Cloud/Fog Water Chemistry at a High Elevation Site in South Korea     

Man-Goo Kim  Bo-Kyoung Lee  Hyun-Jin Kim 《Journal of Atmospheric Chemistry》2006,55(1):13-29

Cloud/fog water samples were collected at Daekwanreung (840 m msl), a ridge site, in South Korea, from March 2002 to September 2003, by using a Caltech type, self fabricated active strand cloud water collector. The pH, electrical conductivity and major ion concentrations were analyzed. The cloud water pH ranged from 3.6 to 6.8 with an average of 5.2, which was close to the atmospheric neutral point. However, the pH calculated from average concentrations of H+ was 4.7, indicating the cloud/fog water was weakly acidified. SO₄ ²⁻, NO₃ ⁻ and NH₄ ⁺ are predominant ions of which average concentrations were 203.1, 128.1, and 211.7 μeq⋅L⁻¹, respectively. Samples were categorized into four groups by applying 48-hour back trajectory analysis, using the HYbrid Single-Particle Largrangian Integrated Trajectory (HYSPLIT) model. Chemical compositions for the four cases significantly differed from each other. For air masses transported from the East Sea (group E), sea salt concentrations, including Na⁺, Cl⁻ Mg²⁺, were relatively high. Principal acidifying pollutants, such as NO₃ ⁻ and nss-SO₄ ²⁻, significantly increased in the case of air masses transported from the Northeast Asian continent through North Korea (group N) and air masses from the Seoul metropolitan area (group W). However, the mean pH of group N was the highest while the mean pH of group W was the lowest. This suggests that most NO₃ ⁻ and nss-SO₄ ²⁻ in cloud/fog water was neutralized by ammonia and calcium compounds under the influence of air masses transported from Northeast Asia. N/S ratio for the group W was significantly higher than those for the other three groups, suggesting nitrogen species transported from the Seoul metropolitan area contributed to acidification of cloud/fog water at Daekwanreung. Principle Component analysis (PCA) was applied to the cloud/fog water data for presenting characteristics in the four different categories.  相似文献   

Parameterization of Entrainment in a Sheared Convective Boundary Layer Using a First-order Jump Model   总被引：1，自引：0，他引：1  

Si-Wan Kim  Soon-Ung Park  David Pino  Jordi Vilà-Guerau de Arellano 《Boundary-Layer Meteorology》2006,120(3):455-475

Basic entrainment equations applicable to the sheared convective boundary layer (CBL) are derived by assuming an inversion layer with a finite depth, i.e., the first-order jump model. Large-eddy simulation data are used to determine the constants involved in the parameterizations of the entrainment equations. Based on the integrated turbulent kinetic energy budget from surface to the top of the CBL, the resulting entrainment heat flux normalized by surface heat flux is a function of the inversion layer depth, the velocity jumps across the inversion layer, the friction velocity, and the convection velocity. The developed first-order jump model is tested against large-eddy simulation data of two independent cases with different inversion strengths. In both cases, the model reproduces quite reasonably the evolution of the CBL height, virtual potential temperature, and velocity components in the mixed layer and in the inversion layer.The part of this work was done when the first author visited at NCAR.  相似文献   

Effect of train dynamics on seismic response of steel monorail bridges under moderate ground motion     

