Application of Variational Analysis of Wind Field Based on Lidar Conical Scans to Air Quality Monitoring

Abstract

Conical scans of Doppler LIDAR were made at a specific elevation angle to monitor the wind fields in cases of plume dispersion in western Australia. To better visualize the airflow patterns in relation to the plume direction, variational analysis is performed on the radial velocity data of the LIDAR to retrieve the 2D wind fields. Compared to the 4DVAR method, the 2D variational analysis as adopted in the present paper is computationally more efficient yet provides sufficient details of the flow patterns. Examples of the plume dispersion are shown with the 2D analyzed wind fields as presented in the paper. In general, the analyzed wind fields are consistent with the plume directions as observed from the backscattered power data of the LIDAR. A 2D wind retrieval algorithm developed for the Hong Kong International Airport (1) is used to derive the wind field from the Doppler LIDAR conical scans for an analysis of the plume dispersion at the Wagerup air quality monitoring experiment in Western Australia in 2006. The radial velocity data obtained from Doppler LIDAR scans are not straightforward for an interpretation of the wind vectors for relating to the plume dispersion. It would be quite handy to have the full wind vectors overlaid on top of the radial velocity data to assist the analysis of the wind dynamics and the dispersion mechanism. The 2D wind retrieval method is computationally more efficient than the four dimensional variational (4DVAR) LIDAR data analysis (2, 3). th and 29 th