On the variance spectra and spatial coherences of equatorial winds

✍ Scribed by D. E. Parker

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: English
• Weight: 520 KB
• Volume: 99
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49709941905

✦ Synopsis

Abstract

The variance spectra of daily zonal and meridional winds in the troposphere and lower stratosphere over Gan (00°41′S, 73°09′E) were investigated. The total zonal variance considerably exceeded the total meridional variance at all the levels studied except the surface. In the upper troposphere the total zonal variance had a marked peak caused almost entirely by effects with periodicities greater than 10 days. The variance due to 4‐ to 5‐day meridional effects usually had a maximum slightly below the tropopause. However, at all the levels investigated this variance fluctuated considerably with time although without showing any long‐term regularities. Some specific 4‐day meridional motions at 150 mb over the equatorial regions between Gan and East Africa appeared to progress westward with a zonal wavelength of between 10,000 and 12,000 km.

The vertical coherence of daily tropospheric winds over Gan was found to be weak on a scale of several km. Correlation coefficients between daily tropospheric winds over Gan and corresponding winds over Port Victoria (04°37′S, 55°27′E) were found to be small except for part of the upper troposphere.