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Author Larow, T.E. ; Krishnamurti, T.N.
Title Initial conditions and ENSO prediction using a coupled ocean-atmosphere model Type $loc['typeJournal Article']
Year 1998 Publication Tellus A Abbreviated Journal Tellus A
Volume 50
Issue 1
Pages 76-94
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 0280-6495
ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @
Serial 543
Permanent link to this record
Author Bourassa, M. A., D. Dukhovskoy, S. L. Morey, and J, J. O'Brien
Title Innovations in Modeling Gulf of Mexico Surface Turbulent Fluxes Type $loc['typeMagazine Article']
Year 2007 Publication Flux News Abbreviated Journal
Volume Issue 3
Pages 9
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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 ISBN Medium
Area Expedition Conference
Funding NOAA, COD, NASA, OVWST, NSF
Approved $loc['no']
Call Number COAPS @ mfield @
Serial 707
Permanent link to this record
Author Stallard, A
Title Comparing SAMOS Document Search Performance Between Apache Solr and Neo4j Type $loc['typeManuscript']
Year 2017 Publication Abbreviated Journal
Volume Issue Pages
Keywords
Abstract
Address Department of Computer Science
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 Approved $loc['no']
Call Number COAPS @ mfield @
Serial 70
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Author Arguez, A.
Title Indexing, Mode Definition, and Signal Extraction in Climate Research: Analysis and Applications Involving the MJO, the AO, and ENSO Type $loc['typeManuscript']
Year 2005 Publication Abbreviated Journal
Volume Issue Pages
Keywords
Abstract There are two objectives of the present study. The primary objective is to undertake the following research projects involving the Arctic Oscillation (AO), the El Niño Southern Oscillation (ENSO), and the Madden Julian Oscillation (MJO): (1) an assessment of the utility of using Cyclo-stationary empirical orthogonal function (CSEOF) analysis to define the AO, (2) an empirical analysis of ENSO impacts based on varying indicator and impact regions, (3) detection and extraction of the MJO signal from QuikSCAT, and (4) the development of a general algorithm for determining optimal filter weights for time series endpoints. A secondary objective is to enumerate the statistical and analytical treatments of the AO, ENSO, and the MJO. This will include comparisons of how these three modes are defined (including their indices) and extracted from geophysical data sets. The AO is defined using empirical orthogonal function (EOF) analysis of sea level pressure north of 20'N. The resulting spatial pattern and time series captures the regional influence of its precursor, the North Atlantic Oscillation (NAO), which is a measure of mid-latitude zonal winds over the North Atlantic. ENSO was originally defined as the pressure difference between Tahiti and Darwin, Australia: the Southern Oscillation Index. Scientists now primarily use sea surface temperature (SST) anomalies averaged over one of the Ni'o regions as ENSO indices. The MJO was originally observed using spectral analysis of zonal wind time series in the Indian Ocean and Western Pacific. Present day researchers use extensions of EOF analysis to construct MJO time series. For all three climate modes, the creation of high quality space-time data sets has allowed for more sophisticated indices, supplanting the simpler point-based metrics. For the AO project, the cyclo-stationarity of Northern Hemisphere sea level pressure variability is considered. CSEOF analysis is an extension of EOF analysis that allows multiple spatial maps per mode. It accomplishes this by cyclically extending the covariance matrix based on a parameter called the nested period. By using a nested period of 12, a climate mode can be decomposed into a series of 12 monthly maps and an associated time series. Unlike EOF PC time series, which typically have larger amplitudes during winter months, CSEOF PC time series do not favor a particular season because the physical evolution of the climate mode is posited in the loading vectors (the maps) rather than the time series. This is impossible to accomplish with regular EOF analysis because it relegates each mode to one single map. A compelling case is made for a cyclo-stationary interpretation of AO variability. The leading CSEOF mode includes AO-type variability during a winter regime, as well as a summer regime characterized by pressure anomalies centered over Mongolia and associated with rainfall variability in the vicinity of the Ganges delta and eastern China. EOF modes that contribute to the resulting maps of the leading CSEOF mode are identified, including the eighth mode, which is deemed responsible for the summertime Asian pattern. CSEOF analysis of the AO mode only exemplifies the power of CSEOF analysis with regard to transferring a mode's physical evolution from a PC time series to a series of loading vectors. For the ENSO project, traditional ENSO impact analysis was recast to investigate the teleconnections between U.S. climate and varying indicator regions of SST anomalies in the tropical Pacific. This serves the dual purpose of finding a targeted indicator region for a particular impact zone (i.e. a localization of the teleconnection pattern) and indirectly assessing the viability of well-established ENSO indices (i.e. the Ni'o indices). Based on a selection of impact grid points with known ENSO responses, it appears that the most appropriate indicator region often varies from one impact grid point to another, as well as from warm SST phase to cold SST phase. In addition, air temperature composites behave differently than precipitation composites. In order to simultaneously consider the 'impact perspective' detailed above with the typical 