Mi-Young Kang

The Fluctuation of Aerosol Number Concentration by Wind Field Variation during Snowfall at the Southwestern Coastal Area

To understand the development mechanism of the aerosols in the surface boundary layer, the variation in the aerosol number concentration due to the divergence and convergence of the wind fields was investigated. The aerosol number concentration was measured in the size ranges of using a laser particle counter(LPC) from 0000 LST on 03 Feb. to 0600 LST on 07 Feb. 2004 at Mokpo in Korea during snowfall. The Velocity Azimuth Display(VAD) technique was used to retrieve the radar wind fields such as the horizontal wind field, divergence, and deformations including the vertical air velocity from a single Doppler radar. As a result, the distribution of the aerosol number concentration is apparently different for particles larger than during snowfall, and it has a tendency to increase at the beginning of the snowfall. The increase and decrease in the aerosol concentration due to the convergence and divergence of the wind fields corresponded to the particles with diameters greater than . It is found that the fluctuations in the aerosol number concentration are well correlated with the development and dissipation of snowfall radar echoes due to the convergence and divergence of horizontal wind fields near the surface boundary layer in the inland during the snowfall.

Rainfall Estimation Using Specific Differential Phase for the First Operational Polarimetric Radar in Korea

To assess the performance of rainfall estimation using specific differential phase observed by Bislsan radar, the first polarimetric radar in Korea, three rainfall cases occurring in 2011 were selected, each caused by different conditions: the first is the Changma front and typhoon, the second is only the Changma front, and the third is only a typhoon. For quantitative use of specific differential phase (), a data quality algorithm was developed for differential phase shift (), composed of two steps; the first involves removal of scattered noise and the second is unfolding of . This order of the algorithm is necessary so as not to remove unfolded areas, which are the real meteorological target. All noise was removed and the folded were unfolded successfully for this study. relations for S-band radar were calculated for 84,754 samples of observed drop size distribution (DSD) using different drop shape assumptions. The relation for the Bringi drop shape showed the best statistics: 0.28 for normalized error, and 6.7 mm for root mean square error for rainfall heavier than 10 mm . Because the drop shape assumption affects the accuracy of rainfall estimation differently for different rainfall types, such characteristics should be taken into account to estimate rainfall more accurately using polarimetric variables.