A. K. Weiss

First comparison between ground‐based and satellite‐borne measurements of tropospheric nitrogen dioxide in the Po basin

in the Mount Cimone area is good (R 2 = 0.9) with the mixing properties of the atmosphere being the most important parameter for a valid comparison of the measurements. However, even when the atmospheric mixing properties are optimal for comparison, the ratio between GOME and ground-based tropospheric column data may not be unity. It is demonstrated that the values obtained (less than 1) are related to the fraction of the satellite ground pixel occupied by the NO2 hot spot. INDEX TERMS: 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry; 0360 Atmospheric Composition and Structure: Transmission and scattering of radiation; KEYWORDS: tropospheric NO2, satellite validation, Po basin

Long-term ozone trends in Northern mid-latitudes with special emphasis on the contribution of changes in dynamics

Abstract Monitoring indicates that stratospheric ozone strongly decreased in the polar regions, most seriously over the Antarctica. It is widely accepted that polar ozone loss is caused by heterogeneous processes activating halogen radicals which originate from the man-made release of ozone depleting substances. Significant ozone decrease peaking in winter/spring also has been observed in mid-latitudes. It started around the beginning of the 1970s. In this paper we review recent studies which indicate that not only long-term trends in chemical composition but also long-term changes in the dynamical structure of the atmosphere have significantly contributed to the ozone decrease over mid-latitudes. Such changes most strongly affected the ozone shield in the lower stratosphere and over Europe. However, they also influence ozone over the entire extra-tropical Northern hemisphere.