This study aims to develop an objective hurricane initialization scheme which produces a model hurricane that not only satisfies forecast model constraints but also incorporates observed features such as the initial intensity (e.g., central sea-level pressure and maximum surface wind) and size (e.g., the radius of 34kt wind). It is based on the four-dimensional variational (4D-Var) bogus data assimilation (BDA) scheme originally proposed by Zou and Xiao (1999). The 4D-Var BDA scheme consists of two steps: (i) specifying a bogus sea level pressure (SLP) field based on parameters observed by the Tropical Prediction Center (TPC) and (ii) assimilating the bogus SLP field under a forecast model constraint adjusting all model variables. This research focuses on improving the specification of the bogus SLP indicated in the first step. First, an empirical linear model is developed for determining the size of the bogus vortex based on the TPC observed radius of 34kt. Numerical experiments are then carried out with and without making use of this model for the initialization and prediction of Hurricane Bonnie (1998) over the Atlantic Ocean. After runing these experimets, the track prediction is found to be less sensitive to bogus SLP than the intensity prediction. The maximum track error is less than 110 km during the entire three-day forecast using 4D-Var BDA generated initial vortices in both situation. However, the experiment using the linear model for the size specification considerably outperforms the other formulations in terms of the intensity prediction of Hurricane Bonnie. A further effort is made to incorporate QuikSCAT surface wind observations into the above hurricane initialization procedure, which aims to produce a more realistic initial vortex. Directly assimilating QuikSCAT surface winds results a negligible impact on hurricane prediction, so an indirect technique needs to be developed in order to maximize the impact of QuikSCAT observations on hurricane prediction. A radial profile of SLP is first derived from QuikSCAT surface winds, which is incorporated into the 4D-Var BDA procedure. Differences using the QuikSCAT-derived bogus SLP (QuikSCAT-BDA) and the above linear-model-derived SLP (LM-BDA) are examined for the prediction of Hurricane Gordon (2000). Compared with an HRD observed radial wind profile for Hurricane Gordon, the QuikSCAT-derived SLP profile is more realistic than the SLP profile specified by LM-BDA. However, numerical results show that LM-BDA performs better than QuikSCAT-BDA for both the track and intensity forecasts. Diagnosis of model output indicates that the LM-BDA generates larger surface fluxes of sensible heat, latent heat and moisture, as well as stronger downward angular momentum transport than the QuikSCAT and other BDA schemes do. These enhanced energy supplies offset the energy lost caused by friction and gravity wave propagation, allowing for the model to maintain a strong and realistic hurricane during the entire forward model integration. / A Dissertation Submitted to the Department of Meteorology in Partial FulfiLlment of the Requirements for the Degree of Doctor of Philosophy. / Spring Semester, 2004. / March 30, 2004. / Data assimilation, 4D-Var, Initialization, Size, Hurricane / Includes bibliographical references. / Xiaolei Zou, Professor Directing Dissertation; Ionel M. Navon, Outside Committee Member; Albert I. Barcilon, Committee Member; T. N. Krishnamurti, Committee Member; Peter S. Ray, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_180506 |
| Contributors | Park, Kyungjeen (authoraut), Zou, Xiaolei (professor directing dissertation), Navon, Ionel M. (outside committee member), Barcilon, Albert I. (committee member), Krishnamurti, T. N. (committee member), Ray, Peter S. (committee member), Department of Earth, Ocean and Atmospheric Sciences (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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