A case study of stably stratified airflow over the pennines using an instrumented glider
✍ Scribed by I. M. Stromberg; C. S. Mill; T. W. Choularton; M. W. Gallagher
- Publisher
- Springer
- Year
- 1989
- Tongue
- English
- Weight
- 952 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0006-8314
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✦ Synopsis
In this paper we present data gathered during a weak case of the Helm wind, an example of supercritical airflow, in the vicinity of Cross Fell in Northern England. Airborne measurements have been made using an instrumented glider with simultaneous ground-based measurements both on a hill summit and on the valley floor downwind of the hill.
It is found that the major features of the airflow both near the surface and aloft, including the lee-wave activity are well reproduced by the airflow model of Carruthers and Choularton (1982). Secondary features including several higher modes of lee-waves and changes in the valley flow associated with nocturnal cooling were observed which could not be accounted for by the simple model.
A CASE STUDY OF STABLY STRATIFIED AIRFLOW OVER THE PENNINES 1.55
Vertical velocity of the air was measured using the sailplane variometer system. In this system, the inherent sink rate at a particular airspeed was automatically subtracted from the total signal to give the vertical velocity of the air itself. The resolution was better than 0.1 m s-l and accuracy to within *O.l m s-l.
The sensors were sampled at 2 s intervals, digitised via an &bit A-D converter and recorded onto tape cassette using a Racal P71 incremental data recorder. Additional information was provided by pilot observations which were also recorded in flight.
4. Meteorological Conditions
- M. STROMBERG ET AL.