New insights for mesospheric OH: multi-quantum vibrational relaxation as a driver for non-local thermodynamic equilibrium
Konstantinos S. Kalogerakis1,Daniel Matsiev1,Philip C. Cosby2,*,James A. Dodd3,Stefano Falcinelli4,Jonas Hedin5,6,Alexander A. Kutepov7,8,Stefan Noll9,10,11,Peter A. Panka8,Constantin Romanescu6,and Jérôme E. Thiebaud6,12Konstantinos S. Kalogerakis et al. Konstantinos S. Kalogerakis1,Daniel Matsiev1,Philip C. Cosby2,*,James A. Dodd3,Stefano Falcinelli4,Jonas Hedin5,6,Alexander A. Kutepov7,8,Stefan Noll9,10,11,Peter A. Panka8,Constantin Romanescu6,and Jérôme E. Thiebaud6,12
1Center for Geospace Studies, SRI International, Menlo Park,
California, USA
2formerly at: Molecular Physics Laboratory, SRI International, Menlo Park, California, USA
3Air Force Research Laboratory (AFRL), Space Vehicles Directorate,
Kirtland Air Force Base, New Mexico, USA
4Department of Civil and Environmental Engineering, University of
Perugia, Perugia, Italy
5Department of Meteorology (MISU), Stockholm University, Stockholm,
Sweden
6formerly at: Physical Sciences Division, SRI International, Menlo Park, California, USA
7The Catholic University of America, Washington DC, USA
8NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
9Institute for Astro- and Particle Physics, University of Innsbruck,
Innsbruck, Austria
10Institute of Physics, University of Augsburg, Augsburg, Germany
11German Remote Sensing Data Center (DFD), German Aerospace Center
(DLR), Oberpfaffenhofen, Germany
12Aeris Technologies, Redwood City, California, USA
*retired
1Center for Geospace Studies, SRI International, Menlo Park,
California, USA
2formerly at: Molecular Physics Laboratory, SRI International, Menlo Park, California, USA
3Air Force Research Laboratory (AFRL), Space Vehicles Directorate,
Kirtland Air Force Base, New Mexico, USA
4Department of Civil and Environmental Engineering, University of
Perugia, Perugia, Italy
5Department of Meteorology (MISU), Stockholm University, Stockholm,
Sweden
6formerly at: Physical Sciences Division, SRI International, Menlo Park, California, USA
7The Catholic University of America, Washington DC, USA
8NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
9Institute for Astro- and Particle Physics, University of Innsbruck,
Innsbruck, Austria
10Institute of Physics, University of Augsburg, Augsburg, Germany
11German Remote Sensing Data Center (DFD), German Aerospace Center
(DLR), Oberpfaffenhofen, Germany
12Aeris Technologies, Redwood City, California, USA
*retired
Correspondence: Konstantinos S. Kalogerakis (ksk@sri.com)
Received: 15 Jun 2017 – Revised: 04 Oct 2017 – Accepted: 15 Nov 2017 – Published: 09 Jan 2018
Abstract. The question of whether mesospheric OH(v) rotational population distributions are in equilibrium with the local kinetic temperature has been debated over several decades. Despite several indications for the existence of non-equilibrium effects, the general consensus has been that emissions originating from low rotational levels are thermalized. Sky spectra simultaneously observing several vibrational levels demonstrated reproducible trends in the extracted OH(v) rotational temperatures as a function of vibrational excitation. Laboratory experiments provided information on rotational energy transfer and direct evidence for fast multi-quantum OH(high-v) vibrational relaxation by O atoms. We examine the relationship of the new relaxation pathways with the behavior exhibited by OH(v) rotational population distributions. Rapid OH(high-v) + O multi-quantum vibrational relaxation connects high and low vibrational levels and enhances the hot tail of the OH(low-v) rotational distributions. The effective rotational temperatures of mesospheric OH(v) are found to deviate from local thermodynamic equilibrium for all observed vibrational levels. Dedicated to Tom G. Slanger in celebration of his 5 decades of research in aeronomy.
The question of whether mesospheric rotational population distributions of vibrationally excited OH are in equilibrium with the local kinetic temperature has been debated over several decades. We examine the relationship of multi-quantum relaxation pathways with the behavior exhibited by OH(v) rotational population distributions and find that the effective rotational temperatures of mesospheric OH(v) deviate from local thermodynamic equilibrium for all observed vibrational levels.
The question of whether mesospheric rotational population distributions of vibrationally excited...
