This study utilizes the FLEXPART Lagrangian Particle Dispersion Model that was adapted to ingest output from the Weather Research and Forecasting (WRF) meteorological model. We perform four series of simulations over Iran and surrounding regions. The tests are designed to document FLEXPART's sensitivities to WRF's 1) horizontal resolution, 2) vertical resolution and vertical level configuration, 3) planetary boundary layer (PBL) physics, and 4) the choice of a land surface model (LSM). Twelve 3-day simulations are performed to examine the transport and dispersion (T&D) of CO in complex terrain due to emissions from anthropogenic and biomass burning sources. Structural characteristics of two primary CO plumes are analyzed by computing their dispersion parameters. Then an object-based (OB) verification technique is employed to verify the simulated CO plumes against AIRS satellite-derived plumes. We also present traditional verification statistics (i.e., RMSE) that compare WRF-derived winds and temperatures to observations, as well as an OB verification of precipitation rates against satellite-derived rates. Finally, the vertical structure of the simulated CO plumes produced by fires is qualitatively compared to CALIPSO's satellite-derived aerosol data by assuming that airborne aerosols approximately follow the trajectories of CO emitted by the fires. Verification results indicate a general improvement in the accuracy of wind speed, wind direction, and precipitation rate when increasing WRF's horizontal and, to a lesser extent, its vertical resolution. However, the results suggest that increasing the horizontal resolution to 1.6 km does not add more skill than the simulation using a 2.67-km grid spacing. This lack of further improvement is determined to be an effect of enhanced errors in the lateral boundary conditions (LBC). Results also show that the various PBL schemes and LSMs produce the greatest changes in the meteorological parameters. Comparison of the simulated plumes to satellite-derived plumes reveal marked changes in the accuracy of the T&D simulations. Two primary plumes are considered in the comparisons, one that formed over the Arabian Desert and another that formed in northern Iran. Results show that the ability to replicate both plumes is considerably xii enhanced by increasing WRF's horizontal and vertical resolution. Again, the simulation at 2.67 km resolution produces a better match than the 1.6 km simulation. The greatest improvements occur when the vertical resolution is increased, especially in the PBL. Results from WRF's various PBL options show that the MYJ and ACM2 schemes produce anomalously low PBL heights in desert regions that degrade the simulations' ability to replicate the Arabian Desert CO plume. Conversely, the models' accuracy in simulating the Iranian plume is increased. The RUC LSM increases the verification score due to its more realistic surface sensible heat fluxes compared to the other LSMs. The Pleim-Xiu LSM matches both plumes with similar accuracy as the 5-Layer LSM, whereas the Noah LSM is found to degrade simulation accuracy. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2009. / December 8, 2008. / Sensitivity, Transport and Dispersion modeling, FLEXPART, WRF / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Anil Rao, Committee Member; Xiaolei Zou, Committee Member; Paul Reasor, Committee Member.

This study explores potential vorticity budgets from the complete Ertel's potential vorticity equation during hurricane genesis. The data sets for these experiments are derived from a high-resolution hurricane forecast that provided reasonable simulation on hurricane genesis. The budgets sort out the relative contribution from the horizontal advection of PV (i.e., related to the conservation of PV in isentropic coordinates), vertical advection of PV (a diabatic contribution), differential heating along the vertical, differential heating along the horizontal, and the frictional contributions. This is aimed to sort out the role of conservation versus non-conservation of PV during the formative stage of a hurricane. The main findings of this study are that conservation of PV was not adequate to explain the large increase in PV during genesis of the storm. The vertical differential of heating made by far the most significant contributions to the changes of PV during the length of the forecast. This term contributed to a net generation of PV over a region of stable air with cyclonic vorticity and increased heating with height. The term is akin to the vortex stretching term in the vorticity equation and is the diabatic stretching of the vortex tube. The effect that convergence has on vorticity in pressure coordinates is entirely analogous to the effect that the diabatic stretching term has on PV in isentropic coordinates. The vertical advection of PV and the horizontal differential of heating each made smaller contributions to changes in PV, but neither was a significant contributor as compared to the other terms. Our analysis includes parcel trajectories along which the PV components (adiabatic and diabatic) of the complete equation are calculated at intervals of every three hours. These were also cast on isentropic surfaces to assess the role of the nonlinear advection of PV and of the diabatic contributions. In the inner rain area of the hurricane a jump in the value of diabatic PV was noted (related to the vertical differential of heating) that was roughly several times larger than that of the nonlinear advection of PV (the latter relates to the conservation of PV while the former is a measure of the non-conservation). / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Fall Semester, 2003. / September 25, 2003. / Vortices, Vortex, Hurricane, Diabatic / Includes bibliographical references. / T. N. Krishnamurti, Professor Directing Thesis; Albert I. Barcilon, Committee Member; Paul H. Ruscher, Committee Member.

