In this study, a modified multi-dimensional ensemble empirical mode decomposition (MEEMD) is devised and employed to understand the temporal-spatial evolution of the sea surface temperature anomalies (SSTAs) of interannual timescales. We take the advantage of empirical orthogonal function (EOF) in lossy compression of temporal-spatially coherent data and decompose the data in the transformed EOF space using ensemble empirical mode decomposition (EEMD) to accelerate the computation of MEEMD. It is demonstrated that the modified MEEMD can eliminate temporally and spatially incoherent noise and recover accurately the temporal-spatial structures of SSTAs on interannual or longer time scales. The modified MEEMD is then applied to characterize the evolution of the observed El Niño-Southern Oscillation (ENSO) phenomenon for the period from 1880 to 2009. To identify the ENSO events through that period, an alternative and more consistent Niño 3.4 index is defined. 31 ENSO warm events are identified with this alternative index and the evolution of each event is examined. It is found that isolated SSTAs off Baja California can propagate southwestward to the equatorial region near dateline in about one year and then propagates eastward with amplification and a faster speed to shape up an El Niño event. In this sense, SSTAs off Baja California are instrumental to ENSO development, especially in triggering the so called central Pacific (CP) ENSO or ENSO Modoki after 1980. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2012. / October 25, 2012. / ENSO, EOF, MEEMD, SST / Includes bibliographical references. / Zhaohua Wu, Professor Directing Thesis; Guosheng Liu, Committee Member; Philip Sura, Committee Member.

Extreme climate events may be defined as atmospheric or oceanic phenomena that occupy the tails of a dataset's probability density function (PDF), where the magnitude of the event is large, but the probability of occurrence is rare. Though these types of events are statistically sparse, it is necessary to understand the distribution of events in the tails, as quantifying the likelihood of climate extremes is an important step in predicting overall climate variability. It has been known for some time that the PDFs of atmospheric phenomena are decidedly non-Gaussian, though the shape of PDF has not been specified explicitly. More recently, it has been shown from observations that many atmospheric variables follow a power law distribution in the tails. This is in agreement with stochastic theory, which asserts that power law distributions should exist in the tails. However, a statistically rigorous study of the resulting power law distributions has not yet been performed. To show the relationship systematically, we examine the PDF tails of dynamically significant atmospheric variables (such as geopotential height and relative vorticity) for evidence of power law behavior. This is achieved by using statistical algorithms that test PDFs for the bounds and magnitude of power law distributions, while estimating the statistical significance of the distribution compared with Gaussianity. Examples of power law distributions in the atmosphere are presented using local time series of atmospheric data. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2012. / February 28, 2012. / Climate Dynamics, Climate Variability, Extreme Events, Non-Gaussian, Power Law, Stochastic / Includes bibliographical references. / Philip Sura, Professor Directing Thesis; Robert Ellingson, Committee Member; Zhaohua Wu, Committee Member.

Here we present a new method of identifying wave activity in the tropical stratosphere. NCEP reanalysis II data from January 1, 1979, to December 31, 2010, was used to diagnose properties of vertically-propagating equatorial waves, including wave speed, wave length, wave tilting, and pressure torque. We band-pass ltered time series of these properties to isolate frequencies corresponding to that of the QBO, of which mean zonal wind anomaly is used as a proxy. Every property was found to display a strong quasi-biennial oscillation, indicating the activity of waves which translate these properties is linked to the QBO. The oscillation of properties which are dependent on wave type (Kelvin or Rossby-gravity wave), such as wave speed and wave length, are in phase with transitional periods from easterly mean zonal flow to westerly. Other properties which relate to the momentum carried by the waves prove to be in phase or of opposing phase as the QBO. This shows that the deposition of momentum by vertically-propagating waves peaks as the mean zonal flow peaks, providing evidence for the critical level absorption and regime descent theories of the QBO. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Sciencein partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2012. / June 11, 2012. / QBO, quasi-biennial / Includes bibliographical references. / Ming Cai, Professor Directing Thesis; Allan Clarke, Committee Member; Philip Sura, Committee Member.

