Smith, S. R. (2004). Report from the 2nd workshop on high-resolution marine meteorology . COAPS Technical Report 04-01. Tallahassee, FL: Center for Ocean-Atmospheric Prediction Studies, Florida State University.
Nunes, A. M. B., & Cocke, S. (2004). Implementing a physical initialization procedure in a regional spectral model: impact on the short-range rainfall forecasting over South America. Tellus A , 56 (2), 125–140.
Jones, B. (2004). Influence of Panamanian Wind Jets on the Southeast Intertropical Convergence Zone . Master's thesis, Florida State University, Tallahassee, FL.
Abstract: Gridded QuikSCAT data has been used to show that a strong confluence zone of the Southeast Pacific Intertropical Convergence Zone (SITCZ) existed in 2000 � 2002 during boreal spring, and the Panama wind jet contributes to its variability. Time series analysis of winds off the Gulf of Panama and convergence advection into the Southern Hemisphere (from 80W to 95W) show these winds kept the SE Trades out of the Northern Hemisphere and created a confluent zone in the Southern Hemisphere. A monthly averaged SITCZ is maintained by the deceleration of the SE Trades that flow from warm water toward the equatorial cold tongue, creating a speed convergent zone south of the equator. Images of wind trajectories show zonally orientated SE Trade winds that were deflected from a divergent zone parallel to the coast of South America converge with more meridional Trades over warm waters. Panamanian winds crossed into the Southern Hemisphere to contribute to this convergence. It is hypothesized that this confluent zone can be intensified by the Panamanian winds. In 2002, the SITCZ confluent zone occurred with more intense Panamanian gap flow than the previous two years. Cross equatorial SE Trades wrapped anti-cyclonically around a divergent pocket in the Northern Hemisphere and became southward winds, which allowed the Panamanian winds to enter the Southern Hemisphere and intensify the SITCZ. Variability in the Panamanian winds makes a substantial contribution to the evolution of the SITCZ.
Kvaleberg, E. (2004). Generation of Cold Core Filaments and Eddies Through Baroclinic Instability on a Continental Shelf . Ph.D. thesis, Florida State University, Tallahassee, FL.
Abstract: The formation of cold core filaments on an idealized continental shelf is investigated using a numerical model to simulate the ocean's response to surface cooling. A horizontal density gradient forms because of uneven buoyancy loss due to the sloping bottom, and this gradient induces an alongshelf current in thermal wind balance, that in time becomes unstable. As the instabilities grow, filaments, and later eddies, are generated so that dense water near the coast is mixed offshore. Scaling arguments of the filament wavelength indicate that the current is baroclinically unstable, and an analytical model of the frontal expansion with time is in very good agreement with the simulations. This study was inspired by satellite observations of sea surface temperature on the West Florida Shelf during the winter months, in which it is clearly seen that cold core filaments extend from a thermal front. Numerical experiments are therefore designed to allow for reliable comparisons with conditions in this region.
Brolley, J. M. (2004). Experimental Forest Fire Threat Forecast . Master's thesis, Florida State University, Tallahassee, FL.
Abstract: Climate shifts due to El Niño (warmer than normal ocean temperatures in the tropical Pacific Ocean) and La Niña (cooler than normal) are well known and used to predict seasonal temperature and precipitation trends up to a year in advance. These climate shifts are particularly strong in the Southeastern United States. During the winter and spring months, El Niño brings plentiful rainfall and cooler temperatures to Florida. Recent los Niños occurred in 1997-1998, one of the strongest on record, with another mild El Niño in 2002-2003. Conversely, La Niña is associated with warm and dry winter and spring seasons in Florida. Temperature and precipitation affect wildfire activity; interannual drivers of climate, like ENSO, have an influence on wildfire activity. Studies have shown a strong connection between wildfires in Florida and La Niña, with the more than double the average number of acres burned (O'Brien et al 2002; Jones et al. 1999). While this relationship is important and lends a degree of predictability to the relative activity of future wildfire seasons, human activities such as effective suppression, prescribed burns, and ignition can play an equally important role in wildfire risks. This study forecasts wildfire potential rather than actual burn statistics to avoid complications due to human interactions. This wildfire threat potential is based upon the Keetch-Byram Drought Index (KBDI). The KBDI is well suited as a seasonal forecast medium. It is based on daily temperature and rainfall measurements and responds to changing climate and weather conditions on time scales of days to months, and this index is high during dry warm weather patterns and low during wet cool patterns. The KBDI has been widely used in forestry in the Southeastern United States since its development in the 1970's, with foresters and firefighters have a good level of familiarity with the index and its applications. The KBDI is calculated daily and used as an index by wildfire managers. This study calculates wildfire potential using a statistical method known as bootstrapping. Many datasets contain approximately a half-century of data, and the limited dataset will introduce biases. Bootstrapping can remedy bias by simulating thousands of years of data, which retain the climatology for the past half-century. Bootstrapping preserves the mean but not the variance. By incorporating this method, this study will improve long-term forest fire risks that will become useful for those living or working near forests and assist in managing forests and wildfires. The Southeast Climate Consortium will also be issuing wildfire risk forecast for Florida and parts of Alabama and Georgia based on ENSO phase and the KBDI. Climate information and ENSO predictions are better served by incorporating them with known climate indices that are routinely used in the forestry sector. Wildfire managers and foresters operationally use the KBDI to monitor and predict wildfire activity (O'Brien et al. 2002). Meteorologists at the Florida Division of Forestry have demonstrated the validity of the KBDI as an indicator of potential wildfire activity in Florida (Long 2004). They showed that the value of the KBDI is not as important as the deviation from the monthly average. The wildfire risk forecast is based on the probabilities of KBDI anomalies and will present the probabilities associated with large deviations from the seasonal normal.
