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.
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Showing 1 to 20 of 112 for “"Physics, Atmospheric Science"”.
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Speciated Local Aerosol Characteristics and Radiative Forcing at a Rural Midwestern Site
This research supports the view that species other than ammonium sulfate, namely EC, OC and dust-like aerosol, have significant radiative effects. Although the mass percentage of EC may be low at rural sites, ignoring the presence of EC aerosol leads to an over estimation of the aerosol forcing.
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Improved Temperature Response Functions for Modeling Photosynthetic Carbon Assimilation in the Context of Rising Carbon Dioxide
Predicting environmental responses of leaf photosynthesis is central for modeling changes in the future global carbon cycle and terrestrial biosphere. The steady-state biochemical model of C3 photosynthesis of Farquhar et al. (1980; Planta 149, 78--90) provides a basis for these larger scale …
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A Model Analysis of Anthropogenic Influences on Ozone and Related Species: The Interaction of Transport and Chemistry
Significant seasonal variations in the concentrations of several trace gases were observed in the southern tropical Pacific during the PEM-TROPICS-A (PT-A) and PEM-TROPICS-B (PT-B) campaigns. In the second part of this thesis, a 3D CTM, MOZART, is used to investigate the ozone budget and identify …
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Gravity Wave/large-Scale Flow Interactions: A Comparison of Model Predication and Observation
These observed interaction signatures are then compared to the interaction signatures predicted by three commonly used gravity-wave parameterizations: critical level filtering, linear saturation filtering, and diffusive filtering. A one-dimensional, time-independent model filters various …
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Generalized Barotropic Models for Studying the Low -Frequency Variability of the Extratropical Atmosphere
Finally, the generalized model is scrutinized in terms of its normal, adjoint, optimal and singular modes. It is found that the modes of the empirically modified model are more stable than the ones of the barotropic model. Also the modified barotropic optimal modes are more difficult to excite than …
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African Easterly Waves: Evolution and Relationship to Atlantic Tropical Cyclones
Every year, a majority of all Atlantic hurricanes originate from African easterly waves. Yet, less than 20% of all African waves originate tropical cyclones (including hurricanes). It is of interest to investigate if African waves involved in cyclogenesis possess special characteristics, or if the …
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Mesoscale Ensemble Prediction of Mid-Latitude Cyclones
… subsets, incorporating initial condition, model physics and lateral boundary uncertainties present in mid-latitude cyclone prediction. The use of separate ensemble subsets permitted direct comparison of the contributions from different uncertainty sources. Through the examination of the ensemble …
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Synoptic and Mesoscale Dynamics of Snowbands in Winter Cyclones
The key findings related to the narrow bands are: (1) The simulated embedded narrow bands were oriented vertically upright, their widths and evolution characteristics similar to radar observations; (2) Conditional symmetric instability did not contribute to the formation of the narrow bands, …
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A Diagnostic and Dynamical Study of the Midwinter Minimum of the Pacific Storm Track
"In NH winter, the Pacific storm track tends to reach its maximum intensity during early and late winter, leaving a distinct minimum in January, which is known as ""midwinter minimum"" (MWMIN) of the Pacific storm track. The main objective of this study is to explain the origin of MWMIN from the …
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Cloud Observations From Eos-Terra: From Conception to Interpretation of Cloud Climatologies With a Focus on Small Clouds
Global comparison between the MISR and MODIS cloud masks shows large discrepancies over regions dominated by small clouds. This discrepancy was further explored using an ASTER dataset at 15m resolution over the tropical western Atlantic. On average, MODIS and MISR overestimate cloud fraction by 18% …
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Barotropic Model Simulations of Low-Frequency Variability
Unforced, subcritical nonlinear simulations fail to produce meaningful variability, indicating that forcing is necessary in maintaining the low-frequency variability in the barotropic system under subcritical condition. Stochastically forced experiments are conducted using spatially homogeneous …
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Rain Formation in Shallow Tropical Convection
Despite the time and space constraints placed on the results by the observed evolution of the updrafts, the calculations showed that the process of rain formation in warm convective clouds is simple and efficient, provided that giant and ultragiant CCN are present near cloud base. While more …
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An Observational and Modeling Study of the Relationships Between United States Precipitation and Pacific Sea Surface Temperature
… suggest some effects of North Pacific SST on the atmospheric circulation.
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Low-Frequency Variability in the Stratosphere
"We have run a dry, nonlinear, primitive equation spectral model with no externally forced variability and with a realistic time mean state, and we have observed low frequency variability (LFV) in the stratosphere with timescales on the order of hundreds of days. Time lagged correlations have …
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Origin, Maintenance and Fine-Scale Structure of 14-15 February 1992 Mesoscale Gravity Wave Observed During Storm-Fest
The gravity wave was generated behind the leading edge of an advancing dry surge moving over a warm frontal inversion. The dry surge, which had the characteristics of density current, originated as a foehn-like downslope flow over the Rocky Mountains of southern Colorado and New Mexico. The …
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Understanding the Maintenance and Seasonal Transitions of the Climatological Stationary Waves in the Atmosphere
The deficiency of the GCM in simulating the observed reanalysis stationary waves mainly originates from the deficiencies of the GCM simulated diabatic heating field. Therefore, a significant improvement in the parameterization schemes and spatial resolution of the GCM is needed for the GCM to …
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The Role of Upstream Lakes in Determining Downstream Severe Lake -Effect Snowstorms
A severe lake-effect snowstorm on 25--26 December 1993 was successfully modeled using the Penn State/NCAR MM5 model at 7 km grid resolution. Another simulation performed with Lake Michigan removed from the domain resulted in a two-thirds reduction in snowfall maxima, reduced vertical ascent (50% …
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Conditions Associated With Cold Season Dense Fog in the Midwestern United States
The physical dimensions and onset time of dense fog appeared to be the best predictors of fog duration for all types of fog. Longer lasting events tended to form earlier in the night, to be more opaque and widespread, and to dissipate several hours later than short-lived events. The longer …
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Influence of Soluble Surface-Active Organic Material on Droplet Activation
Both theoretical and experimental approaches also show that despite the a depression, S$\sb{\rm c}$ of a particle that contains SDS is always higher than that of a pure NaCl particle with the same dry size. The degree of this deviation increases with increasing SDS% in the mixtures, indicating an …
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