Abstract

A periodic wave structure with a vertical wave length of about 2 km between 12 and 19 km has been identified in Rayleigh lidar measurements at 589 nm of low altitude relative density profiles that were made by the University of Illinois group during the March/April Arecibo Initiative for Dynamics of the Atmosphere (AIDA) 1989 campaign effort. The equivalent temperature fluctuations are several degrees in magnitude. Also seen in one series of three successive nights were temperature fluctuations of about 10 °K at altitudes of 25 km with a vertical extent of 1 km. Both of these phenomena show a downward phase speed between 1 and 3 cm/s. The lower periodic structure is believed to be the same phenomenon seen previously in 430 MHz measurements of winds obtained at Arecibo Observatory. The identity of this structure remains uncertain. Cornish and Larsen [1989] and Sato and Woodman [1982a] considered this structure to be a quasi-inertial long period wave. Hines [1989] proposed instead the identification of this structure with a stationary wave system generated by orographic waves caused by the interaction of the sub-tropical tradewinds with the mountainous terrain of Puerto Rico. The higher altitude feature seen in the AIDA lidar observations is believed to be a manifestation of a region of clear air turbulence, which is known to occur in the lower stratosphere.

© 1993 Optical Society of America