This story first appeared in the SERC quarterly Newsletter Fall 2006

Attenuating Circumstances

Catching some rays in Greece with SERC Research Associate Maria Tzortziou is no day at the beach. This summer, Tzortziou spent the better part of July on the roof of the Physics Department of the Aristotle University of Thessaloniki analyzing solar radiation.

She was participating in a multi-national research effort by NASA and the University to learn how aerosols and trace gases modulate ultraviolet (UV) radiation from the sun, and providing ground measurements of ozone, trace gases and aerosol columns to compare with and validate satellite readings.

Ozone and aerosols such as smog and soot from pollution absorb and scatter UV rays and can reduce UV-radiation reaching the Earth. Estimates suggest that sulfate aerosols (primarily from burning fossil fuels) have decreased surface UV-B irradiances by five to 18 percent in some heavily industrialized regions of the northern hemisphere. However, not all aerosols scatter and absorb UV in the same way. While scattering by aerosols always decreases the total amount of surface UV irradiance, it can actually increase the UV exposure on non-horizontal surfaces, such as your face.

The summer field research is part of a larger effort called the SCOUT-03 program (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere) which aims to inform policy-makers about the connections between air chemistry, changes in ozone and UV radiation and climate impacts.

For more information, or to reach Dr. Tzortziou, please contact SERC science writer Kristen Minogue.