• Ocean and Polar Research
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• 제30권3호
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• pp.277-287
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• 2008

We collected information on seasonal and interannual variability of surface chlorophyll a concentration between 1997-2007 from the Northwest Pacific Ocean. Satellite data were used to acquire chlorophyll a and sea surface temperature from six regions: East Sea/Ulleung Basin, East China Sea, Philippin Sea, Warm Pool region, Warm Pool North region, and Warm Pool East region. Mixed layer depth (MLD) was calculated from temperature profiles of ARGO floats data in four of the six regions during 2002-2007. In the East Sea/Ulleung Basin, seasonal variability of chlorophyll a concentration was attributed to seasonal change of MLD, while there was no significant relationship between chlorophyll a concentration and MLD in the Warm Pool region. Interannual anomaly in sea surface temperature were similar among the East Sea, East China Sea, Philippin Sea, and Warm Pool North region. The anomaly pattern was reversed in the Warm Pool East region. However, the anomaly pattern in the Warm Pool region was intermediate of the two patterns. In relation to chlorophyll a, there was a reversed interannual anomaly pattern between Warm Pool North and Warm Pool East, while the anomaly pattern in the Warm Pool region was similar to that of Warm Pool North except for the El $Ni\tilde{n}o$ years (1997/1998, 2002/2003, 2006/2007). However, there was no distinct relationship among other seas. Interestingly, in the Warm Pool and Warm Pool East regions, sea surface temperature showed a pronounced inverse pattern with chlorophyll a. This indicates a strong interrelationship among sea surface temperature-MLD-chlorophyll a in the regions. In the Warm Pool and Warm Pool East, zonal distribution of chlorophyll a concentration within the past 10 years has shown a good relationship with sea surface temperature which reflects ENSO variability.

• Ocean and Polar Research
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• 제41권1호
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• pp.1-10
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• 2019

Right after the 2007 Hebei Spirit Oil Spill phytoplankton ecosystems were investigated for 11 years based on the seasonal monitoring of the composition and abundance of phytoplankton species. Comparable time-series data from the 1989 Exxon Valdez or the 2010 Deepwater Horizon Oil Spill sites were not available. It was suggested that the ecological healthiness of phytoplankton ecosystems at EVOS sites had recovered after 10 years following the oil spill based on chlorophyll concentrations even though these concentrations only represented phytoplankton communities in most cases. Chlorophyll concentrations can only reflect limited aspects of highly complex phytoplankton ecosystems. During the last 11 years following the 2017 HSOS, extreme variabilities were met in the seasonally averaged ratios of diatoms to phototrophic flagellates including dinoflagellates based on the microscopic cell countings. Summer phytoplankton communities exhibited some cyclic interannual changes in dominant groups every 2-4 years. During the early years (2008-2010) cryptophytes or raphidophytes (Chattonella spp.) dominated alternately each year, which was repeated again in 2014, 2015 and 2017. Two thecate dinoflagellates, Tripos fusus and Tripos furca, together accounted for 52.5% and 50.0% of all organisms in the summers of 2011 and 2012, respectively, which was repeated again in 2018. Summer occurrence and dominance by the phototrophic flagellates including HABs (Harmful Algal Blooms) species as well as their interannual variabilities in the oil spill sites could be utilized as markers for the stable and long-term management of healthy ecosystems. For this type of scientific ecosystem management monitoring of chlorophyll concentrations may sometimes be insufficient to gain a proper and comprehensive understanding of phytoplankton communities located in areas where oil spills have occurred and harmed the ecosystem.

