• Journal of the Korean earth science society
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• v.25 no.7
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• pp.629-636
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• 2004

In order to study developments of the marine atmosphere boundary layer in cloud incoming, important parameters like heat advection, surface layer heat flux, and radiation energy were estimated using the rawinsonde, AWS data, satellite images, and buoy data which was installed at the East Sea. We explained the variation and the development of mixed layer in terms of surface layer heat flux and long wave radiation under the cloudy sky. The heat flux was obtained by means of the bulk method. Conservation of heat was analysed by heat budget equation, which was consist of buoy data in the East sea, and sounding data at Ulleungdo and at Pohang. During the inflow of cloud, radiative cooling at the surface after was suppressed and long wave radiation from cloud played a role of warming. The surface layer temperature was also remained warm by influence of warm advection from south-easterly direction. The air temperature in night was increased, as a result, mixed layer was not destroyed and The nocturnal boundary layer was composed of the mixed layer and the residual layer.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.351-358
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• 2017

A new method to decompose the footprints of marine atmosphere boundary layer (MABL) on Synthetic Aperture Radar (SAR) imagery into characteristic spatial scales is proposed. Using two-dimensional Empirical Mode Decomposition (EMD) we obtain three Intrinsic Mode Functions (IMFs), which mainly present longitudinal rolls, three-dimensional cells and atmospheric gravity waves (AGW). The rolls and cells have spatial scales between 3.0 km and 3.8 km and between 5.3 km and 7.1 km, respectively. Based on previous observations and mixed-layer similarity theory, we estimated MABL's depths that vary from 0.95 km to 1.2 km over the rolls and from 3.0 km to 3.8 km over the cells. The AGW has maximum spectrum at 14.3 km wavelength. The method developed in this work can be used to decompose other satellite imageries into individual features through characteristic spatial scales.

• Ocean Science Journal
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• v.43 no.4
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• pp.165-173
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• 2008

In this article, we describe a simple yet effective method for insertion of observational datasets in a mesoscale atmospheric model used in one-dimensional configuration through Nudging. To demonstrate the effectiveness of this technique, vertical profiles of meteorological parameters obtained from GLASS Sonde launches from a tiny island of Kaashidhoo in the Republic of Maldives are injected in a mesoscale atmospheric model - Advanced Regional Prediction System (ARPS), and model simulated parameters are compared with the available observational datasets. Analysis of one-time nudging in the model simulations over Kaashidhoo show that incorporation of this technique reasonably improves the model simulations within a time domain of +6 to +12 Hrs, while its impact on +18 Hrs simulations and beyond becomes literally null.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.2
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• pp.69-78
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• 1978

It is well known that the aluminizing steel is excellent in corrosion resistance and heat resistance. Therefore it has been used as boiler parts, heat exchanger parts and guide rails which are used under comparatively simple conditions. Recently, it has been noticed that aluminizing steel has high resistance to various atmosphere, high temperature oxidation and seawater resistance. So its usage has been extended widely to the production of parts such as intake and exhaust valve of internal combustion engine, turbine blade and pipelines On ships which required such properties. It is considered that aluminium coated steel is excellent in wear resistance because of high hardness on main ingredient FezAIs of Fe-AI alloy layer existed in diffusion coating layer. And it will beused as a new material taking wear resitance with seawater resistance in marine field. However it is difficult to findout any report concering the wear behaviors or properties of alum in izing steel. In this study the experiment was carried out under the condition of rolling-sliding contact using an Amsler-type wear testing machine at 0.80, 0.91, 1. 10, 1. 25% of slip ratio and 55.43, 78.38, 110.85 kg/mm^2 of Hertz's contact stress in run-in period for the purpose of service-ability test of aluminizing steel as a wear resisting material and obtaining the available design data. The followings are the obtained results from the experimen tal study; 1) The 2nd diffusion material has most excellent wear resistance. This material has brought out about 18% decrease of wear weight in a lower friction load level and 40~G decrease in a higher level comparing to the raw material. 2) Satisfactory effect of wear resistivity cannot be much expected in 2nd diffusion specimens. This is considered due to the formation of fine void in the alloy layer near the boundary to the aluminium layer. 3) Fracture on friction surface of aluminizing steel by the rolling-sliding contact is spalling, and spalling crack occurres initially beneath the specimen surface near the boundary in diffusion coating layer.

