ImprovingtheVortexInitializationofHurricaneKarl(2010)Throughthe
AssimilationofTropicalCycloneVitalsQuadrantWindRadiiEstimates
RobertNystrom1,FuqingZhang1,andJasonSippel21 PennStateUniversity
2 NCEP
HurricaneKarl(2010)• Initiallyformedasatropicaldepression12zSeptember14th,2010• Becameatropicalstorm18zonthe14th
• MadelandfallontheYucatanPeninsulashortlyafter12zonthe15th
• EmergedinthebayofCampecheandrapidlyintensifiedintoacategory3hurricanebeforemakinglandfallinVeracruz~17zonthe17th
FromTropical Cyclone ReportHurricane Karl
WhatareQuadrantWindRadiiEstimates?• Representthelargestdistancefromthecenterofthestormanywhereinaspecificquadrantthatawindspeed(34,50,or64knots)canbefoundorifitcanbefound.
NE
SE
NW
SW
TCVitalsQuadrantWindRadiiEstimates• Estimatedradiiofthe34/50/64 knotwindsarecontainedinTCVitals foreachquadrantofthestormwhenavailable.• Containsinformationonthepossibleasymmetricwindstructureofthestorm• Largeerrors!• EstimatedradiioftheRMWisalsogivenbutnoinformationonwhereitislocated
64kt wind radii
50kt wind radii
34kt wind radii
Whatisthevarianceintheradiiforagivenwindspeedbetweenthequadrants?Variance of64ktRadii Variance of50ktRadii Varianceof34ktRadii
~0.18 ~0.23 ~0.40
CreationofSyntheticWindObservations
• Hourlysyntheticwindobservationscreatedbylinearlyinterpolatingbetween6hourlyTCvitals data• Alsointerpolatedtocardinaldirection(maximumof8observationsperwindspeed)• WindsspeedsestimatedabovethePBLsothattheycanbeassumedapproximatelytangential• 1500and3000m
• ROIcalculatedasafunctionofradius• Increaseswithincreasing radius
Franklin etal.2003
ExperimentalSet-up• 3two-waynesteddomainsof27,9,and3kmrespectively• 60memberensemble• Forecastinitialized12zonthe16th
• 7hourspin-uptimefrom12zto19z• Airborneradardataassimilatedat19,20and21z• HPIorHPIandTCwinds thenassimilatedhourlybeginningat22z16thuntil0z18th • Alpha=0.8forrelaxation
12z16th19z16thAirborne
20z16thAirborne
21z16thAirborne
22z16thHPI
23z16thHPI
0z18thHPI
12z16th19z16thAirborne
20z16thAirborne
21z16thAirborne
22z16thHPI+
TCwinds
23z16thHPI+
TCwinds
0z18thHPI+
TCwinds
HPISimulation:
HPI+TCwinds Simulation:
NoDA Simulation:
12z16th19z16thAirborne
20z16thAirborne
21z16thAirborne
0z18th
HPI
HPI+TCwinds
HPI HPI+TCwinds
HPI HPI+TCwinds
HPI HPI+TCwinds
HPI HPI+TCwinds
HPI HPI+TCwinds
ThoughtsandNextSteps• Somepossiblebenefittoassimilatingquadrantwindradiiestimates
• Specifically tohelpconstrainthesizeofthevortex
• Examineacasewithouttheinfluenceofaircraftobservations• Verifyagainstquadrantwindradiiestimates• ExploremethodstoaccountforasymmetryinRMWestimates• ExamineimpactsonforecastsandimpactsofTCwinds withotherconventionalobservationsincluded• Investigate3hourlyassimilationofquadrantwindradiiestimates• ExaminebetterlocalisationmethodsandfuturereducedobservationerrorofTCquadrantwindradiiestimates
