MLS Research
Hydrogen Chemistry
Contact Luis Millan
The odd-hydrogen radicals, OH and HO2 (collectively known as HOx), play fundamental roles in the middle atmospheric photochemistry due to their ability to destroy odd oxygen (O3 and O). In particular, at altitudes above ~40 km, the major catalytic O3 loss is controlled by reactions involving HOx species.
A better understanding of the trend in HOx thus helps to properly identify the recovery of the O3 layer. In this region of the atmosphere, HOx mainly come from the photolysis of O3 (i.e., the break down of O3 by sunlight) followed by reaction with H2O. In addition, chemical destruction of H2 and direct photolysis of H2O are also sources of HOx, especially above 80 km. The distribution of HOx species and the chemistry involved are sensitive to solar forcing such as the diurnal cycle, the seasonal cycle, the solar 11-year and 27-day cycles, and solar proton events (SPEs) .
Before the launch of Aura, the investigation of hydrogen chemistry had been greatly limited due to the lack of multi-year systematic observations on a global scale. The only available long-term records were a number of ground-based measurements of OH total column abundance. Large discrepancies among measurements and between model predictions and observations were reported.
MLS provides the first global daily measurements of HOx vertical profiles in the stratosphere and the mesosphere, making it possible to resolve some of these discrepancies, and significantly improve our understanding of the chemistry involved and the response to external forcing.
In particular, MLS observations will help to investigate the discrepancy between modeled and observed O3 in the upper stratosphere, known as the "O3 deficit", which implies that there could be a gap in the current understanding of hydrogen chemistry.
In addition, the magnitude of the solar effects on hydrogen chemistry is currently unclear, given the large discrepancies between observed and modeled response of O3 and OH to the solar cycle.
MLS-related publications concerning stratospheric and mesospheric hydrogen chemistry
Nishiyama, T., M. Taguchi, H. Suzuki, P. Dalin, Y. Ogawa, U. Brändström and T. Sakanoi
Temporal evolutions of N2 Meinel (1,2) band near 1.5µm associated with aurora breakup and their effects on mesopause temperature estimations from OH Meinel (3,1) band
James, A., D. Moon, W. Feng, P. Lakey, V. Frankland, D. Heard and J. Plane
The uptake of HO2 on meteoric smoke analogues
Davis, S., K. Rosenlof, B. Hassler, D. Hurst, W. Read, H. Vömel, H. Selkirk, M. Fujiwara and R. Damadeo
The Stratospheric Water and Ozone Satellite Homogenized SWOOSH database: a long-term database for climate studies
Rong, P.P., J.M. Russell, B.T. Marshall, D.E. Siskind, M.E. Hervig, L.L. Gordley, P.F. Bernath and K.A. Walker
Version 1.3 AIM SOFIE measured methane CH4: Validation and seasonal climatology
Zawedde, A., H.N. Tyssøy, R. Hibbins, P. Espy, L. Ødegaard, M. Sandanger and J. Stadsnes
The impact of energetic electron precipitation on mesospheric hydroxyl during a year of solar minimum
Andersson, M.E., P.T. Verronen, C.J. Rodger, M.A. Clilverd and A. Seppala
Missing driver in the Sun–Earth connection from energetic electron precipitation impacts mesospheric ozone
Khosravi, M., P. Baron, J. Urban, L. Froidevaux, A.I. Jonsson, Y. Kasai, K. Kuribayashi, C. Mitsuda, D.P. Murtagh, H. Sagawa, M.L. Santee, T.O. Sato, M. Shiotani, M. Suzuki, T. von Clarmann, K.A. Walker and S. Wang
