Large-scale influences on tropical cyclogenesis for selected storms in the 2005 Atlantic hurricane season

Unpreparedness of large and increasing populations to Atlantic tropical cyclones (TCs) in North and Central America often causes a significant percentage of human casualties and economic losses, which results in part from the difficulty of forecasting tropical cyclogenesis (TCG) and changes in TC track and intensity. Although the mechanisms that lead to TCG have been studied extensively, lack of knowledge still exists about the relative importance of the precursor factors responsible for TCG, especially in the Gulf of Mexico/Caribbean basin where no clear genesis mechanism has been identified for TCs. A series of studies in this dissertation examines influences of large-scale atmospheric circulation on TCG and intensity change mechanisms for Tropical Storm Arlene and Hurricanes Cindy, Dennis, and Wilma in 2005 by using various derived and observed data sets. To support the main analyses of the large-scale circulations GOES-12 satellite water vapor imagery and the Weather Research and Forecasting (WRF) model (V.3.2.1) are used. Six-hourly NCEP FNL (final) operational global analysis data and daily “real-time global” (RTG) sea surface temperature (SST) data are used as WRF model inputs. Results show that large-scale, low-level circulations incurred by subtropical high pressure systems in the surrounding ocean basins or triggered by mid-latitude troughs over northeastern North America play critical roles in the TCG process in the western North Atlantic. In particular, the convergence of temporary westerly winds from the eastern North Pacific and the southeasterly/easterly winds from the Atlantic under the orographic effects of Central America creates conditions in the lower atmosphere that favor the development of a meso-scale vortex over the warm sea surface, leading to TCG. WRF model simulation revealed that the interaction between the mid-latitude systems and tropical atmosphere determined the success or failure of the TCG forecast, which suggests that large-scale, low-level circulations heavily affect TCG and that every large-scale vortex and circulation component in the immediately-neighboring region of the storm development is important for TCG forecasting. This study shows that the global WRF has a potential to be used for operational short-range TCG forecasting

Indiana’s Past & Future Climate: A Report from the Indiana Climate Change Impacts Assessment

Indiana’s climate is changing. Temperatures are rising, more precipitation is falling and the last spring frost of the year has been getting steadily earlier. This report from the Indiana Climate Change Impacts Assessment (IN CCIA) describes historical climate trends from more than a century of data, and future projections that detail the ways in which our climate will continue to change

Dynamical downscaling of tropical cyclones from CCSM4 simulations of the Last Glacial Maximum

Dynamical downscaling of simulations of the Last Glacial Maximum (LGM) and late twentieth century (20C) were conducted using the Weather Research and Forecasting (WRF) model with the aim of (1) understanding how the downscaled kinematic and thermodynamic variables influence simulated tropical cyclone (TC) activity over the western North Pacific during the LGM and the 20C periods and (2) to test the relevance of TC genesis factors for the colder LGM climate. The results show that, despite the lower temperatures during the LGM, the downscaled TC climatology over the western North Pacific in the LGM simulation does not differ significantly from that in the 20C simulation. Among the TC environmental factors, the TC potential intensity, mid‐tropospheric entropy deficit, and vertical wind shear during the LGM were consistent with previous analyses of TC genesis factors in LGM global climate model simulations. Changes in TC genesis density between the LGM and the 20C simulations seem to be well represented by the ventilation index, a nondimensional measure of the combined effects of vertical wind shear, and thermodynamic properties, suggesting the potential applicability of those factors for TC activity evaluation during the LGM and possibly other climates

An Investigation of the Tropical Cyclogenesis of Arlene (2005) Using ERA-Interim Reanalysis and the WRF Model Simulation

The process and development sequence of meso-beta-scale vortices at multiple levels and the synoptic-scale environmental conditions for the genesis of Tropical Storm Arlene (2005) were analyzed using ERA-Interim Reanalysis data and Weather Research and Forecasting (WRF) model simulations. Results from the two agree in that although the confluence of low-level westerly winds from the eastern North Pacific and low-level easterly winds from the North Atlantic preceded tropical cyclogenesis over the western Caribbean Sea, midlevel enhanced wind surges over Lake Nicaragua were also important in the pregenesis period. A closer examination of the WRF simulation revealed that the midlevel enhanced wind surges were produced by the interactions between the 500 hPa anticyclone over Mexico and a wind stream from northern South America. The 500 hPa surges augmented the vorticity of the incipient storm as it passed over Lake Nicaragua. Due to the subsequent influxes of strong westerly and easterly winds in the lower atmosphere, the midlevel vortex development was followed by a low-level vorticity increase, enhancing the vertical structure of the vortex motion of the storm from the 500 hPa level downward. This vortex development resulted in tropical cyclogenesis at 1800 UTC on 8 June and a tropical storm by 0600 UTC on 9 June

