The Flux Divergence Method Applied to Nitrogen Emissions in The Netherlands

Master thesis (2022)

Authors

C.A. Bryan Electrical Engineering, Mathematics and Computer Science

Contributors

A.W. Heemink Mathematical Physics - EEMCS (mentor)
H.J. Eskes Royal Netherlands Meteorological Institute (KNMI) (graduation committee member)
N.V. Budko Numerical Analysis - EEMCS (graduation committee member)
Faculty
Electrical Engineering, Mathematics and Computer Science, Electrical Engineering, Mathematics and Computer Science
Copyright: © 2022 Lotte Bryan
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Published Date

14-12-2022

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

Emission of ammonia and nitrogen oxides puts pressure on vulnerable ecosystems in The Netherlands. Satellite data from TROPOMI and CrIS gives vertical column density (VCD) maps for nitrogen dioxide and ammonia respectively. The Flux-Divergence method converts a VCD map to an emission map, by temporally averaging the divergence of the flux of the trace gas and estimating a sink term. This research proposes two improvements to the current implementation of the Flux-Divergence method at the KNMI for nitrogen dioxide. On the one hand, noise is reduced by computing the divergence before interpolating TROPOMI data to a regular grid. On the other hand, some emission locations are enhanced by reducing divergence in the wind field. An algorithm is provided to reduce this divergence. This thesis also explores the sensitivities of the method to different choices in its implementation. Finally, this research implements the Flux-Divergence method for ammonia. The thesis shows that, for ammonia, the method depends strongly on the estimation of the sink term, as the flux-divergence map is not able to capture homogeneous, spread-out emission sources.