Virendra P. Ghate and Bruce A. Albrecht (U Miami) Christopher W. Fairall (NOAA ESRL)
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Transcript of Virendra P. Ghate and Bruce A. Albrecht (U Miami) Christopher W. Fairall (NOAA ESRL)
Annual cycle of cloud fraction and surface radiative cloud forcing in the
South-East Pacific Stratocumulus region
Virendra P. Ghate and Bruce A. Albrecht (U Miami)
Christopher W. Fairall (NOAA ESRL)
Robert A. Weller (Woods Hole Oceanographic Institution)
• Significant Component of Earth’s radiation budget.
• 20% increase can offset global warming due to doubling of CO2.
• Strong feedback with ENSOKlein & Hartmann 1993
WORS• Wood’s Hole
Oceanographic Institute (WHOI)’s Ocean Reference Station (WORS).
• Location: 20° S 85° W• Continuous observations
of surface broadband radiative fluxes and thermodynamic variables since October 2000.
•http://uop.whoi.edu/archives/dataarchives.htm
Cruise Name Cruise Period
EPIC 2001 Oct 9-25
PACS 2003 Nov 11-24
Stratus 2004 Dec 5-23
Stratus 2005 Oct 5-20
Stratus 2006 Oct 9-27
Seasonal variation of meteorology at WORS
Seasonal Variations: Other Properties
Surface fluxes of sensible and latent heat, LCL, convective velocity scale, and temperature and moisture advection
Estimating Low Cloud Fraction fro a Buoy
cld clrLW CF LW (1 CF) LW
• LW = Measured downwelling longwave radiation at the surface.
• CF = Cloud Fraction
• LWcld = Cloud emitted longwave radiation
• LWclr = Clear sky longwave radiation.
Technique
cld clrLW CF LW (1 CF) LW
• LW = Observed at WORS
• LWcld = σTLCL4
• LWclr = f(qsfc,Tsfc,IVsfc); Fairall et al. 2007
clr
cld clr
LW LWCF
LW LW
Technique Evaluation:Ceilometer Observations
Model-satellite comparison
Seasonal Cycle: Monthly Means
Cloud Fraction
Annual cycle 0.5-0.7
Cloud Forcing: Surface radiative fluxes
Annual Cycle:
Solar -125 to -65 W/m2
IR 55 to 35 W/m2
Diurnal Cycle
Diurnal Cycle Cloud Fraction
Months Range PhaseMean
Night-time
DJF 0.33 18 0.68
MAM 0.22 19 0.59
JJA 0.11 18 0.64
SON 0.23 17 0.79
More Detailed Data Sets
• Annual Cruises
• VOCALS field ProgramFall 2008
http://www.esrl.noaa.gov/psd/people/Simon.deSzoeke/synthesis.html
http://www.eol.ucar.edu/projects/vocals/
0 5 10 15 201000
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x-01 o-03 dia-04 rt tri-05 *06
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