HurricanesInnovative Grid-Enable Multiple-scale Hurricane modeling system

Konstantinos Menelaou

International Hurricane Research CenterDepartment of Earth SciencesFlorida International University

Physical structure of Hurricanes

• Hurricanes are intense whirling storms that develop over the tropical oceans in regions of very warm surface water.

• Hurricanes are distinguished by their driving force—heating from an underlying warm ocean—and by their intensity .

• The kinetic energy of hurricanes is maintained in the presence of boundary layer by the conversion of latent heat energy acquired from the underlying ocean.

• This energy conversion is carried out by circulation associated with the hurricane.

• This circulation inflow into a region of enhanced conversion surrounding the storm center that is referred as the eyewall.

Why hurricane boundary layer turbulence is important?

Hurricane boundary layer turbulent processes have a direct socio-economic impact on coastal communities and resources.

It is through the boundary layer that a hurricane gets energy.

Turbulence

Warm ocean surface

Hea

t

Friction

Wat

er V

apor

Mom

entu

m

Up-scale impact on hurricane by providing energy to maintain hurricane vortex.Down-scale impact on coastal communities during landfall.

Turbulent transport

1800 180 18 1.8 0.18 0.018Scale (km)Van de Hoven

xclouds turbulence

Parameterization

y

Large eddy simulation

100 m

Operational modelGrid-size

Can current boundary layer turbulence parameterization schemes realistically represent the turbulent transport in high hurricane wind conditions?

How can we predict the HBL organizedstructures and the associated damaging winds for hurricane wind damageMitigation?

Classic Large eddy simulation (LES)

Simulation domain cannot be very large, typically about tens of kilometers.Initialized with idealized vertical profiles and forced with uniform surface conditions and horizontal homogeneous large-scale atmospheric forcings.

Hurricane vortex is a moving target. Swirling hurricane wind changes the speed and direction continuously.

Classic LES cannot be used to study HBL

Hurricane Ivan

WRF large-eddy simulation (WRF-LES)

Portable Wind Tower (PWT)

• The problem can be solved by increasing model resolution so that small scale processes, such as large turbulent eddies and clouds, are explicitly resolved.

• LES can be executed in a weather forecasting mode by nesting an LES domain in mesoscale models (Zhu 2007).

• Such multi-scale simulations open the door to simulate background flow, hurricane vortex, and down to turbulent eddies in a unified system.

PROPOSAL : Developmen of a multi-scale modeling system from Weather Forecast & Research (WRF) model including an online LES domain to explicitly simulate large turbulent eddies in a weather forecasting mode.