Numerical simulation of tropical cyclones in a coupled atmosphere-ocean model with nonuniform mixed layer depth

• Other Authors: Mao, Qi., Florida State University
• Format: Text
• Language: English
• Subjects: Physics; Atmospheric Science; Fluid and Plasma; Engineering; Marine and Ocean; Pacific; North Atlantic
• Online Access: http://purl.flvc.org/fsu/lib/digcoll/etd/3088360; http://fsu.digital.flvc.org/islandora/object/fsu%3A77165/datastream/TN/view/Numerical%20simulation%20of%20tropical%20cyclones%20in%20a%20coupled%20atmosphere-ocean%20model%20with%20nonuniform%20mixed%20layer%20depth.jpg

A coupled 3D atmosphere-ocean model is developed to study the effect of the oceanic mixed layer depth (OMLD) on the intensification and the motion of the tropical cyclones. We first study the baroclinic response of the ocean with uniform and nonuniform initial OMLD to the steady forcing of an axisymmetric TC moving at a prescribed translating speed. Emphases are placed on the TC-ocean interactions in the coupled model simulations. Results from 96-hour integrations show TC that move into deeper (shallower) OMLD regions experience rates of increase (decrease) in their intensities once the OMLD is 10 m deeper (2.5 m shallower) than that of the TC's origin. The rightward bias of the sea surface temperature (SST) response appears in every numerical experiment and the maximum SST cooling is about 1-2$\sp\circ$C, depending on the initial OMLD distribution and the TC's translating speed. Wind induced near inertial oscillation of the mixed layer current and subinertial oscillation of the mixed layer depth are found in the wake of the storm. The TC in the atmosphere-only model tends to displace toward the north further than the TC in the coupled model does. The deviation of the two tracks begins to occur after 36 hours. The maximum difference between the tracks is about 89 km occurring at 93 hours. A good correlation is found between the maximum wind speed and the northward deflection of the TC. Results of this study compare favorably with the statistics of the TC's track in the western North Pacific and the North Atlantic. Source: Dissertation Abstracts International, Volume: 55-04, Section: B, page: 1480. Major Professor: Richard L. Pfeffer. Thesis (Ph.D.)--The Florida State University, 1994.