This work describes the design, implementation, and calibration of NOAA's coherent, pulsed, Doppler lidar. This lidar was used to acquire 252 high quality, independent measurements of atmospheric backscattering profiles from 4 to 30 km altitude over Boulder, Colorado, at a wavelength of 10.6 micrometers between May 1981 and May 1983, a period that includes the injection and removal of debris from the El Chichon eruptions. Statistical analyses of the data set by computer show that atmospheric backscattering is approximately lognormally distributed for all but the lowest altitudes, and a theoretical explanation is offered for this property. Seasonally-averaged profiles and altitudinally-stacked, filtered time sequences show the volcanic cloud appearing in the stratosphere and falling through the tropopause into the troposphere at rates far higher than can be explained by gravitational settling alone. The dynamic process of tropopause folding is proposed as the dominant mechanism for the observed exchange of volcanic debris from the stratosphere to the troposphere. This hypothesis is supported by case studies of mid-tropospheric backscatter-enhancing events. Mie calculations and comparisons with other measurements show that vertically-integrated backscatter is a good long-term measure of total atmospheric mass loading of volcanic debris. It is found that the time constant which characterizes debris removal is 208 days for the stratosphere and 60 days for the troposphere. No appreciable debris is removed before the volcanic cloud falls to 6 km altitude 420 days after the volcanic eruptions.

We have constructed the thermal structure of Neptune's stratosphere and low thermosphere with pressures between 10⁻³ μbar and 100 mbar using a radiative-conductive model which includes solar UV and EUV heating, non-LTE cooling by hydrocarbon fundamental bands, cooling by H₂ collisional induced opacities, and heating by the CH₄ near and far infrared bands. We have thoroughly investigated the availabilities of different techniques in modeling the CH₄ near-IR bands (3.3, 2.3, and 1.7 μm) and calculating the heating rates of these bands for pressures between 10⁻³ μbar and 100 mbar and temperatures between 50 K to 300 K. We have established an accurate and efficient way which is a combined method of correlated-k model and the Baines et al. (1993) empirical model to calculate these heating rates. The same method can also be applied to any other atmosphere of a Jovian planet. Through comparing the calculated temperature profiles and the measured one of Neptune's upper atmosphere, we have set constraints on the magnitudes, locations and the regions those are extended by for the stratospheric aerosol heating, heating by the source located in the mesosphere and heating by the conducted flux from the thermosphere. We also found that by using a constant CH₄ mixing ratio in the stratosphere of Neptune, 1.3 x 10⁻³, obtained by Yelle et al. (1993) through analyzing Voyager solar occultation data, the measured stratospheric temperatures between 20 to 100 mbar can be best matched by the calculational results.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xviii, 154 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Jeffery C. Rogers, Dept. of Atmospheric Science. Includes bibliographical references (p. 142-153).

Simple one-dimensional heat balance equations have been used to understand climate concepts since the 1960s, when a class of models was developed known as energy balance models (EBMs). EBMs use the growth or loss of polar surface ice as a climatic feedback, giving rise to surprisingly complex non-linear behaviours. One aspect of EBMs that has been relatively poorly examined is the effects of feedbacks caused by the other two phases of water in Earth’s climate other than ice: water clouds and water vapour. Cloud and water vapour play a critical role in the energy balance of Earth’s climate, and yet are some of the least well understood elements of the global climate system. This thesis explores the behaviour and interrelationships of climatic feedbacks caused by water in all three phases as it exists in the climate: surface ice caps, water vapour, and liquid water clouds. A two-layered EBM was modified with parameterizations of water vapour and liquid water clouds in order to conduct experiments. Three variants of the model were produced, each with progressively more water feedbacks than the last: a 1 phase model (with only surface ice feedback), a 2 phase model (with surface ice and water vapour) and a 3 phase model (with surface ice, water vapour, and cloud). The models were found to give generally realistic results, but with an underestimation of water vapour density, which in turn reduced the generated cloud fraction in the 3 phase model. Thus, the impacts of these extra feedbacks were likely to be underestimated in the analysis in general. The sensitivity of the model to several prognostic variables was studied by observing the changes in the model to a range of each variable. The 3 phase model was less sensitive to changes to the solar constant, S0, which measures incoming solar radiation, than the 1 phase model. This was probably caused by cloud reflecting and absorbing some radiation from the sun that would have otherwise reached the surface, changing the ratio of atmospheric heat transport to surface heat transport from 2.4953 for the 1 phase model to 2.0626 for the 3 phase model. Changing surface and ice albedo values resulted in changes in the model’s stability. The model was found to be insensitive to changes in surface humidity that drives the amount of water vapour the system has available, due to underestimation of water vapour in the model. The stability of the model was examined, and the 1 phase model was found to respond faster to changes in S0 than the 3 phase model. The model was tested for hysteresis, which was confirmed for all three model variants. The 1 phase model showed less stability then the 3 phase model as S0 was increased, but both models were similarly stable as S0 was decreased.

Thesis (Ph.D.) -- University of Texas at Arlington, 2009.

Thesis (M.S. in Physics)--Naval Postgraduate School, December 1990. / Thesis Advisor(s): Weaver, Wm. Bruce. Second Reader: Cleary, David D. "December 1990." Description based on title screen as viewed on March 29, 2010. DTIC Identifier(s): Atmosphere Models, Photons, Parameters, Photosphere, Theses. Author(s) subject terms: Simulation, Solar absorption lines, Radiative transfer theory. Includes bibliographical references (p. 56-57). Also available in print.

