Soundings were made to measure the winds between the surface and 30 kilometre altitude using a lock-follow radar to track a reflector carried aloft by a free balloon. Where possible the descending reflector, or a cloud of radar window was tracked after burst of the balloon. To reduce error in the wind velocity measurements the radar dials were read at frequent intervals and several readings used to give each velocity. The accuracy of the radar was determined and the expected error in velocity shown to be significantly less than the amplitudes of wind fluctuations at ranges of less than 40 kilometres with a 54" corner reflector. At greater raves the error increased rapidly due to poor signal-to-noise ratio. Some statistical analysis of the wind fluctuations as components of a turbulent field was undertaken but is of uncertain significance as no suitable objective criteria could be devised for determining an appropriate mean wind field from the winds measured on a single sounding. Certain more pronounced irregularities on some of the soundings were observed to persist with little change for periods of several hours. In particular, layers of pronounced shear persisted in the troposphere and could be related in many cases to temperature inversions or frontal surfaces shown by temperature soundings at Crawley (50 kilometre distant). Two sequences of sounding made thrown jet streams gave information on the structure beneath the jet, but wind measurements within the core were subject to large errors. Wind fluctuations with amplitudes 1.11) to 7m/sec, horizontal wavelength of order of 300 kilometres, and vertical wavelengths between 1 and 2.5 kilometres were observed in the stratosphere. A model of the wind structure of these fluctuations is proposed which fits the observed features as found in our soundings and in those of the Meteorological Office. Their properties are shown to be consistent in some respects with the properties of inertial waves investigated theoretically by Sawyer (1961). Clouds of window were tracked by the radar and it is shown that differences in fall speed of pieces within the cloud accounted for far more expansion than small scale turbulence. Clouds of a new type of window made from copper wire wore found to provide a useful anemometer in the stratosphere with characteristics similar to those of a balloon. Estimates of the lateral spread of these clouds gave a value of diffusivity, K, of 0.1 m2/sec.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:602131 |
| Date | January 1962 |
| Creators | Thomas, David Corin |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/13575 |
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