Model studies of the meteorology and chemical composition of the troposphere over the North Atlantic during August 18-30, 1993

A mesoscale chemistry transport model driven by meteorological data from a numerical weather prediction model is used to calculate ozone, carbon monoxide, oxides of nitrogen, and other chemical species over the North Atlantic for a 13-days period (August 18-30, 1993). The model has a circumpolar grid so that the boundary condition problems are minimized, and the influence of North American emissions on the chemical composition of the troposphere over the North Atlantic and Europe is calculated. During the first part of the period there is a zonal flow across the North Atlantic in the free troposphere; later, there is a strong north-south as well as vertical component in the advection field. The variability in the concentrations of ozone in the free troposphere is mainly caused by dynamical processes, while the chemical modification is small over an integration time of less than two weeks. A continental plume off the North American continent extending 2000 km or more into the North Atlantic is identified toward the end of the calculation period. There is then a maximum in the concentration of ozone around 1 km above the sea surface, with a much lower concentration in the marine boundary layer close to the ocean surface. Measurements from the U.K. Meteorological Office Hercules C-130 in the free troposphere off the Atlantic Provinces, across the Atlantic Ocean, and around the Azores together with ozone soundings from the Azores, Bermuda, and Iceland were used for model comparison. The calculations indicate that in the free troposphere the initial conditions as well as the upper boundary conditions are important for ozone distribution. In the upper troposphere the net change in the chemical formation rate of ozone due to a change in the NOx concentration is quite independent of the absolute value of the ozone concentration itself and, consequently, the choice of boundary conditions for ozone is not so important in this context, In the lower troposphere the change in the net chemical formation rate of ozone, which follows from a change in the concentration of NOx, shows a marked dependence on the concentration of ozone

Regional Nitric Oxide Enhancements in the North Atlantic Flight Corridor Observed and Modeled during POLINAT 2 - A Case Study

In situ measurements of nitrogen oxides and other trace chemicals were performed aboard the DLR Falcon in September and October 1997 during POLINAT 2 over the eastern North Atlantic in areas with predicted high impact of aircraft emissions to search for flight corridor effects. During survey flights in the upper troposphere from the centre of the flight corridor to regions south of or below the major transatlantic aircraft routes, large-scale enhancements in mixing ratios of NO of about 50 to 150 pptv were observed in corridor areas compared to the NO abundance measured outside the corridor. Using simultaneous tracer measurements, back trajectory analyses for the air masses sampled, the actual distribution of the North Atlantic air traffic, and comparisons of observed and predicted NO distributions from a regional model of simulations including or excluding aircraft emissions, these enhancements were attributed mainly to aircraft NOx

Contribution of forest fire emissions in atmospheric pollutant levels

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: 8 th International Conference Protection and Restoration of the Environment VII

Contribution of natural emissions to atmospheric pollution in the eastern mediterranean area

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: European Aerosol Conferenc