Diurnal variation of stratospheric and lower mesospheric HOCl, ClO and HO2 at the equator: comparison of 1-D model calculations with measurements by satellite instruments
Wang, S., K.F. Li, T.J. Pongetti, S.P. Sander, Y.L. Yung, M.C. Liang, N.J. Livesey, M.L. Santee, J.W. Harder, M. Snow and F.P. Mills
Midlatitude atmospheric OH response to the most recent 11-y solar cycle
Andersson, M.E., P.T. Verronen, S. Wang, C.J. Rodger, M.A. Clilverd and B.R. Carson
Precipitating radiation belt electrons and enhancements of mesospheric hydroxyl durign 2004-2009
Shapiro, A.V., E. Rozanov, A.I. Shapiro, S. Wang, T. Egorova, W. Schmutz and Th. Peter
Signature of the 27-day solar rotation cycle in mesospheric OH and H2O observed by the Aura Microwave Limb Sounder
Verronen, P.T., C.J. Rodger, M.A. Clilverd and S.H. Wang
First evidence of mesospheric hydroxyl response to electron precipitation from the radiation belts
Dyrland, M.E., C.M. Hall, F.J. Mulligan and M. Tsutsumi
Improved estimates for neutral air temperatures at 90 km and 78°N using satellite and meteor radar data
Englert, C.R., M.H. Stevens, D.E. Siskind, J.M. Harlander and F.L. Roesler
Spatial Heterodyne Imager for Meospheric Radicals on STPSat-1
Pickett, H.M., B.J. Drouin, T. Canty, R.J. Salawitch, R.A. Fuller, V.S. Perun, N.J. Livesey, J.W. Waters, R.A. Stachnik, S.P. Sander, W.A. Traub, K.W. Jucks and K. Minschwaner
Validation of Aura Microwave Limb Sounder OH and HO2 measurements
Wang, S., H.M. Pickett, T.J. Pongetti, R. Cheung, Y.L. Yung, C. Shim, Q. Li, T. Canty, R.J. Salawitch, K.W. Jucks, B. Drouin and S.P. Sander
Validation of Aura Microwave Limb Sounder OH measurements with Fourier Transform Ultra-Violet Spectrometer total OH column measurements at Table Mountain, California
Kovalenko, L.J., K.W. Jucks, R.J. Salawitch, G.C. Toon, J-F. Blavier, D.G. Johnson, A. Kleinbohl, N.J. Livesey, J.J. Margitan, H.M. Pickett, M.L. Santee, B. Sen, R.A. Stachnik and J.W. Waters
Observed and Modeled HOCl Profiles in the Midlatitude Stratosphere: Implication for Ozone Loss
Verronen, P.T., C.J. Rodger, M.A. Clilverd, H.M. Pickett and E. Turunen
Latitudinal extent of the January 2005 solar proton event in the Northern Hemisphere from satellite observations of hydroxyl
Canty, T., H.M. Pickett, R.J. Salawitch, K.W. Jucks, W.A. Traub and J.W. Waters
Stratospheric and Mesospheric HOx: Results from Aura MLS and FIRS-2
Pickett, H.M.
Microwave Limb Sounder THz Module on Aura
Pickett, H.M., W.G. Read, K.K. Lee and Y.L. Yung
Observation of Night OH in the Mesosphere
Pickett, H.M., B.J. Drouin, T. Canty, L.J. Kovalenko, R.J. Salawitch, N.J. Livesey, W.G. Read, J.W. Waters, K.W. Jucks and W.A. Traub
Validation of Aura MLS HOx measurements with remote-sensing balloon instruments
Verronen, P.T., A. Seppala, E. Kyrola, J. Tamminen, H.M. Pickett and E. Turunen
Production of Odd Hydrogen in the Mesosphere During the January 2005 Solar Proton Event
Osterman, G.B., R.J. Salawitch, B. Sen, G.C. Toon, R.A. Stachnik, H.M. Pickett, J.J. Margitan, J-F. Blavier and D.B. Peterson
Balloon-borne measurements of stratospheric radicals and their precursors: Implications for the production and loss of ozone
Pickett, H.M. and D.B. Peterson
Comparison of measured stratospheric OH with prediction
Stachnik, R.A., J.C. Hardy, J.A. Tarsala, J.W. Waters and N.R. Erickson
Submillimeterwave heterodyne measurements of stratospheric ClO, HCl, O3, and HO2: First results