Trend Analysis of Stratospheric BrO: Comparison between SCIAMACHY LIMB and Ground-Based UV-Visible Observations
Francois Hendrick(1), Alexei Rozanov(2), Paul Johnston(3), Olga Puentedura(4), Heinrich Bovensmann(2), John Burrows(2), Martine De Mazière(1), Manuel Gil(4), Karin Kreher(3), Bjoern-Martin Sinnhuber(2), Nicolas Theys(1) and Michel Van Roozendael(1)
(1) BIRA-IASB, 3, Avenue Circulaire, B-1180 Brussels, Belgium
(2) University of Bremen, P.O. Box 330440, D-28334 Bremen, Germany
(3) NIWA, Omakau, Central Otago, New Zealand
(4) INTA, , Torrejon de Ardoz, Spain
Recently, long-term time-series of ground-based UV-visible observations of stratospheric bromine monoxide (BrO) have revealed a decline in the stratospheric bromine loading. Given the mean age of air in the stratosphere, this trend follows the reported decline of long-lived bromine source gases observed since 1998, as a result of the Montreal Protocol restrictions limiting the production of brominated and chlorinated substances.
In the present study, a trend analysis is performed of stratospheric BrO vertical profiles measured by the SCIAMACHY limb instrument aboard the ENVISAT satellite. A statistical model including a linear trend and seasonal components represented by polyharmonic functions is used. The inclusion of such functions in the model enables to fit the strong seasonality of BrO in the stratosphere. We focus on SCIAMACHY observations collocated with four NDACC (Network for the Detection of Atmospheric Composition Change) stations where long-term times-series of ground-based UV-visible measurements of stratospheric BrO are available: Harestua (60°N, 11°E), Observatoire de Haute Provence (44°N, 6°E), Izaňa (28°N, 16°W), and Lauder (45°S, 170°E). Preliminary comparison results at Harestua show good consistency between the trend values obtained from SCIAMACHY limb and ground-based UV-visible observations.