Atmospheric Chemistry and Climate Group
  • Español
  • English
Analysis of reactive halogen species measurements from Space

Reactive halogen species, such as bromine monoxide (BrO) and iodine monoxide (IO), play an important role in the tropospheric chemistry, affecting the composition and the oxidizing capacity of the troposphere. The role of these species in the troposphere is link to ozone depletion events (ODE), changes in the OH/HO2 and NO/NO2 ratio, oxidation of compounds such as dimethyl sulfide (DMS), rapid oxidation of atomic mercury in polar environment (leading to complete removal of gaseous mercury into the snowpack), and new particle formation.

As part of the algorithm development for the UVAS instrument, the group has been working on BrO and IO column measurements from the GOME-2 satellite instrument, on board ESA Met-Op satellite.

The Global Ozone Monitoring Experiment-2 (GOME-2), mounted to the flight direction side of the MetOp satellite, is a scanning spectrometer that captures light reflected from the Earth's surface and atmosphere. With a spatial resolution of 80 x 40 km2, the spectrometer splits the light into its spectral components to map concentrations of atmospheric ozone as well as nitrogen dioxide, sulfur dioxide, other trace gases.

The BrO slant columns are directly determined by fitting GOME-2 radiances in the 320-360 nm spectral region. The slant columns abundance that minimizes the chi-square between measured and calculated radiance is retrieved using a non-linear least squares inversion method based on the Levenberg-Marquardt formulation.

For the IO retrieval the Differential Optical Absorption Spectroscopy (DOAS) approach is employed, using the 416-430 nm fitting window.

The vertical columns are obtained by inverting the line-of-sight slant column observation using a geometric air mass factor. Radiative transfer models are used to determine the improved molecular air mass factors.

BrO S 20081003


BrO N 20080411

Spatial and temporal distribution of tropospheric BrO during springtime in the South and North Poles


This project is carried out in collaboration with Kelly Chance and Thomas Kurosu from the Harvard-Smithsonian Center for astrophysics and the Jet Propulsion Laboratory of NASA respectively.