• Fisheries and Aquatic Sciences
• /
• v.11 no.4
• /
• pp.212-218
• /
• 2008

Time series changes in the chlorophyll $\alpha$ concentrations before and after the ship Prestige oil spill on 13 November 2002 were analyzed using NCEP wind data and ocean color data. Following the oil spill, southwesterly winds pushed the oil towards the Spanish coast. In addition, the daily chlorophyll $\alpha$ concentration decreased dramatically from the middle of November to the end of December 2002, with the minimum value being recorded in December. Additionally, the mean chlorophyll $\alpha$ concentration in November and December 2002 was lower than the average value recorded for the same months from 2000 to 2005; however, with the exception of 2000, the concentration was higher in October 2002 before the spill and in January-March 2003 after the spill during the same period from 2000 to 2005.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.296-297
• /
• 2006

In order to support wind power development, the wind resource database of Jejudo has been established by meteo-statistical analysis on meteorological-mast measurements of KIER. Analysis processes contain correlation of monthly wind speed and power-law exponent among neighboring sites, Measure-Correlated-Predict for long-term correlation, classification of exposure category using satellite image and so forth. It is found that the monthly variations of wind speed and power-law exponent depend on seasonal winds and characterize wind system of Jejudo.

• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.309-312
• /
• 2008

The advent of high resolution products of surface wind and temperature derived by satellite data has permitted us to investigate ocean and atmosphere interaction studies in detail. Especially the Kuroshio extension region of the western North Pacific is considered to be a key area for such studies. We have constructed gridded products of surface wind/wind stress over the world ocean using satellite scatterometer (Qscat/SeaWinds), available as the Japanese Ocean Flux data sets with Use of Remote sensing Observation (J-OFURO). Using new data based on improved algorithm which have been recently delivered, we are reconstructing gridded product with higher spatial resolution. Intercomparison of this product with the previous one reveals that there are some discrepancies between them in short-period and high wind-speed ranges especially in the westerly wind region. The products are validated by not only comparisons with in-situ measurement data by mooring buoys such as TAO/TRITON in the tropical Pacific and the Kuroshio Extension Observation (KEO) buoys, but also intercomparison with numerical weather prediction model (NWPM) products (the NRA-1 and 2). Our products have much smaller mean difference in the study areas than the NWPM ones, meaning higher reliability compared with the NWPM products. Using the high resolution products together with sea surface temperature (SST) data, we examine a new type of relationship between the lower atmosphere and upper ocean in the Kuroshio Extension region. It is suggested that the spatial relation between the wind speed and SST depends upon, more or less, the surrounding oceanic condition.

• Korean Journal of Remote Sensing
• /
• v.32 no.6
• /
• pp.703-719
• /
• 2016

We investigated the changes with temporal and spatial movements of cold water events in summer season around the East Sea of Korea. Several data analyses were performed based on the various environmental factors using satellite and in-situ (winds, air/sea surface temperatures) data in the summer season during 2013. For analyzing the influence of cold water life cycle we employed AVISO geostrophic current and daily Geostationary Ocean Color Imager (GOCI) chlorophyll concentration (chl) data. Also, we used daily Advanced Very High Resolution Radiometer-Sea Surface Temperature (AVHRR-SST) data to trace the movements of cold water events. We found out the cold water events occurred in the early summer season and disappeared in the late summer season, and the cold water life cycle is repeated in this period. Additionally, we could show that the chl were increased in late summer season due to the inertial influence of cold water zone.

