Radar and Optical Observations of Irregular Midlatitude Sporadic E Layers Beneath MSTIDs
An irregular sporadic E ionization layer was observed by the Arecibo incoherent scatter radar and a coherent scatter radar imager located on St. Croix during the passage of an MSTID observed by the Boston University all-sky camera in 630 nm imagery. The MSTID in question was not very intense and was barely detectable in the vertical F region plasma drifts measured by Arecibo. The intensity of the coherent scatter from small-scale irregularities in the sporadic E layer appeared nonetheless to be modulated by the MSTID and was strongest in the F region airglow crests, mapped along magnetic field lines to the E region volume being observed. The coherent scatter Doppler shifts were highly correlated with altitude displacements in the sporadic E layer, and the sign of the correlation was controlled by the sign of the background zonal electric field. The MSTID did not appear to modulate the morphology of the sporadic E layer irregularities themselves, which took the form of convective rolls and which drifted with the ambient neutral wind.
KeywordsDoppler Shift Hall Conductivity Neutral Wind Convective Roll Plasma Drift
This work was supported by awards ATM-0541526 and ATM-0541593 from the National Science Foundation to Cornell University, Clemson University, and the University of the Virgin Islands. The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation. We appreciate the assistance of the USDA in hosting the St. Croix radar.
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