• Atmosphere
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• v.22 no.1
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• pp.97-107
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• 2012

To investigate variation of aerosol number concentration at each different size with three-dimensional (3D) wind components in ocean area, aerosol particles and 3D wind components were measured in the Ieodo Ocean Research Station, which is located to 419 km southwest from Marado, the southernmost island of Korea, from 25 June to 8 July 2010. The Laser Particle Counter (LPC) and ultrasonic anemometer were used to measure the size of aerosol particles and 3D wind components (zonal (u), meridional (v), and vertical (w) wind) respectively. Surface weather chart, NCEP/NCAR reanalysis data and sounding data were used to analyze the synoptic condition. The distribution of aerosol number concentration had a large variation from bigger particles more than 1.0 ${\mu}m$ in diameter by wind direction during precipitation. In the number concentration of aerosol particles with respect to the weather conditions, particles larger than 1.0 ${\mu}m$ in size were decreased and sustained to the similar concentration at smaller particles during precipitation. The increase in aerosol number concentration was due to the sea-salt particles which was suspended by southwesterly and upward winds. In addition, the aerosol number concentration with vertical wind flow could be related with the occurrence and increasing mechanism of aerosol in marine boundary layer.

• Atmosphere
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• v.26 no.2
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• pp.243-256
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• 2016

Total number concentration of aerosols larger than 10 nm ($N_{CN10}$), 3 nm ($N_{CN3}$), and cloud condensation nuclei ($N_{CCN}$) were measured during four different ship cruises over the Yellow Sea. Average values of $N_{CN10}$ and $N_{CCN}$ at 0.6% supersaturation were 6914 and $3353cm^{-3}$, respectively, and the minimum value of $N_{CN10}$ was $2000cm^{-3}$, suggesting significant anthropogenic influence even at relatively clean marine environment. Although $N_{CN10}$ and $N_{CN3}$ increased near the coast due to anthropogenic influence, $N_{CCN}$ was relatively constant and therefore $N_{CCN}/N_{CN10}$ ratio tended to decrease, suggesting that coastal aerosols were relatively less hygroscopic. In general $N_{CN10}$, $N_{CN3}$, and $N_{CCN}$ during the cruises seemed to be significantly influenced by wet scavenging effects (e.g. fog) and boundary layer height variation. Only one new particle formation (NPF) event was observed during the measurement period. Interestingly, the NPF event occurred during a dust storm event and spatial scale of the NPF event was estimated to be larger than 100 km. These results demonstrate that aerosol and CCN concentration over the Yellow Sea can vary due to various different factors.

• Journal of the Korean earth science society
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• v.42 no.5
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• pp.536-555
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• 2021

Sea-surface wind is an important variable in ocean-atmosphere interactions, leading to the changes in ocean surface currents and circulation, mixed layers, and heat flux. With the development of satellite technology, sea-surface winds data retrieved from scatterometer observation data have been used for various purposes. In a complex marine environment such as the Korean Peninsula coast, scatterometer-observed sea-surface wind is an important factor for analyzing ocean and atmospheric phenomena. Therefore, the validation results of wind accuracy can be used for diverse applications. In this study, the sea-surface winds derived from ASCAT (Advanced SCATterometer) mounted on MetOp-A/B (METeorological Operational Satellite-A/B) were validated compared to in-situ wind measurements at 16 marine buoy stations around the Korean Peninsula from January to December 2020. The buoy winds measured at a height of 4-5 m from the sea surface were converted to 10-m neutral winds using the LKB (Liu-Katsaros-Businger) model. The matchup procedure produced 5,544 and 10,051 collocation points for MetOp-A and MetOp-B, respectively. The root mean square errors (RMSE) were 1.36 and 1.28 m s^-1, and bias errors amounted to 0.44 and 0.65 m s^-1 for MetOp-A and MetOp-B, respectively. The wind directions of both scatterometers exhibited negative biases of -8.03° and -6.97° and RMSE values of 32.46° and 36.06° for MetOp-A and MetOp-B, respectively. These errors were likely associated with the stratification and dynamics of the marine-atmospheric boundary layer. In the seas around the Korean Peninsula, the sea-surface winds of the ASCAT tended to be more overestimated than the in-situ wind speeds, particularly at weak wind speeds. In addition, the closer the distance from the coast, the more the amplification of error. The present results could contribute to the development of a prediction model as improved input data and the understanding of air-sea interaction and impact of typhoons in the coastal regions around the Korean Peninsula.