THE BRAZIL GUARA EQUATORIAL SPREAD-F CAMPAIGN - RESULTS OF THE LARGE-SCALE MEASUREMENTS/

The Guara campaign equatorial spread F rocket was launched from Alcant ara, Brazil, on 14 October 1994 at 1955 LT (2255 UT) into an active to pside spread F event. Spread F plasma irregularities observed up to 82 2 km altitude correlate well with plumes observed simultaneously with a coherent backscatter radar. Matching 1-10 km features in the rocket and radar data over the altitude range 300-800 km implies an eastward drift speed of similar to 110 m/s, versus 95 m/s at 400-500 km based o n radar interferometry. Combining these two measurements implies an av erage upward drift of 30 m/s for the highest altitude structures. The amplitude difference between low- and high-altitude 10-km density stru ctures, if attributed to temporal effects, implies an effective diffus ion coefficient (decay time constant) of 500-1000 m(2)/s (2-4x10(-4) s (-1)), which agrees with previous estimates from other techniques and supports the idea that the decay of spread F turbulence occurs in a sc ale-independent manner.