Wind Speed Extremes In The Northern Hemisphere 30 Through 60 Km

The Design Climatology Branch of the Air Force Cambridge Research Laboratories had the scientific responsibility for leading a DoD Task Group effort to revise MIL-STD-210A 'Climatic Extremes for Military Equipment'. This document represents the fruition of the goals of the task group. It relates the background studies supporting the values in MIL-STD-210B, so that MIL-STD-210B users need to consult only this single document for an elaboration on the MIL- STD-210B extremes. In addition, the report contains information on the origin, necessity for and the events leading to a revision of MIL-STD-210A. Discussions of the major changes in the Standard's philosophy and its contents are also provided.

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The work described in this report is in support of MAC SON 508-78, Pre-Strike Surveillance and Reconnaissance System (PRESSURS), which has identified deficiencies in the Air Force's ability to acquire meteorological observations in uncontrolled and hostile airspace. Primary requirements include temperature, pressure, humidity, winds, cloud field parameters, and visibility. Suitable sensors are identified and evaluated for deployment with various scenarios, that is, remotely-piloted vehicle, dropsonde, and ground implantation. Where deficiencies in the state-of-the-art exist, programs were initiated for the development of new instrumentation, and where necessary, models were constructed for translation of sensor output into useful operational weather information.

Strong wind and vertical wind shear must be considered for design and operation of vehicles that will either operate in or penetrate the upper stratosphere and mesosphere. Global extremes of these atmosphere parameters are estimated in this report for altitudes above 30 km. For the Northern Hemisphere estimated 90, 95, and 99% winds, related to the windiest months and locations, are provided for altitudes between 30 and 80 km. Speed increases up to about 55 km and appears to decrease thereafter up to at least 75 or 80 km in November, December, and January. The 99% winds can be expected to approach 215 mps near 55 km at certain locations between latitudes 35 and 60N. For the Southern Hemisphere 90, 95, and 99% winds are provided for altitudes between 30 and 60 km. The 99% winds reach roughly 200 mps near 55 km. Since estimates for the Southern Hemisphere are not necessarily representative of either the windiest month or location, results are uncertain and speeds probably will be somewhat larger than indicated. For the same percentiles, 1-km thick vertical wind shears have been estimated for altitudes between 30 and 70 km. Shears generally increase, and maximum values tend to move equatorward with altitude. (Author).