Extended Abstract (80K)P2.13
Finding Boundary Layer Top for the Stable Layer: Application of a Haar Wavelet Covariance Transform to Lidar Observations
Ian M. Brooks, SIO/Univ. of California, La Jolla, CA
The Haar wavelet has been used by a number of recent studies as a basis function for algorithms designed to detect transitions that can be idealized as step changes in a data series; for example the change in lidar backscatter at the top of the boundary layer. The method has been shown to work well for the determination of boundary layer top in well-mixed, convective conditions where the boundary-layer top is sharp and well defined. In the case of the stable boundary layer complications arise due to the less sharply defined nature of the inversion, the presence of multiple layers, and gradients in backscatter both within and above the boundary layer.
This paper examines the problems involved in applying the technique to these less than ideal conditions using lidar measurements from the NCAR Scanning Aerosol Backscatter Lidar (SABL) obtained during the Coastal Wave 96 field program off the coast of northern California. Problems arising during the course of the development of an algorithm to process the data are discussed and approaches to solving them presented. These include the identification of cloud, the presence of broken cloud below the inversion level, the presence of multiple layers and ‘stepped’ inversions, and the choice of appropriate wavelet dilations. The effectiveness of this approach is compared with that of a more traditional backscatter-gradient algorithm
A companion paper (Lidar Observations of Entrainment Zone Structure at the Top of the Stable Marine Atmospheric Boundary Layer) presents the results of the analysis.
Poster Session 2, Observational Methods
Monday, 15 July 2002, 2:00 PM-2:00 PM
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