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CBLAST
Collaborators :
Peter Black (HRD) Flight Planning, Dropsondes
Robert Black (HRD) Cloud Physics
Eric Uhlhorn (HRD) Hurricane surface flux
Gustavo Goni (AOML/HRD) Ocean heat content
Paul Chang (NESDIS/ORA) Satellite applications
David McLaughlin (UMass) SFR, web, data archive
Jeff French (ARL) ET Probe, BAT
Eric DAsaro (APL/UW) Lagrangian Float
Kerry Emanuel (MIT) Theory, dropsondes
Eric Terrill (Scripps) Floats
Jeff Nystuen (APL/UW) Acoustics of wave and precipitation
Ken Melville (Scripps) Wave breaking
Ed Walsh (NASA) SRA
Chris Fairall (ETL) Sea Spray (CPC)
Bill Asher (APL/UW) Sea Spray (PDA)
Pearn Niiler (Scripps) Drifters
Wil Drennan (UM/RSMAS) Moisture flux
Shuyi Chen (UM/RSMAS) Coupled modeling
Nick Shay (UM/RSMAS) Ocean responce
Chi-Sann Liou (NRL) COAMPS modeling
LONG-TERM GOALS
Our primary goal is to improve our understanding of air-sea surface
flux processes in high winds, specifically in the complex conditions
of tropical hurricanes where swell, sea spray and secondary boundary
layer circulations play a role. Our ultimate goal and prime motivation
for this work is to parameterize these new observations and improve
the accuracy of hurricane intensity prediction.
2005 Update on CBLAST
OBJECTIVES
The objective of this work is to develop a new surface wave-dependent
flux parameterization for the high wind hurricane boundary layer
containing secondary (roll-vortex) circulations over fetch limited
seas in the presence of sea spray and one or more swell components
from an airborne platform. We propose to test the following
hypotheses:
- that surface momentum exchange coefficients increase
with wind speed for moderate winds (>30 m/s), are enhanced by
fetch-limited waves or opposing swell, but level off or decrease
above a high wind threshold (>45 m/s), especially in quadrants
where swell has a significant downwind component,
- that compensating mechanisms for enhanced surface
air-sea enthalpy fluxes over and above current parameterizations
must exist for storm maintenance and growth above some high-wind
threshold wind speed, and
- that candidate mechanisms are separable and can be
estimated, such as a) enhanced turbulent fluxes due to wave
interactions, b) spray evaporation and c) secondary flow circulations
(roll-vortex type).
APPROACH
Our approach is to implement a multifaceted observational program
among several investigators to simultaneously measure air-sea fluxes
using several independent methods while at the same time measuring
two-dimensional surface wave spectra, as well as spray droplet spectra
, in wind speed regimes ranging from 20-40 m/s, and possibly higher.
The secondary goal is to use existing data sets to inter-compare
various published wave-dependent bulk flux parameterizations, with
and without wave age effects and with and without spray
parameterizations, using never-before-available surface inputs
from GPS dropsondes, AXBTs, model-generated as well as
remotely-measured wave spectra and remotely-measured surface winds
in gale- and hurricane-force conditions.
Our strategy will be to obtain new parameterizations of momentum,
heat and moisture fluxes from these observations including accurate
estimates of the exchange coefficients as a function of wind speed
and to estimate the modulation of the fluxes by fetch-limited wind
waves, long-wavelength swell, sea spray and PBL secondary circulations,
i.e.roll vortices.
CBLAST experiments flown
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Last modified: 5/16/2003
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