Products » Bromine Monoxide total column (BrO)





Algorithm

The operational BrO total column products are generated using the algorithm GDP (GOME Data Processor) version 4.x integrated into the UPAS (Universal Processor for UV/VIS Atmospheric Spectrometers) processor for generating level 2 trace gas and cloud products.
Activities on further improvements of the BrO column algorithm are ongoing [Van Roozendael and Theys (2005), Theys et al. (2009b)] This work focuses on optimizing the accuracy of global total BrO columns, as well as polar tropospheric BrO columns.

DOAS slant column fitting

On the basis of noise driven considerations, the fitting window 336-351.5 nm was selected for the GOME-2. A BrO cross-section is included in the fit, as well as the cross-sections of the interfering trace gases: ozone, NO2, O2-O2. Two Ring reference spectrums are included as an additive fitting parameter. The detailed DOAS settings used for GOME-2 BrO slant columns retrieval are given in the [DLR/GOME-2/ATBD].

AMF and VCD determination

The AMF is calculated with the LIDORT 3.3 model for the fitting window mid-point, since BrO is an optically thin absorber in this wavelength region. To incorporate the seasonal and latitudinal variation in stratospheric BrO in the AMF calculations, a stratospheric BrO profile climatology is used [Bruns et al. (2003)]. This climatology contains monthly mean BrO profiles as a function of latitude, based on the chemistry transport model SLIMCAT.

Remark

In the region of the Southern Atlantic Anomaly (SAA), the GOME-2 satellite instrument is subject to an increased particle flux which creates spurious signals in individual detectors resulting in a reduced quality of the retrieved GOME-2 trace gas columns, i.e. increased scatter in trace gas columns over South America and the Southern Atlantic.

Scientific Papers


Acknowledgments

GDP 4.x for total BrO retrieval is being developed by scientists from BIRA and DLR:
• BIRA: Michel Van Roozendael, Nicolas Theys
• DLR: Nan Hao, Pieter.Valks, Walter Zimmer, Sunil Emmadi
and is funded by EUMETSAT O3M-SAF and national contributions.

For further information please contact:

Nan Hao, DLR-IMF
E-Mail: Nan.Hao [at] dlr.de

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