'indicator perspective' (in which climate impacts are computed based on the well-established Ni'o indices), EOF analysis of composited climate fields, conditioned on SST phase, as functions of indicator region and impact zone was performed. The resulting modes represent indicator-impact pairs. Each mode has an impact amplitude function (a spatial temperature or precipitation anomaly signature over the impact region) and an associated indicator weighting function, which modulates the impact amplitude function based on the location of the indicator region. Based on this approach, the unusual yet well-established La Ni'a air temperature impact over the U.S. when using the Ni'o 1+2 region is accounted for as the superposition of two EOF modes. In addition, a teleconnection between tropical Pacific SST and Southeastern U.S. temperature anomalies is documented that is not related to ENSO. For the MJO project, wind data from the SeaWinds instrument on the QuikSCAT satellite are investigated to ascertain how well the surface manifestation of the MJO can be resolved. The MJO signal is detected in non-filtered gridded data using Extended EOF analysis of the zonal wind field, overshadowed by annual, semi-annual, and monsoon-related modes. After bandpass filtering with Lanczos weights, MJO signals are clearly detected in several kinematic quantities, including the zonal wind speed, the zonal pseudostress, and the velocity potential. Extraction of the MJO using QuikSCAT winds compares favorably with extraction using NCEP Reanalysis 2, except that the QuikSCAT signal appears to be more robust. For the filtering project, least squares techniques are utilized to retain endpoint intervals that are normally discarded due to filtering with convolutions in the time domain. The techniques minimize the errors between the pre-determined frequency response function (FRF) of interior points with FRF's that are to be determined for each position in the endpoint zone. The least squares techniques are differentiated by their constraints: (1) unconstrained, (2) equal-mean constraint, and (3) an equal-variance constraint. The equal-mean constraint forces the new weights to sum up to the same value as the pre-determined weights. The equal-variance constraint forces the new weights to be such that, after convolved with the input values, the expected variance is identical to the expected variance of the interior points. These 3 least squares methods are tested under three separate filtering scenarios and compared to each other as well as to the spectral filtering method, which is the standard of comparison. The results indicate that all 4 methods (including the spectral method) possess skill at determining suitable endpoints estimates. However, both the unconstrained and equal-mean schemes exhibit bias toward zero near the terminal ends due to problems with appropriating variance. The equal-variance and spectral techniques do not show evidence of this attribute and were never the worst performers. The equal-variance method showed great promise in the ENSO project involving a 5-month running mean filter, and performed at least on par with the other methods for virtually all time series positions in all three filtering scenarios.
Address Department of Meteorology
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 590
Permanent link to this record
Author Ford, K. M.
Title Uncertainty in Scatterometer-Derived Vorticity Type $loc['typeManuscript']
Year 2008 Publication Abbreviated Journal
Volume Issue Pages
Keywords Vorticity, Scatterometer, Cyclone Genesis, Rrror Analysis, Tropical Storm
Abstract A more versatile and robust technique is developed for determining area averaged surface vorticity based on vector winds from the SeaWinds scatterometer on the QuikSCAT satellite. This improved technique is discussed in detail and compared to two previous studies by Sharp et al. (2002) and Gierach et al. (2007) that focused on early development of tropical systems. The error characteristics of the technique are examined in detail. Specifically, three independent sources of error are explored: random observational error, truncation error and representation error. Observational errors are due to random errors in the wind observations, and determined as a worst-case estimate as a function of averaging spatial scale. The observational uncertainty in vorticity averaged for a roughly circular shape with a 100 km diameter, expressed as one standard deviation, is approximately 0.5 x 10 -5 s-1 for the methodology described herein. Truncation error is associated with the assumption of linear changes between wind vectors. For accurate results, it must be estimated on a case-by-case basis. An attempt is made to determine a lower bound of truncation errors through the use of composites of tropical disturbances. This lower bound is calculated as 10-7 s-1 for the composites, which is relatively small compared to the tropical disturbance detection threshold set at 5 x 10-5 s-1, used in an earlier study. However, in more realistic conditions, uncertainty related to truncation errors is much larger than observational uncertainty. The third type of error discussed is due to the size of the area being averaged. If the wind vectors associated with a vorticity maximum are inside the perimeter of this area (away from the edges), it will be missed. This type of error is analogous to over-smoothing. Tropical and sub-tropical low pressure systems from three months of QuikSCAT observations are used to examine this error. This error results in a bias of approximately 1.5 x 10-5 s-1 for area averaged vorticity calculated on a 100 km scale compared to vorticity calculated on a 25 km scale. The discussion of these errors will benefit future projects of this nature as well as future satellite missions.
