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Mixed-Layer Depth Determination in the Barcelona Coastal Area From Regular Lidar Measurements: Methods, Results and Limitations 总被引:2,自引:0,他引:2
M. Sicard C. Pérez F. Rocadenbosch J. M. Baldasano D. García-Vizcaino 《Boundary-Layer Meteorology》2006,119(1):135-157
Regular aerosol backscatter measurements using an elastic-backscatter lidar were performed between May 2000 and December 2002
in Barcelona (Spain), within the framework of the European project EARLINET (European Aerosol Research Lidar Network). The
mixed-layer depth was one of the major parameters to be retrieved. Three derivative methods have been tested in this complex
coastal area using the range-squared-corrected lidar signal: (1) the minimum of its first derivative, (2) the minimum of its
second derivative, and (3) the minimum of the first derivative of its logarithm. The second method was found to give statistically
the best results when compared to radiosoundings, and was used to process the whole dataset. A number of 162 days and 660
profiles averaged over 30 min have been examined. Between 1000 and 1500 UTC, the mixed-layer depth oscillates between 300
and 1450 m in summer and between 390 and 1420 m in winter. The standard deviation for this portion of the day is 180 and 256
m, respectively, in summer and winter. In summer, low heights (mainly limited to 400–800 m) are associated with large mesoscale
compensatory subsidence over the sea and to the thermal internal boundary-layer formation. The strong coastal and orographic
influences and the climatological settling of Barcelona determine the complexity of the boundary-layer dynamics and the high
heterogeneity of the lidar signals. In many cases, single lidar analyses do not allow an unambiguous determination of the
mixed-layer depth. Two diurnal cycle measurements are discussed together with synoptic maps, backtrajectories and radiosoundings
in order to outline the complexity of the area and the limitations of the methods. 相似文献
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Ekaterine Batchvarova Svan-Erik Gryning Charlotte Bay Hasager 《Boundary-Layer Meteorology》2001,99(3):489-507
Based on measurements at Sodankylä Meteorological Observatory the regional (aggregated) momentum and sensible heat fluxes are estimated for two days over a site in Finnish Lapland during late winter. The forest covers 49% of the area. The study shows that the forest dominates and controls the regional fluxes of momentum and sensible heat in different ways. The regional momentum flux is found to be 10–20% smaller than the measured momentum flux over the forest, and the regional sensible heat flux is estimated to be 30–50% of the values measured over a coniferous forest.The regional momentum flux is determined in two ways, both based on blending height theory. One is a parameterised method, the other represents a numerical solution of an aggregation model. The regional sensible heat flux is determined from the theory of mixed-layer growth. At near neutral conditions the regional momentum flux can be determined independently of the regional sensible heat flux. At unstable conditions the two models become coupled.The information that is needed by the parameterised blending height method and by the mixed-layer evolution method in order to derive the regional fluxes of momentum and sensible heat can be obtained from radiosonde profiles of wind speed and temperature. 相似文献
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