Mesospheric observations were obtained by the EISCAT UHF and VHF radars during the solar proton event of March 1990. We present the ®rst comparison of incoherent-scatter spectral measurements from the middle mesosphere using simultaneous, colocated observations by the two radars. VHF spectra observed with a vertical antenna were found to be signi®cantly narrower than model predictions, in agree...

Several techniques exist for computing vertical motions. In this paper, radiosonde wind observations are used to compute vertical motions by the kinematic method. The presence of cumulative bias errors necessitates adjustment techniques. Simple tests of two techniques indicate that, for the period of this study, a divergence adjustment that is a function of pressure yields the best adjusted ver...

We examine the tropical ozone mixing ratio perturbation fields generated from a monthly ozone climatology using 1998 to 2006 ozonesonde data from the Southern Hemisphere Additional Ozonesondes (SHADOZ) network and the 13-year satellite record from 1993 to 2005 obtained from the Halogen Occultation Experiment (HALOE). The long time series and high vertical resolution of the ozone and temperature...

We study the modulation of atmospheric nonisothermality and wind shears on the propagation of seismic tsunami-excited gravity waves by virtue of the vertical wavenumber, m (with its imaginary and real parts, mi and mr, respectively), within a correlated characteristic range of tsunami wave periods in tens of minutes. A generalized dispersion relation of inertio-acoustic-gravity (IAG) waves is o...

The existence, scale, and growth rates of subsynoptic-scale warm-core circulations are investigated with a simple parameterization for latent heat release in a nonconvective basic state using a linear two-layer shallow-water model. For a range of baroclinic flows from moderate to high Richardson number, conditionally stable lapse rates approaching saturated adiabats consistently yield the most ...

Tsunamis propagate at the surface of the deep ocean horizontal phase speeds of approximately 200 m/s, which is about two-thirds of the lower atmospheric sound speed. They have large horizontal wavelengths that are typically of a few hundred kilometers, and they remain coherent over large propagation distances. They also have large horizontal extents (sometimes a few thousand kilometers) paralle...

The sounding rocket for the DELTA (Dynamics and Energetics of the Lower Thermosphere in Aurora) campaign was successfully launched from Andoya at 00:33 UT on Dec 13, 2004. Though it was cloudy at the time of launch, the Weber Na lidar was operating intermittently between 20:00 UT and 23:30 UT on Dec 12, observing Na density, temperature and meridional wind between 80 and 100 km. Throughout the ...

mixed layer is a part of the atmospheric boundary layer in which pollutants are uniformly distributed. it is sensitive to the earth’s surface, controls the flow of heat and momentum between the surface and the free atmosphere, thus playing a key role in atmospheric circulation. most of atmospheric pollution models require the height of the mixed layer as an input to determine the depth of atmos...

Two independent wind profiles were measured every hour during Februa j 1986 with a five-beam, UHF (405 MHz) wind Profiler at Platteville, Colorado. Our analysis of the horizontal wind components over all heights for the entire month gave a standard deviation of about 1.3 m s-' for the measurement errors one can expect for three-beam Profilers in clear air. This study demonstrated that it is imp...