Abstract
The results of two years of laser radar observations, of the mesosphere and lower thermosphere over Kingston, Jamaica (18.0N, 76.8W), are described. These show the existence of a clear annual variation in atmospheric density with a maximum occurring between January and March and an amplitude of a few percent. Superimposed on this is a longer term trend producing a decrease in the mean density over the period of observation. A comparison is made with the U. S. Standard Atmosphere Supplements for 15N and with an existing model for atmospheric density variations based on other measurement techniques.
