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Author (up) Godinez, H.C.; Reisner, J.M.; Fierro, A.O.; Guimond, S.R.; Kao, J.
Title Determining Key Model Parameters of Rapidly Intensifying Hurricane Guillermo (1997) Using the Ensemble Kalman Filter Type $loc['typeJournal Article']
Year 2012 Publication Journal of the Atmospheric Sciences Abbreviated Journal J. Atmos. Sci.
Volume 69 Issue 11 Pages 3147-3171
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Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4928 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 236
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Author (up) Guimond, S
Title Tropical Cyclone Inner-Core Dynamics: A Latent Heat Retrieval and Its Effects on Intensity and Structure Change; and the Impacts of Effective Diffusion on the Axisymmetrization Process Type $loc['typeManuscript']
Year 2010 Publication Abbreviated Journal
Volume Issue Pages
Keywords Hurricanes, Doppler Radar, Latent Heat, Axisymmetrization, Diffusion, Numerical Modeling
Abstract Despite the fact that latent heating in cloud systems drives many atmospheric circulations, including tropical cyclones, little is known of its magnitude and structure due in large part to inadequate observations. In this work, a reasonably high-resolution (2 km), four-dimensional airborne Doppler radar retrieval of the latent heat of condensation is presented for rapidly intensifying Hurricane Guillermo (1997). Several advancements in the retrieval algorithm are shown including: (1) analyzing the scheme within the dynamically consistent framework of a numerical model, (2) identifying algorithm sensitivities through the use of ancillary data sources and (3) developing a precipitation budget storage term parameterization. The determination of the saturation state is shown to be an important part of the algorithm for updrafts of ~ 5 m s-1 or less. The uncertainties in the magnitude of the retrieved heating are dominated by errors in the vertical velocity. Using a combination of error propagation and Monte Carlo uncertainty techniques, biases were found to be small, and randomly distributed errors in the heating magnitude were ~16 % for updrafts greater than 5 m s-1 and ~156 % for updrafts of 1 m s- 1. The impact of the retrievals is assessed by inserting the heating into realistic numerical simulations at 2 km resolution and comparing the generated wind structure to the Doppler radar observations of Guillermo. Results show that using the latent heat retrievals outperforms a simulation that relies on a state-of-the-art microphysics scheme (Reisner and Jeffery 2009), in terms of wind speed root-mean-square errors, explained variance and eye/eyewall structure. The incorrect transport of water vapor (a function of the sub-grid model and the numerical approximations to advection) and the restrictions on the magnitude of heat release that ensure the present model's stability are suggested as sources of error in the simulation without the retrievals. Motivated by the latent heat retrievals, the dynamics of vortex axisymmetrization from the perspective of thermal anomalies is investigated using an idealized, non-linear atmospheric model (HIGRAD). Attempts at reproducing the results of previous work (Nolan and Grasso 2003; NG03) revealed a discrepancy with the impacts of purely asymmetric forcing. While NG03 found that purely asymmetric heating led to a negligible, largely negative impact on the vortex intensification, in the present study the impacts of asymmetries are found to have an important, largely positive role. Absolute angular momentum budgets revealed that the essential difference between the present work and that of NG03 was the existence of a significant, axisymmetric secondary circulation in the basic-state vortex used in the HIGRAD simulations. This secondary circulation was larger than that present in NG03's simulations. The spin-up of the vortex caused by the asymmetric thermal anomalies was dominated by the axisymmetric fluxes of angular momentum at all times, indicating fundamentally different evolution of asymmetries in the presence of radial flow. Radial momentum budgets were performed to elucidate the mechanisms responsible for the formation of the physically significant secondary circulation. Results show that explicit (sub-grid) diffusion in the model was producing a gradient wind imbalance, which drives a radial inflow and associated secondary circulation in an attempt to re-gain balance. In addition, the production of vorticity anomalies from the asymmetric heating was found to be sensitive to the eddy diffusivity, with large differences between HIGRAD and the widely used WRF model for the exact same value of this uncertain parameter.
Address Department of Earth, Ocean and Atmospheric Science
Corporate Author Thesis $loc['Ph.D. thesis']
Publisher Florida State University Place of Publication Tallahassee, FL Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 573
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Author (up) Guimond, S. R.