• Wind and Structures
• /
• v.26 no.3
• /
• pp.147-161
• /
• 2018

For wind engineering applications downbursts are, presently, almost exclusively modeled, both experimentally and numerically, as transient impinging momentum jets (IJ), even though that model contains none of the physics of real events. As a result, there is no connection between the IJ-simulated downburst wind fields and the conditions of formation of the event. The cooling source (CS) model offers a significant improvement since it incorporates the negative buoyancy forcing and baroclinic vorticity generation that occurs in nature. The present work aims at using large-scale numerical simulation of downburst-producing thunderstorms to develop a simpler model that replicates some of the key physics whilst maintaining the relative simplicity of the IJ model. Using an example of such a simulated event it is found that the non-linear scaling of the velocity field, based on the peak potential temperature (and, hence, density) perturbation forcing immediately beneath the storm cloud, produces results for the radial location of the peak radial outflow wind speeds near the ground, the magnitude of that peak and the time at which the peak occurs that match well (typically within 5%) of those produced from a simple axi-symmetric constant-density dense source simulation. The evolution of the downdraft column within the simulated thunderstorm is significantly more complex than in any axi-symmetric model, with a sequence of downdraft winds that strengthen then weaken within a much longer period (>17 minutes) of consistently downwards winds over almost all heights up to at least 2,500 m.

• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.192-195
• /
• 2004

Products of gridded surface wind and windstress vectors over the world ocean have been constructed by satellite scatterometer data with highly temporal and spatial resolutions. Even if the ADEOS-II/SeaWinds has supplied surface wind data only for short duration in Apr. to Oct. 2003 to us, it permits us to construct a product with higher resolution together with the Qscat/SeaWinds. In addition to our basic product with its resolution of $1^{\circ}\times1^{\circ}$ in space and daily in time, we try to construct products with $1/2^{\circ}\times1/2^{\circ}$ and semi- and quarter-daily resolution. These products are validated by inter-comparison with in-situ data (TAO and NDBC buoys), and also compared with numerical weather prediction(NWP) ones (NCEP reanalysis). Result reveals that our product has higher reliability in the study area than the NCEP's. For the open ocean regions in the middle and high latitudes where there are no in-situ data, we find that there are clear differences between them. Especially in the southern westerly region of 400-600S, the' wind-stress magnitudes by the NCEP are significantly larger than the others, suggesting that they are overestimated. We also calculate wind-stress curl field that is an important factor for ocean dynamics and focus its spatial character in the northwestern Pacific around Japan. Positive curl areas are found to cover from southwest to northeast in our focus region and almost correspond to the Kuroshio path. It is suggested that the vorticity field in the lower atmosphere is related to the upper oceanic one, and thus an aspect of air-sea interaction process.

• Korean Journal of Remote Sensing
• /
• v.39 no.4
• /
• pp.441-458
• /
• 2023

Tropical cyclones frequently occur in the Southwest Pacific Ocean and are considered one of the driving forces for coastal alterations. Therefore, this study investigates the frequency and intensity of tropical cyclonesfrom 2000 to 2021 and their influence on the surface winds and wave conditions around the atoll nation Tuvalu. Cyclone best-track and ERA5 single-level reanalysis data are utilized to analyze the condition of the surface winds, significant wave heights, mean wave direction, and mean wave period. Additionally, the scatterometer-derived wind information was employed to compare wind conditions with the ERA5 data. On average, nine cyclones per year originated here, and the frequency increased to 11 cyclones during the last three years while the intensity decreased by 25 m/s (maximum sustained wind speed). Besides, a total of 14 cyclones were observed around Tuvalu during the period from 2015 to 2021, which showed an increase of 3 cyclones compared to the preceding period of 2001 to 2007. During cyclones, the significant wave height reached the highest 4.8 m near Tuvalu, and the waves propagated in the east-southeast direction during most of the cyclone events (52%). In addition, prolonged swells with a mean wave period of 7 to 11 seconds were generated in the vicinity of Tuvalu, for which coastal alteration can occur. After this preliminary analysis, it was found that the waves generated by cyclones have a crucial impact in altering the coastal area of Tuvalu. In the future, remotely sensed high-resolution satellite data with this wave information will be used to find out the degree of alterations that happened in the coastal area of Tuvalu before and after the cyclone events.