The steps involved in establishing and implementing a quality control procedure for AIRS radiance data prior to its use in a mesoscale model are discussed. The Limited Cloud-Clearing Data Removal (LCCDR) Algorithm utilizes AIRS channel maximum weighting function (WF) height, vertical structure of WF, and cloud height at each pixel to remove cloud-contaminated data points. Biweight statistics, which include a weighted average and weighted standard deviation, are implemented to remove remaining data with large model deviations from observations. Two test cases are examined: a non-precipitation case and a case involving Hurricane Charley. The LCCDR algorithm effectively removes outliers due to cloud-contamination, producing a reduction in the mean difference between simulated and observed brightness temperatures. Biweight statistics further exclude points where simulated values disagree with AIRS data. For both cases, large discrepancies are found between AIRS observations and simulated surface brightness temperatures in terms of the range of brightness temperature change and intensity. Overall, AIRS radiances compared more favorably with simulated data shown by the reduction in root mean square error values after quality control and the increase in correlation coefficient values. Future work includes improving model ability to predict dry versus moist air boundaries and cyclone intensity through assimilation of AIRS radiance observations. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2006. / April 4, 2006. / Data Assimilation, Biweight / Includes bibliographical references. / Xiaolei Zou, Professor Directing Thesis; Robert Ellingson, Committee Member; Ming Cai, Committee Member.

In the high latitudes during cold seasons, a substantial portion of precipitation falls in the form of snow. Measuring snow precipitation has many applications such as forecasting hazardous weather, understanding hydrological water budget, and evaluating the cooling and freshening effects of snow onto ocean surface. However, unlike rainfall, snowfall measurement is extremely limited due to technical difficulties, especially over ocean and in the Polar Regions. The goal of this study is to assess the feasibility of measuring snowfall from satellite observations. From the temporal analysis of surface radar data, a diurnal variation of snowfall in the Wakasa Bay area is detected, which is not identified by satellite infrared data. Snowfall signatures are analyzed using satellite and airborne microwave radiometer measurements at frequencies ranging from 37 to 340 GHz. Data used in the analysis include satellite data from the Advanced Microwave Scanning Radiometer-EOS and the Advanced Microwave Sounding Unit-B, and airborne data from a millimeter-wave radiometer and a dual-frequency precipitation radar during January 2003 near Japan. An investigation of the sensitivity of microwave channels to snowfall associated with shallow convective clouds shows that microwave radiation at higher frequencies ( >= 150 GHz) is sensitive to scattering by snow/ice. Through data analysis and radiative transfer modeling, a snowfall retrieval algorithm based on Bayesian theorem is developed using high frequency satellite microwave data. In the Bayesian snowfall retrieval algorithm, observational data from airborne and surface-based radars are used to construct the a-priori database that is the most important component in the algorithm. Two size distributions for snowflakes and ten observed atmospheric sounding profiles are used to diversify the results and reduce the errors in the radiative transfer model. The scattering properties of the snowflakes are calculated based on realistic nonspherical shapes using discrete dipole approximation for the radiative transfer modeling. The algorithm is validated by independent surface radar/gauge data, subsequently applied to satellite AMSU-B data for winter snowstorms near Japan. The retrieved results show reasonable agreement with surface radar observations, which shows the possibility of applying this algorithm globally by expanding the database.= 150 GHz) is sensitive to scattering by snow/ice. Through data analysis and radiative transfer modeling, a snowfall retrieval algorithm based on Bayesian theorem is developed using high frequency satellite microwave data. In the Bayesian snowfall retrieval algorithm, observational data from airborne and surface-based radars are used to construct the a-priori database that is the most important component in the algorithm. Two size distributions for snowflakes and ten observed atmospheric sounding profiles are used to diversify the results and reduce the errors in the radiative transfer model. The scattering properties of the snowflakes are calculated based on realistic nonspherical shapes using discrete dipole approximation for the radiative transfer modeling. The algorithm is validated by independent surface radar/gauge data, subsequently applied to satellite AMSU-B data for winter snowstorms near Japan. The retrieved results show reasonable agreement with surface radar observations, which shows the possibility of applying this algorithm globally by expanding the database. / A Dissertation submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2006. / December 6, 2005. / Bayesian Theorem, Retrieval, Snowfall, Radiative Transfer Model, Satellite / Includes bibliographical references. / Guosheng Liu, Professor Directing Dissertation; Ruby Krishnamurti, Outside Committee Member; T. N. Krishnamurti, Committee Member; Sharon E. Nicholson, Committee Member; Mark A. Bourassa, Committee Member.