Satellite data is compared to objectively analyzed wind data from the Hurricane Research Division's H*Wind software to attempt to quantify the value that satellite data could bring to the objective analysis. Previous research (DiNapoli et al. (2012), A.C. Moyer et al. (2007) and Powell and Reinhold (2007)) have highlighted the importance of accurately determining the outer wind radii for a variety of needs, including accurate representations of wind radii (Moyer) and Integrated Kinetic Energy (Powell and Reinhold). Advanced Scatterometer (ASCAT) and Tropical Rainfall Measurement Mission Microwave Imager (TRMM.TMI) will be compared to H*Wind objective analyses interpolated to the satellite overpass times. Comparisons that will be done include wind speed difference plots, which will show the magnitude difference between the objective analyses and the satellite data along with the difference between the lowest radius of tropical storm (TS) winds and the highest. The difference in the TS wind radii forms the foundation for the rest of the comparisons, including a correlation scatterplot (which will look at wind speed magnitude trends between the satellite and analysis data), frequency distribution (which will help quantify the value that the satellite data could provide to the objective analyses), average wind variation, and variance changes over time. The overall findings are that there seems to be better agreement between ASCAT and the analysis winds, and the difference in frequency distribution between the ASCAT and objective analysis winds shows that there may be more value in adding ASCAT to the analysis than TRMM. Obviously more work must be done to confirm whether these conclusions are accurate for more storms, more satellite data types, and different analysis compositions. The end results should help to benefit researchers, forecasters, and emergency planners. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Sciencein partial fulfillment of the requirements of the degree of Master of Science. / Fall Semester, 2012. / August 30, 2012. / ASCAT, H*Wind, TRMM, Tropical Cyclone, Wind Radii / Includes bibliographical references. / Xiaolei Zou, Professor Directing Thesis; Mark Powell, Committee Member; Robert Hart, Committee Member; Guosheng Liu, Committee Member.

A diurnal warming model is used create a new data set of global, diurnally varying sea surface temperatures over a five year period from 2000 to 2004. The model is forced with atmospheric bulk variables, precipitation rate, and radiation fluxes from NASA's MERRA reanalysis whereas bulk SST is approximated by the Reynolds OI AVHRR-only SST dataset. The model simulates the diurnal warming magnitude (dSST) and sensible heat flux and latent heat flux computed with and without a diurnally varying skin temperature at every hour for each day. Differences between each of the fluxes with and without a diurnally varying SST are examined. Characteristics of the dataset are identified on a daily and semi-seasonal scale over the globe. Diurnal warming is concentrated in areas with climatologically low surface wind speed regimes, for example, in the low level convergence zones of the tropics, the Indian Ocean as a result from the Asian monsoon wind variability, the Mediterranean Sea in the summer months, the central Pacific coastlines near mountain ranges in the early months of the year, and the mid-Atlantic in association with the Bermuda High. Maximum averaged diurnal warming reaches roughly 0.3˚C and latent heat flux deficits of 15 W/m2 particularly in the Indian Ocean over a two-month period. With the exception of persistent diurnal warming in the central tropical Pacific just south of central Mexico, the duration of diurnal warming as a percentage of total daylight hours between the tropics and midlatitudes is quite comparable. In the mid-Atlantic, dSSTs can exceed roughly 0.7˚C up to 25% of the time in the two month period. Similarly, latent heat fluxes are underestimated by at least 10 W/m2 up to 25% of the time. Sensitivity of diurnal warming is specific to particular ranges of low wind speed and large solar radiation. Best guess bias corrections to the MERRA wind speeds results in increases as large as 1.5°C. Bimonthly averages, however, are generally less than 0.06°C and latent heat fluxes are less than 2 W/m2. While precipitation is the smallest contributor compared to winds and radiation, the model configurations allows conditions that are contrary to the underlying model physics in which precipitation increases diurnal warming. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2012. / November 9, 2011. / Includes bibliographical references. / Mark Bourassa, Professor Directing Thesis; Vasubandhu Misra, Committee Member; Phillip Sura, Committee Member.

pending / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Sciencein partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester, 2012. / August 10, 2012. / Blue Ridge, Elkahatchee, Zana / Includes bibliographical references.