Chul‐Woo Kim  Mitsuo Kawatani 《地震工程与结构动力学》2006,35(10):1225-1245

This study is intended to investigate the seismic response of steel monorail bridges using three‐dimensional dynamic response analysis. We particularly consider monorail bridge–train interaction when subjected to ground motion that occurs with high probability. A monorail train car with two bogies with pneumatic tires for running, steering and stabilizing wheels is assumed to be represented sufficiently by a discrete rigid multi‐body system with 15 degrees of freedom (DOFs). Bridges are considered as an assemblage of beam elements with 6 DOFs at each node. Modal analysis is used for dynamic response analysis under moderate earthquakes. The seismic response of an advanced monorail bridge that adopts a simplified structural system and composite girders is investigated through comparison with seismic responses of a conventional bridge. The acceleration response of a monorail train is also calculated to investigate the effect of structural types of bridges on the train's dynamic response during earthquakes. Results show that the seismic responses of the advanced bridges are greater than those of the conventional monorail bridge because of the simplified structural system and increased girder weight that is attributable to composite girders of the advanced bridge. Moreover, the train on the advanced bridge shows greater dynamic response than that on the conventional bridge. Observations reveal that the dynamic monorail train system acts as a damper on the monorail bridge. That fact shows that the existing design, which considers a train as additional mass, yields a conservative result. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Seasonal trend of particulate PAHs at Gosan, a background site in Korea between 2001 and 2002 and major factors affecting their levels     

Ji Yi Lee  Yong Pyo Kim  Chang-Hee Kang  Young Sung Ghim   《Atmospheric Research》2006,82(3-4):680

The concentrations of particulate Polycyclic aromatic hydrocarbons (PAHs) were measured at Gosan, a background site in Korea for 1 year between November 2001 and November 2002. The total concentrations of 14 PAH compounds at Gosan were between 0.52 and 14.76 ng m^− 3 and about 3–15 times higher than those at other rural or remote sites in the world. Seasonal trend was observed for particulate PAHs concentrations at Gosan with higher levels during heating season due to increased fossil fuel usage and the movement of air parcels from Asian continent. Principal component factor analysis (PCF) for PAHs showed three factors; combination of coal combustion and vehicular emission, natural gas combustion, and unidentified one. However, PCF for the combined data of PAHs, inorganic ions, and elements revealed that the unidentified factor consists of crustal species, sea salts, and four PAH compounds. Thus, this factor is thought to be transport of crustal species with organics from combustion sources. The major variables which determine the sources of PAHs are the heating season and the movement of air parcels from Asian continent.  相似文献   

Comparison of satellite measurements of the low-latitude nighttime upper ionosphere with IRI     

Heejun Kim  Kyoungwook Min  Jaeheung Park  Jaejin Lee  Ensang Lee  Hyosub Kil  Vitaly P. Kim  Sunmie Park 《Journal of Atmospheric and Solar》2006,68(18):2107-2118

In this paper, we report the results of our comparison study between satellite measurements and the International Reference Ionosphere (IRI) model on the seasonal and longitudinal changes of the low-latitude nighttime topside ionosphere during the period of solar maximum from June 2000 to July 2001. Satellite measurements were made by KOMPSAT-1 and DMSP F15 at 685 km altitude and 840 km altitude, respectively. The results show that the IRI2001 model gives reasonable density estimations for the summer hemisphere and the March equinox at both altitudes. However, the observed wintertime densities are smaller than the predictions of the IRI2001 model, especially at a higher (840 km) altitude, manifesting strong hemispheric asymmetries. The observed electron temperatures generally reside between the two estimations of IRI2001, one based on the Aeros–ISIS data and the other based on Intercosmos, and the latter estimation better represents the observations. With more or less monotonic increase with latitude, the temperature profiles of the IRI2001 model do not predict the enhancement seen around 15° magnetic latitude of the winter hemisphere. Longitudinal variation, probably caused by the zonal winds, is seen in all seasons at both altitudes, while the IRI2001 model does not show a large variation. The observed density and temperature show significant changes according to the F10.7 values in the whole low-latitude region from 40°S to 40°N geomagnetic latitude. The effect is manifested as increases in the density and temperature, but not in the hemispheric asymmetry or in the longitudinal variation.  相似文献   

激发极化法在呼市草原水源勘探中的应用   总被引：1，自引：0，他引：1  

孟建春  池海 《中国煤田地质》2006,18(2):62-63,68

在呼市草原古隆起带，第四系地层沉积较薄，地下1-5m即为安山岩，玄武岩和火山碎屑岩，找水有一定难度。为得到可靠的电性参数，减小测量误差，府保证一次电位差不于小300mV，并采用无极差电极作测量电极，以增大Ip测量信号。在总结该区宴测资料的基础上，绘制出不同富水程度的地电响应特征。  相似文献   

