Hurricanes Working Group Report Suzana J. Camargo Lamont-Doherty Earth Observatory Columbia University Palisades, NY With contributions from all members.

Hurricanes Working Group Report

Suzana J. CamargoLamont-Doherty Earth Observatory

Columbia UniversityPalisades, NY

With contributions from all members of the Hurricanes WG

U.S. CLIVAR 2011 Summit18-21 July 2011Woods Hole, MA

US CLIVAR Hurricanes Working Group

Formed in January 2011 Co-leaders:

Suzana Camargo, LDEO, Columbia University Gabriel Vecchi, NOAA GFDL Kevin Walsh, Melbourne University, Australia

Members of CLIVAR working group:

James Elsner, Florida State University

Kerry Emanuel, MIT James Kossin, NOAA

NCDC Christopher Landsea,

NOAA AOML Siegfried Schubert,

NASA GSFC

Adam Sobel, Columbia University

Gabriele Villarini, Princeton University

Hui Wang, NOAA NCEP

Ming Zhao, NOAA GFDL

Additional Contributing Members

Lennart Bengtsson, U. Reading, UK

In-Sik Kang, Seoul National University, Korea

K. Oouchi, JAMSTEC, Japan

Enrico Scoccimarro, INGV-CMCC, Italy

Julio Bacmeister, NCAR

Ping Chang and R. Saravanan, Texas A&M

Malcolm Roberts, UK Met Office, and Pier Luigi Vidale, U. Reading, UK

Christiane Jablonowski U. Michigan and Michael Wehner, Lawrence Berkeley National Lab.

Monika Esch, MPI, Germany

Terms of reference:

Define common experiments for model simulations by participating model groups Supply common data sets and tropical cyclone metrics for those experiments Coordinate the evaluation and reporting of common experiments and the storage of model output Organize a series of workshops to present and discuss the results

Hurricane WG - Background:

Preliminary attempts of multi-model intercomparison:

– TCMIP (K. Walsh)

– Discussions: Camargo, Walsh, Schubert, Sobel, Emanuel, ...

High-resolution global climate models: improved performance simulating tropical cyclone variability (GFDL, FSU, NCEP, Met Office) in interannual and decadal time-scales

Vecchi proposed US CLIVAR led the idea of US CLIVAR WG.

Significant improvement in an agreeement among models of changes in tropical cyclone activity under climate change:

Intensity: higher occurrence of most intense TCs (globally)

Frequency: smaller global number of TCs (in many models)

Dynamical Models Exhibit Skill in Seasonal Basin-wide Hurricane Frequency

Statistical-dynamical hybrid model

18-km regional model

100km SST-forced AGCM

50km SST-forced AGCMFigure adapted from Knutson et al (2010, Nat. Geosci.)

Problems:

CC projections: regional estimates - models diverge

Reasons for differences among models' projections are unclear:

Different forcing for future scenarios Different sensitivity to forcing Different definitions for TCs

TC data – data quality problems, especially out of the Atlantic.

Principal Issues Lack of climate-relevant theory of genesis/basin-wide frequency

Uncertainty in past (and future) large-scale changes (e.g., SST, upper tropospheric/tropopause layer temperature)

Sensitivity studies with AGCMs not coordinated

Historical cyclone database corrections adjustments need assessment, continued effort and extension needed (more, different paleo-proxies)

Climate predictions/projections beyond frequency (landfall, extremes)

Statistical models/downscaling techniques need to be compared and evaluated for skill/relevance to various applications (e.g., prediction, projection, proxy)

Coupled model biases in tropical Atlantic

Contribution: G. Vecchi

Scientific Objectives I

An improved understanding of interannual variability, and trends, in tropical cyclone activity from the beggining of the 20th century to the present.

TC response to common increase in SST Sensitivity to differences in SST What is the potential predictability of TCs? Statistics

of TCs constrained by SST x stochasticity of the model response

Model Response Exhibits Sensitivity To Forcing Used

Tropical Storm Frequency Response to Same AGCM but different estimates of observed SST

Contribution: G. Vecchi & M. Zhao

AGCM is 100km version of Zhao et al (2009, J. Clim.)

ObsAGCM

ObsAGCM

HadISST forced NOAA-OI.v2 forced

Scientific Objectives II

Quantifying changes in the characteristics of tropical cyclones under a warming climate.

Uniform warming x specific anomalies CO2 x SST warming Relationship between local versus remote forcing

in hurricane formation in the Atlantic - tropical mean increase in SST and increase in Atlantic SST only.

Remote x local response to SST in other regions of the world.