Over the past 40 years radiative transfer models have consistently under-predicted the amount of solar absorption by clouds. Estimates of the size of this discrepancy at the beginning of its discovery were ~10 W/m^2, but in 1995 jumped to 40-100 W/m^2, which ARESE I was formed to resolve. ARESE I being inconclusive, ARESE II was conducted and further studies brought the estimates back to ~10 W/m^2. Part of the problem lies with the difficulty of obtaining accurate measurements of the absorbed solar insolation as well as constructing models that represent real atmospheric conditions. So after ARESE II was completed an experiment was performed to test the effectiveness of a new technique-the stabilized platform. A pyranomter mounted on a stabilized platform, which kept the instrument on board the Proteus aircraft in the earth's horizontal plane, was used to measure the solar flux. Another pyranomter, mounted on a standard fixed platform, was also aboard the Proteus. Since the observations of the fixed platform have to be corrected for the movements and deformation of the aircraft, there is an additional source of uncertainty. Thus the aim of this study was to determine the flux and absorption uncertainties observed from the fixed and stabilized platforms. The fixed platform flux uncertainties, at 4.4-14.8 W/m^2, were ~1.8 times those of the stabilized platform which were 3.8-8.2 W/m^2. However, the fixed flux uncertainties were not so great as to invalidate the pre-ARESE I and ARESE I studies / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2006. / December 5, 2005. / Cloud Absorption Anomaly, Stabilized Platform, Solar Correction Factor / Includes bibliographical references. / Robert Ellingson, Professor Directing Thesis; Paul H. Ruscher, Committee Member; Guosheng Liu, Committee Member.

Twenty turbulent flux parameterizations are compared globally and regionally with a focus on the differences associated with episodic events. The regional focus is primarily upon the Gulf Stream and Drake Passage, as these two regions contain vastly different physical characteristics related to storm and frontal passages, varieties of sea-states, and atmospheric stability conditions. These turbulent flux parameterizations are comprised of six stress-related parameterizations [i.e., Large and Pond (1981), Large et al. (1994), Smith (1988), HEXOS (Smith et al. 1992, 1996), Taylor and Yelland (2001), and Bourassa (2006)] which are paired with a choice of three atmospheric stability parameterizations ['Neutral' assumption, Businger-Dyer (Businger 1966, Dyer 1967, Businger et al. 1971, and Dyer 1974) relations, and Beljaars-Holtslag (1991) with Benoit (1977)]. Two remaining turbulent flux algorithms are COARE version 3 (Fairall et al. 2003) and Kara et al. (2005), where Kara et al. is a polynomial curve fit approximation to COARE; these have their own separate stability considerations. The following data sets were used as a common input for parameterization: Coordinated Ocean Reference Experiment version 1.0, Reynolds daily SST, and NOAA WaveWatch III. The overlapping time period for these data sets is an eight year period (1997 through 2004). Four turbulent flux diagnostics (latent heat flux, sensible heat flux, stress, curl of the stress) are computed using the above parameterizations and analyzed by way of probability distribution functions (PDFs) and RMS analyses. The differences in modeled flux consistency are shown to vary by region and season. Modeled flux consistency is determined both qualitatively (using PDF diagrams) and quantitatively (using RMS differences), where the best consistencies are found during near-neutral atmospheric stratification. Drake Passage shows the least sensitivity (in terms of the change in the tails of PDFs) to seasonal change. Specific flux diagnostics show varying degrees of consistency between stability parameterizations. For example, the Gulf Stream's latent heat flux estimates are the most inconsistent (compared to any other flux diagnostic) during episodic and non-neutral conditions. In all stability conditions, stress and the curl of stress are the most consistent modeled flux diagnostics. Sea-state is also a very important source of modeled flux inconsistencies during episodic events for both regions. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Summer Semester, 2008. / April 24, 2008. / Parameterizations, Parameterization, Algorithm, Probability Density, Probability Distribution, Pdf, Drake Passage, Kuroshio, Gulf Stream Ect, Cold Tongue, Indian Ocean, Pacific Ocean, Southern Oceans, Atlantic Ocean, Tropics, Sea-State / Includes bibliographical references. / Mark Bourassa, Professor Directing Thesis; Eric Chassignet, Committee Member; Carol Anne Clayson, Committee Member; Philip Cunningham, Committee Member.