• Ocean and Polar Research
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• 제30권1호
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• pp.21-31
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• 2008

Analyzing the results of East Sea Regional Ocean Model using a 3-dimensional variational data assimilation scheme, we investigated spatial and temporal variability of the North Korean Cold Current (NKCC) in the East Sea. The climatological monthly mean transport of the NKCC clearly shows seasonal variation of the NKCC within the range of about 0.35 Sv ($=0^6m^3/s$), which increases from its minimum (about 0.45 Sv) through December-January to March, decreases during March and May, and then increases again to the maximum (about 0.8 Sv) in August-September. The volume transport of the NKCC shows interannual variation of the NKCC with the range of about 1.0 Sv that is larger than seasonal variation. The southward current of the NKCC appears often not only in summer but in winter as well. The width of the NKCC is about 35 km near the Korean coast and its core is located under the East Korea Warm Current. The North Korean Cold Water (NKCW), characterized by low salinity and low temperature, is located both under the Tsushima Warm Water and in the western side of the maximum southward current of the NKCC that means the NKCC advects the NKCW southward along the Korean coast. It is revealed that the intermediate low salinity water, formed off the Vladivostok in winter, flows southward to the south of $37^{\circ}N$ through $2{\sim}3$ paths; one path along the Korean coast, another one along $132^{\circ}E$, and the middle path along $130^{\circ}E$. The path of the intermediate low salinity varies with years. The reanalysis fields suggest that the NKCW is advected through the paths along the Korean coast and along $130^{\circ}E$.

• 한국해안해양공학회지
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• 제8권2호
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• pp.215-220
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• 1996

동한만을 중심으로 한 동해 북서해역의 계절별 및 연별 표층해황 특성을 고찰하였다. 동한만의 계절별 해황은 춘계에 동한난류수의 세력이 우세하다가 하리에 북한한류의 강화와 더불어 냉수역이 발달하는 형과, 봄부터 냉수의 세력이 탁월하다가 여름이 되면서 동한난류수의 영향을 받는 형의 두가지 유형을 보인다. 경년변동 특성도 동한난류와 북한한류간의 흐름의 상대적 세기와 유로에 따라 4가지 유형으로 분류된다. 각각의 경우, 동한만 부근에는 대ㆍ소규모의 저기압성 냉수과 혹은 고기압성 난수과가 발달하는 것이 한 특징이다.

• 한국지구과학회지
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• 제31권4호
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• pp.335-347
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• 2010

이 연구에서는 기상청에서 관측한 최근 7년(2002-2008)간의 낙뢰자료를 이용하여 남한지역에서 발생한 구름-지면 낙뢰 현상의 극성별 시 공간적 특성을 분석하였다. 낙뢰빈도는 극성에 관계없이 강한 경년변동, 계절변동 및 일 변동을 보이고 있다. 낙뢰빈도는 여름과 겨울에 각각 최대(74%) 및 최소(0.6%)를 보이고 있다. 또한 계절과 극성에 따라 다르지만 낙뢰는 평균적으로 새벽과 오후에 최대로 발생하는 일 변동을 보이고 있다. 정극성 비율(정극성/부극성)은 여름에 7.3%로 낮으나 겨울에는 62.5%로 강한 계절 변동을 보이고 있다. 낙뢰강도는 경년 및 일 변동은 거의 보이지 않고 있으며 낙뢰가 많이 발생하는 여름에 약하고 낙뢰가 적게 발생하는 겨울에 강한 계절 변동을 보이고 있다. 또한 정극성 낙뢰강도는 강한 계절 변동을 보이는 반면 부극성은 상대적으로 약한 계절 변동을 보이고 있다. 낙뢰밀도는 영동과 동해 지역보다 서부 내륙 및 서 남해상에서 높게 나타나고 있다. 낙뢰강도의 경우 극성에 관계없이 내륙에서보다 바다, 특히 동해상에서 강하게 나타나고 있다.

