Stratospheric Wind Velocities Research Articles

Parameters of Acoustic Signals Generated by the Atmospheric Meteoroid Explosion over Romania on January 7, 2015

System spectral analysis of temporal variations in the level of acoustic signals recorded at a number of European infrasound stations is carried out. The prevailing periods that varied within 3–5 s are found. Initial kinetic and acoustic energies of the Romanian meteoroid and infrasound parameters are calculated: celerity (280 m/s), acoustic efficiency, and stratospheric wind velocity (about 20 m/s). Parameters of cylindrical and explosive shock waves are found: duration, characteristic size, and amplitude. The dependence of the attenuation of infrasonic waves on distance is estimated. The results of the estimates are in good agreement with the results of the observations.

Design requirements for the SWIFT instrument

The Stratospheric Wind Interferometer for Transport studies (SWIFT) instrument is a proposed limb-viewing satellite instrument that employs the method of Doppler Michelson interferometry to measure stratospheric wind velocities and ozone densities in the altitude range of 15–45 km. The values of the main instrument parameters including filter system parameters and Michelson interferometer parameters are derived using simulations and analyses. The system design requirements for the instrument and spacecraft are presented and discussed. Some of the retrieval-imposed design requirements are also discussed. Critical design issues are identified. The design optimization process is described. The sensitivity of wind measurements to instrument characteristics is investigated including the impact on critical design issues. Using sensitivity analyses, the instrument parameters were iteratively optimized in order to meet the science objectives. It is shown that wind measurements are sensitive to the thermal sensitivity of the instrument components, especially the narrow filter and the Michelson interferometer. The optimized values of the main system parameters including Michelson interferometer optical path difference, instrument visibility, instrument responsivity and knowledge of spacecraft velocity are reported. This work also shows that the filter thermal drift and the Michelson thermal drift are two main technical risks.

Performance evaluation of a thermal Doppler Michelson interferometer system

The thermal Doppler Michelson interferometer is the primary element of a proposed limb-viewing satellite instrument called SWIFT (Stratospheric Wind Interferometer for Transport studies). SWIFT is intended to measure stratospheric wind velocities in the altitude range of 15-45 km. SWIFT also uses narrowband tandem etalon filters made of germanium to select a line out of the thermal spectrum. The instrument uses the same technique of phase-stepping interferometry employed by the Wind Imaging Interferometer onboard the Upper Atmosphere Research Satellite. A thermal emission line of ozone near 9 microm is used to detect the Doppler shift due to winds. A test bed was set up for this instrument that included the Michelson interferometer and the etalon filters. For the test bed work, we investigate the behavior of individual components and their combination and report the results.

An intense stratospheric jet on Jupiter.

The Earth's equatorial stratosphere shows oscillations in which the east-west winds reverse direction and the temperatures change cyclically with a period of about two years. This phenomenon, called the quasi-biennial oscillation, also affects the dynamics of the mid- and high-latitude stratosphere and weather in the lower atmosphere. Ground-based observations have suggested that similar temperature oscillations (with a 4-5-yr cycle) occur on Jupiter, but these data suffer from poor vertical resolution and Jupiter's stratospheric wind velocities have not yet been determined. Here we report maps of temperatures and winds with high spatial resolution, obtained from spacecraft measurements of infrared spectra of Jupiter's stratosphere. We find an intense, high-altitude equatorial jet with a speed of approximately 140 m s(-1), whose spatial structure resembles that of a quasi-quadrennial oscillation. Wave activity in the stratosphere also appears analogous to that occurring on Earth. A strong interaction between Jupiter and its plasma environment produces hot spots in its upper atmosphere and stratosphere near its poles, and the temperature maps define the penetration of the hot spots into the stratosphere.

Climatology of the three coastal Antarctic stations Dumont d'Urville, Neumayer, and Halley

Long term air and snowfall chemistry measurements have been performed at the three coastal Antarctic stations Dumont d'Urville (66°40′S, 140°1′E), Neumayer (70°39′S, 8°15′W), and Halley (75°35′S, 26°19′W). The results have to be interpreted and compared with respect to the regional meteorological conditions. In this study the 3‐hourly synoptic surface observations taken at the three stations between 1991 and 1995, as well as the daily upper air soundings from 1993, are analyzed to describe the aspects of station climatologies relevant for the air and snowfall chemistry measurements discussed in the papers of this special section. Although the three stations are comparable, being situated close to the coastline of Antarctica, the meteorological conditions differ. While at Dumont d'Urville katabatic winds cause predominant strong and relatively dry surface winds from the interior of Antarctica, Neumayer and Halley are frequently influenced by easterly winds associated mostly with eastward moving cyclones. From April through October the wind field above 5 km is governed by a circumpolar vortex with westerly winds increasing in intensity with height. Dumont d'Urville represents a station at the edge of this vortex with extreme stratospheric wind velocities up to above 50 m s−1. Neumayer and Halley are mostly situated within the vortex and isolated from air masses advecting from lower latitudes into the upper troposphere and lower stratosphere during the Austral winter.

Stratospheric Wind Velocity Determination from Long Duration Balloon Flights

Abstract Two long duration balloons, Infrared Montgolfieres, floating between 20 and 30 km for more then 20 days, were launched in the Southern Hemisphere in November 1988. The tracking of these balloon trajectories allowed stratospheric wind velocity to be determined and showed the importance of this type of balloon as a complement to satellite determinations.