Fire-derived compounds have received considerable attention as a refractory form of dissolved organic carbon (DOC), the largest carbon pool in the ocean. Due to its recalcitrant nature, pyrogenic or black carbon, which is produced by the incomplete combustion of biomass and fossil fuel on land, is an important compound for potential long-term carbon sequestration. The major objective of this dissertation was to test the hypothesis that dissolved pyrogenic organic carbon accounts for a significant fraction of DOC in different environmental systems, and that the distribution and transport of pyrogenic DOC may be an important key to understanding of how terrestrial and marine DOC are linked. To test this hypothesis, solid phase extraction of DOC was coupled with the benzene polycarboxylic acid (BPCA) method for accurate analysis of combustion-derived compounds in the Southern Ocean, rivers and estuaries in southeastern Brazil, Minnesota's peatlands, and the groundwater and coastal ocean of the Gulf of Mexico. The homogenous distribution of the thermogenic signatures including pyrogenic and non-pyrogenic sources found in marine DOC across whole water masses in the deep ocean indicated that thermogenic DOC can act as a long-term sink. Approximately 2% of the DOM in the deep ocean was determined to be of thermogenic origin, derived from ancient biomass burning, and, possibly, the geothermal flux in the deep sea. Dissolved pyrogenic carbon was found to account for up to 9 ± 2% of riverine and estuarine DOC. Pyrogenic DOC entering the watersheds in Brazil appeared to be derived mainly from former forest fires rather than current agricultural uses, in particular sugarcane burning. Dissolved pyrogenic carbon flux was affected by seasonal variability in runoff and water management in reservoirs. Inputs of pyrogenic DOC to the ocean via groundwater were identified, revealing groundwater discharge as a newly-discovered source of marine dissolved pyrogenic carbon. Large amounts of pyrogenic DOC were found in the peatlands of northern Minnesota. Such fire-derived materials are likely derived from old peat soil, thus, the export of aged condensed aromatic compounds from peatlands has implications for our understanding of the oceanic carbon cycle. Results of lignin phenols analysis indicated that the pyrogenic DOC in the peatlands might have originated from non-vascular plant-derived materials with highly altered lignin signatures. A multi-proxy approach, including both molecular tracers (BPCA and lignin oxidation products) and the stable carbon isotopic composition of bulk DOC, was adopted to investigate the sources and cycling of terrestrial and pyrogenic organic matter in a fire-impacted coastal watershed in the northern Gulf of Mexico. The distinct trends in the temporal and spatial variations of pyrogenic DOC in groundwater reflected the coupling of groundwater discharge and estuarine processes in creating the conditions for the transport of terrestrial DOC to the ocean. The calculated pyrogenic DOC flux transport by groundwater was similar to the flux discharged by the Apalachicola River in the Gulf of Mexico. The results of this study demonstrated that the loading of terrestrial and pyrogenic DOC from groundwater-fed estuaries in the ocean could have significance on a regional scale. / A Dissertation submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2012. / June 20, 2012. / Includes bibliographical references. / Jeffrey P. Chanton, Professor Directing Dissertation; William T. Cooper, University Representative; Thorsten Dittmar, Committee Member; Marcus Huettel, Committee Member; William Landing, Committee Member.

