HR: 1340h
AN: A13A-0893    [Abstracts]
TI: FFT and Wavelet analysis for the study of gravity wave activity over a modeled hurricane environment
AU: * Kuester, M A
EM: Michele.Kuester@Colorado.EDU
AF: University of Colorado, Program in Atmospheric and Oceanic Sciences (PAOS) 311 UCB, Boulder, CO 80309
AU: Alexander, J
EM: alexand@cora.nwra.com
AF: Colorado Research Associates (CoRA), A Division of NorthWest Research Associates, Inc. 3380 Mitchell Lane, Boulder, CO 80301
AU: Ray, E
EM: Eric.Ray@noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305
AB: Understanding of gravity waves and their sources are important for driving global circulations in climate and weather forecasting models. Temperature fluctuations associated with gravity waves near the tropopause also affect cirrus cloud formation, which is important to the study of radiative forcing in the atmosphere. Deep convection is believed to be a major source for these waves and hurricanes may be particularly long-lived and intense sources. Simulations of Hurricane Humberto have been studied using the Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) fifth-generation Mesoscale Model (MM5). Humberto is simulated at both tropical storm and hurricane stages. Information about gravity waves and their sources can be inferred from horizontal wind and temperature variances in the troposphere and lower stratosphere. Both Fast Fourier Transform (FFT) and Wavelet analyses are employed to investigate wave properties and behavior in the lower stratosphere. FFT analysis gives an overall view of storm affects while Wavelet analysis gives a local picture of gravity wave activity. It is found that a hurricane can be a significant source of deep heating which actively triggers gravity waves from the hot tower region of the storm eye wall. Convectively generated gravity waves are observed in the lower stratosphere of this model with horizontal scales of 10-250 km, vertical scales around 5 km and with intrinsic periods of approximately 20 minutes. Some specific characteristics of gravity waves found above the storm will be presented along with further discussion from the wave activity observed with the model. Deep convection over the oceans is thought to play a key role in atmospheric forcing via the creation of vertically propagating gravity waves and hurricane induced gravity waves may play a role in stratospheric forcing during the hurricane season.
DE: 0399 General or miscellaneous
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005