Diurnal Variation of Wind Profiles Across Mountainous Terrain during and Air Stagnation Period.
Abstract
The diurnal variation of wind profiles across mountainous terrain during an air stagnation period was evaluated for 7 days in July, 1957. The study was conducted across the North-Central Appalachian Mountains, an area of heavy pollution concentration; it was divided into easterly (16-18 July) and westerly (19-22 July) flow across the mountains. Examination over the 7 days showed a diurnal variation in boundary layer winds on the eastern side of the mountain range with a maximum amplitude of about 3 to 4 m/sec at 1000-1500 m MSL in both the easterly and westerly flows. On the western side of the mountain range, a diurnal variation with a maximum amplitude of about 4 m/sec at 600-1100 m MSL occurred in both flows. This oscillation in the lower levels showed the presence of a low-level jet, which was unexpected in that this study was conducted during an air stagnation period. The low-level jet in the easterly flow across the mountains reaches a maximum wind speed at approximately 0600 GMT at about 300 m above ground level. In the westerly flow, the low-level jet occurs at approximately 1200 GMT at 600-800 m above the ground. This low-level jet is due to an inertial type oscillation driven by the diurnal variation of the frictional forces aided by thermal forcing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1978
- Accession Number
- ADA065468
Entities
People
- Julius Augustus Jackson Jr
Organizations
- Air Force Institute of Technology