Characterisation of the mixing height temporal evolution by means of a laser dial system in an urban area – intercomparison results with a model application

摘要

Measurements of vertical and temporal variations in ozone and aerosol asextinction over an urban area in Segovia, central Spain, were performedduring two summer months in 2004 by means of a commercial Nd:YAG laser DIALremote sensing system. The Differential Absorption Lidar (DIAL) techniquewas applied and its description is given. From the profile data, a practicaldetermination of mixing height may be derived. A diurnal evolution for thewhole dataset is observed, the highest mean mixing height being reached at16:00 GMT, 2150 m. The presence of a double-layer structure at night wasobserved and the layers can be considered residual. On average, the lowerlayer is formed at 670 m and the upper layer yielded mean heights rangingbetween 1270 and 1390 m. The estimated mixing heights during the day arealso compared with those obtained from the Lagrangian HYSPLIT model. Theresults show good statistical agreement between both approaches, mainly inthe early afternoon, with correlation coefficients around 0.7.