期刊
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
卷 137, 期 -, 页码 190-203出版社
WILEY-BLACKWELL
DOI: 10.1002/qj.757
关键词
turbulent moisture flux; convective boundary layer; differential absorption lidar
资金
- Deutsche Forschungsgemeinschaft (DFG) [SPP-1167, WU 356/42]
Vertical profiles of the latent heat flux in a convective boundary layer (CBL) are obtained for the first time over complex terrain with airborne water vapour differential absorption lidar and Doppler wind lidar. During the Convective and Orographically-induced Precipitation Study (COPS) over the Black Forest mountains in south-western Germany both lidars were installed nadir-viewing onboard the Falcon research aircraft of the Deutsches Zentrum fur Luft- und Raumfahrt (DLR). On 30 July 2007, additional in situ measurements by the Karlsruhe Institute of Technology (KIT) were performed with a Dornier-128 aircraft that flew below the Falcon. This unique instrument configuration allows us to validate the lidar-derived fluxes and to assess lidar-specific issues such as instrument noise and data gaps that impinge on the results. The cospectra of in situ humidity and vertical velocity peak at wavelengths between 1 and 3 km and reveal that the dominant scales of turbulent transport are larger than 700 m in dimension. Consequently the airborne lidars' horizontal and vertical resolution of similar to 200 m is sufficient to capture most of the flux. The lidar and in situ fluxes of five collocated 45 km flight legs agree within +/- 20%; the average difference over the total distance of 225 km is 3%. A flux comparison with ground-based water vapour Raman and wind lidars shows agreement within the instruments' accuracies under low-wind conditions. All latent heat fluxes vary between 100 and 500 W/m(2) in the CBL and have small vertical divergences. Vertical velocity spectra in the mid-CBL enable us to estimate the dissipation rate of turbulent kinetic energy that amounts to 5 x 10(-4) m(2) s(-3) in the Rhine Valley and 10(-3) m(2) s(-3) over the Black Forest mountains. This new airborne lidar instrumentation proves to be a valuable tool for the study of CBL processes and variability, particularly over complex terrain. Copyright (C) 2011 Royal Meteorological Society
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