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Park S.-U.,Center for Atmospheric and Environmental Modeling | Park M.-S.,Engine World
Atmospheric Environment | Year: 2014

Aerosol size distributions of observed mass concentrations at the Naiman site in Inner Mongolia that is one of the major Asian dust source regions have been examined for the period from April 2010 to July 2012. The total number of 262 sampled data using the 10-stage quartz crystal microbalance (QCM) cascade impactor is obtained by presetting the frequency changes of 40Hz during April 2010, 60Hz for the period of 28 April-16 September 2010 and 70Hz from 1 November 2010-29 July 2012. The total mass concentrations (PM10) measured by the QCM cascade impactor are modified to have the same sampling time of 60min with the help of the 1-h averaged PM10 concentration measured by the beta gauge at the same site. These modified QCM data are classified into the local dust emission case of 196 and the dust advection case of 66. The local dust emission case is defined when the calculated dust flux with the two-level (3m and 15m high) measured PM10 concentrations by the beta-gauge is upward and the PM10 concentration measured at 3m high exceeds 100μgm-3 while all the rest of QCM sampled data are classified as the dust advection case. The results indicate that the spectral mass concentration distribution of the local dust emission case shows a two-modal distribution with one additional mode of the large particle that cannot be resolved by the QCM cascade impactor whereas that of the advection case reveals a three-modal distribution with one additional unresolved large particle mode. The percent spectral mass concentration distribution of the unresolved mode (stage 1) for the local dust emission case is larger than that for the dust advection case. The modal distributions of both cases can be regressed optimally with log-normal distribution functions. The resolved log-normal distribution functions of the mass concentration distribution by the QCM cascade impactor are found to be the particle mean diameter (the standard deviation) of 0.28 (2.07) and 3.15μm (1.41μm) for the local emission case and 0.16 (1.51), 0.60 (1.41) and 2.88μm (1.38μm) for the advection case. This clearly suggests that the spectral mass concentration shifts toward the larger particle size for the local emission case. © 2013 Elsevier Ltd. Source

Park S.-U.,Center for Atmospheric and Environmental Modeling
Atmospheric Environment | Year: 2015

Aerosol Modeling System (AMS) that is consisted of the Asian Dust Aerosol Model2 (ADAM2) and the Community Multi-scale Air Quality (CMAQ) modeling system has been employed to document the geographical distributions of both the annual averaged Asian dust aerosol and the anthropogenic aerosols concentrations and their total depositions in the East Asia region for the year 2010. It is found that AMS simulates quite well the monitored PM10 concentration with a root mean square error (RMSE) of 9.2μgm-3 and a normalized mean square error (NMSE) of 5.5% in South Korea and the RMSE of less than 33μgm-3 with a NMSE of less than 7.8% at the monitoring sites in China. The annual mean surface (column integrated) aerosol concentrations in the East Asia region affect in a wide region as a complex mixture of the Asian dust (AD) aerosol and the anthropogenic aerosol (AA), more predominated by the AD aerosol in the Asian dust source region of northern China and Mongolia with the annual mean (column integrated) PM10 concentration of more than 200μgm-3 (350mgm-2). Whereas AA is dominated in the high pollutant emission regions of southern and eastern China and northern India with the annual mean surface (column integrated) concentration of more than 110μgm-3 (140mgm-2) in eastern China. On the other hand the mixed aerosols (AD+AA) are dominated in the downwind regions of the Yellow Sea, the East China Sea, the Korean peninsula, Japan, and the Northwest Pacific Ocean. It is also found that the annual total deposition of aerosols in the model domain is 4.9×108t (3.7×108t by AD aerosol and 1.2×108t by AA), of which 66% (3.2×108t) is found to be contributed by the dry deposition (3.1×108t by AD aerosol and 1.3×107t by AA) and 34% (1.7×108t) by the wet deposition (1.0×108t by AA and 6.6×107t by AD aerosol), suggesting significant impacts of aerosols on environment and the terrestrial and marine eco-systems in East Asia. © 2015 Elsevier Ltd. Source

Park M.-S.,Center for Atmospheric science and Earthquake Research | Joo S.J.,Center for Atmospheric and Environmental Modeling | Park S.-U.,Center for Atmospheric and Environmental Modeling
Advances in Atmospheric Sciences | Year: 2014

