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Revision of United States standard atmosphere 90 to 700 kilometers
Author(s) -
Champion Kenneth S. W.,
Minzner Raymond A.
Publication year - 1963
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/rg001i001p00057
Subject(s) - altitude (triangle) , atmosphere (unit) , atmospheric models , environmental science , atmospheric sciences , density of air , scale height , effects of high altitude on humans , atmospheric temperature , meteorology , physics , mathematics , geometry
A 1962 revision of the United States standard atmosphere was recently announced. The high‐altitude part of the previous standard was based upon a small number of relatively inaccurate pressure and density data available in 1955. High‐altitude atmospheric data obtained with IGY rockets and satellites demonstrated the inadequacies of the standard and provided the basis for a major revision above 20‐km altitude. The large amount of satellite‐drag density data and rocket‐derived pressure data required the use of model‐generation processes involving both pressure‐temperature altitude relationships and density‐temperature altitude relationships. A high‐altitude model (90–700 km) was developed by using the process of linearly segmented temperature functions, starting from reference values and working upward, matching observed pressure‐altitude and density‐altitude profiles. This technique of model generation permitted continuity with an independently developed low‐altitude model (20–90 km). The imposed requirement that the high‐altitude part of the new standard be defined in terms of molecular‐scale temperature functions that are linear with respect to geometric, rather than geopotential, altitude, introduced considerable complexity to the defining equations. With molecular‐scale temperature as the principal defining property, it was necessary to establish a molecular‐weight function as a secondary defining property in order to compute kinetic temperatures and other atmospheric properties not directly related to molecular‐scale temperature. The assumption that diffusive equilibrium dominates the atmosphere above 120‐km altitude, coupled with numerous assumptions concerning photodissociation and recombination rates of known atmospheric molecules, served as the basis for the computation of number density of the various species and, hence, mean molecular weight as a function of altitude. The definitions of this revised atmospheric model were adopted by the Committee on Extension to the United States standard atmosphere on March 15, 1962, and thereby this model became the basis for the 90‐ to 700‐km region of the revised United States standard atmosphere.