• Fisheries and Aquatic Sciences
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• 제3권2호
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• pp.163-171
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• 2000

A series of numerical experiments are performed to examine the generation of inter-annual variations by an inertial current in an idealized semi-enclosed basin with dimension comparable to that of the East Sea. Model results indicate that the inter-annual variations dominate the kinetic energy spectrum with a peak around the time scales of 2-3 years. These variations are mostly due to the westward propagating meanders and large eddies induced by the instability of current, indicating their dependency on the eddy-resolving capacity of the model. They are generated in the interior of the basin but their energy is largely confined near the western boundary such that the east-west dimension of the basin cannot be considered as a critical factor as long as the basin covers enough western boundary region. Overall, this study suggests that the inter-annual variation observed in the East Sea is due to the meandering and large eddies induced by the instability of the current.

• 대한원격탐사학회지
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• 제17권2호
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• pp.111-119
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• 2001

This study analyzes time variability of the normalized difference vegetation index (NDVI), the leaf area index (LAI) and surface temperature (Ts) estimated from AVHRR data collected from across the Korean peninsula from 1981 to 1994. In the present study, LAI defined as vegetation density, as a function of NDVI applied for the vegetation types and Ts defined by the split-window formulation of Becker and Li (1990) with emissivity of a function of NDVI, are used. Results of the inter-annual, intra-annual and intra-seasonal variabilities in Korea show: (1) Inter-annual variability of NDVI is generally larger in the southem and eastern parts of the peninsula than in the western part. This large variability results from the significant mean variation. (2) Inter-annual variability of Ts is larger in the areas of smaller NDVI. This result shows that the NDVI play a small role in emissivity. (3) Inter-annual variability of LAI is larger in the regions of higher elevation and urban areas. Changes in LAI are unlikely to be associated with NDVI changes. (4) Changes in NDVI and Ts are likely dominant in July and are relatively small in spring and fall. (5) Urban effect would be obvious on the time-varying properties of NDVI and Ts in Seoul and the northern part of Taejon, where NDVI decreases and Ts increases with a significant magnitude.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.352-355
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• 2006

In this study, the seasonal and inter-annual variation of sea surface current in the Gulf of Thailand were revealed through the use of WOD temperature and salinity data and monthly sea surface dynamic heights (SSDH) from TOPEX/Poseidon and ERS-2 altimetry data during 1995-2001. The mean dynamic height and mean geostrohic current were derived from the climatological data while SSDH data gave monthly dynamic heights and their geopstrophic currents. The mean geostrophic current showed strong southward and westward flow of South China Sea water along the gulf entrance. Counterclockwise eddy in the inner gulf and the western side of the gulf entrance associated with upwelling in the area. Seasonal geostrophic currents show basin-wide counterclockwise circulation during the southwest monsoon season and clockwise circulation during the northeast monsoon season. Upwelling was enhanced during the southwest monsoon season. The circulation patterns varied seasonally and inter-annually probably due to the variation in wind regime. And finally we found that congregation, spawning, and migration routes of short-bodied mackerel conform well with coastal upwelling and surface circulation in the gulf.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2001년도 춘계 학술대회 논문집 통권 4호 Proceedings of the 2001 KSRS Spring Meeting
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• pp.92-97
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• 2001

The intra-annual and interannual variations of total, high, middle, low clouds, and cloud forcing net solar radiation flux, cloud forcing net long-wave radiation flux, and SSTs over the tropical oceans are investigated with the use of ISCP D2, NCEP/NCAR Reanalysis for January 1983-December 1993. The intra-annual variation of total cloudiness is dominated by high and middle clouds in the western Pacific and central tropical oceans, the interannual variation of total cloudiness is also dominated by high and middle clouds in the central Pacific and Atlantic. The dominant intra-annual and interannual EOFs of total cloudiness have spatially coherent link with those SSTs. For the interannual EOFs, total cloudiness and SSTs are related to E1 nino-Southern Oscillation(ENSO). The second most important intra-annual EOFs of total cloudiness are related to Inter Tropical Convergence Zone(ITCZ). The third most important intra-annual EOFs show coherent relation in the western Pacific. The correlation analysis between cloud radiative effects and SSTs show spatially coherent relation over the tropical oceans even though cloud forcing cooling effect is much higher than heating effect.

• 한국환경과학회지
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• 제22권10호
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• pp.1305-1316
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• 2013

A long-term wind resource map was made to provide the key design data for the 2.5 GW Korean West-South Offshore Wind Project, and its reliability was validated. A one-way dynamic downscaling of the MERRA reanalysis meteorological data of the Yeongwang-Gochang offshore was carried out using WindSim, a Computational Fluid Dynamics based wind resource mapping software, to establish a 33-year time series wind resource map of 100 m x 100 m spatial resolution and 1-hour interval temporal resolution from 1979 to 2012. The simulated wind resource map was validated by comparison with wind measurement data from the HeMOSU offshore meteorological tower, the Wangdeungdo Island meteorological tower, and the Gochang transmission tower on the nearby coastline, and the uncertainty due to long-term variability was analyzed. The long-term variability of the wind power was investigated in inter-annual, monthly, and daily units while the short-term variability was examined as the pattern of the coefficient of variation in hourly units. The results showed that the inter-annual variability had a maximum wind index variance of 22.3% while the short-term variability, i.e., the annual standard deviation of the hourly average wind power, was $0.041{\pm}0.001$, indicating steady variability.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.140-143
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• 1999