The carbon dioxide (CO2) concentrations and fluxes measured at a height of 17.5 m above the ground by a sonic anemometer and an open-path gas analyzer at an urban residential site in Seoul, Korea from February 2011 to January 2012 were analyzed. The annual mean CO2 concentration was found to be 750 mg m-3, with a maximum monthly mean concentration of 827 mg m-3 in January and a minimum value of 679 mg m-3 in August. Meanwhile, the annual mean CO2 flux was found to be 0.45 mg m-2 s-1, with a maximum monthly mean flux of 0.91 mg m-2 s-1 in January and a minimum value of 0.19 mg m-2 s-1 in June. The hourly mean CO2 concentration was found to show a significant diurnal variation; a maximum at 0700-0900 LST and a minimum at 1400-1600 LST, with a large diurnal range in winter and a small one in summer, mainly caused by diurnal changes in mixing height, CO2 flux, and surface complexity. The hourly mean CO2 flux was also found to show a significant diurnal variation, but it showed two maxima at 0700-0900 LST and 2100-2400 LST, and two minima at 1100-1500 LST and 0300-0500 LST, mainly caused by a diurnal pattern in CO2 emissions and sinks from road traffic, domestic heating and cooking by liquefied natural gas use, and the different horizontal distribution of CO2 sources and sinks near the site. Differential advection with respect to wind direction was also found to be a cause of diurnal variations in both the CO2 concentration and flux. © 2014 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg. Source

Jugder D.,Institute of Meteorology and Hydrology | Jugder D.,Tottori University | Shinoda M.,Tottori University | Sugimoto N.,Japan National Institute of Environmental Studies | And 5 more authors.
Global and Planetary Change | Year: 2011

Dust mass concentrations of PM10 and PM2.5 from four monitoring stations in the Gobi Desert region of Mongolia were analyzed for a 16-month period in 2009-2010. Annual averaged PM10 concentration ranged from 9μgm-3 to 49μgm-3 at these stations during 2009. Concentrations were high in winter owing to air pollution and in spring owing to dust storms; the monthly mean concentrations of PM10 (PM2.5) at the three stations except for Sainshand reached yearly maxima in December and January, ranging from 60 (38) μgm-3 to 120 (94) μgm-3. Diurnal variations of PM10 and PM2.5 concentrations at two sites, Dalanzadgad and Zamyn-Uud, included two maxima in the morning and evening and two minima in the afternoon and early morning. However, at Erdene PM10 maxima occurred in the afternoon and evening. Both PM10 and PM2.5 concentrations were enhanced from March to May by dust storms. Dust storms raised huge amounts of fine dust particles in the Gobi of Mongolia. Maximum daily mean PM10 (PM2.5) concentrations reached 821 (500) μgm-3 at Dalanzadgad, 308 (129) μgm-3 at Zamyn-Uud, and 1328μgm-3 at Erdene. Hourly maximum PM10 (PM2.5) concentrations were as high as 6626 (2899) μgm-3 at Dalanzadgad during a dust storm. © 2011 Elsevier B.V. Source

Park S.-J.,Seoul National University | Park S.-U.,Center for Atmospheric and Environmental Modeling | Ho C.-H.,Seoul National University
Terrestrial, Atmospheric and Oceanic Sciences | Year: 2010

Latent heat flux at the surface is largely dependent on the roughness length for water vapor (z0q). The determination of z0q is still uncertain because of its multifaceted characteristics of surface properties, atmospheric conditions and insufficient observations. In this study, observed values from the Fluxes Over Snow Surface II field experiment (FLOSS-II) from November 2002 to March 2003 were utilized to estimate z 0q, over various land surfaces: bare soil, snow, and senescent grass. The present results indicate that the estimated z0q, over bare soil is much smaller than the roughness length of momentum (z0m; thus, the ratio z0m/z0q, is larger than those of previous studies by a factor of 20 -150 for the available flow regime of the roughness Reynolds number, Re. > 0.1. On the snow surface, the ratio is comparable to a previous estimation for the rough flow (Re. > 1), but smaller by a factor of 10 - 50 as the flow became smooth (Re. < 1). Using the estimated ratio, an optimal regression equation of Z0m/z0q is determined as a function of Re. for each surface type. The present parameterization of the ratio is found to greatly reduce biases of latent heat flux estimation compared with that estimated by the conventional method, suggesting the usefulness of current parameterization for numerical modeling. Source

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