Studies of tropical cyclone (TC) structure, dynamics, and thermodynamics have long benefitted from databases of in-situ aircraft and dropwindsonde observations. With the first deployment of Doppler radar equipped aircraft into TCs in 1982, three-dimensional documentation of the wind field has become routine. A historical review of analyzed cases reveals how the development of radar scanning strategies designed to capture vortex evolution, combined with advancements in data synthesis techniques, have made airborne Doppler radar an indispensible tool in the study of TC dynamics. Unlike conventional sources of TC wind data, the accurate estimation of winds from Doppler radar requires a time-intensive quality control process and synthesis procedure, thus limiting the widespread use of the airborne Doppler data. In this thesis a database of airborne Doppler radar analyses is proposed, and its initial construction is presented. The initial database consists of eight distinct aircraft passes from four different storms. The raw Doppler data was provided by the Hurricane Research Division of NOAA's Atlantic Oceanographic and Meteorological Laboratory. A standard methodology for quality control and synthesis of the airborne Doppler data is suggested to ensure uniformity across the cases. The quality of each Doppler wind analysis is assessed through a statistical comparison with in-situ aircraft data, and then a direct comparison of wind structure resolved in both data sets. The usefulness of the database is demonstrated through an examination of five specific topics of current TC research: 1) variability of the symmetric vortex structure, 2) impact of baroclinicity on the dynamical response to heating, 3) vortex asymmetry in the hurricane inner core, 4) vertical shear forcing of hurricane asymmetry, and 5) eyewall budgets of angular momentum. In an effort to make the database more easily accessible to future investigators, a table of parameters grouped into synoptic, intensity, and structure categories was synthesized from the cases presently included. The utility of the synthesis table in selecting cases, and even revealing relationships amongst the variables, is discussed. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2008. / April 10, 2008. / Vorticity, Baroclinity, Baroclinicity, Katrina, Ivan, Guillermo Olivia, Radar, Hurricane, Asymmetry, Shear, Momentum / Includes bibliographical references. / Paul D. Reasor, Professor Directing Thesis; Robert Hart, Committee Member; T. N. Krishnamurti, Committee Member.

This study aims to develop an objective hurricane initialization scheme which produces a model hurricane that not only satisfies forecast model constraints but also incorporates observed features such as the initial intensity (e.g., central sea-level pressure and maximum surface wind) and size (e.g., the radius of 34kt wind). It is based on the four-dimensional variational (4D-Var) bogus data assimilation (BDA) scheme originally proposed by Zou and Xiao (1999). The 4D-Var BDA scheme consists of two steps: (i) specifying a bogus sea level pressure (SLP) field based on parameters observed by the Tropical Prediction Center (TPC) and (ii) assimilating the bogus SLP field under a forecast model constraint adjusting all model variables. This research focuses on improving the specification of the bogus SLP indicated in the first step. First, an empirical linear model is developed for determining the size of the bogus vortex based on the TPC observed radius of 34kt. Numerical experiments are then carried out with and without making use of this model for the initialization and prediction of Hurricane Bonnie (1998) over the Atlantic Ocean. After runing these experimets, the track prediction is found to be less sensitive to bogus SLP than the intensity prediction. The maximum track error is less than 110 km during the entire three-day forecast using 4D-Var BDA generated initial vortices in both situation. However, the experiment using the linear model for the size specification considerably outperforms the other formulations in terms of the intensity prediction of Hurricane Bonnie. A further effort is made to incorporate QuikSCAT surface wind observations into the above hurricane initialization procedure, which aims to produce a more realistic initial vortex. Directly assimilating QuikSCAT surface winds results a negligible impact on hurricane prediction, so an indirect technique needs to be developed in order to maximize the impact of QuikSCAT observations on hurricane prediction. A radial profile of SLP is first derived from QuikSCAT surface winds, which is incorporated into the 4D-Var BDA procedure. Differences using the QuikSCAT-derived bogus SLP (QuikSCAT-BDA) and the above linear-model-derived SLP (LM-BDA) are examined for the prediction of Hurricane Gordon (2000). Compared with an HRD observed radial wind profile for Hurricane Gordon, the QuikSCAT-derived SLP profile is more realistic than the SLP profile specified by LM-BDA. However, numerical results show that LM-BDA performs better than QuikSCAT-BDA for both the track and intensity forecasts. Diagnosis of model output indicates that the LM-BDA generates larger surface fluxes of sensible heat, latent heat and moisture, as well as stronger downward angular momentum transport than the QuikSCAT and other BDA schemes do. These enhanced energy supplies offset the energy lost caused by friction and gravity wave propagation, allowing for the model to maintain a strong and realistic hurricane during the entire forward model integration. / A Dissertation Submitted to the Department of Meteorology in Partial FulfiLlment of the Requirements for the Degree of Doctor of Philosophy. / Spring Semester, 2004. / March 30, 2004. / Data assimilation, 4D-Var, Initialization, Size, Hurricane / Includes bibliographical references. / Xiaolei Zou, Professor Directing Dissertation; Ionel M. Navon, Outside Committee Member; Albert I. Barcilon, Committee Member; T. N. Krishnamurti, Committee Member; Peter S. Ray, Committee Member.

