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ProgressinCalculatingTropicalCycloneSurfaceWind
Inflowà Upflowà OutflowfromOVWObservations
RalphFoster,APL,UniversityofWashington,Seattle,WA
JunZhang,HRD,NOAA,Miami,FLPeterBlack,Salinas,CA
ResearchsupportedbyNASA:OceanVectorWindsScienceTeam
IOVWSTmeeting,2-4May,2017,LaJolla,CA
ForceEmanuel“CarnotCycle”WithSAR-derivedPBLSolution
• Inputdata:Katrina,27Aug,200511:30– OVW(SAR,RadarSAT-1,1km)– SST(MW+IR,fromRSS,9km)
• Foster(2009,2017)PBLsolution(fromSAR)generateslowerBCtoEmanuel(1986)– PrimarilyWalongPBLtop– (“Ringthetroposphere’sbell”)
• Calculatetropospheric(U,V,W)• FirstGoal:CanIgetcorrectorderofmagnitude?
1. DeriveSea-LevelPressure(SLP)fromSatelliteOVW(Foster,2017)2. DeriveGradientWindatthePBL-Top(h)fromSLP3. DerivePBL(U,V,W)fromSLP andOVWusingFoster(2009)4. Emanuel(1986)“Carnot”Cycle:
1. TCtroposphereisneutraltoSlant-wiseconvection↔2. AngularMomentum(M)surfacesareparalleltoSaturated,
equivalentPotentialTemperature(𝜃"∗)
3. OverturningSecondaryCirculationStreamfunction(ψ)isparalleltoM
5. UseSLP&Sea-SurfaceTemperature(SST)tofind𝜃"∗asfunctionof
Height(z)6. Find(R,z)profileofM atRMW(T(z))7. MoonandNolan(2010):𝑉 𝑡𝑟𝑜𝑝𝑜𝑠𝑝ℎ𝑒𝑟𝑒 isself-similartoV(h)8. Calculate𝑀 𝑡𝑟𝑜𝑝𝑜𝑠𝑝ℎ𝑒𝑟𝑒 from𝑉 𝑡𝑟𝑜𝑝𝑜𝑠𝑝ℎ𝑒𝑟𝑒9. Calculateψ(h) fromPBLsolution(-.
-/= 𝑟𝑤,−-.
-3= 𝑟𝑢)
10.Interpolateψ intotroposphereknowing𝑀 ℎ11.Calculate(U,W)inTroposphere
(skip)
ColdR-ZCross-Section
WarmR-ZCross-Section
RadarSAT-1(1kmOVW)
CombinedMW+IRSSTRemoteSensingSystems9kmSST
Summary
• FirstestimateofTCTroposphericwindsfromOVWandSSTalone
• FirstcutatcouplingNon-linearPBLmodeltoEmanuel(1986)TCmodel
• Resultsarelowerthan,butwithinorder-of-magnitudeof,compositeobservations
• Year3:PBLmodelimprovementsin-progress• Year3:Morecompletecouplingplanned• Year4:ComparetoGlobalHawkObservations