Abstract

At the Arecibo Observatory we use a variety of radar and optical instruments to measure the properties of the Earth's atmosphere and ionosphere. With the incoherent scatter radar we are sensitive to the ionized portion of the upper atmosphere from about half an Earth radius (R_E) down to nearly 60 km during daylight, and 100-150 km during the night when the molecular ionization of this lower part recombines. During both day and night, the winds and turbulent layer structures of the troposphere and stratosphere are accessible up to 25 km with the coherent scatter radar systems. We also use a variety of optical spectro-photometric instruments at Arecibo to study airglow emissions originating from various layers within the atmosphere. Because of the nature of the emitters and their corresponding chemistry, optical remote sensing more preferentially samples the condition of the neutral atmosphere. Thus, by combining simultaneous radar and optical techniques, we can investigate a variety of problems, such as the electrodynamics of the thermosphere, which require data on both the neutral and ionized atmosphere. Much of this instrumentation at Arecibo has been in operation and actively collecting data since the mid-1960s.

© 1993 Optical Society of America