Title A diagnostic study of the effects of trough interactions on tropical cyclone QPF. Type $loc['typeManuscript']
Year 2007 Publication Abbreviated Journal
Volume Issue Pages
Keywords Satellites, Precipitation, Tropical Cyclones, Troughs
Abstract A composite study is presented analyzing the influence of upper-tropospheric troughs on the evolution of precipitation in twelve Atlantic tropical cyclones (TCs) between the years 2000 � 2005. The TRMM Multi-Satellite Precipitation Analysis (TMPA) is used to examine the enhancement of precipitation within a 24 h window centered on trough interaction (TI) time in a shear-vector relative coordinate system. Eddy angular momentum flux convergence (EFC) computed from European Centre for Medium-Range Weather Forecasts (ECMWF) operational analyses is employed to objectively determine the initiation of a TI while adding insight, along with vertical wind shear, into the intensification of TC vortices. The relative roles of the dynamics (EFC and vertical wind shear) and thermodynamics (moist static energy potential) in TIs are outlined in the context of precipitation enhancement that provides quantitative insight into the “good trough”/“bad trough” paradigm. The largest precipitation rates and enhancements are found in the down-shear left quadrant of the storm, consistent with previous studies of convective asymmetries. Maximum mean enhancement values of 1.4 mm/h are found at the 200 km radius in the down-shear left quadrant. Results indicate that the largest precipitation enhancements occur with “medium” TIs; comprised of EFC values between 17 � 22 (m/s)/day and vertical wind shear Sensitivity tests on the upper vertical wind shear boundary reveal the importance of using the tropopause for wind shear computations when a TC enters mid-latitude regions. Changes in radial mean precipitation ranging from 29 � 40 % across all storm quadrants are found when using the tropopause as the upper boundary on the shear vector. Tests on the lower boundary using QuikSCAT ocean surface wind vectors expose large sensitivities on the precipitation ranging from 42 � 60 % indicating that the standard level of 850 hPa, outside of the boundary layer in most storms, is more physically reliable for computing vertical wind shear. These results should help to improve TC quantitative precipitation forecasting (QPF) as operational forecasters routinely rely on crude statistical methods and rules of thumb for forecasting TC precipitation.
Address Department of Meteorology
Corporate Author Thesis $loc['Master's thesis']
Publisher Florida State University Place of Publication Tallahassee, FL Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Funding NASA, OVWST Approved $loc['no']
Call Number COAPS @ mfield @ Serial 610
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Author (up) Guimond, S. R.; Turk, J.; Blankenship, C.; Hawkins, J.
Title Detecting tropical cyclone structural change with the TRMM Precipitation Radar (PR) and Advanced Microwave Sounding Unit (AMSU) Type $loc['typeConference Article']
Year 2006 Publication 86th Annual American Meteorological Society Meeting, Office of Naval Research, Atlanta, Georgia, USA Abbreviated Journal
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 920
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Author (up) Guimond, S.R.; Bourassa, M.A.; Reasor, P.D.
Title A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part I: The Algorithm and Observations Type $loc['typeJournal Article']
Year 2011 Publication Journal of the Atmospheric Sciences Abbreviated Journal J. Atmos. Sci.
Volume 68 Issue 8 Pages 1549-1567
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Abstract
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4928 ISBN Medium
Area Expedition Conference
Funding NASA, OVWST, NOAA, OCO Approved $loc['no']
Call Number COAPS @ mfield @ Serial 298
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Author (up) Guimond, S.R.; Heymsfield, G.M.; Turk, F.J.
Title Multiscale Observations of Hurricane Dennis (2005): The Effects of Hot Towers on Rapid Intensification Type $loc['typeJournal Article']
Year 2010 Publication Journal of the Atmospheric Sciences Abbreviated Journal J. Atmos. Sci.
Volume 67 Issue 3 Pages 633-654
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Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4928 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 347
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Author (up) Guimond, S.R.; Reisner, J.M.
Title A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part II: Numerical Simulations Type $loc['typeJournal Article']
Year 2012 Publication Journal of the Atmospheric Sciences Abbreviated Journal J. Atmos. Sci.
Volume 69 Issue 11 Pages 3128-3146
Keywords
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4928 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 235
Permanent link to this record

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