The 45th Weather Squadron (45WS) provides weather support to America's space program at Florida's Cape Canaveral Air Force Station (CCAFS), Kennedy Space Center (KSC), and Patrick Air Force Base (PAFB). Since CCAFS/KSC lies within Florida's "Lightning Alley", summer thunderstorms and associated hazards are a special concern for space launches and all other outdoor activities at CCAFS/KSC. Therefore, the 45WS has developed the Lightning Launch Commit Criteria (LLCC) to help minimize hazards from lightning (both naturally occurring and triggered) and vehicle electrification during the ascent phase of launch. This study has documented the spatial distributions and time evolution of total lightning and radar reflectivity in and around thunderstorms, attached anvil clouds, and detached anvil clouds near CCAFS/KSC on 30 active lightning days between 2008-11. Our goal was to determine if some of the current LLCC thresholds are too restrictive and represent missed launch opportunities, or not restrictive enough and represent a safety risk. CG flashes originating inside the convective core or its anvil can strike the ground away from the cloud edge. Since these side flashes often strike the ground under clear skies, they commonly are referred to as "bolts from the blue". Our results indicate that the vast majority of CG flashes (~94%) strike the ground = 5 n mi from cloud edge (0 dBZ) whereas 73% of CG flashes are = 3 n mi outside 0 dBZ. Three positive bolts from the blue were documented, and all came from the same storm on 29 May 2009. One of the positive flashes propagated 8.91 n mi from cloud edge. Anvil initiated lightning can distribute charge after detachment, but only for a short period. We analyzed 100 anvils within 100 km of KSC; 895 IC flashes in the anvil were initiated in the core of the storms. The first core initiated flash of each anvil typically propagated = 10 n mi. Cellular thunderstorms produce the greatest percentage of total lightning (~84%) in our dataset, but average flash distances from the core are greatest in attached anvils (~4.98 n mi). To our knowledge this is the first study to quantify the distances that lightning can extend beyond the edge of clouds. We believe the results of this research should be considered before making additional changes to the LLCC. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2012. / March 15, 2012. / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Philip G. Sura, Committee Member; Sharon E. Nicholson, Committee Member.

The growth of a locally isolated strain of green algae, Chlorella sp., selected for its promise as a biodiesel feedstock, was studied in wastewater effluent from the municipal wastewater treatment plant in Tallahassee FL. Nutrient concentration and microbial community composition within the effluent were profiled at monthly intervals. Adequate nutrients for algal cultivation were observed along with a dynamic microbial community of zooplankton, green algae, diatoms, and a bacterial community that included Proteobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Actinobacteria. The importance of this microbial community in the cultivation of Chlorella and the impact on biofuel production was investigated utilizing mesocosm incubations. Size exclusion was employed to examine the biogeochemical interactions between the Chlorella culture and the resident wastewater microorganisms. The accumulation of algal cells and chl a biomass, the production of oxygen, and the consumption of inorganic carbon and nutrients, along with changes in the microbial community composition were monitored in treatments that included the total wastewater microbial community, the wastewater bacterial community, and the Chlorella culture with no effluent microorganisms. The treatment that excluded the wastewater microbial community and allowed the Chlorella culture to grow uninfluenced, consistently demonstrated the highest abundances of algal cells. A limited abundance of algal cells and chl a biomass were observed in the treatments that contained the total wastewater microbial community, while no limitation in oxygen production or nutrient consumption was observed in these treatments. Given the presence of zooplankton that are known to graze on algal cells, it appears that a top-down control inhibits the accumulation of algal biomass in raw wastewater effluent from a municipal treatment plant. In the treatments that contained the native bacterial community, competition between the Chlorella culture and phototrophic bacteria, i.e. cyanobacteria, was observed. These treatments demonstrated high chl a biomass, but limited accumulation of algal cells, as well as significant consumption of nutrients, indicating that cyanobacteria may out-compete Chlorella for limiting nutrients. However, the heterotrophic bacterial community did appear to have a significant impact on algal growth. Treatments in which the cyanobacterial community was inhibited did not demonstrate a draw-down of limiting nutrients or a limitation in the accumulation of algal cells. In addition, shifts in the composition of the bacterial community, including a reduction in the relative abundance of Betaproteobacteria with a simultaneous increase in the relative abundance of Alphaproteobacteria, Nostocophycideae, and Oscillatoriophycideae were observed, but these shifts occurred independently of the presence of the Chlorella culture, implying that there is not a strong relationship between these two groups. The limitation that occurred in the growth of Chlorella due to competition and top-down controls indicates that without significant manipulations of the microbial community, the cultivation of an algal monoculture in wastewater effluent from a municipal treatment plant may be unrealistic for efficient biofuel feedstock production. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2012. / April 2, 2012. / Algae, Biofuel, Effluent, Wastewater / Includes bibliographical references. / Jeffrey Chanton, Professor Directing Thesis; Markus Huettel, Committee Member; William Landing, Committee Member; Joel Kostka, Committee Member.

