Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 26 for “"Middle Atmosphere"”.
-
Middle Atmosphere Structure and Dynamics: Lidar Studies and Gravity Wave Spectral Modeling
Finally, a new gravity wave spectral model is developed. We employ more realistic models of the source spectra and diffusive filtering theory (DFT) to model the one-dimensional and two-dimensional spectra of horizontal and vertical winds, atmospheric density, and temperature. Although more …
-
LIDAR Studies of the Middle Atmosphere Temperatures and Iron Layer at South Pole
Similar to the Na observations at South Pole in 1995--1997, the seasonal variations in Fe column abundance, height, and width exhibit a strong annual cycle. The Fe and Na densities exhibit strong 12-month oscillations with the amplitudes comparable to the background level, resulting in extremely …
-
Studies of gravity wave and thermal tide and their interactions in the middle atmosphere
… two strongest and most persistent waves in the middle atmosphere of the Earth. They are usually generated in the lower atmosphere and propagate upward to the middle and upper atmosphere, where they play important roles in the atmospheric composition, chemistry, dynamics and energetics. This …
-
Middle atmosphere structure and dynamics: Lidar studies at the South Pole, Syowa and Urbana
We present lidar observations of the middle atmosphere at the South Pole (90$\sp\circ$S), Syowa (69$\sp\circ$S, 39$\sp\circ$E), and Urbana (88$\sp\circ$W, 40$\sp\circ$N). The South Pole stratospheric observations yield a high resolution data set of stratospheric temperature and polar stratospheric …
-
Seasonal and Diurnal Variations in the Temperature and Sodium Density Structure of the Middle Atmosphere
More than 1000 hours of high-resolution sodium lidar observations were taken at the Urbana Atmospheric Observatory from February 1996 to April 1998. Temperature and Na density were measured in the mesosphere and lower thermosphere (MLT) during both day and night throughout the annual cycle. …
-
Theory and Observations of Horizontal and Vertical Structure of Gravity Wave Perturbations in the Middle Atmosphere
Gravity wave models for the horizontal wave number spectra of atmospheric velocity and density fluctuations are derived by assuming that both saturated and unsaturated waves obey the polarization and dispersion relations and that the joint $(m{,}\omega)$ spectrum is separable. The models show that …
-
Understanding Middle Atmospheric Composition Variability from the Solar Occultation for Ice Experiment Instrument and Other Datasets
… comprises multiple studies surrounding the middle atmosphere's chemistry, composition, and dynamics. The middle atmosphere refers to the region from ~ 10 km to ~ 100 km and consists of the Stratosphere, Mesosphere, and Lower Thermosphere. The Stratosphere, Mesosphere, and Thermosphere are …
-
An Observational Investigation on Gravity Wave Characteristics and Propagation in the Lower Stratosphere and Mesopause
… waves are conducted in two regions of the middle atmosphere: the lower stratosphere using high-resolution radiosonde at South Pole and the mesopause region using OH airglow imager at Maui, Hawaii and Cerro Pachon, Chile. Wave characteristics at these regions are deduced and the seasonal …
-
Lidar studies of sporadic sodium layers, gravity waves and density spectra in the mesopause and stratopause regions at Urbana and Arecibo
… study of vertical and temporal structures of the middle atmosphere. This thesis paper first presents what are believed to be the first observations of meteor ablation trails with a lidar. Next, the simultaneous observations of a sporadic E layer by the Arecibo 430 MHz incoherent scatter radar and …
-
Study of the Martian upper atmosphere using radio tracking data
… the first in situ observations of the Martian atmosphere were made by the twin Viking landers, we have learned considerably more about its composition, dynamics and variability. Not only did the new data on global atmospheric densities generate opportunities to understand the atmospheric …
-
The Influence of Obliquely Propagating Monsoon Gravity Waves on the Polar Summer Mesosphere
… troposphere. While propagating through the middle atmosphere, these waves can carry their momentum up to the mesosphere, following either a vertical or an oblique path. This upward and oblique propagation of gravity waves refers to the latitudinal propagation, away from their low-latitude …
-
Modelling Mesopause OH* Emissions using a Global Circulation Model
Nightglow within the mesopause region of the atmosphere is dominated by the infrared emissions from vibrationally excited hydroxyl (OH*) radicals at ~87km altitude. These emissions provide a signal from which the behaviour of the middle atmosphere can be studied and in recent years a wealth of …
-
Investigation of the Oxygen Isotope Exchange Between Carbon Dioxide and O3 via O(1D)
Carbon dioxide in the middle atmosphere shows an increasing enrichment in the heavy oxygen isotopes with altitude which preferential enrichment for 17O according to d17O =1.7 d18O. This is contrary to tropospheric CO2 where d17O ~ 0.5d18O. These isotope enrichments are transferred from O3 into CO2, …
-
A Survey of Seasonal, Hemispheric and Interannual Variations in the Gravity Wave Spectrum in the Upper Stratosphere and Lower Mesosphere
… analysis of gravity waves (GWs) in the Earth's middle atmosphere using satellite observations from the Cloud Imaging and Particle Size (CIPS) instrument and the Atmospheric Infrared Sounder (AIRS). Data from the years 2019–2021 are examined, covering both stratospheric and mesospheric altitudes …
-
Study of Acoustic-Gravity Wave Spectra in the Atmosphere Using Mesosphere-Stratosphere- Troposphere Radar (Propagation, Universal Spectrum)
… influence the large-scale dynamics of the middle atmosphere. The morphology and structure of the atmospheric processes which cause this phenomenon can be better understood by the study of acoustic-gravity wave spectra. In order to use the meso-scale wind fluctuation data measured by MST …
-
Studies of wave-mean interaction relevant to the middle atmospheric circulation
… 5), Rossby waves and their mean effects in the middle atmosphere are investigated within the framework of quasi-geostrophic theory. Chapter 2 describes a simple thought experiment to highlight the usefulness of the description of wave-mean interactions in terms of wave-induced transport of …
-
A Quasiclassical Trajectory Study Of Impulsive Collisions Between Hydroxyl (nu = 1--9, K = 1,2,5,10) And Molecular Oxygen In The Upper Mesophere
… used as a remote sensing tool in the study of middle atmosphere dynamics. To assess the validity of this technique, a comprehensive understanding of the excitation and emission processes is required. The effect of collisional quenching of vibrationally excited OH by {dollar}rm Osb2{dollar} …
-
Analysis of light curves from the 2003 Nov 14 occultation by Titan of TYC 1343-1855-1
… scintillation spikes in the occulting body's atmosphere. Temperatures derived with this method are equal to or warmer than those measured by the Huygens Atmospheric Structure Instrument. Using the highly structured, three-peaked central flash, we confirmed the shape of Titan's middle …
-
An Investigation of the Distribution of Ozone-depleting Substances in the Upper Troposphere and Lower Stratosphere
… the specified dynamics mode of the Canadian Middle Atmosphere Model (CMAM30) by comparing its output to the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) profile measurements of CFC-11, CFC-12, HCFC-22, and N2O. In the CMAM30 simulation, the meteorological fields …
-
Influence of the Quasi-biennial Oscillation on Interannual Variability in the Northern Hemisphere Winter Stratosphere
Observations show that the interannual variability of the Northern Hemisphere (NH) extratropical winter stratosphere is strongly correlated with the quasi-biennial oscillation (QBO) of tropical stratospheric winds, particularly during early winter. Most current general circulation models (GCMs) do …
Page 1 of 2