Vecchi, Swanson and Soden (2008, Science)

Observed ActivityAbsolute SSTModel Abs. SST

High-resolutionmodel activity change

Relative SSTModel Rel. SST

Emanuel et al (08),Knutson et al (08)Oouchi et al (06),Bengtsson et al (07)

Contribution: G. Vecchi

Idealized Forcing Experiments

If local SST the dominant control, as opposed to relative SST:

• Similar Atlantic Response to Atlantic and Uniform Forcing

• Little Pacific Response to Atlantic compared to Uniform

Contribution: G. Vecchi

North Atlantic Response to Idealized SST

Atlantic ForcingUniform ForcingNear-equatorial Forcing

Similar TS frequency response to:0.25° local warming4° global cooling

Contribution: G. Vecchi

Participating ModelsModel Resolution Institution

CAM5.2 0.25 deg NCAR, USA

CAM5.1 0.25 deg U. Michigan & LBNL, USA

CSIRO 60km U. Melbourne, Atlantic

ECHAM5 T159 L31 CMCC INGV, Italy

ECHAM6 T127 L95 MPI, Germany

FSU/COAPS T126 L27 FSU, USA

GEOS5 1/2 degree L72 NASA, USA

HADGEM3 60km, L85 U. Reading Met Office, UK

HIRAM2.1 50 km L32 GFDL, USA

NASA GISS 1 degree L40 NASA GISS, USA

NCEP GFS T126 L64 NCEP, USA

NICAM 14km L40 JAMSTEC, Japan

SNU/KAU-AGCM 35km, L20 SNU, South Korea

WRF, domain: Atlantic 27km Texas A&M U., USA

Std CAM5 #1 Std CAM5 #2

Std CAM5 #3 IBTraCS

Storms with U>33 ms-1: June 1 to Dec 1 2005

Contribution J. Bacmeister

Time spent at Categories by tropical cyclones (hours)All basins

Northern hemisphere TC season June – Dec

Cat1 Cat2 Cat3 Cat4 Cat5TSTD

3 CAM5 runs 2005

CAM4 2004, 2005

IBTrACS 2004, 2005

CAM5 no deep conv 2005

CAM5 w/ param condensate loading

Hours

Defect in tracking algorithm

Contribution J. Bacmeister

Tropical Cyclones as simulated by CMCC-INGV fully coupled climate models:INGV-SXG (atm: echam4, T106) and CMCC_MED (atm: echam5, T159)

- Changes in Tropical Cyclone Activity due to Global Warming: Results from a High-Resolution CGCM. Gualdi et al. 2008 - J. of Climate, Vol. 21, pp. 5204-5228

- Effects of Tropical Cyclones on Ocean Heat Transport in a High Resolution CGCM. Scoccimarro et al. 2011 - J. of Climate, in press. Doi: 10.1175/2011JCLI4104.1

OBS INGV-SXG (T106)

CMCC_MED (T159)

TCs/y 93.8 66.2 80.2

STD 10.9 9.2 7.5

Annual TCs number and variability

Hurricane detection in CMCC_MED: 10m wind speed > 33 m/s

1000 Km

CMCC_MED TCs annual number and Power Dissipation Index (PDI)

6hourly 10 meter wind speed [m/s]Yearly accumulated PDI [m3/s2]

TCs Annual Number series

Contribution E. Scoccimarro

2005 Atlantic storm track at N512: 5 members initialised on 1 May

Contribution: M. Roberts & P.L. Vidale

TAMU-CRCM DomainSimulated TC tracks

(9km)(9km)

• Simulated TCs are too weak (no Cat-4 & 5 storms)• Number of TCs tends to be too high• Simulated tracks tend to shift to the north

Contribution: P. Chang & R. Saravanan

Uncoupled WRF simulations without SST cooling effect over-estimate TC’s intensity and size.

Coupled

Uncoupled

Difference

Coupled

Uncoupled

Contribution: P. Chang & R. Saravanan

NICAM 3.5 km mesh 2008/06/20 12UTC

TC Fengshen

5 days after theInitial condition

TC Fengshen simulation

11-20 June

Onset of Western Pacific Monsoon & Weak MJO equatorial westerly

Horizontal grid spacing: 14 km, 3.5 km

Vertical domain: 0 m ~ 38,000 m (40-levels)

Integration:

10 days from 00UTC 15 Jun 2008

Initial conditions:

ECMWF YOTC Operational data

NCEP final analysis (land surface, SST)

Boundary conditions:

slab ocean (nudging to Reynolds weekly SST)

--- Fengshen formed on 17 Jun 2008

PALAU2008 Field Experiment

Contribution: K. Oouchi

Tier 1 experiments:

1. Interannual – 20 years (1981-1990) forced with observed SST.

2.Climatology – Climatological SST

3.Global 2K : Climo SST+ Global 2K

4.Double CO2: Climo SST + Double CO2

5.Global 2K & Double CO2: Climo SST+ Global 2K + Double CO2

6. Global Warming: Climo SST + Specified SST anomalies

Tier 2 experiments:

Atlantic 1K: Climo SST + 1K Atlantic

Pacific 1K: Climo SST + 1K Pacific

Slab Ocean

High Resoluton snapshots

Varying horizontal resolutions

Diagnostics:

Common tracking techniques: 2 – 3 for comparison Dependency of thresholds

Large-scale diagnostics: Enviromental variables: vertical shear, humidity,

vorticity, precipitation. Genesis Indices Potential intensity ENSO, AMM, AMO, MJO: modulation of TCs in

models Statistical-dynamical techniques (Emanuel) Statistical analysis/modeling

Where are we now?

Bi-monthly teleconferences Webpage in progress Modelling groups running tier 1

experiments (a few are finished). Final negotiation stages for NCDC to

archive and host data. ASAP: Model data available for the

WG. Next telecon: discussion of

diagnostics. 1st workshop: January 2012 (after

annual AMS meeting) Unforseen issue: some groups not

sticking to protocol.