Maue, R. N. (2004). Evolution of Frontal Structure Associated with Extratropical Transitioning Hurricanes . Master's thesis, Florida State University, Tallahassee, FL.
Abstract: Many tropical cyclones move poleward, encounter vertical shear associated with the midlatitude circulation, and undergo a process called extratropical transition (ET). One of the many factors affecting the post-transition extratropical storm in terms of reintensification, frontal structure, and overall evolution is the upper-level flow pattern. Schultz et al. (1998) categorized extratropical cyclones according to two of the many possible cyclone paradigms in terms of the upper-level trough configuration: The Norwegian cyclone model (Bjerknes and Solberg 1922) associated with high-amplitude diffluent trough flow and the Shapiro-Keyser cyclone lifecycle (1990) with low-amplitude confluent troughs. Broadly speaking, the former category is associated with a strong, meridionally oriented cold front with a weak warm front while the latter lifecycle usually entails a prominent, zonally oriented warm front. However, as will be shown, simple antipode lifecycle definitions fail to capture hybrid or cross-lifecycle evolution of transitioned tropical cyclones. To exemplify the importance upper-level features such as jet streaks and troughs, a potential vorticity framework is coupled with vector frontogenesis functions to diagnose the interaction between the poleward transitioning cyclone and the midlatitude circulation. Particular focus is concentrated upon the evolution and strength of frontal fracture from both a PV and frontogenesis viewpoint. The final outcome of extratropical transition is highly variable depending on characteristics of the tropical cyclone, SSTs, and environmental factors such as strength of vertical shear. Here, three storms (Irene 1999, Fabian 2003, and Kate 2003) typify the inherent variability of one such ET outcome, warm seclusion. Very strong winds are often observed in excess of 50 ms-1 along the southwestern flank of the storm down the bent-back warm front. The low-level wind field kinematics are examined using vector frontogenesis functions and QuikSCAT winds. A complex empirical orthogonal function (CEOF) technique is adapted to temporally interpolate ECMWF model fields (T, MSLP) to overpass times of the scatterometer, an improvement over simple linear interpolation. Overall, the above diagnosis is used to support a hypothesis concerning the prevalence of hurricane-force winds surrounding secluded systems.
Keywords: Extratropical Transition, Frontogenesis, Fronts, Quikscat, Cyclone Lifecycles, Warm Seclusion, Frontal Fracture, Potential Vorticity, Hurricane Kate, Hurricane Irene, Hurricane Fabian, Tropical Cyclones
Lombardi, K. C. (2004). Resolving the Diurnal and Synoptic Variance of Scatterometer Vector Wind Observations . Master's thesis, Florida State University, Tallahassee, FL.
Abstract: Scatterometer observations of vector winds are used to examine the amplitudes of synoptic and diurnal cycles. Scatterometers have the advantage of providing global coverage over water; however, irregular temporal sampling complicates the analyses. A least squares technique is used in determination of the amplitudes and phases of the diurnal and synoptic cycles on spatial scales of 5°, 15°, and 30°. In open ocean areas and regions with sufficient open water, the magnitudes of the diurnal and synoptic cycles are 1.0 ms-1 and 3.5ms-1, respectively. Diurnal amplitudes are highest in the polar regions and close to land surfaces due to sea breeze effects. The fraction of variance explained by the diurnal cycle is greatest near the equator. Synoptic amplitudes are consistently larger downwind of land from storm tracks and in the southern polar region as the time analyzed is during the southern winter season.
Arruda, W. Z., Nof, D., & O'Brien, J. J. (2004). Does the Ulleung eddy owe its existence to beta and nonlinearities? Deep Sea Research Part I: Oceanographic Research Papers , 51 (12), 2073–2090.
Bourassa, M. A. (2004). An improved sea state dependency for surface stress derived from in situ and remotely sensed winds. Advances in Space Research , 33 (7), 1136–1142.
Penduff, T., Barnier, B., Dewar, W. K., & O'Brien, J. J. (2004). Dynamical Response of the Oceanic Eddy Field to the North Atlantic Oscillation: A Model-Data Comparison. J. Phys. Oceanogr. , 34 (12), 2615–2629.
