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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.
Keywords: Central American Wind Jets
|Kara, A. B., Hurlburt, H. E., Rochford, P. A., & O'Brien, J. J. (2004). The Impact of Water Turbidity on Interannual Sea Surface Temperature Simulations in a Layered Global Ocean Model*. J. Phys. Oceanogr., 34(2), 345–359.|
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.
|Kvaleberg, E., Morey, S. L., & O'Brien, J. J. (2004). (J. Cote, Ed.). Research Activities in Atmospheric and Ocean Modeling, Report No. 34. Geneva, Switzerland: World Meteorological Organization.|
|LaRow, T. E., & Cocke, S. (2004, Spring). Methods for Multi¬Model Proxies for Climate Studies. CLIVAR Exchanges Newsletter.|
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.
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
|Morey, S. L., & O'Brien, J. J. (2004). Vertical resolution impacts on modeled Gulf of Mexico loop current eddies (J. Cote, Ed.). Research Activities in Atmospheric and Ocean Modeling, Report No. 34. Geneva, Switzerland: World Meteorological Organization.|
|Murty, V. S. N. (2004). A new technique for the estimation of sea surface salinity in the tropical Indian Ocean from OLR. J. Geophys. Res., 109(C12).|
|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.|