Developing an Inner-Core SST Cooling Parameter for use in SHIPS

Developing an Inner-Core SST Cooling Parameter for use in

SHIPS

Developing an Inner-Core SST Cooling Parameter for use in

SHIPSPrincipal InvestigatorPrincipal Investigator: : Joseph J. Cione Joseph J. Cione

NOAA’s Hurricane Research DivisionNOAA’s Hurricane Research Division

Co-Investigators:Co-Investigators: John Kaplan John Kaplan (HRD)(HRD); Chelle ; Chelle Gentemann Gentemann (Remote Sensing Systems)(Remote Sensing Systems); Mark ; Mark

Demaria Demaria (NESDIS)(NESDIS)

IHC 2004 IHC 2004

Joint Hurricane TestbedJoint Hurricane Testbed

March 3, 2004March 3, 2004

+ What is the magnitude of inner core SST cooling + What is the magnitude of inner core SST cooling typically observed ?typically observed ?

+ What about storm to storm variability ?+ What about storm to storm variability ?

Project Motivation…..

On average do post storm ‘cold wake’ SST reductions on the order of 4-6oC adequately approximate SST cooling patterns typically found within the high wind TC inner core ?

Project Motivation…..

On average do post storm ‘cold wake’ SST reductions on the order of 4-6oC adequately approximate SST cooling patterns typically found within the high wind TC inner core ?

Cione and Uhlhorn (2003) documented SST change Cione and Uhlhorn (2003) documented SST change within the high wind TC inner core environmentwithin the high wind TC inner core environment……

Using existing surface Using existing surface buoy and AXBT observations buoy and AXBT observations from 23 hurricanes (33 events) between 1975-2002.from 23 hurricanes (33 events) between 1975-2002.

A focused effort to answer these questions….

Cione and Uhlhorn (2003)

A focused effort to answer these questions….

Cione and Uhlhorn (2003)

Defining the SST change Parameters used in Cione and Uhlhorn (2003)

(inner-core minus ‘ambient’)

Defining the SST change Parameters used in Cione and Uhlhorn (2003)

(inner-core minus ‘ambient’)

‘‘Ambient’ SST Ambient’ SST out AHEAD of the stormout AHEAD of the storm (>200km from TC center in RF or LF quadrant)(>200km from TC center in RF or LF quadrant)

‘‘Inner core’ SST/mixed layer temperature Inner core’ SST/mixed layer temperature (<(<60km 60km or <or <200km200km from TC center) - from TC center) - SSTSSTIC IC ; ; SSTSSTICWICW

Hurricanes only…Hurricanes only… Pre-landfallPre-landfall South of 36NSouth of 36N

Table 2 Magnitude of SST Change by StormHurricane Year Observing

PlatformΔ SSTIC (

o )CSST IC- SSTA

Δ SSTICW (o )C

SST ICW- SSTAAlicia 1983 42008 -1.8 -2.7Georges 1998 42040 -1.5 -3.4Emily 1993 44019 -1.5 -1.5Erika 1997 AXBT -1.5 -1.5Belle 1976 41002 -1.2 -1.5Elena 1985 42007 -1.0 -1.7Earl 1998 42003 -0.9 --Luis 1995 41519 -0.9 --Georges 1998 SANF1 -0.8 -1.4Dennis 1999 AXBT -0.8 --Georges 1998 DRY 1F -0.8 -0.9Dennis 1999 AXBT -0.8 --Lili 2002 42001 -0.7 -1.9Georges 1998 SMKF1 -0.7 -1.2Danielle 1998 AXBT -0.7 --Andrew 1992 FWYF1 -0.7 --Allison 1995 42003 -0.6 -0.6Bob 1991 DSLN -0.6 -0.6Anita 1977 42002 -0.6 -1.4Irene 1999 AXBT -0.6 --Frederic 1979 42003 -0.5 -0.8Dennis 1999 AXBT -0.5 -0.5Earl 1998 42040 -0.4 -0.5Eloise 1975 42001 -0.3 -0.8Bonnie 1998 AXBT -0.3 -0.3Bret 1999 AXBT -0.3 -0.4Lili 2002 AXBT -0.3 -0.7Opal 1995 42001 -0.1 -0.3Earl 1998 AXBT -0.1 -0.8Isidore 2002 AXBT -0.1 -0.2Edouard 1996 41611 0.0 0.0Edouard 1996 41614 0.0 -0.2Andrew 1992 42003 0.0 -0.1