• 한국지구과학회지
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• 제27권6호
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• pp.653-658
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• 2006

대기 대순환 모형인 GCPS를 이용하여 북서태평양에서의 태풍 활동의 계절 예측 가능성을 조사하였다. 1979년부터 2003년까지 각 해에 대해 해수면 온도 관측 자료를 사용하여 5개월간 초기 조건을 달리한 10개의 앙상블 멤버를 적분하였다. 모형은 발생 빈도의 평균적인 월변화 경향과 발생 분포를 관측과 유사하게 모의하였으나, 발생 빈도의 경년 변화는 신빙성 있게 예측하지 못하였다. 이는 관측과 모형간 태풍 발생 빈도와 ENSO의 상관성 차이에 인한 것으로 실제 태풍 발생 빈도와 ENSO가 뚜렷한 상관 관계를 갖지 않는 것과 달리, 모형에서는 엘니뇨 시기에 평년에 비해 많은 태풍이 발생하고 라니냐 시기에 평년에 비해 적은 태풍이 발생하는 경향을 보였기 때문이다. 반면에, 관측과 모형 모두 ENSO와의 상관 관계가 높게 나타난 태풍 발생 경도의 경우에는 모형이 발생 경도의 경년 변화를 관측과 유사하게 모의하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.21-24
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• 2006

Processes controlling the interannual variation of mixed layer temperature (MLT) averaged over the NINO3 domain ($150-90^{\circ}W$, $5^{\circ}N-5^{\circ}S$) are studied using an ocean data assimilation product that covers the period of 1993 to 2003. Advective tendencies are estimated here as the temperature fluxes through the domain's boundaries, with the boundary temperature referenced to the domain-averaged temperature to remove the dependence on temperature scale. The overall balance is such that surface heat flux opposes the MLT change but horizontal advection and subsurface processes assist the change. The zonal advective tendency is caused primarily by large-scale advection of warm-pool water through the western boundary of the domain. The meridional advective tendency is contributed mostly by Ekman current advecting large-scale temperature anomalies though the southern boundary of the domain. Unlike many previous studies, we explicitly evaluate the subsurface processes that consist of vertical mixing and entrainment. In particular, a rigorous method to estimate entrainment allows an exact budget closure. The vertical mixing across the mixed layer (ML) base has a contribution in phase with the MLT change. The entrainment tendency due to temporal change in ML depth is negligible comparing to other subsurface processes. The entrainment tendency by vertical advection across the ML base is dominated by large-scale changes in wind-driven upwelling and temperature of upwelling water. Tropical instability waves (TIWs) result in smaller-scale vertical advection that warms the domain during La Ni? cooling events. When the advective tendencies are evaluated by spatially averaging the conventional local advective tendencies of temperature, the apparent effects of currents with spatial scales smaller than the domain (such as TIWs) become very important as they redistribute heat within the NINO3 domain. However, such internal redistribution of heat does not represent external processes that control the domain-averaged MLT.

• 한국지구과학회지
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• 제24권6호
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• pp.558-567
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• 2003

해수면 온도에 대한 구름복사 강제력의 지역 의존도가 조사되었다. 이 조사는 경년 변동과 계절 시간규모에 대해서 각각 조사되었다. 적도 동태평양에서 경년 변동의 경우 해수면 온도가 1$^{\circ}$C 증가할 때 순 구름복사 강제력은 약 3Wm$^{-2}$가 증가하였으며, 계절변동이 포함된 경우 약 3.5Wm$^{-2}$가 증가하는 것으로 나타났다. 반면 열대 해양전체에서 경년 변동의 경우 해수면 온도가 1$^{\circ}$C 증가할 때 순 구름복사 강제력은 1.5Wm$^{-2}$ 감소하였으나, 계절변동이 포함된 경우 약 2.9Wm$^{-2}$로 증가하였다. 따라서 해수면 온도에 대한 구름복사 강제력의 의존도는 적도 동태평양에서 열대 해양으로 넓어질수록 경년 변동에 의해 영향에서 계절변동에 의한 영향이 더 지배적으로 작용한다. 계절 변동이 포함된 경우 해역에 관계없이 해수면온도가 1$^{\circ}$C 증가할 때, 순 구름복사 강제력은 약 2${\sim}$3Wm$^{-2}$ 증가하였다. 이러한 결과는 해수면 온도의 경년 변동이 뚜렷한 적도 동태평양에서는 경년 변동에 의한 구름복사 강제력이 대기를 가열하는 반면, 열대 해양 전체에서는 계절변동에 의한 구름복사 강제력이 대기를 가열한다는 것을 의미한다.

