The COSPAR International Reference Atmosphere (CIRA) is an empirical model of the atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

 of Earth. It consists of a set of tables of average air pressure

Pressure

Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

s, altitude

Altitude

Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...

s and temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

s. The CIRA models are developed by the Committee on Space Research (COSPAR) and have been important for the planning of spaceflight.

History

Orbit determinations and flight planning of the very first satellite

Satellite

In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

s proved to be more complicated than expected due to a lack of knowledge on the upper atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

. The Committee on Space Research therefore set up a long lasting special project to elaborate a reference model of the most important parameters of the upper atmosphere. The first CIRA appeared 1961 as CIRA1961. It was a set of tables reconsidered year for year by the Task group on the CIRA originally chaired by Hildegard Kallmann-Bijl.

Today

Presently CIRA 1986 covers the height range up to 120 km as a set of tables. In the thermosphere, above about 100 km, CIRA-86 is identical to the more complicated NASA MSIS-86 model. All models are now available on the Web. The task group takes account of more recent data at bi-annual meetings in connection to COSPAR

COSPAR

The Committee on Space Research was established by the International Council for Science in 1958.Among COSPAR's objectives are the promotion of scientific research in space on an international level, with emphasis on the free exchange of results, information, and opinions, and providing a forum,...

meeting.

Literature

• http://ccmc.gsfc.nasa.gov/modelweb/atmos/cospar1.html
• http://badc.nerc.ac.uk/data/cira/ (description)
• K.Labitzke, J.J.Barnett, B.Edwards,Middle Atmosphere Programme, MAP Handbook16, Urbana,1985 (source).
• Rees D., Editor, "COSPAR International Reference Atmosphere: 1986 Part 1: Thermosphere", in Adv. Space Res. Vol. 8, Nos 5&6, published by Pergamon Press, 1988 (source).
• Rees D., J.J. BARNETT and K. LABITSKE, "COSPAR International Reference Atmosphere: 1986, Part II, Middle Atmosphere Models, Adv. Space Res., Vol. 10, No. 12, published by Pergamon Press, 1990 (source).
• M.J.Rycroft, G.M.Keating, D.Rees,Upper Atmosphere Models and Research, Adv. Space Res.10#6,1990.
• G.M. Keating, COSPAR International Reference Atmosphere: 1986, Part III: Trace Constituent Reference Models, Adv. Space Res., Vol. 10, Nos. 9 &10, published by Pergamon Press, 1990 (source).