TY - JOUR
T1 - Approximated solution on the properties of the scavenging gap during precipitation using harmonic mean method
AU - Jung, Chang H.
AU - Bae, Soo Ya
AU - Kim, Yong P.
N1 - Funding Information:
This work was funded by the Korea Meteorological Administration Research and Development Program under Grant RACS 2010-3006 and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0008005).
PY - 2011/3
Y1 - 2011/3
N2 - Wet deposition refers to both natural and artificial processes where particles are scavenged by atmospheric hydrometeors. Below-cloud atmospheric particles are removed by raindrops via Brownian diffusion, interception, and impaction. The overall scavenging coefficient has a broad and distinctive minimum for aerosol penetration between 0.1 and several micrometers in diameter. In this study, the approximated analytical solution for most penetrating particle size during precipitation was obtained. Brownian diffusion and interception were considered under the assumption of the inertial impaction can be neglected in this study conditions. Both the minimum collection efficiency and minimum scavenging coefficient particle size were estimated using the harmonic mean type approximation, with the solution compared to the numerically calculated results. The approximated results were comparable with the numerical solutions. The results showed that collection efficiency diameter is a function of terminal velocity and the collection mechanisms included. When considering Brownian diffusion and interception, most penetrating particle size increases as drop diameter increases, which shows a contrary to the study of Wang (1978) and this shows that most penetrating particle size depends on collection efficiency mechanism, flow velocity and collector diameter. Consequently, this study analytically approximated general type-solutions for scavenging gap particle size and minimum collection efficiency during precipitation.
AB - Wet deposition refers to both natural and artificial processes where particles are scavenged by atmospheric hydrometeors. Below-cloud atmospheric particles are removed by raindrops via Brownian diffusion, interception, and impaction. The overall scavenging coefficient has a broad and distinctive minimum for aerosol penetration between 0.1 and several micrometers in diameter. In this study, the approximated analytical solution for most penetrating particle size during precipitation was obtained. Brownian diffusion and interception were considered under the assumption of the inertial impaction can be neglected in this study conditions. Both the minimum collection efficiency and minimum scavenging coefficient particle size were estimated using the harmonic mean type approximation, with the solution compared to the numerically calculated results. The approximated results were comparable with the numerical solutions. The results showed that collection efficiency diameter is a function of terminal velocity and the collection mechanisms included. When considering Brownian diffusion and interception, most penetrating particle size increases as drop diameter increases, which shows a contrary to the study of Wang (1978) and this shows that most penetrating particle size depends on collection efficiency mechanism, flow velocity and collector diameter. Consequently, this study analytically approximated general type-solutions for scavenging gap particle size and minimum collection efficiency during precipitation.
KW - Below cloud scavenging
KW - Harmonic mean
KW - Minimum collection efficiency particle size
KW - Minimum scavenging coefficient particle size
KW - Scavenging gap
UR - http://www.scopus.com/inward/record.url?scp=79451471844&partnerID=8YFLogxK
U2 - 10.1016/j.atmosres.2010.11.023
DO - 10.1016/j.atmosres.2010.11.023
M3 - Article
AN - SCOPUS:79451471844
SN - 0169-8095
VL - 99
SP - 496
EP - 504
JO - Atmospheric Research
JF - Atmospheric Research
IS - 3-4
ER -