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 Approved $loc['no']
Call Number COAPS @ mfield @
Serial 608
Permanent link to this record
Author Goto, Y.
Title Improved Vegetation Characterization and Freeze Statistics in a Regional Spectral Model for the Florida Citrus Farming Region Type $loc['typeManuscript']
Year 2008 Publication Abbreviated Journal
Volume Issue Pages
Keywords Ensemble Forecast, Climate Model
Abstract This study focused on the effective use of a numerical climate model for agriculture in Florida, especially in the citrus farming region of the Florida peninsula, because of the impact of agriculture to Florida's economy. For the analyses of the ensemble, the climate models used in this study were the FSU/COAPS Global Spectral Model and FSU/COAPS Regional Spectral Model (FSU/COAPS RSM) coupled with a land-surface model. The multi-convective scheme method and variable initial conditions were used for the ensembles. Severe freezes impacting agriculture in Florida were associated with some major climate patterns, such as El Niño and Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO). In the first part of this study, seasonal ensemble integrations of the regional model were examined for the tendencies of freezes in the Florida peninsula during each ENSO or NAO phase is examined. Mean excess values of minimum temperatures from thresholds on the basis of the Generalized Pareto Distribution (GPD), which represents the extreme data in a dataset, were used to analyze the freezes in the regional model. According to some previous studies, El Niño winters obtain fewer freezes than the other ENSO phases. Although the ensemble comprised only 19 winters, the ensemble found variability patterns in minimum temperatures in each climate phase similar to the findings in the previous studies which were based on the observed data. The FSU/COAPS RSM was coupled with Community Land Model 2.0 (CLM2), to represent the land-surface conditions. Although the coupling improved the temperature forecast of the RSM, it still has a cold bias and simulates smaller diurnal temperature changes than actually occur in southern Florida. Among the prescribed surface data, Leaf Area Index (LAI) for southern Florida in the CLM2 is lower than those observed by MODIS (Moderate Resolution Imaging Spectroradiometer). In the first experiment of this part, the sensitivity of the temperature forecast to the LAI in the climate models was investigated, by modifying the LAI data in the CLM2 based on the monthly MODIS observations. In the second experiment, newly created prescribed datasets of LAI and plant functional types for the CLM2 based on the MODIS observations were applied to the RSM. The substitution increased the diurnal temperature change in southern Florida slightly but almost consistently.
Address Department of Meteorology
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 586
Permanent link to this record
Author Gouillon, F
Title Internal Wave Propagation and Numerically Induced Diapycnal Mixing in Oceanic General Circulation Models Type $loc['typeManuscript']
Year 2010 Publication Abbreviated Journal
Volume Issue Pages
Keywords spurious mixing, numerical modeling, internal wave, tide
Abstract Numerical ocean models have become powerful tools for providing a realistic view of the ocean state and for describing ocean processes that are difficult to observe. Recent improvements in model performance focus on simulating realistic ocean interior mixing rates, as ocean mixing is the main physical process that creates water masses and maintains their properties. Below the mixed layer, diapycnal mixing primarily arises from the breaking of internal waves, whose energy is largely supplied by winds and tides. This is particularly true in abyssal regions, where the barotropic tide interacts with rough topography and where high levels of diapycnal mixing have been recorded (e.g., the Hawaiian Archipelago). Many studies have discussed the representation of internal wave generation, propagation, and evolution in ocean numerical models. Expanding on these studies, this work seeks to better understand the representation of internal wave dynamics, energetics, and their associated mixing in several different classes of widely used ocean models (e.g., the HYbrid Coordinate Ocean Model, HYCOM; the Regional Ocean Modeling System, ROMS; and the MIT general circulation model, MITgcm). First, a multi-model study investigates the representation of internal waves for a wide spectrum of numerical choices, such as the horizontal and vertical resolution, the vertical coordinate, and the choice of the numerical advection scheme. Idealized configurations are compared to their corresponding analytical solutions. Some preliminary results of realistic baroclinic tidal simulations are shown for the Gulf of Mexico. Second, the spurious diapycnal mixing that exists in models with fixed vertical coordinates (i.e., geopotential and terrain following) is documented and quantified. This purely numerical error arises because, in fixed-coordinate models, the numerical framework cannot properly maintain the adiabatic properties of an advected water parcel. This unrealistic mixing of water masses can be a source of major error in both regional and global ocean models. We use the tracer flux method to compute the spurious diapycnal diffusivities for both a lockexchange scenario and a propagating internal wave field using all three models. Results for the lock exchange experiments are compared to the results of a recent study. Our results, obtained by using three different model classes, provide a comprehensive analysis of the impact of model resolution choice and numerical framework on the magnitude of the spurious diapycnal mixing and the representation of internal waves.