The observations made near Grahamstown (33 .3°S, 26.5°E), South Africa and Adelaide (34.5°S, 138.5°E), Australia over the years 1987 to 1994 are used to study the dynamics of the mesosphere and lower thermosphere (ML T) region with a focus on ∼ 90 km altitude. In particular this thesis deals with on the atmospheric mean flow and the solar diurnal and semi diurnal oscillations with a view to (i) deducing their patterns at the two sites, (ii) comparing the dynamic structures observed at the two sites with special emphases on longitudinal variations, and (iii) putting these observations in a global context by comparing with other ground-based observations, satellite observations and numerical simulations. The main findings are summarised below. The mean flow and the tides at Grahamstown and Adelaide are characteristically variable at planetary time scales. Wavelet spectral and multiresolution analyses reveal that the dominant planetary oscillation is the quasi-16-day oscillation. However, no apparent correlation in the 16-day waves of the mean flow, the diurnal tide and the semidiurnal tide was found. The short-term fluctuations were also investigated using complex demodulation and bispectral techniques and it was found that some of the observed variations in tides could be due to non-linear wave-wave interactions. The long-term trends of the mean flow and tides show patterns that are in broad agreement with theory, results from elsewhere (ground-based and satellite) and the results of the Global-Scale Wave Model and various models by Portnyagin and others. In general the mean flow, the amplitudes and phases of both tides were found to exhibit seasonal and interannual variations which are thought to be related to various factors including (i) changes in the atmospheric mean environment, (ii) thermotidal forcing (iii) gravity wave effects, (iv) planetary scale influence, (v) long-term (e.g. quasi-biennial oscillation) modulation, and (vi) solar activity. There are significant longitudinal differences in the dynamic structure between Grahamstown and Adelaide. More especially, Grahamstown tends to have stronger mean flow and tidal activity than Adelaide. For tides, these differences are thought to be partly due to nonmigrating tidal modes but, in general, migrating modes were found to be dominant.

The spacecraft Voyager 2 UVS occultation experiments measured the ultraviolet absorption properties of the upper atmosphere of Saturn. In the extreme-ultraviolet wavelength region from 1300 Å to 1700 Å, CH₄, C₂H₂, C₂H₄, C₂H₆ and C₄H₂ are the major absorbers in the Saturnian upper atmosphere. In this dissertation, using the linear constrained matrix method, the Saturnian stellar EUV occultation data has been inverted. This results in, for the first time, the number density distributions of the 5 major hydrocarbons over an altitude range from 1030 km to 630 km. The synthetic transmission curves based on these inverted distributions exhibit excellent agreement with the observed transmission curves in all usable wavelength channels. There are two major findings in the Saturnian upper atmosphere from the inverted hydrocarbon profiles: (1) The number densities of CH₄ and C₂H₆ are comparable. It is even likely that there is more C₂H₆ than CH₄ in Saturn's upper atmosphere between 1000 km and 800 km. (2) C₂H₄, rather than C₂H₂, is the 3rd most abundant hydrocarbon. From 1000 km down to 600 km, the number density of C₂H₄ is greater than the number density of C₂H₂. These two findings are generally in conflict with the expectations from photochemical models for the atmospheres of the giant planets.

Cirrus cloud forecasting is of particular importance to various Department of Defense programs. This thesis takes a case study approach to study Air Force Weather Agency Mesoscale Model 5 (AFWA MM5) skill in forecasting cirrus clouds, which are not represented explicitly by the model (ice water mixing ratio is used as a surrogate.) Two cases are selected for study. For each case, an initial forecast time of interest is determined which serves as the beginning point for the case study. GOES data and 3-hourly MM5 data are then obtained at 3- hourly intervals to coincide with model forecast time steps between the initial time through the 30-hour forecast. A standard analysis is performed on all data to determine general atmospheric structure for each case at each 3- hourly point. Following this, the model's relative humidity with respect to ice, explicit ice water content, vertical velocity, and other fields are considered to determine if the model possesses the proper dynamical factors for cirrus formation. Finally, model coverage of ice cloud is compared to the ABL cloud mask results to determine how well the model s ice cloud forecasts verify against each 3-hourly observed ice water field taken from the GOES data. Results indicate that the MM5 underforecasts cirrus coverage, and that the 90% relative humidity field with respect to ice may be a better approximation of observed cirrus coverage than the ice water field.

Cosmic rays measured by the fluorescence detectors of the Pierre Auger Observatory contain two large sources of error; the degree of scatter created by the atmosphere and the amount of Cherenkov contamination that has been recorded by a detector. When an event is viewed in stereo, these two sources of error can be accounted for directly by using the light profiles calculated by the two detectors. In this thesis accounting for the atmospheric scatter was explored by the use of a program called AerosolMin described in Chapter 5. This program could reconstruct the scattering parameters of the atmosphere by comparing the two profiles of the light produced by an air shower, as calculated by two detectors, as they should be identical in size. When using AerosolMin it was found that only the highest energy events ( > 10 [superscipt 20] eV ) could use this technique and that for the event that occurred at the GPS second of 799137161 a layer of fog was present that could not be accounted for with the simplistic atmospheric profile currently used by the reconstruction software. In Chapter 6 the Cherenkov profiles that had been miscalculated by a detector were replaced to increase the reconstruction statistics. The program that performed this replacement, FdCherenkovReplacer was most successful on events that had recorded a large amount of direct Cherenkov light. The event that occurred at the GPS second of 772256331 is explored in Chapter 7. The Coihueco detector that recorded this event was contaminated by direct Cherenkov light, but when replaced by FdCherenovReplacer it was found to have miscalculated the geometry of the event by 0.4 °. / Thesis (M.Sc.)--School of Chemistry and Physics, 2007.