Una nuova metodologia per lo studio delle dinamiche di emissione di polveri minerali dal deserto del Gobi (Cina settentrionale) mediante eddy covariance e per la valutazione dell' impatto della vegetazione nella mitigazione dei processi di desertificazione
Author(s)
Fratini, Gerardo
Date Issued
September 12, 2008
Type
Doctoral Thesis
Abstract
In this thesis we address a new methodology for studying wind erosion, with particular reference to the development of a new instrumentation for measuring dust emissions. The instrumentation, called EOLO and based on the eddy covariance approach, was optimized for measuring vertical fluxes of mineral dust during intense erosion events and specifically designed to serve as a model validation tool. The system makes use of a 3D sonic anemometer and of an optical particle counter and provides size-segregated number fluxes on a 30-minutes base. Surface, volume and mass fluxes are also estimated.
EOLO was firstly applied in two monitoring campaigns in Northern China, in the framework of the WinDust project. It has been used to evaluate emission fluxes during a dust storm in the Gobi desert, and to investigate the relation between such fluxes and friction velocity. The effects of natural vegetation on the emissions during this event is addressed and analyzed; results are also compared with simulations from a wind erosion model. Although limited by the number of events recorded, results obtained provide useful information to parameterize the emission process during both dust storms and intense emission events.
EOLO has been also used to evaluate the potentialities of emission reduction of mitigation interventions, such as large scale, air-sowing reforestation and field scale implementations of conservative agricultural practice. First results show that reductions can vary from 40% in the case of conservative agriculture, to 99% in the case of air-sowing. However, further research is needed to assess the quality of the measurements, to quantify biases and uncertainties related to the measuring chain and to strengthen reliability of results.
Additional information
Dottorato di ricerca in Ecologia forestale
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