Daytime rocket and thomson scatter studies of the lower ionosphere

The results of rocket and ground-based radar Thomson scatter (incoherent scatter) measurements of electron densities and temperatures obtained at the same time and location are presented. Two-electrode spherical electrostatic analyzers were used in the rocket experiments. This report describes the experimental techniques and compares the experimental results and theoretical predictions. Good agreement is found between the results obtained on two daytime rocket flights and the radar measurements over the altitude range of comparison, 100 to 180 km. The rocket electron temperature measurements are consistently 10 to 15% higher than the radar data. The electron densities agree within 25%, which is within the experimental error of the two techniques. Comparison of measured electron temperatures with values calculated from the solution of the heat conduction equation by using methods developed by Dalgarno et al. shows good agreement below 160 km. Between 200 and 350 km the measured temperatures are 200° to 300° higher than predicted. Electron cooling rates were calculated from the experimental results for the relevant cooling mechanisms and were compared with the theoretical heat input to the electron gas. The results imply that the differences between theoretical and experimental temperatures above 200 km are primarily due to an underestimation of the heat input by a factor of 3 to 5.