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 17 of 17 for “"mesosphere and lower thermosphere"”.
-
Long-range Propagation, Interaction, and Dissipation of Small-Scale Gravity Waves in the Mesosphere and Lower Thermosphere
… compressible numerical model [<em>Snively and Pasko, </em> 2008] is used in conjunction with ray-theory to investigate the long-range propagation, dissipation and interaction of small-scale gravity waves in the Mesosphere and Lower Thermosphere (MLT) region. The research in this thesis is …
-
Dynamical Processes of Gravity Waves Propagation and Dissipation, and Statistical Characteristics of Their Momentum Flux in the Mesosphere and Lower Thermosphere
<p>The mesosphere and lower thermosphere (MLT) (⇠80–110 km) is dominated by abundant atmospheric waves, of which gravity waves are one of the least understood due to large varieties in wave characteristics as well as potential sources. Gravity waves play an important role in the atmosphere by …
-
Fabry-Perot Observations of Midlatitude Neutral Winds and Atmospheric Gravity Wave Activity
<p>The mesosphere and lower thermosphere displays a wide range of dynamical phenomena resulting in a complex and variable regions. Governed primarily by fluid dynamics, the motion of the upper atmosphere is modulated by a number of atmospheric waves propagating upward from various sources in the …
-
Analysis of Ionospheric Data Sets to Identify Periodic Signatures Matching Atmospheric Planetary Waves
… to the low-latitude ionosphere. To better understand this coupling, this study investigates times when oscillations seen in both atmospheric planetary waves and ionospheric data-sets have similar periodicity. The planetary wave data-set used are temperature observations made by Sounding of the …
-
Seasonal and Diurnal Variations in the Temperature and Sodium Density Structure of the Middle Atmosphere
… 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. Coverage over the complete diurnal cycle produces unbiased, background profiles and enables an accurate …
-
An investigation of atmospheric turbulence in the 100-105 km region over Cerro Pachón, Chile
… above 97 km. Using the lidar system at the Andes Lidar Observatory in Cerro Pachón, Chile (30.3ºS, 70.7ºW), a novel reconstruction algorithm measuring turbulence fluctuation power at smaller signal-to-noise ratios (SNRs) than existing methods is derived and validated. Results are compared …
-
Investigation of a gravity wave ducting event in the upper mesosphere
… an important role in the transport of energy and momentum throughout the Earth’s atmosphere. GW effects couple the lower regions of the atmosphere with the middle and upper regions of the atmosphere and the neutral atmosphere with the ionosphere. The effects are particularly strong in the …
-
Role of Planetary Wave-Tide-Gravity Wave Interactions In Whole Atmosphere Coupling
… in this dissertation utilizes observational data and numerical simulations, with a particular emphasis on sudden stratospheric warming (SSW) events. The development of a new multi-static meteor radar at 30ºS, named Chilean Observation Network De MeteOr Radars (CONDOR), provides a key dataset for …
-
Non-LTE diagnostics of the infrared observations of the planetary atmosphere
… astrophysics for spectrum formation calculations and for the computation of non-LTE model stellar atmospheres. This new for atmospheric science technique is not subject to the limitations of the traditional matrix and conventional lambda iteration methods which dominate the studies dealing with …
-
3D Simulator for Wind Interferometer Data-Model Comparison
The connection between earth and space weather has numerous impacts on spacecraft, radio communications and GPS signals. Thus, predicted & modeling this region is important, yet models (both empirical and first principles) do a poor job of characterizing the variability of this region. One of the …
-
An Observational Investigation on Gravity Wave Characteristics and Propagation in the Lower Stratosphere and Mesopause
… 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 variation of wave …
-
On the Interaction between Gravity Waves and Atmospheric Thermal Tides
<p>Gravity waves and thermal tides are two of the most important dynamical features of the atmosphere. They are both generated in the lower atmosphere and propagate upward transporting energy and momentum to the upper atmosphere. This dissertation focuses on the interaction of these waves in the …
-
Development of ground and space based instrumentation for middle and upper atmospheric studies
… Rayleigh lidar to measure neutral density and temperature in the upper atmosphere, into the lower thermosphere (>90 km). The scientific interest with this system is to obtain measurements of atmospheric tides, planetary and gravity wave amplitudes and phase in the lower thermosphere. …
-
Understanding Middle Atmospheric Composition Variability from the Solar Occultation for Ice Experiment Instrument and Other Datasets
… 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 bounded by pauses where the strongest changes …
-
Dynamics of Atmospheric Gravity Wave Breaking in the Mesopause Region
<p>GWs significantly impact the Mesosphere and Lower Thermosphere (MLT), and as a consequence of GW breaking, atmospheric turbulence plays an essential role in the mixing and transport of momentum, mass, and chemical materials in MLT. The main focus of this research for the fulfillment of the …
-
Studies of gravity wave and thermal tide and their interactions in the middle atmosphere
Gravity waves (GWs) and tides are 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, …