Reunion Island, 21°S

Introduction

In the perspective of the installation (not before 2010) of a new NDACC station on Mt Maido (2200m), Reunion Island, BIRA-IASB has already operated a MAX-DOAS instrument at Saint Denis (21°S), for one year (from July 2004 to July 2005). The instrument covered a very large spectral window, from 300 nm to 450 nm in order to measure, NO2, BrO, HCHO and also to detect SO2 events.

Instrument and operation

The MAXDOAS instrument consisted of a grating spectrometer covering the spectral range from 300 to 450 nm and a back-illuminated CCD operated at -40°C. A fiber optic bundle mounted on a telescope and coupled to a rotating mirror was used to collect the skylight scattered at different elevation angles from 3° to zenith within a field of view of approximately one degree. The whole system was placed inside a thermally regulated container directed towards the north.

View of the Reunion Island instrument in 2004/2005.

Data

Data are available on request. Please, contact Nicolas Theys.

Scientific highlights

The instrument allowed the detection of all primary gases (NO2, O3, HCHO, SO2 and BrO). More specifically, the analysis of BrO has received a special attention. A new retrieval scheme has been designed to infer the tropospheric and stratospheric BrOcolumns based on an analysis of the complete diurnal evolution of the measured column. The evaluation makes uses of a multiple scattering radiative transfer code coupled to a chemical box model that properly accounts for the large gradients in the stratospheric BrO field at twilight. Results have confirmed the presence of a free tropospheric BrO background. The total columns were consistent with simultaneous observations from satellites measurements.

Time-series of stratospheric and tropospheric BrO columns retrieved for 80° SZA, displayed separately for sunrise and sunset.

List of publications

N. Theys, M. Van Roozendael, F. Hendrick, C. Fayt, C. Hermans, J.-L. Baray, F. Goutail, J.-P. Pommereau, and M. De Mazière
Retrieval of stratospheric and tropospheric BrO columns from Multi-Axis DOAS measurements at Reunion Island (21°S, 56°E)
Atmos. Chem. Phys., 7, 4733-4749, 2007.

N. Theys, F. Hendrick, M. Van Roozendael, I. De Smedt, C. Fayt, R. van der A
Retrieval of BrO columns from SCIAMACHY and their validation using ground-based DOAS measurements
Proceedings, Atmospheric Science Conference, ESA-ESRIN, Frascati, Italy, 8-12 May 2006.

N. Theys, M. Van Roozendael, Q. Errera, F. Hendrick, F. Daerden, S. Chabrillat, M. Dorf, K. Pfeilsticker, A. Rozanov, W. Lotz, J.P. Burrows, J.-C. Lambert, F. Goutail, H.K. Roscoe, and M. De Mazière
A global stratospheric bromine monoxide climatology based on the BASCOE chemical transport model
Atmos. Chem. Phys. Discuss., 8, 17581-17629, 2008
http://www.atmos-chem-phys-discuss.net/8/17581/2008/