• Journal of the Korean earth science society
• /
• v.34 no.7
• /
• pp.693-710
• /
• 2013

This study investigates the distribution of suspended particulates during the Asian dust period in Busan, Korea in the spring of 2009. Weather map and automatic weather system (AWS) data were used to analyze the synoptic weather conditions during the period. Particulate matter 10, laser particle counter data, satellite images and a backward trajectories model were used to analyze the aerosol particles distribution and their origins. In Case 1 (20 February 2009), when the $PM_{10}$ concentration increased, the aerosol volume distribution of small ($0.3-1.0{\mu}m$) particles decreased, while the concentration of large ($1.0-10.0{\mu}m$) particles increased. When the $PM_{10}$ concentration decreased, the aerosol volume distribution was observed to decrease as well. The prevailing winds changed from weak northerly winds to strong southwesterly winds when the concentration of the large particles increased. The correlation coefficient between the $PM_{10}$ concentration and aerosol volume distribution of large particles showed a high positive value of over 0.9. The results from the trajectory model show that the Asian dust originated in the Gobi desert and the Nei Mongol plateau. In Case 2 (25 April 2009), when the $PM_{10}$ concentration increased, the aerosol volume concentration of small ($0.3-0.5{\mu}m$) particles decreased, but the concentration of large ($0.5-10.0{\mu}m$) particles increased. The opposite was observed when the $PM_{10}$ concentration decreased. The prevailing winds changed from northeasterly winds to southwesterly and northeasterly winds. The correlation coefficient between the $PM_{10}$ concentration and aerosol volume distribution of large particles ($1.0-10.0{\mu}m$) showed a high positive value of about 0.9. The results from the trajectory model show that the Asian dust originated in Manchuria and the eastern coast of China.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.8 no.1
• /
• pp.46-52
• /
• 2005

A marine environmental information system (MEIS) useful for optimal route planning of ships running in the ocean was developed. Utilizing the simulated marine environmental data produced by the European Center for Medium-Range Weather Forecasts based on global environmental data observed by satellites, the real-time forecast and long-term statistics of marine environments around planned and probable ship routes are provided. The MEIS consists of a land-based data acquisition and analysis system(MEIS-Center) and a onboard information display system(MEIS-Ship) for graphic description of marine information and optimal route planning of ships. Also, it uses of satellite communication system for data transfer. The marine environmental components of winds, waves, air pressures and storms are provided, in which winds are described by speed and direction and waves are expressed in terms of height, direction and period for both of wind waves and swells. The real-time information is characterized by 0.5° resolution, 10 day forecast in 6 hour interval and daily update. The statistic information of monthly average and maximum value expected for a return period is featured by 1.5° resolution and based on 15 year database. The MEIS-Ship include an editing tool for route simulation and the forecasting and statistic information on planned routes can be displayed in graph or table. The MEIS enables for navigators to design an optimal navigational route that minimizes probable risk and operational cost.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.5
• /
• pp.508-520
• /
• 2016

In this study, variations in water temperature after the passage of typhoons in Korean waters from 2009-2015 were analyzed. Sea surface temperature (SST) images derived from satellite remote sensing data were used, and water temperature information came from real-time mooring buoys at Yangyang, Gangneung, Samcheok and Yeoungdeok, while wind data was supplied by the Korea Meteorological Administration. Differences in SST observed before and after the passage of a typhoon using the SST images were found to be affected by wind direction as well as hot and cool seasonal tendencies. Coastal water temperatures of the eastern part of the Korean peninsula, located to the right of a typhoon, as in the case of typhoons Muifa, Chanhom, Nakri and Tembin, were lowered by a coastal upwelling system from southerly winds across the water's surface at depths of 15m and 25m. In particular, typhoons Chanhom and Tembin decreased water temperatures by about $8-11^{\circ}C$ and $16^{\circ}C$, respectively. However, temperatures to the left of the typhoons were increased by a downwelling of offshore seawater with a high temperature through the mid and lower seawater layers. After the passage of the typhoons, further mixing of seawater at a higher or lower temperature due to southerly or northerly winds, according to the context, lasted for 1-2 or 4 days, respectively.