Suchergebnisse

Air pollution, Nitrogen Oxides, Shipping, Atmospheric Chemistry, Satellite Observations, Climate Change. - Nitrogen oxide and dioxide emissions (NO NO2=NOx) by international shipping account for approximately 9-15% of NOx global emission totals. As NOx participates in the catalytic production of tropospheric ozone, global chemistry climate models cannot neglect ship induced NOx in their forecast of future atmospheric development. Both the knowledge of the NOx emission flux as function of time and place and an understanding of the chemical processes transforming NOx in the atmosphere are needed. This work addresses both aspects. The first part of this thesis analyses the method used by global models to include NOx ship emissions. For this purpose, the dispersion and chemical conversion of emissions in the near-field of a single ship are studied with two different modelling approaches. While both techniques use the same photochemical box model to solve the chemical equations, the dilution of the exhaust into the background air is different. One approach uses a Gaussian plume model and accounts for the expansion phase of a plume. The other one instantaneously disperses the emissions over a large gridbox, a technique commonly used by large scale models. The ozone change is overestimated by the global-model approach by up to a factor of three. One possibility to account for these sub-grid processes in global models is the use of effective emissions, i.e. actual emissions are changed and emissions of additional compounds like ozone are introduced in a way that they take sub-grid processes into account. It is shown for this case that the method is able to account for the neglect of sub-grid processes in global models for ...

Aus Sicht der DDR

Aus Sicht der DDR