A major theme of recent research is the investigation of the nature of climate variability and the current capability to measure, model, and predict it. This is a formidable task that involves understanding complex interactions and exchanges of energy between the major elements of the Earth system. With their ability to store and release vast quantities of heat, the oceans are an integral element of climate variability. Accurately modeling coupled atmosphere-ocean variability relies upon a proper characterization of the exchanges of heat and momentum across the air-sea interface. The exchange of heat takes place through net shortwave and terrestrial radiative fluxes and turbulent exchanges of heat and moisture. Estimating these interactions with sufficient accuracy is a difficult challenge. These processes contain inherent errors due to insufficient knowledge of physics, observational uncertainty, and parameterization deficiencies. Uncertainties arising from the estimation of the surface turbulent and radiative processes generate limitations to the understanding of the primary mechanisms governing oceanic variability. This work elucidates the impact of uncertainties in the estimation of turbulent and radiative heat fluxes on the analysis of the mixed layer temperature balance, an effect that has not been properly quantified although recognized in most previous analyses. In particular, this work focuses on variability at seasonal and intraseasonal time scales. The analyses of this work include: i) an updated characterization of uncertainties in current state-of-the-art estimates of the turbulent and radiative heat fluxes, ii) an examination of the closure of the mixed layer temperature balance on seasonal and intraseasonal time scales, iii) an evaluation of the sensitivity of the mixed layer temperature balance to differences between surface heat flux estimates, iv) the development of a flexible approach by which to determine required accuracies of the net surface heat flux, and v) an exploration of the role of mixed layer depth variability on the mixed layer temperature balance. Taken together, the results of these analyses provide a framework to understand the impact of surface heat flux uncertainties within the context of upper ocean mixed layer variability. The analyses performed in this study have exploited a set of eight turbulent and six radiative heat flux estimates. An intercomparison of these products has revealed that the typical spread between products has been reduced relative to previous generations of estimates. Differences between radiative and turbulent heat flux estimates are typically within 15-20% of one another on regional and seasonal scales although larger uncertainties remain in traditionally problematic regions (e.g., cloud-topped boundary layers, western boundary currents). On both intraseasonal and seasonal time scales, the ocean mixed layer is controlled most strongly by the net shortwave and turbulent latent heat fluxes over the world oceans with the exception of the deep tropics wherein oceanic processes are also important. The current ensemble mean estimates of the net surface heat fluxes and oceanic process are capable of resolving the upper ocean mixed layer temperature seasonal cycle quite well in many locations; areas of strong net heat flux warming are somewhat problematic. On intraseasonal time scales, small signal to noise ratios and large residual imbalances leave little room to make definitive conclusions on the role of individual elements of mixed layer forcing. However, general features of the relative importance of surface heat flux variability versus oceanic variability are supported from previous studies. The mixed layer temperature balance is found to be most sensitive to uncertainties in the latent and net shortwave heat fluxes. The timing of the shoaling of the mixed layer depth is also important to the sensitivity of the mixed layer temperature balance. Taking into account mixed layer depth variability is found to be important to understanding the role of the net surface heat fluxes in generating mixed layer temperature warming and cooling. Current estimates of the net heat flux uncertainty are outside of the traditional 10 W m &minus 2 goal on seasonal time scales and spatial scales on the order of 1000 km. The approach designed within this investigation suggests that a 10 W m &minus 2 limit is somewhat too restricting if the aim is to resolve the seasonal mixed layer temperature evolution. In short, the use of the ocean mixed layer temperature balance has provided a unique framework for translating uncertainties in the surface heat flux estimates into a practical context. It is hoped that a better appreciation of these uncertainties will lead to an improved ability to model and understand the mechanisms by which the oceans contribute to variability of Earth's climate. / A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2011. / August 19, 2011. / ocean mixed layer, surface heat flux, turbulent fluxes, uncertainties / Includes bibliographical references. / Carol Anne Clayson, Professor Directing Thesis; Doron Nof, University Representative; Mark Bourassa, Committee Member; Philip Sura, Committee Member; Paul Ruscher, Committee Member.