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Titolo:
Water vapor flux measurements from ground-based vertically pointed water vapor differential absorption and Doppler lidars
Autore:
Giez, A; Ehret, G; Schwiesow, RL; Davis, KJ; Lenschow, DH;
Indirizzi:
DLR, Inst Atmospher Phys, Oberpfaffenhofen, Germany DLR OberpfaffenhofenGermany Atmospher Phys, Oberpfaffenhofen, Germany Natl Ctr Atmospher Res, Boulder, CO 80307 USA Natl Ctr Atmospher Res Boulder CO USA 80307 er Res, Boulder, CO 80307 USA
Titolo Testata:
JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY
fascicolo: 2, volume: 16, anno: 1999,
pagine: 237 - 250
SICI:
0739-0572(199902)16:2<237:WVFMFG>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
CONVECTIVE BOUNDARY-LAYER; 720-NM WAVELENGTH REGION; SYSTEM; TROPOSPHERE; TURBULENCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Giez, A DLR, Inst Phys Atmosphare, Postfach 116, D-82230 Wessling, GermanyDLR Postfach 116 Wessling Germany D-82230 82230 Wessling, Germany
Citazione:
A. Giez et al., "Water vapor flux measurements from ground-based vertically pointed water vapor differential absorption and Doppler lidars", J ATMOSP OC, 16(2), 1999, pp. 237-250

Abstract

For the first, time, two lidar systems were used to measure the vertical water vapor flux in a convective boundary layer by means of eddy correlation. This;was achieved by combining a water vapor differential absorption lidar and a; heterodyne wind lidar ina ground-based experiment. The results prove that the combined lidar system can determine vertical flux profiles with a height resolution of approximately 100 m. Vertical averaging oi er ii greater height interval reduces the error sufficiently that the changes in Aux occurring throughout the day as a result of solar heatingcan;be resolved. Horizontal and, fdr the first time, vertical integral scales were calculated from the lidar signals. The error analysis based on these results indicates that instrumental white noise and sampling error are the main sources of the statistical error in the flux measurement. Since thelidars measure simultaneously at many levels throughout the boundary layer; these errors can be reduced by vertical averaging to less than 50% for a;40 min time series,depending on how much vertical resolution is required inthe flux profile. The combined lidar system was used to measure the height-resolved water vapor flux associated with boundary layer circulations induced by active fair-weather cumulus clouds. A cloud-modulated flux of up to 300 W m(-2) was observed in the upper third of the boundary layer The measurement also showedthe breakdown of that flux during the transition from active to passive cumulus clouds.

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Documento generato il 04/12/20 alle ore 18:36:26