Comparison of two physical sensor models for satellite images: Position–Rotation model and Orbit–Attitude model     

Taejung  Kim  Ian  Dowman 《The Photogrammetric Record》2006,21(114):110-123

The main objective of this paper is to compare two types of physical sensor models of linear pushbroom satellite images: one that uses position and rotation angles as model parameters and one that uses orbit and attitude angles as model parameters. Comparison is carried out by two accuracy measures: the accuracy of bundle adjustments and the accuracy of estimating exterior orientation parameters. The first measure has been used widely to indicate the mapping accuracy of sensor models. It is argued that the second measure is also important for certain applications. The two types were implemented with different sets of unknown parameters and tested with two KOMPSAT-1 Earth Observing Camera (EOC) scenes and GPS-derived control points. In terms of the first measure the two models produced similar results whereas in terms of the second measure the one based on orbit and attitude outperformed the other. It seems better to use this model if one wishes to retrieve satellite orbit or attitude through bundle adjustments.  相似文献   

Mapping of Titan's tropopause and surface temperatures from Voyager IRIS spectra     

R. Courtin  S.J. Kim 《Planetary and Space Science》2002,50(3):309-321

  相似文献   

A k - *epsiv Turbulence Closure Model For The Atmospheric Boundary Layer Including Urban Canopy     

Vu Thanh Ca  Yasunobu Ashie  Takashi Asaeda 《Boundary-Layer Meteorology》2002,102(3):459-490

A numerical model for the computation of the wind field,air temperature and humidity in the atmospheric boundary layer (ABL) including the urbancanopy was developed for urban climate simulation. The governing equations of the modelare derived by applying ensemble and spatial averages to the Navier–Stokes equation, continuityequation and equations for heat and water vapour transfer in the air. With the spatial averagingprocedure, effects of buildings and other urban structures in the urban canopy can be accounted for byintroducing an effective volume function, defined as the ratio between the volume of air in acomputational mesh over the total volume of the mesh. The improved k - model accounts for the anisotropyof the turbulence field under density stratification. In the improved k - model, the transportof momentum and heat in the vertical direction under density stratification is evaluated based onthe assumption of a near-equilibrium shear flow where transport effects on the stresses andheat fluxes are negligible. The heating processes at surfaces of buildings and ground are alsomodelled. The comparison of the computational results obtained with the present modeland existing observational data and numerical models shows that the present model is capableof predicting the structure of turbulence in the urban canopy layer under density stratification.Numerical experiments with the new model show that the flow behaviour of the air in the urbancanopy layer is strongly affected by the existence of buildings and density stratification.  相似文献   

Forest fire ash impact on micro- and macroalgae in the receiving waters of the east coast of South Korea     

Shin HW  Sidharthan M  Young KS 《Marine pollution bulletin》2002,45(1-12):203-209

Mountain forest fire ash flushed into the eastern coastal waters of South Korea is known to contain cadmium as one of its significant constituents. To study its impact, two representatives of the micro- and macroalgal communities, Ulva pertusa and Nannochloropsis oculata, were exposed to the concentration range of Cd indicated from the forest fire localities. At low concentrations of 0.224–0.448 mg L⁻¹, a 20% reduction in growth rate of N. oculata was observed. Chlorophyll a pigment concentration was proportionate to the growth reduction while at higher concentrations (1.792 mg L⁻¹) pigments were completely leached. In the macrophyte U. pertusa, a similar trend of pigment leaching was observed. Bioaccumulation factors obtained for these rapidly growing algal species revealed excessive bioconcentration of Cd. Variations in the concentration of Cd among the samples collected along the Korean coast clearly indicated the additional source of metal influx from the forest fires.  相似文献