scholarly journals Observations of the Leonids in Central Asia

1998 ◽  
Vol 11 (2) ◽  
pp. 1022-1022
Author(s):  
P.B. Babadzhanov
Keyword(s):  
Central Asia ◽  
Density Range ◽  
Dust Grains ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere

Observations in Central Asia in 1965-1966 by both photographic and radar methods allowed a determination of the radiants and orbits of Leonids (Babadzhanov and Getman 1970). Photographs showed that meteoroids undergo quasi-continuous fragmentation (QCF) in the Earth’s atmosphere. Taking account of QCF, the density of the Leonid meteoroids were found to lie between 1 and Agcm-3 the average being 2gcm-3 (Babadzhanov 1994), in agreement with the density range of between 0.2 and 6gcm-3 given by Maas et al (1990) for dust grains from comet P/1 Halley, with values below 0.6 being rare. Further, the icy grains have a density of about 1gcm-3 while silicate grains have a mean density 2.5 times higher.

scholarly journals Diagnostics of internal atmospheric wave saturation and determination of their characteristics in Earth’s stratosphere from radiosonde measurements

2018 ◽  
Vol 4 (2) ◽  
pp. 76-85
Author(s):  
Владимир Губенко ◽  
Vladimir Gubenko ◽  
Иван Кириллович ◽  
Ivan Kirillovich
Keyword(s):  
Energy Dissipation ◽  
Wind Speed ◽  
Internal Wave ◽  
Wave Amplitude ◽  
Internal Gravity Waves ◽  
Lower Atmosphere ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere ◽  
Amplitude Growth

Internal gravity waves (IGW) significantly affect the structure and circulation of Earth’s atmosphere by transporting wave energy and momentum upward from the lower atmosphere. Since IGW can propagate freely through a stably stratified atmosphere, similar effects may occur in the atmospheres of Mars and Venus. Observations of temperature and wind speed fluctuations induced by internal waves in Earth’s atmosphere have shown that wave amplitudes increase with height, but not quickly enough to correspond to the amplitude increase due to an exponential decrease in the density without energy dissipation. The linear theory of IGW explains the wave amplitude growth rate as follows: any wave amplitude exceeding the threshold value leads to instability and produces turbulence, which hinders further amplitude growth (internal wave saturation). The mechanisms that contribute most to the energy dissipation and saturation of IGW in the atmosphere are thought to be the dynamical (shear) and convective instabilities. The assumption of internal wave saturation plays a key role in radio occultation (RO) monitoring of IGW in planetary atmospheres. A radiosonde study of wave saturation processes in Earth’s atmosphere is therefore actual and important task. We report the results of determination of actual and threshold amplitudes, saturation degree, and other characteristics for the identified IGW in Earth’s atmosphere obtained from the analysis of SPARC (Stratospheric Processes And their Role in Climate) radiosonde measurements of wind speed and temperature [http://www.sparc.sunysb.edu/].

ASSESSING RADIATION EXPOSURE INSIDE THE EARTH’S ATMOSPHERE

2020 ◽  
Vol 190 (4) ◽  
pp. 427-436
Author(s):  
Anastasia Tezari ◽  
Pavlos Paschalis ◽  
Helen Mavromichalaki ◽  
Pantelis Karaiskos ◽  
Norma Crosby ◽  
...  
Keyword(s):  
Situational Awareness ◽  
European Space Agency ◽  
Software Application ◽  
Dose Rates ◽  
Earth’S Atmosphere ◽  
Service Centre ◽  
Space Agency ◽  
Earth's Atmosphere ◽  
New Feature

Abstract The study of the particle showers created inside the Earth’s atmosphere due to interactions of cosmic rays of solar and galactic origin is of great importance for the determination of the radiation impact on technological and biological systems. DYASTIMA is a Geant4-based software application that simulates the evolution of secondary particle cascades inside the atmosphere of Earth. DYASTIMA-R is a new feature especially created for assessing the exposure of flight-personnel and frequent flyers to cosmic radiation by performing calculations of radiobiological quantities, such as dose and equivalent dose rates for several air-flight scenarios. In this work, the validation of DYASTIMA/DYASTIMA-R, according to internationally accepted ICRP and ICRU standards, is discussed. Initial results for radiobiological quantities for several air-flight scenarios are also included. The results for specific scenarios calculated by DYASTIMA/DYASTIMA-R are provided as a federated product through the European Space Agency Space Situational Awareness Space Weather Service Centre Network.

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