CEDAR: Investigations of Sporadic E Layers and Quasiperiodic Echo Structure in Puerto Rico Using Arecibo and a Coherent Scatter Radar

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The investigators will study quasi-periodic (QP) echoes associated with sporadic E layers using the Arecibo Observatory incoherent scatter radar, a high frequency (HF) coherent scatter radar to be located on St. Croix, and the Arecibo sodium lidar. Sporadic E and the QP echoes are the result of complex neutral atmosphere/ionization interactions in the mesosphere and lower thermosphere. The goals are (1) to determine the horizontal spatial structure of the ionization and the relationship between that structure and the location of QP echoes observed with the coherent radar, (2) to determine the vertical spatial extent of the ionization structures, and (3) to determine the relationship between the motion of the ionization structures and the Doppler velocities and range rates measured by the coherent scatter radar. To accomplish this, dual-beam azimuth scans will be carried out with the incoherent scatter radar to provide information about the horizontal spatial variations and the vertical extent of the electron density structure and to determine the velocity at which the structures move from one beam to the other. The coherent scatter high frequency radar will be set up in a location on St. Croix so that the beam will be perpendicular to the magnetic field lines in the E region above the Arecibo Observatory so that the two radar have a common volume in the E region. The sodium lidar will be operated in dual-beam mode as well in order to provide information about the horizontal and vertical spatial structure in the lower E region and the motions of the neutral atmosphere. By combining the various measurements, the dataset can be used as a test of the various theories that have been proposed to explain the initiation of the QP echoes.