++ Inner core SST change Inner core SST change (core - ambient)(core - ambient) is MUCH less is MUCH less thanthan 4-6 4-6ooC ‘cold wake’ SST C ‘cold wake’ SST reductions typically reductions typically observedobserved 31/33 horizontal SST transects 31/33 horizontal SST transects << 1.5 1.5ooC (23 Hurricanes)C (23 Hurricanes) Mean Mean ΔΔSSTSSTICIC = 0.7 = 0.7ooCC Relatively Relatively small changes in inner-core SSTsmall changes in inner-core SST (0.5(0.5ooC) C) can can

significantly alter surface energy fluxes significantly alter surface energy fluxes (-40% or more)(-40% or more)

++ For the 33 cases analyzed, theFor the 33 cases analyzed, the magnitude of inner core magnitude of inner core SST cooling (core - ambient) SST cooling (core - ambient) waswas highly correlated with highly correlated with subsequent changes storm intensitysubsequent changes storm intensity

Key Findings: Cione and Uhlhorn (2003)

Key Findings: Cione and Uhlhorn (2003)

Scatter plot of 24h TC intensity change as a function of SST cooling (inner core - ambient SST) for 23hurricanes between 1975-2002. The resulting polynomial (2nd order) best-fit is illustrated. Here, 38.8% ofthe variance with intensity change is explained (i.e. r2=0.388). The units for intensity change are given as

m s-1 24 h-1 while SST is measured in oC. [Figure from Cione and Uhlhorn (2003)].

In addition, In addition, TC latitude TC latitude andand initial storm speed initial storm speed were were found to be statistically linked to observed found to be statistically linked to observed changes in changes in inner-core SSTinner-core SST for this 33 event sample. for this 33 event sample.

As a direct result of these findings a proposal entitled As a direct result of these findings a proposal entitled “Developing an Inner-Core SST Cooling Parameter “Developing an Inner-Core SST Cooling Parameter for use in SHIPS”for use in SHIPS” was submitted to the JHT In the was submitted to the JHT In the spring of 2003….spring of 2003….

Key Findings: Cione and Uhlhorn (2003) Continued…

Key Findings: Cione and Uhlhorn (2003) Continued…

Developing an Inner-Core SST Cooling Parameter for use in SHIPS

Developing an Inner-Core SST Cooling Parameter for use in SHIPS

The The OverallOverall Goal of this JHT project is… Goal of this JHT project is…

To Investigate how To Investigate how changes in the TC inner-core ocean changes in the TC inner-core ocean surface boundary conditionsurface boundary condition potentially potentially impacts impacts changes in changes in storm intensitystorm intensity within the context of SHIPS operation model. within the context of SHIPS operation model.

Early results….Algorithm Development Early results….Algorithm Development

+ Since June 2003,+ Since June 2003, several multiple linear regression several multiple linear regression relationships designed to relationships designed to predict inner core SST changepredict inner core SST change have have been tested and developed…been tested and developed…

+ Continued analysis has + Continued analysis has yieldedyielded a statistically robust baseline a statistically robust baseline TC Inner-Core SST Cooling AlgorithmTC Inner-Core SST Cooling Algorithm that utilizes three that utilizes three independent predictors:independent predictors:

Initial TC latitude, storm speed and ambient SSTInitial TC latitude, storm speed and ambient SST

Scatter plot of in-situ SST vs. predicted inner-core SST [using the hurricane inner-core SST coolingalgorithm developed from the 23-hurricane (1975-2002) sample from Cione and Uhlhorn (2003)].

The linear best-fit shown explains 87.5% of the variance (i.e. r2=0.875). SST is given in oC.

