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Journal of Geophysical Research

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During the Structure and Atmospheric Turbulence Environment (STATE) campaign in June 1983, three small rockets (Super Arcas) containing dc probes to measure electron density irregularities with high spatial resolution were launched at Poker Flat, Alaska. The rockets were launched at three different times when the nearby MST (mesospheric, stratospheric, and tropospheric) radar showed intense regions •f •,•.v ....... in t• m•ses?•re. The first and third flights (STATE 1 and STATE 3) were perfectly successfulp, roviding high-quality electron density measurements'S TATE 2 did not produce any useful results. When the electron density measurements are compared with the radar echo power as a function of altitude for STATE 1 and 3, large fluctuations and strong gradients in the electron density profiles are observed in the region of most intense backscatter. The electron density profiles show different characteristics in the peak scattering region with respect to altitude, electron density gradients, and irregularities. Power spectra of the electron density spatial fluctuations were derived from the measured electron densities for the region from approximately 65 to 90 km for several height intervals, with the smallest being approximately 100 m. In the region of most intense backscatter, the spectral power over the entire frequency range increases by almost 3 orders of magnitude for both rocket data sets. For STATE 1 a linear fit to the log-log power spectral plots between 1.0-80 Hz (i.e., spatial scales from about 500 to 5 m) can be approximated by a power law with an index of about -(5/3), as would be expected in an inertial subrange of homogeneous, isotropic turbulence. The spectra, moreover, show a continuous steepening of the spectral slope in the viscous subrange at frequencies above 100 Hz (approximately 4.5-0.5 m), giving a much higher spectral index. The STATE 3 spectra, on the other hand, show a steeper spectral index near -2.0 in the inertial subrange but steepening at the higher frequencies, as do the STATE 1 data. A detailed intercomparison of the probe data is presented, followed by an absolute comparison between the radar and rocket measurements. Reasonable agreement is seen between the observed echo power profile and the profile calculated using the 3-m electron density fluctuations obtained from the rocket data.