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Seasonal Effects on Distributions of Minor Neutral Constituents in the Mesosphere and Lower Thermosphere
Author(s) -
Shimazaki T.,
Laird A. R.
Publication year - 1972
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs007i001p00023
Subject(s) - thermosphere , airglow , mesosphere , atmospheric sciences , zonal and meridional , oxygen , atmospheric chemistry , ozone , chemistry , environmental science , ionosphere , physics , meteorology , stratosphere , organic chemistry , astronomy
Calculations have been made of the diurnal variations in minor neutral constituents in the mesosphere and lower thermosphere for the condition of 60° latitude, summer and winter, using the method developed by the authors [ Shimazaki and Laird, 1970 ]. The excited molecular oxygen O 2 ( 1 Δ g ) has been added and the effects of absorption of Schumann‐Runge bands have been taken into account. The results show significant seasonal differences, which may be interpreted mainly in terms of the difference of penetration of solar radiation and the duration of sunlit hours. However, the comparison of the observed seasonal and diurnal variations in the airglow emissions from hydroxyl, atomic oxygen (5577 Å), and O 2 ( 1 Δ g ) with those calculated from models suggests that effects of large‐scale meridional circulation (horizontal and vertical transports) may be important in explaining these observations. It is shown that the concentration of the constituents whose main loss mechanism is recombination with atomic oxygen decreases sharply above ˜80 km. These constituents include OH, HO 2 , H 2 O 2 , and NO 2 (nighttime) and the extension of this general theory may explain the sudden decrease observed by rockets in the water‐cluster ion concentration above ∼80 km. Ion‐neutral chemistry should be important in explaining an observed increase in [NO] above ∼85 km.