Developing an Inner-Core SST Cooling Parameter for use in SHIPS

Developing an Inner-Core SST Cooling Parameter for use in SHIPS

Current JHT Project -Current JHT Project -

Early results….Dependant Testing in SHIPSEarly results….Dependant Testing in SHIPS

+ + PreliminaryPreliminary testing testing of the of the TC Inner-Core SST TC Inner-Core SST Cooling AlgorithmCooling Algorithm on thousands of TC forecast on thousands of TC forecast events found in the events found in the 1989-2002 SHIPS storm 1989-2002 SHIPS storm databasedatabase have have yielded very encouraging results…. yielded very encouraging results….

Results using thousands of observations from the 1989-2002 SHIPS data archive show that the Results using thousands of observations from the 1989-2002 SHIPS data archive show that the inner-core cooling algorithm developed under this JHT project is very stable…inner-core cooling algorithm developed under this JHT project is very stable…

Dependant sample testing in SHIPS illustrated Dependant sample testing in SHIPS illustrated significant improvements with respect to significant improvements with respect to observed changes in TC intensityobserved changes in TC intensity over over ALL 12-120h forecast intervalsALL 12-120h forecast intervals, , regardless of sample regardless of sample stratification.stratification.

Some of the major highlights from this SHIPS analysis include:Some of the major highlights from this SHIPS analysis include: For All TC cases (N=12887) an avg For All TC cases (N=12887) an avg 1.0-2.5% improvement in skill1.0-2.5% improvement in skill was found over the 24-120h fcst pd was found over the 24-120h fcst pd For Hurricane cases (N=4528) an avg For Hurricane cases (N=4528) an avg 1.5-3.5%1.5-3.5% improvement in skillimprovement in skill “ “ ““ For all For all Major HurricanesMajor Hurricanes (N=1011) an avg (N=1011) an avg 2.7-7.0%2.7-7.0% improvement in skillimprovement in skill ““ ““ For the For the Top 10% “Rapid Intensifier”Top 10% “Rapid Intensifier” events events an avg an avg 4.5-8.0%4.5-8.0% improvement in skillimprovement in skill “ ““ “ For the For the Bottom 10% “Rapid Filler”Bottom 10% “Rapid Filler” events events an avg an avg 2.0-13.5%2.0-13.5% improvement in skillimprovement in skill “ ““ “

NOTE: Regardless of stratification or forecast interval, NOTE: Regardless of stratification or forecast interval, ZERO degradation in mean SHIPS forecast ZERO degradation in mean SHIPS forecast skillskill was found when the Inner core SST cooling algorithm was used… was found when the Inner core SST cooling algorithm was used…

Future work, if funded in year two, would include independent testing by running a parallel version Future work, if funded in year two, would include independent testing by running a parallel version of SHIPS during the 2004 Atlantic Hurricane Season. In addition, attempts would be made to of SHIPS during the 2004 Atlantic Hurricane Season. In addition, attempts would be made to identify a reliable subsurface ocean predictor and improve upon existing Reynolds weekly SSTs identify a reliable subsurface ocean predictor and improve upon existing Reynolds weekly SSTs currently used in SHIPS (Gentemann - high spatial and temporal resolution microwave SSTs). currently used in SHIPS (Gentemann - high spatial and temporal resolution microwave SSTs). Additionally, focused on potentially incorporating a version of the cooling algorithm into the Atlantic Additionally, focused on potentially incorporating a version of the cooling algorithm into the Atlantic RI index have recently begun (Kaplan). Preliminary findings have been promising.RI index have recently begun (Kaplan). Preliminary findings have been promising.

SST Cooling Algorithm: Preliminary Findings….SST Cooling Algorithm: Preliminary Findings….

AMSR-E and Reynolds OI SST analyses for September 26, 2002. The tracks and intensities(magnitude of circle size) for the 2002 Atlantic Hurricanes Isidore (black) and Lili (white) areillustrated. On average, the AMSR-E SST analysis was found to be 1-2K cooler in the centralGulf of Mexico region (relative to the Reynolds OI analysis) due to the presence HurricaneIsidore’s cool post-storm wake.