Planetary-Scale Low-Level Circulation and the Unique Development of Hurricane Wilma in 2005

Large‐scale atmospheric and oceanic conditions in the western Atlantic basin were analyzed to understand the unique tropical cyclogenesis (TCG) and intensification mechanism of Hurricane Wilma in 2005, the most intense Atlantic basin tropical cyclone (TC) on record. An analysis of 850 hPa circulations depicted in the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data suggests that anomalous development of the 850 hPa circulation pattern triggered by Hurricane Vince (October 8–11, 2005) contributed to the development of a large‐scale low‐level vortex that preceded Wilma\u27s TCG in the eastern Caribbean. In particular, weakened easterly winds in the central tropical Atlantic assisted the unique large‐scale cyclonic circulation over the western Atlantic about a week before Wilma\u27s TCG. The unprecedented rapid intensification of Wilma was investigated considering the interactions between mid‐latitude troughs and large‐scale low‐level circulations as well as anomalously warm SST conditions. The global Weather Research and Forecasting (WRF) model run for Hurricane Wilma suggests that the role of mid‐latitude systems in TC activity is more important than previously believed and that every in situ large‐ or meso‐scale vortex and circulation component at least in the immediately neighboring region of TCG seems to have a significant influence on TCG processes

Tropical Cyclogenesis in the Intra-Americas Sea: Hurricane Cindy (2005)

The tropical cyclogenesis (TCG) of Atlantic Hurricane Cindy (2005) was investigated to study environmental conditions preceding mesoscale vortex development in the Intra-Americas Sea (IAS; i.e., the Gulf of Mexico and Caribbean Sea) using the ERA-Interim Reanalysis pressure level data. Major findings include that the development of a mesoscale vortex occurred downward over Central America due to 600 hPa level enhanced winds downstream of southeasterly winds from northern South America, triggering Cindy\u27s TCG in a few days. The contribution of midlevel enhanced winds should be noted as a potential precursor of other TCGs in the IAS

Robust Extrinsic Calibration of Multiple RGB-D Cameras with Body Tracking and Feature Matching

RGB-D cameras have been commercialized, and many applications using them have been proposed. In this paper, we propose a robust registration method of multiple RGB-D cameras. We use a human body tracking system provided by Azure Kinect SDK to estimate a coarse global registration between cameras. As this coarse global registration has some error, we refine it using feature matching. However, the matched feature pairs include mismatches, hindering good performance. Therefore, we propose a registration refinement procedure that removes these mismatches and uses the global registration. In an experiment, the ratio of inliers among the matched features is greater than 95% for all tested feature matchers. Thus, we experimentally confirm that mismatches can be eliminated via the proposed method even in difficult situations and that a more precise global registration of RGB-D cameras can be obtained

Low-Level Westerly Winds, Topography, and Tropical Cyclogenesis of Arlene (2005): Observations and Model Simulations

The evolution process of the low-level westerly winds over the eastern North Pacific is investigated to understand the tropical cyclogenesis (TCG) of Tropical Storm Arlene (2005) over the Intra-Americas Sea (IAS). Also considered are the influences of the topography of the Central American mountain region interacting with the low-level westerly winds on Arlene\u27s TCG by comparing results from a modified-topography simulation of Arlene\u27s TCG with those from a simulation with the original topography in the Weather Research and Forecast (WRF) model. Interactions among large-scale circulations associated with subtropical highs in both hemispheres and an anticyclone over the warm eastern North Pacific produced low-level westerly winds into the IAS. WRF model experiments with a virtually elevated terrain filling in mountain passes in Central America resulted in the delayed and suppressed development of the incipient storm. The model experiments suggest that the low-level winds and moisture fluxes from the eastern North Pacific passing through the low-level mountain passes in Central America could play a critical role in the TCG process and perhaps also sustenance of storms over the western Caribbean