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The MLS HO2 Product

Contact: Shuhui Wang


Basic Information

HO2 is an important reactive species in atmospheric chemistry.                    
The HO2 Molecule
 HO2 molecule visualization


How it is part of MLS Science Objectives

MLS is making the first global measurements of HO2 that, along with its measurements of OH, are providing needed new information on stratospheric hydrogen chemistry that affects ozone. Lack of global OH and HO2 measurements has previously been a major limitation in constraining models of stratospheric chemistry


How EOS MLS measures HO2

The standard product for HO2 is taken from the 640 GHz (Core+R4A) retrieval. Simulations indicate closure for HO2 day/night differences to better than 10% above 22 hPa. Without taking day/night (ascending/descending) differences the closure in the simulations is at times larger than the expected daytime HO2 concentration.

Significant averaging (e.g., weekly zonal means) is required to obtain useful HO2 data from MLS observations. Averages of nighttime observations (from the descending part of the orbit), when HO2 abundances are expected to be essentially zero show significant non-zero values, indicative of biases. These need to be removed before any scientific study by taking day/night (or ascending/descending) differences. We believe that these differences will be reliable at levels at and above the 22 hPa pressure surfaces. At pressures greater than 22 hPa the bias is larger than we can confidently expect simple day/night differences to remove.

HO2 is being validated using the balloon-borne FIRS-2 instrument. Preliminary results for September 23, 2004, for the region of Ft. Sumner, NM show excellent agreement between FIRS-2 and MLS [Pickett et al., 2005].1

Sample HO2 observation map
(map from 2005d264)
HO2 Information from the Spectroscopy Database


Quick Product Information for data version v3.3

**Day/night differences should be used in analyzing this product**
  • Swath Name: HO2
  • Vertical Resolution:4 - 7 km at 10 - 0.10 hPa
    10 km at 0.10 - 0.046 hPa
  • Useful Range: 22 - 0.046 hPa
  • DAAC Short Name: ML2HO2
  • Precision:
    6-50 106cm-3 (height dependent)
  • Quality Threshold: N/A


v3.3 HO2 Averaging Kernel
HO2 averaging kernel diagrams

colored lines are individual kernels; thick dashed line is full width at half maximum, thick solid is integrated kernel value


Publications related to the MLS HO2 data product

2011

  1. Jackman, C.H., "Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005", vol doi:10.5194/acp-11-6153-2011, num 11, 2011. Preprint

2008

  1. Pickett, H.M., "Validation of Aura Microwave Limb Sounder OH and HO2 measurements", vol doi:10.1029/2007JD008775, num 113, 2008. Reprint Preprint

2007

  1. Kovalenko, L.J., "Observed and Modeled HOCl Profiles in the Midlatitude Stratosphere: Implication for Ozone Loss", vol doi:10.1029/2007GL031100, num 34, 2007. Reprint Preprint
  2. Mueller, E.R., "Terahertz local oscillator for the Microwave Limb Sounder on the Aura Satellite", num 46, pgs. no. 22, 2007. Preprint
  3. Verronen, P.T., "Latitudinal extent of the January 2005 solar proton event in the Northern Hemisphere from satellite observations of hydroxyl", num 25, 2007. Preprint

2006

  1. Canty, T., "Stratospheric and Mesospheric HOx: Results from Aura MLS and FIRS-2", vol doi:10.1029/2006GL025964, num 33, 2006. Reprint Preprint
  2. Cofield, R.E., "Design and field-of-view calibration of 114-660 GHz optics of the Earth Observing System Microwave Limb Sounder", num 44, pgs. no. 5, 2006. Preprint
  3. Pickett, H.M., "Observation of Night OH in the Mesosphere", vol doi:10.1029/2006GL026910, num 33, 2006. Preprint
  4. Pickett, H.M., "Validation of Aura MLS HOx measurements with remote-sensing balloon instruments", vol doi:10.1029/2005GL024048, num 33, 2006. Reprint Preprint

1997

  1. Osterman, G.B., "Balloon-borne measurements of stratospheric radicals and their precursors: Implications for the production and loss of ozone", num 24, 1997. Preprint

1992

  1. Stachnik, R.A., "Submillimeterwave heterodyne measurements of stratospheric ClO, HCl, O3, and HO2: First results", num 19, 1992. Reprint Preprint



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