Accession Number : ADA319898

Title :   On the Causes of Tropical Cyclone Motion and Propagation.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : McElroy, Carl A.

PDF Url : ADA319898

Report Date : 09 JAN 1997

Pagination or Media Count : 144

Abstract : The physics of tropical cyclone (TC) motion and propagation are examined using both climatological and composite rawinsonde data. Propagation is defined as TC motion relative to its surrounding steering flow. Tropical cyclones are observed to move 1-2 ms to the minus first power faster and usually 10-20 deg to the left of the surrounding deep layer steering current(850- 300mb deep layer flow averaged through a 5-7 deg radial band). Tropical cyclones move in response to a deep tropospheric current which advects them after they form. The primary factor causing TCs to propagate faster than their steering flow is their formation and continued residence within a baroclinic environment. This baroclinic environment is evidenced by positive and negative tropospheric wind shears on opposite sides of the storm track. The presence of this wind shear on each side of the storm track causes a deep layer wind profile with the weakest flow away from the storm center. Hence, the TC center is embedded in the strongest tropospheric mean flow. The deep layer parallel wind flow to each side of the TC in the (MOT) frame of reference must, as a consequence of the temperature gradient induced wind shears, be weaker than the deep layer flow over the TC center. Tropical cyclones are situated in the warmest part of the environment with a cooler deep layer current to both right and left sides. These deep layer flow properties are applicable to the vicinity of the TC regardless of latitude or direction of motion. Most TCs propagate to the left of their steering flow because they move from a relatively warm environment to a relatively cool environment. Westward moving TCs in the Atlantic are the exception. These are a special class of TCs which move from a relatively cool to a relatively warm environment. In this case, rear (cold) to front (warm) relative environmental temperatures cause a ri

Descriptors :   *ATMOSPHERIC MOTION, *TROPICAL CYCLONES, *CYCLOGENESIS, TEMPERATURE, ENVIRONMENTS, WIND, PATHS, COOLING, PROFILES, PHYSICS, CLIMATE, STORMS, WIND SHEAR, FLOW, RADIOSONDES, MEAN, TROPOSPHERE, CURRENTS, DEEP OCEANS, LATITUDE, DEEP SCATTERING LAYERS.

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE