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Atomic hydrogen in the mesopause region derived from SABER: Algorithm theoretical basis, measurement uncertainty, and results
Author(s) -
Mlynczak Martin G.,
Hunt Linda A.,
Marshall B. Thomas,
Mertens Christopher J.,
Marsh Daniel R.,
Smith Anne K.,
Russell James M.,
Siskind David E.,
Gordley Larry L.
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd021263
Subject(s) - mesopause , thermosphere , mesosphere , atmospheric sciences , airglow , ozone , atmosphere (unit) , chemistry , radiative transfer , hydrogen , atmospheric chemistry , sciamachy , stratosphere , meteorology , physics , troposphere , ionosphere , geophysics , optics , organic chemistry
Atomic hydrogen (H) is a fundamental component in the photochemistry and energy balance of the terrestrial mesopause region (80–100 km). H is generated primarily by photolysis of water vapor and participates in a highly exothermic reaction with ozone. This reaction is a significant source of heat in the mesopause region and also creates highly vibrationally excited hydroxyl (OH) from which the Meinel band radiative emission features originate. Concentrations (cm −3 ) and volume mixing ratios of H are derived from observations of infrared emission from the OH ( υ = 9 + 8, Δ υ = 2) vibration‐rotation bands near 2.0 µm made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. The algorithms for deriving day and night H are described herein. Day and night concentrations exhibit excellent agreement between 87 and 95 km. SABER H results also exhibit good agreement with observations from the Solar Mesosphere Explorer made nearly 30 years ago. An apparent inverse dependence on the solar cycle is observed in the SABER H concentrations, with the H increasing as solar activity decreases. This increase is shown to be primarily due to the temperature dependence of various reaction rate coefficients for H photochemistry. The SABER H data, coupled with SABER atomic oxygen, ozone, and temperature, enable tests of mesospheric photochemistry and energetics in atmospheric models, studies of formation of polar mesospheric clouds, and studies of atmospheric evolution via escape of hydrogen. These data and studies are made possible by the wide range of parameters measured simultaneously by the SABER instrument.