Estimating the components of the sensible heat budget of a tall forest canopy in complex terrain |
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| Authors: | U Moderow C Feigenwinter C Bernhofer |
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| Institution: | 1.Institute of Hydrology and Meteorology, Department of Meteorology,Technische Universit?t Dresden,Dresden,Germany;2.Institute of Meteorology, Climatology and Remote Sensing,University of Basel,Basel,Switzerland;3.Unitè de Physique des Biosytèmes,Gembloux,Belgium |
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| Abstract: | Ultrasonic wind measurements, sonic temperature and air temperature data at two heights in the advection experiment MORE II
were used to establish a complete budget of sensible heat including vertical advection, horizontal advection and horizontal
turbulent flux divergence. MORE II took place at the long-term Carbo-Europe IP site in Tharandt, Germany. During the growing
period of 2003 three additional towers were established to measure all relevant parameters for an estimation of advective
fluxes, primarily of CO2. Additionally, in relation to other advection experiments, a calculation of the horizontal turbulent flux divergence is proposed
and the relation of this flux to atmospheric stability and friction velocity is discussed. In order to obtain a complete budget,
different scaling heights for horizontal advection and horizontal turbulent flux divergence are tested. It is shown that neglecting
advective fluxes may lead to incorrect results. If advective fluxes are taken into account, the sensible heat budget based
upon vertical turbulent flux and storage change only, is reduced by approximately 30%. Additional consideration of horizontal
turbulent flux divergence would in turn add 5–10% to this sum (i.e., the sum of vertical turbulent flux plus storage change
plus horizontal and vertical advection). In comparison with available energy horizontal advection is important at night whilst
horizontal turbulent flux divergence is rather insignificant. Obviously, advective fluxes typically improve poor nighttime
energy budget closure and might change ecosystem respiration fluxes considerably. |
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| Keywords: | Advection Divergence Energy budget Sensible heat flux |
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