Principal Investigator - I. Tolstoy Short Title of Work - a Study of Extremely Low Frequency Waves and Propa- Gating Ionospheric Disturbances in Detecting Atmospheric Nuclear Explosions

s of papers in press: 1. Phase Height Pluctuutions in the Ionosphere beiweon 130 and 250 km, I. Toli'.toy and II. Montes Journal of Terrestrial and Atmospheric Physics, 1971. Power spectra of CW phase-path sounders operating at 6.0, 4.8 and 2.4 MHz often display peak or slope changes at periods in the 5-20 minute range. Plots of these periods vs. real height tend to follow mean VUisälä frequency curves calculated from Standard Atmosphere models. This suggests that statistical properties of CW phase-path sounder fluctuation can be used to monitor certain mean physical parameters of the upper atmosphere. 2. Generation of long Internal Gravity Waves in Waveguides by Rising Buoyant Air Masses and other Sources. I. Tolstoy and J. Lau Journal of the Atmospheric Sciences, 1971. The displacement fields generated in an internal gravity wave waveguide between plane rigid walls are compared for two types of source: an explosive point source and a rising buoyant sphere moving at constant speed. It is concluded that, for large enough spheres and comparable energy expenditures, the buoyant sphere is a far more efficient source of long internal gravity waves. In particular it appears possible to conclude that, in the case of large events such as nuclear or volcanic explosions in the atmosphere« the rising heated air mass can generate long wavelength (X > 500 km) internal gravity waves at ionospheric heights. 3. Dumping of very long Intornal Ciruvity Wuvos in tho Atmosphere. I. Tolstoy Journal of the Atmospheric Sciences, 1971. Assuming most of the energy absorption to take place in a viscous surface layer, it is possible to make a simple calculation for the attenuation of long internal gravity waves in the atmospheric waveguide. This calculation indicates that wavelengths longer than a few hundred kilometers may propagate to considerable ranges as waveguide modes. Papers published in 1970: 1. Tolstoy, I. and T. J. Herron, 1970: Atmospheric gravity waves from nuclear explosions, J. Atmos. Sei., 27, 55-61. 2. Tolstoy, I. and P. Pan, 1970: Simplified atmospheric models and the properties of long period internal and surface gravity waves, J. Atmos. Sei., 27, 31-50. 3. Tolstoy, I. and J. Lau, 1970: Ground level pressure fluctuations connected with ionospheric disturbances, J. Atmos. Sei, 27, 494-503. 4. Tolstoy, I. 1970: Ceoacoustic mode structure, atmospheric parameters and nuclear atmospheric tests, ARPA-AFOSR Symposium report. Spring 1970. 5. Tolstoy, I., H. Montes, G. Rao and E. Willis, 1970: Long period sound waves in the thermosphere from Apollo launcher, J. Geophys. Res., 75, 28, 5621-5625. GHNIiRATION OF LONG INTERNAL GRAVITY WAVES IN WAVEGUIDES BY RISING BUOYANT AIR MASSES AND OTHER SOURCES by I. Tolstoy and J. Lau