SSH(Sea Surface Height) from TOPEX/Poseidon and SST data are analyzed to estimate characteristics of annual and inter-annual variations in the East Asian seas(110E - l80E, 20N - 50N) from November 1992 to May 1998. In EOF analysis of SSH and SST, 57% and 97% of the variance are represented by the first two modes. The first mode of SSH and SST shows strong annual variations expected for steric changes. The second mode of SSH shows a long-term variation, but that of SST shows 3 - 4month offset from annual variation. In the EOF analysis of the SSH and SST, 61% and 54% of the total variance are represented by the first three modes. The first mode represented a long-term variation, and the third mode reflected the bi-ennial variation. The first three mode were not strongly correlated with ENSO. We further apply Canonical Correlation Analysis(CCA) to find the dominant correlation patterns with ENSO.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.450-453
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• 2006

Hydrographic data including particulate organic carbon (POC) from the Northeastern Gulf of Mexico (NEGOM) study were used along with remotely sensed data obtained from NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS) to develop POC algorithms to estimate POC concentration based on empirical and model-based principal component analysis (PCA) methods. In Case I and II waters empirical maximized simple ratio (MSR) and model-based PCA algorithms using full wavebands (blue, green and red wavelengths) provide more robust estimates of POC. The predicted POC concentrations matched well the spatial and seasonal distributions of POC measured in situ in the Gulf of Mexico. The ease in calculating the MSR algorithm compared to PCA analysis makes MSR the preferred algorithm for routine use. In order to determine the inter-annual variations of POC, MSR algorithms applied to calculate 100 monthly mean values of POC concentrations (September 1997-December 2005). The spatial and temporal variations of POC and sea surface temperature (SST) were analyzed with the empirical orthogonal function (EOF) method. POC estimates showed inter-annual variation in three different locations and may be affected by El $Ni{\tilde{n}}o/Southern$ Oscillation (ENSO) events.

• 대한토목학회논문집
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• 제30권1B호
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• pp.1-11
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• 2010

본 논문에서는 측우기 관측 자료계열(CWK)과 근대우량계 관측 자료계열(MRG)의 월별 장기변화 특성을 파악하기 위하여 통계적 경향성 검정방법 5가지를 이용하여 각 자료계열의 경향성 여부를 검정하였다. 더불어 각 자료계열별로 연도별 시간축과 월별 시간축을 동시에 고려한 2차원 LOWESS 회귀분석을 실시하여 강우의 변동 특성을 분석하였다. 경향성 분석결과 검정방법별로 95% 신뢰수준에서 경향성에 대해 큰 유의성이 있다고 보기는 어려웠다. 4가지 강우특성에 대한 2차원 LOWESS 회귀분석 결과, 1980년 이후부터 강우의 양적 증가추세와 더불어 강우의 월간 변화폭도 급격한 증가추세를 보이고 있는 것으로 나타났다.

• 한국농림기상학회지
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• 제6권4호
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• pp.235-241
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• 2004

1월의 최저기온을 대상으로 1951년부터 2000년까지 14개 지점의 관측자료를 분석한 결과 11개 지점에서 전반기(1951-1980)에 비해 후반기(1971-2000)의 연차 변이가 오히려 감소한 것으로 나타났다 표준편차로 표현할 경우 제주, 전주, 울릉도를 제외한 나머지 11개 지점에서 많게는 0.35(서울)에서 적게는 0.03(강릉)까지 고르게 연차변이가 감소하였다. 이는 최근의 난동화 경향과 함께 겨울철 최저기온의 연차변이가 더 심해지고 있다는 당초의 예상과 다른 결과이다 연차변이의 공간분포양상은 최저기온의 절대값과 정의 상관을, 관측점의 해발고도와는 부의 상관을 보였다. 이 관계를 이용하여 남한전역의 1월 최저기온 30년 표준 편차 분포도를 작성하였으며, 이를 토대로 재현기간별로 기대되는 전국의 극최저기온 분포도를 제작하여 지역별 동해위험 평가에 이용토록 하였다.

• 한국수자원학회논문집
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• 제30권3호
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• pp.247-256
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• 1997

1961년 이전에 관측이 시작되어 30년 이상의 관측자료가 있는 기상청의 15개 관측소의 강수량 자료를 이용하여 우리나라의 여름철 강수량 분포 특성을 조사하였다. 특히 이 연구에서는 우리나라 강수량 기후 평년값을 이용하여 기후적 특성을 조사하였으며, 지역별로 연 강수량, 여름철 강수량, 장마기간중 강수량의 연도별 변동을 비교 분석하고 그 상관을 조사하였다. 대체로 우리나라의 경우 연 강수량의 반 이상이 6, 7, 8월의 여름철에 집중되어 있고, 또 이 여름철 강수량은 장마에 크게 영향을 받는다. 또 지역별로 여름철 강수량 및 장마가 연 강수량에 미치는 기여도를 조사한 결과 서울을 비롯한 중서부 내륙지방이 장마의 영향을 가장 많이 받으며 동해안 중북부 지역과 제주도 지역은 상대적으로 장마의 영향이 적고, 국지적인 지형적 영향을 많이 받는 것으로 나타났다. 또한 우리나라의 경우 강수량의 연도별 변동이 심한 것으로 나타났으며, 특히 연 강수량보다 여름철 강수량과 장마기간중 강수량의 변화가 더 심한 것으로 나타났다. 따라서 국가 수자원 문제와 관련하여 연 강수량의 변동을 파악하기 위해서는 여름철 강수량의 변동에 대한 이해가 중요하며 아울러 장마의 특성 즉 몬순에 대한 파악이 함께 이루어져야 한다.