ}E-160^{\circ}E$, $22^{\circ}N-27^{\circ}N$: Region B), unlike Region A, vertical heat advection predominantly causes the decrease of heat storage in autumn and winter. In spring and summer, surface heat flux contributes to the increase of heat storage in Region B and the period is two times longer than the period for Region A. In this season, shoaling of the mixed layer depth plays an important role in the increase of SST.

• 한국해양학회지
• /
• v.29 no.4
• /
• pp.325-337
• /
• 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 Korea Institute of Military Science and Technology
• /
• v.11 no.5
• /
• pp.84-91
• /
• 2008

The spectral radiance received by a remote sensor at a given temperature and wavelength region is consisted of the self-emitted component directly from the object surface, the reflected component of the solar irradiation at the object surface, and the scattered component by the atmosphere without ever reaching the object surface. The IR image of a ship is mainly affected by location, meteorological condition(atmosphere temperature, wind direction and velocity, humidity etc.), atmospheric transmittance, solar position and ship surface temperature etc. Computer simulations for prediction of the IR signatures of ships are very useful to examine the effects of various meteorological conditions. In this paper, we have acquired the IR signature for different meteorological conditions by using two different computer programs. The numerical results show that the IR image contrast as compared to the background sea considering the atmosphere temperature and wind velocity.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.26 no.2
• /
• pp.151-166
• /
• 1990

Using the data observed on the Oshoro-maru from November 4 to November 12, 1989 in the East China Sea, the oceanographic conditions were investigated. The results are as follows: The oceanographic condition of surface layer was divided into two regions. One was the Tsushima Current Waters and the other was the China Coastal Waters. The oceanic front was formed between above two waters. Tsushima Current Waters had high temperature ranging 22~24$^{\circ}C$, high salinity ranging 33.5~34.5$\textperthousand$ and low D.O less than 4.5ml/l. And China Coastal Waters had low temperature ranging 18~2$0^{\circ}C$, low salinity less than 23.0$\textperthousand$ and high D.O ranging 4.0~5.0ml/l. In the case of the bottom layer, Tsushima Current Waters and China Coastal Waters appeared the same as the surface layer. In addition, the Yellow Sea Bottom Cold Waters and the Southern Bottom Waters of East China Sea distributed together with two surface waters above. The was temperature ranging 15~19$^{\circ}C$, salinity 34.5$\textperthousand$ and low D.O ranging 2.0~3.5ml/l and that was temperature less than 1$0^{\circ}C$, salinity less than 33.3$\textperthousand$ and high D,O greater than 4.5ml/l. The waters of intermediate characteristics between China Coastal Waters and Tsushima Current Waters seem to be resulted from the mixing occurred between the above tow waters, and it had temperature of 20.5~22.$0^{\circ}C$, salinity of 32.3~33.3$\textperthousand$.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.6
• /
• pp.701-707
• /
• 2021

In this study, we examined the sea surface temperature (SST), air temperature (AT), and their time lag in response to an extreme cold wave in 2018 and a weak cold wave in 2019, cross-correlating these to the northern wind direction frequency. The data used in this study include SST observations of seven ocean buoys Real-time Information System for Aquaculture Environment provided by the National Institute of Fisheries Science and automatic weather station AT near them recorded every hour; null data was interpolated. A finite impulse response filter was used to identify the appropriate data period. In the extreme cold wave in 2018, the seven locations indicated low SST caused by moving cold air through the northern wind direction. A warm cold wave in 2019, the locations showed that the AT data was similar to the normal AT data, but the SST data did not change notably. During the extreme cold wave of 2018, data showed a high correlation coefficient of about 0.7 and a time lag of about 14 hours between AT and SST; during the weak cold wave of 2019, the correlation coefficient was 0.44-0.67 and time lag about 20 hours between AT and SST. This research will contribute to rapid response to such climate phenomena while minimizing aquaculture damage.

• 한국데이터정보과학회:학술대회논문집
• /
• 2002.06a
• /
• pp.151-154
• /
• 2002

적도에서 중위도 북태평양 사이의 대기-해양의 변동을 알아보기 위해 NCEP/NCAR 재분석 자료로 경도풍과 SST(Sea Surface Temperature)를 비교하였다. 그 결과 경도풍과 SST가 반대의 경향을 보였다. 즉, 동서류가 강할 때는 해수의 혼합이 강해서 해수 표면의 온도가 낮아지고, 동서류가 약할 때는 해수의 혼합이 약해서 해수 표면의 온도가 높아진다. 또한 보편적인 비교를 위해 지역 풍속 지수 AWI(Area Wind Index)를 만들었다. 그래서 PNA(Pacific/North American), AOI(Artic Oscillation Index), 그리고 SST(Sea Surface Temperature)와 비교를 하였다.