Aura MLS


Contact: Luis Millan Valle

Bromine monoxide (BrO) is important in the catalytic destruction of stratospheric ozone, especially in the lower stratosphere (below about 20 km).

Model studies indicate that catalytic cycles involving BrO may account for as much as 60% of ozone loss for very cold Arctic winters. Bromine monoxide is the main daytime constituent of stratospheric inorganic bromine (Bry), making up about 50% of Bry. The other Bry constituents are Br, HOBr, BrONO2, HBr, and BrCl. In contrast, for stratospheric inorganic chlorine (Cly), the reactive constituents (Cl and ClO) make up only a few percent of Cly.

To quantify the impact of inorganic bromine on stratospheric ozone loss, accurate measurements of its abundance are needed. However, because of their low abundances (several ppt), relatively few measurements have been made of its constituents. Therefore Bry is typically estimated from stratospheric measurements of BrO, combined with estimates of the other constituents from photochemical models. One current problem is that estimates of Bry from measurements of stratospheric BrO obtained by various satellite and balloon-borne instruments show some disagreement.

A second current problem is that estimates of Bry from measurements of stratospheric BrO tend to exceed predictions of Bry based on measurements of the organic source gases from which Bry is believed to be derived (CH3Br and halons). It is currently strongly suspected that there may be additional sources of stratospheric inorganic bromine.

How it is part of MLS Science Objectives

One of the objectives for MLS and the Aura mission is to understand and monitor changes in the chemistry and atmospheric composition that can affect stratospheric ozone. Measurements of stratospheric BrO, the dominant form of bromine in the stratosphere and the dominant form of bromine directly involved in ozone destruction, will help quantify the contribution of Bry to ozone loss.

How EOS MLS measures BrO

The standard product for BrO is taken from the 640-GHz CoreR4AB14 retrieval. The spectral signature of BrO in the MLS radiances is very small, leading to a very poor signal-to-noise ratio on individual MLS observations. Significant averaging (e.g., monthly zonal means) is required to obtain scientifically useful results.

BrO Information from the Spectroscopy Database

Quick Product Information for data version v5

  • Swath Name: BrO
  • Status Flag: Only use profiles for which the Status field is an even number.
  • Useful Range: 10 – 3.2 hPa (day/night differences needed)
  • DAAC Short Name: ML2BRO
  • Precision: Only use values for which the estimated precision is a positive number.
  • Quality Threshold: >1.3
  • Convergence Threshold: <1.05

Download Aura MLS BrO v5 data

Latest Publications (BrO)

  1. Stachnik, R.A., L. Millan, R. Jarnot, R. Monroe, C. McLinden, S. Kühl, J. Puķīte, M. Shiotani, M. Suzuki, Y. Kasai, F. Goutail, J.P. Pommereau, M. Dorf and K. Pfeilsticker
    Stratospheric BrO abundance measured by a balloon-borne submillimeterwave radiometer
    Atmos. Chem. Phys. doi:10.5194/acp-13-3307-2013, 2013
  2. Millan, L., N.J. Livesey, L. Froidevaux, D. Kinnison, R. Harwood, I.A. MacKenzie and M.P. Chipperfield
    New Aura Microwave Limb Sounder observations of BrO and implications for Bry
    Atmospheric Measurement Techniques doi:10.5194/amt-5-1741-2012, 2012
  3. Kovalenko, L.J., N.J. Livesey, R.J. Salawitch, C. Camy-Peyret, M.P. Chipperfield, R.E. Cofield, M. Dorf, B.J. Drouin, L. Froidevaux, R.A. Fuller, F. Goutail, R.F. Jarnot, K. Jucks, B.W. Knosp, A. Lambert, I.A. MacKenzie, K. Pfeilsticker, J-P. Pommereau, W.G. Read, M.L. Santee, M.J. Schwartz, W.V. Snyder, R. Stachnik, P.C. Stek, P.A. Wagner and J.W. Waters
    Validation of the Aura Microwave Limb Sounder BrO observations in the stratosphere
    J. Geophys. Res. doi:10.1029/2007JD008817, 2007
  4. Cofield, R.E. and P.C. Stek
    Design and field-of-view calibration of 114-660 GHz optics of the Earth Observing System Microwave Limb Sounder
    IEEE Trans. Geosci. Remote Sensing doi:10.1109/TGRS.2006.873234, 2006
  5. Livesey, N.J., L.J. Kovalenko, R.J. Salawitch, I.A. MacKenzie, M.P. Chipperfield, W.G. Read, R.F. Jarnot and J.W. Waters
    EOS Microwave Limb Sounder observations of upper stratospheric BrO: Implications for total bromine
    Geophys. Res. Lett. doi:10.1029/2006GL026930, 2006
  6. Yamada, M.M., M. Kobayashi, H. Habara, T. Amano and B.J. Drouin
    Submillimeter-wave Measurements of the Pressure Broadening of BrO
    J. Quant. Spectrosc. Radiat. Transfer doi:10.1016/S0022-4073(03)00165-1, 2003
  7. Drouin, B.J., C.E. Miller, H S.P. Muller and E.A. Cohen
    The rotational spectra, isotopically independent parameters, and interatomic potentials for the X1 2Pi3 and X2 2Pi1/2 states of BrO
    J. Mol. Spec. doi:10.1006/jmsp.2000.8252, 2001