Global Air Pollution Crossroads over the Mediterranean

TLDR

The Mediterranean Intensive Oxidant Study (summer 2001) mapped pollution layers extending from the surface up to 15 km. The study found that the boundary layer over the Mediterranean consistently exceeds air‑quality standards from European sources, aerosols diminish surface solar radiation and rainfall, while Asian and some North American pollutants reach the middle troposphere and even the lower stratosphere via upper‑tropospheric transport.

Abstract

The Mediterranean Intensive Oxidant Study, performed in the summer of 2001, uncovered air pollution layers from the surface to an altitude of 15 kilometers. In the boundary layer, air pollution standards are exceeded throughout the region, caused by West and East European pollution from the north. Aerosol particles also reduce solar radiation penetration to the surface, which can suppress precipitation. In the middle troposphere, Asian and to a lesser extent North American pollution is transported from the west. Additional Asian pollution from the east, transported from the monsoon in the upper troposphere, crosses the Mediterranean tropopause, which pollutes the lower stratosphere at middle latitudes.