Radiation belt electrons precipitated by controlled injection of VLF signals from a ground based transmitter have been directly observed for the first time. These observations were part of the SEEP (Stimulated Emission of Energetic Particles) experiment conducted during May ‐ December 1982. Key elements of SEEP were the controlled modulation of VLF transmitters and a sensitive low altitude satellite payload to detect the precipitation. An outstanding example of time‐correlated wave and particle data occurred from 8680 to 8740 seconds U.T. on 17 August 1982 when the satellite passed near the VLF transmitter at Cutler, Maine (NAA) as it was being modulated with a repeated ON (3‐s)/OFF (2‐s) pattern. During each of twelve consecutive pulses from the transmitter the electron counting rate increased significantly after start of the ON period and reached a maximum about 2 seconds later. The measured energy spectra revealed that approximately 15 to 50 percent of the enhanced electron flux was concentrated near the resonant energies for first order cyclotron interactions occurring close to the magnetic equator with the nearly monochromatic waves emitted from the transmitter.

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The measurements of the mobility and concentration of ions and the ionic conductivity in the lower stratosphere are reviewed. The measurements are made from rocket, parachute, and balloon platforms. The typical mass of the ions inferred from rocket and parachute platform measurements of the ionic mobilities is -.•30 amu or lower, while that from a balloon platform measurement is -.• 1000 amu. Recent in situ ion measurements made at -•35 km with mass spectrometers on balloon platforms indicate that ion masses as high as -.• 140 amu and -.•300 amu for the positive and negative ions, respectively, are present. The ion masses obtained from direct and inferred measurements on rocket platforms are therefore significantly lower than those obtained with balloon platforms. The positive ion concentrations measured from rocket and parachute platforms during quiet times are generally lower than those predicted from a cosmic ray ionization source, while those made from the balloon platforms agree with predictions. During disturbed conditions the measured and predicted ion concentrations agree for high ion densities of -• 10 5 cm -3. The ionic conductivities appear to be approximately independent of the type of measurement platform used. It is suggested that there may be large ions in the lower stratosphere that are broken up in the sampling process with the experimental techniques employed on the rocket and parachute platforms. The large ionic masses inferred from the mobility measurements on the balloon platform suggest that some fragmentation of the ions may have also taken place in the mass spectrometer samplings on the rocket platform. It is suggested that if these discrepancies are to be resolved, more experiments should be conducted on balloons in which measurements of the ionic mobilities, ionic concentrations, and ionic mass are made on the same platform. , PAR Symposium on the Solar Particle Event of November 1969, AFCRL Rep. 72-0474, edited by J. C. Ulwi'ck, pp. 131-139, Air Force Cambridge Research Laboratories, Bedford, Mass., 1972. Young, C. E., and W. E. Falconer, Water cluster ions: Formation and decomposition of cluster ions in the oxygen-water system, J. Chem. Phys., 57, 918-929, 1972. (

The solar particle event (SPE) of August 1972 is one of the largest that has occurred in the last 20 years. Since it is so well documented, it can serve as a good example of a major perturbation to the atmospheric electric system. In this paper, ion production rates and conductivities from the ground to 80 km at the peak intensity of the event on August 4 and for 30, 35, and 40 km for the 6‐day duration of the event are presented. At the peak of the event, the proton and electron precipitation currents, the ohmic current, and the vertical electric field are calculated inside the polar cap. The particle precipitation currents at this time greatly exceed the normal air earth current at altitudes above 30 km and produce reversals in the vertical electric field at 28 km and above. Calculations are presented of the vertical electric field at altitudes near 30 km where balloon measurements were made. Good agreement between the calculated and the measured vertical electric field verifies our ability to calculate disturbed conductivities at these altitudes from satellite measurements of proton spectra incident on the atmosphere. Despite the fact that at the peak of the event the vertical electric field near 30 km was shorted out by the solar particles and that the current carried by the solar particles exceeded the fair weather air‐earth current density in the stratosphere by large factors, it is concluded that the largest effect of an SPE of this magnitude on the atmospheric electric circuit is due to the Forbush decrease in the galactic cosmic ray flux rather than to the large increase in solar proton flux.

Ground‐based microwave measurements of upper atmospheric water vapor were made during late 1981 at Penn State University using the spectral line decomposition of solar microwave (22.235 GHz) radiation transmitted through the atmosphere. One measurement per day was accomplished by integrating the signal over the daylight hours from sunrise to sunset while accurately tracking the sun with a 2.4 m cassegrain parabola antenna. Preliminary retrievals for the period 13‐21 December 1983 are presented, which show reasonable agreement with recent emission microwave measurements.