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Characteristics of the atmospheric boundary layer over a scots pine forest

By D. Schindler

Abstract

The atmospheric boundary layer is structured vertically into several conceptual sublayers because the main airflow characteristics, e.g. the velocity field, air temperature, and air moisture, show different height dependent features. To investigate mean airflow characteristics over a Scots pine forest up to several stand heights, remote sensing and in situ measurements (profile and eddy covariance method) were conducted at the forest meteorological experimental site Hartheim in the Upper Rhine Valley. This methodological combination enables the continuous measurement of the main airflow characteristics exceeding the measuring range of tower-based measurements. Up to now airflow characteristics of the atmospheric boundary layer over forests exceeding the range of tower-based instrumentation are little experimentally studied because - remote sensing devices for operational use are available only for a short time, - of the extensive infrastructure and the problematic experimental setup. Therefore, airflow characteristics above and within forests were often studied based on selected time series and in a narrow range of atmospheric stability conditions when air-flow characteristics were most pronounced (Lu and Fitzjarrald, 1994; Brunet and Irvine, 2000). Furthermore, most of the knowledge of turbulent airflow characteristics and air mass exchange processes between tall plant canopies and the atmosphere has been gained of studies in relatively dense plant canopies (Green et al., 1995; Poggi et al., 2004). Few studies investigated turbulence characteristics in thinly stocked plant canopies such as the Hartheim Scots pine forest. Starting from these deficits the aim of this study is to examine airflow characteristics above and within the Hartheim Scots pine forest the under more general conditions as a function of - atmospheric stability conditions, - seasonal dynamics, up to a height of 200 m a.g.l. Target quantities are variables, which are suitable to describe the turbulent air mass exchange between the Scots pine forest and the atmosphere (e.g. normalised standard deviations of the wind vector components (#sigma#_u/u_*, #sigma#_w/u_*), integral streamwise and vertical length scales (L_u, L_w), streamwise and vertical velocity skewnesses (Sk_u, Sk_w)). (orig.)Available from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Topics: 08M - Atmospheric sciences, ATMOSPHERES, BOUNDARY LAYERS, FORESTS, PINES, METEOROLOGY, TURBULENT FLOW, AIR FLOW, STATISTICS, SEASONAL VARIATIONS
Year: 2004
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Provided by: OpenGrey Repository
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