Tornado reports are combined with hurricane data to generate a dataset of tornadoes associated with tropical cyclones affecting the coastal Gulf of Mexico and Florida's East Coast between 2000 – 2008. A pool of 28 potential predictors of tornado occurrence in tropical cyclone environments is narrowed to 7 using classic stepwise regression. The result is a composite parameter for forecasting the number of tornadoes per cyclone quadrant during a 12 h period. The equation is applied to five cases from the past nine years to qualitatively assess the parameter and compare its performance with two composite indices developed for classical severe storms (the Significant Tornado Parameter and the Energy Helicity Index). Results show that our Tropical Cyclone Tornado Parameter (TCTP) has skill at identifying regions of tornadic potential although its ability to quantify this potential remains uncertain. Tornadoes in some tropical systems appear to be over predicted, but under predicted in other systems. Comparisons with the classic severe parameters show that TCTP forecasts well, particularly for tropical cyclones making landfall as hurricanes. The shear and instability terms in our guidance product indicate that shear is larger in the northeast quadrant of tropical cyclones when tornadoes occur, compared to when they do not occur. Similar to the results of previous studies, a small negative correlation between instability and tornado occurrence is noted. TCTP is developed with the goal of aiding forecasters in a time-limited forecast environment. In this way, TCTP can provide a "quick look" at regions where a forecaster could then conduct detailed analyses. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2010. / December 10, 2009. / Forecast, Hurricane, Tornado / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Robert Hart, Committee Member; Paul H. Ruscher, Committee Member; Andrew I. Watson, Committee Member.

During the austral spring months of September and October when biomass burning is prevalent in the Southern Hemisphere, long-range transport can move the biomass burning byproducts from southern Africa to the Pacific Basin. Meteorological data from September 1996 were used to examine the transport from Africa using forward trajectories. Long-range transport is defined as trajectories that extend from Africa eastward to at least 110°E within 10 days. Five categories were found from trajectory analysis to constitute the major long-range transport pathways: zonal flow (35%) and four anticyclonic flows over Australia (5%), the western Pacific (5%), Easter Island (0.8%) and South America (0.9%). Chemical data collected during NASA's Pacific Exploratory Mission-Tropics, Phase A (PEM-Tropics A) and Transport and Atmospheric Chemistry near the Equator- Atlantic (TRACE-A) missions were studied to determine the chemical evolution of burning byproducts during the long-range transport. Photochemical decay and physical mixing with background air were both found to be important dilution processes, with estimates of physical mixing lifetimes shorter than photochemical decay lifetimes. Greater values of pollution were detected at mid-tropospheric altitudes over the Pacific Basin, suggesting that more pollution is transported to mid-levels at long ranges. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Summer Semester, 2005. / July 13, 2005. / Pollution, Chemical Transport, Trajectory / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Jon Ahlquist, Committee Member; Philip Cunningham, Committee Member.