Address Department of Oceanography
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 571
Permanent link to this record
Author Hite, M. M.
Title Vorticity-Based Detection of Tropical Cyclogenesis Type $loc['typeManuscript']
Year 2006 Publication Abbreviated Journal
Volume Issue Pages
Keywords Quikscat, Seawinds, Tropical Disturbance, Tropical Cyclogenesis, Vorticity
Abstract Ocean wind vectors from the SeaWinds scatterometer on QuikSCAT and GOES imagery are used to develop an objective technique that can detect and monitor tropical disturbances associated with the early stages of tropical cyclogenesis in the Atlantic basin. The technique is based on identification of surface vorticity and wind speed signatures that exceed certain threshold magnitudes, with vorticity averaged over an appropriate spatial scale. The threshold values applied herein are determined from the precursors of 15 tropical cyclones during the 1999-2004 Atlantic hurricane seasons using research-quality QuikSCAT data. Tropical disturbances are found for these cases within a range of 19 hours to 101 hours before classification as tropical cyclones by the National Hurricane Center (NHC). The 15 cases are further subdivided based upon their origination source (i.e., easterly wave, upper-level cut-off low, stagnant frontal zone, etc). Primary focus centers on the cases associated with tropical waves, since these waves account for approximately 63% of all Atlantic tropical cyclones. The detection technique illustrates the ability to track these tropical disturbances from near the coast of Africa. Analysis of the pre-tropical cyclone (TC) tracks for these cases depict stages, related to wind speed and precipitation, in the evolution of an easterly wave to tropical cyclone.
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 Approved $loc['no']
Call Number COAPS @ mfield @
Serial 616
Permanent link to this record
Author Griffin, J
Title Characterization of Errors in Various Moisture Roughness Length Parameterizations Type $loc['typeManuscript']
Year 2009 Publication Abbreviated Journal
Volume Issue Pages
Keywords Boundary Layer Meteorology, Roughness Length Parameterization, Moisture Roughness Lengths
Abstract Often the parameterization of the moisture roughness length is not seen as being important, as long as the parameterization seems reasonable; that is, it is within the rather considerable bounds of error for the data sets used to determine the parameterization. However, the choice of parameterization does influence height adjustments of humidity and calculations of turbulent heat fluxes. This paper focuses on the calculation of the turbulent heat fluxes using different parameterizations of roughness length. Five roughness length parameterizations are examined herein. These parameterizations include wall theory; the Clayson, Fairall, Curry parameterization; the Liu, Katsaros, Businger parameterization; Zilitinkevich et al. parameterization; and the COARE3.0 parameterization. Turbulent heat fluxes are calculated from each parameterization of the roughness length and are compared to observed turbulent heat flux values. The bulk latent heat flux estimates have a much better signal to noise ratio than the sensible heat fluxes, and are therefore the focus of the comparison to observations. This comparison indicates how to improve the proportionality in the above roughness length parameterizations, which are causing modeled turbulent heat flux magnitudes to be too large in four of the five parameterizations. The modeled turbulent heat fluxes are evaluated again after the modification of the parameterizations. Significant improvements in both the bias and the root mean square error (RMSE) are seen. Three parameterizations see roughly the same improvements of around 17Wm^-2 in the bias and roughly 10Wm^-2 in the RMSE. The largest improvements are in the Liu, Katsaros, Businger parameterization with bias improvements of over 45Wm^-2 and a RMSE reduction of nearly 32Wm^-2.
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 Approved $loc['no']
Call Number COAPS @ mfield @
Serial 603
Permanent link to this record
Author 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
Permanent link to this record