• 대기
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• 제25권2호
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• pp.295-308
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• 2015

Based on the CMIP5 historical simulation datasets, we assessed the performance of state-of-the-art climate models in respect to the relationship between interannual variabilities of the North Pacific synoptic eddy (NPSE) and East Asian winter monsoon (EAWM). Observation (ERA-Interim) shows a high negative correlation (-0.73) between the interannual variabilities of East Asian winter monsoon (EAWM) intensity and North Pacific synoptic eddy (NPSE) activity during the period of 1979~2005. Namely, a stronger (weaker) EAWM is related to a weaker (stronger) synoptic eddy activities over the North Pacific. This strong reverse relationship can be well explained by latitudinal distributions of the surface temperature anomalies over East Asian continent, which leads the variation of local baroclinicity and significantly weakens the baroclinic wave activities over the northern latitudes of $40^{\circ}N$. This feature is supported by the distribution of the meridional heat flux (${\overline{{\nu}^{\prime}{\theta}^{\prime}}}$) anomalies, which have negative (positive) values along the latitudes $40{\sim}50^{\circ}N$ for strong(weak) EAWM years. In this study, the historical simulations by 11 CMIP5 climate models (BCC-CSM1.1, CanESM2, GFDL-ESM2G, GFDL-ESM2M, HadGEM2-AO, HadGEM2-CC, IPSL-CM5A-LR, MPI-ESM-LR, MPI-ESM-MR, MRI-CGCM3, and NorESM1-M) are analyzed for DJF of 1979~2005. Correlation coefficient between the two phenomena is -0.59, which is comparable to that of observation. Model-to-model variation in this relationship is relatively large as the range of correlation coefficient is between -0.76 (HadGEM2-CC and HadGEM2-AO) and -0.33 (MRI-CGCM3). But, these reverse relationships are shown in all models without any exception. We found that the multi-model ensemble is qualitatively similar to the observation in reasoning (that is, latitudinal distribution of surface temperature anomalies, variation of local baroclinicity and meridional heat flux by synoptic eddies) of the reverse relationship. However, the uncertainty for weak EAWM is much larger than strong EAWM. In conclusion, we suggest that CMIP5 models as an ensemble have a good performance in the simulation of EAWM, NPSE, and their relationship.

• 한국측량학회지
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• 제35권4호
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• pp.249-260
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• 2017

UHI (Urban Heat Island) is an important environmental issue occurring in highly developed (or urbanized) area such as Seoul Metropolitan City of Korea due to modification of the land surface by man-made structures. With the advance of the remote sensing technique, land cover types and LST (Land Surface Temperature) influencing UHI were frequently investigated describing that they have a positive relationship. However, the concept of land cover considers material characteristics of the urban cover in a comprehensive way and does not provide information on how human activities influence on LST in detail. Instead, land use reflects ways of land use management and human life patterns and behaviors, and explains the relationship with human activities in more details. Using this concept, LST was segmented according to land use types from the Landsat imagery to identify the human-induced heat from the surface and interannual and seasonal variation of LST with GIS. The result showed that the LST intensity of Seoul was greatest in the industrial area and followed by the commercial and residential areas. In terms of size, the residential area could be defined as the major contributor among six urban land use types (i.e., residential, industrial, commercial, transportation, etc.) affecting UHI during daytime in Seoul. For temperature, the industrial area was highest and could be defined as a major contributor. It was found that land use type was more appropriate to understand the human-induced effect on LST rather than land cover. Also, there was no significant change in the interannual pattern of LST in Seoul but the seasonal difference provided a trigger that the human life pattern could be identified from the satellite-derived LST.