L’area sorgente dei flussi superficiali: stima sperimentale con misure di correlazione turbolenta su piccola scala
Author(s)
Arriga, Nicola
Date Issued
February 10, 2009
Type
Doctoral Thesis
Abstract
In this thesis we faced the experimental evaluation of footprint of mass and
energy fluxes measured by eddy correlation technique. Specifically the behaviour of
routinely exploited systems has been tested in situation of restricted surface of the
fluxes source area and with sampling extremely close to the exchange interface, to test
the reliability of small scale measurements. With this objective three distinct experimental setups have been implemented with multiple identical equipment of eddy correlation for the estimate of carbon dioxide fluxes, each one realized with a sonic anemometer and an open path infrared gas analyzer In the first experiment characteristics of turbulence measurements have been
evaluated at different heights, both routinely used in the practice both exceptionally
close to the ground, while in the remaining two we manipulated natural and artificial sources of CO2 whose flux has been detected at different heights.
This allowed us to highlight the most limiting factors in the exploitation of turbulent measurements at very small distances, of the order of some tens of centimetres, away from the exchange surface and the technical upgrades to be tested in these situations. Moreover the experimental estimates of source area extension with the two distinct methods of natural and artificial emission of carbon dioxide indicated a
limited extension of surface influencing measurement systems. Results showed a
reduction of approximately one order of magnitude of the source area, both empirically
evaluated both using a commonly adopted analytical footprint model.
The development directions are already well delimited and consist essentially in
the use of different technical solutions for the measurements on small spatial scales and
in the improvement of the simulations of the detectors footprint with most recent
developments of computational fluid dynamics.
Additional information
Dottorato di ricerca in Ecologia forestale
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