Predicting the Earth System Across Scales: Both Ways

Holland, CCSM Workshop 0606 ESSLESSL

Predicting the Earth System Across Scales: Both Ways

Predicting the Earth System Across Scales: Both Ways

Summary:Summary:

RationaleRationale

Approach and Current FocusApproach and Current Focus

Improved Simulation of Tropical ModesImproved Simulation of Tropical Modes

Requirements for Tropical Cyclone Response to Climate Requirements for Tropical Cyclone Response to Climate ChangeChange

Greg HollandGreg HollandNCARNCAR


Rationale: Regional ClimateRationale: Regional Climate

• Downscaling

• Upscaling


Downscaling and Upscaling: Atlantic Tropical Cyclone Trends

Downscaling and Upscaling: Atlantic Tropical Cyclone Trends

1900 1920 1940 1960 1980 2000 20200

5

10

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20

25

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Year

Tro

pic

al C

yclo

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Nu

mb

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North Atlantic Tropical Cyclones 1905-2005

Individual Year

9-Year Running Mean1995

Satellites


Upscaling: Mean RainfallUpscaling: Mean Rainfall


Upscaling and Downscaling: Tropical Modes

Upscaling and Downscaling: Tropical Modes

ObservedObserved CCSMCCSM

All tropical modes are poorly handled by current climate All tropical modes are poorly handled by current climate models. This impacts everything from tropical cyclones to models. This impacts everything from tropical cyclones to ENSO and interactions with the extratropics.ENSO and interactions with the extratropics.

(Lin et al 2006)(Lin et al 2006)


The OpportunityThe Opportunity

WRF Community ModelCCSM/CAM Community Models


Approach and Current FocusApproach and Current Focus

Approach: Nesting the NCAR Weather Research and Forecasting Model into CAM as a 2-way Nested Regional Climate Model (NRCM);– Stage 1: Downscaling over North America (done);– Stage 2: 2-way atmospheric scale interactions in the

tropics (current);– Stage 3: NRCM in CAM/CCSM, with coupled ocean model;

as a community facility (next).

Current Focus: Tropical scale interactions:– Importance of mesoscale organization of convection

and its related surface exchanges and radiative influences for forcing tropical modes;

– Tropical mode forcing of tropical cyclone Tropical mode forcing of tropical cyclone development and intensification.development and intensification.


Model SetupModel Setup

Tropical Channel, 36 km, N/S boundaries 1-way nested into Tropical Channel, 36 km, N/S boundaries 1-way nested into NCEP Reanalysis with specified SST, Kain-Fritsch Cu NCEP Reanalysis with specified SST, Kain-Fritsch Cu Parameterization, CAM radiation and YSU boundary layer.Parameterization, CAM radiation and YSU boundary layer.

4 km nested domain inside 12 km 4 km nested domain inside 12 km and 36 km domains, fully 2-way and 36 km domains, fully 2-way interactive, Dudia cloud physics, interactive, Dudia cloud physics, CAM radiation and YSU boundary CAM radiation and YSU boundary layer.layer.Wind Speed (m/s)

Precipitable Water (mm)Precipitable Water (mm)


NRCM ExperimentsNRCM Experiments• CAM at T170 Resolution: Jan 1, 1966 to Jan 1 2001

• 36km Channel Model: Jan 1, 1996 to Jan 1, 2001

• 36km Channel + high resolution SST's: Jan 1, 1999 to Jan 1, 2000

• 36km Channel + fluxes: Jan 1, 1996 to Jan 1 1998 • 36km Channel + 12km Maritime domain: Jan 1, 1996 to Feb

12, 1998

• 36km Channel + 12/4km Maritime domains: Jan 1, 1997 to Jul 1, 1997


Precipitable Water: 1997Precipitable Water: 1997


Power SpectraPower SpectraNCEP AnalysisNCEP Analysis

Improved Rossby Wave, Kelvin and MJO ModesImproved Rossby Wave, Kelvin and MJO ModesInertia-Gravity Inertia-Gravity Modes present, but Modes present, but too smalltoo small

NRCM SimulationNRCM Simulation


MJO and Easterly Wave Simulation MJO and Easterly Wave Simulation


July 22July 22ndnd over over eastern Indonesiaeastern Indonesia

August 19August 19thth in in eastern North eastern North PacificPacific

October 8October 8thth westerly wind westerly wind burstburst

MJO wet phaseMJO wet phase28 days28 days

39 days39 days


Easterly Wave Interactions with MJOEasterly Wave Interactions with MJO

0722:000722:00 0711:120711:12

0708:120708:12

0705:120705:12

0701:120701:12

0722:120722:12

0718:120718:12

0715:120715:12


NRCM Tropical Cyclone Simulation: Seasonal Distribution 1996-1998

NRCM Tropical Cyclone Simulation: Seasonal Distribution 1996-1998

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1.0

2.0

3.0

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SWP NRCM

SWP OBS

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1.0

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NIO NRCM

NIO OBS

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ENP NRCM

ENP OBS

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NAT NRCM

NAT OBS

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ber o

f TCs

SIO NRCM

SIO OBS

ObservedSimulated


Annual Tropical Cyclone StatisticsAnnual Tropical Cyclone Statistics

0

5

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35

SW

IO N

RC

M

SW

IO O

BS

Wau

s N

RC

M

Wau

s O

BS

SW

P N

RC

M

SW

P O

BS

NIO

NR

CM

NIO

OB

S

WN

P N

RC

M

WN

P O

BS

EN

P N

RC

M

EN

P O

BS

NA

T N

RC

M

NA

T O

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SWIO WAUS SWP NIO NWP ENP NAT

An

nu

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ber 19971997

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NR

CM

OB

S

NR

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OB

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NR

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NR

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OB

S

NR

CM

OB

S

NR

CM

OB

S

NR

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An

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19961996

0

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NR

CM

OB

S

NR

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OB

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NR

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OB

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NR

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OB

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NR

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OB

S

NR

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OB

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NR

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An

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ber

19981998Yellow are Observed; Blue are Simulated. Yellow are Observed; Blue are Simulated.

SWIO: Southwest Indian Ocean; SWIO: Southwest Indian Ocean; WAUS: Western Australia WAUS: Western Australia SWP: Southwest Pacific SWP: Southwest Pacific NIO: North Indian Ocean;NIO: North Indian Ocean; NWP: Northwest Pacific;NWP: Northwest Pacific; ENP: Eastern North Pacific;ENP: Eastern North Pacific; NAT: North Atlantic.NAT: North Atlantic.


Tropical Cyclones and Climate ChangeTropical Cyclones and Climate Change

1850 1900 1950 2000

-0.5

0

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1850 1900 1950 2000

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AEW DevelopmentAEW Development

1900 1920 1940 1960 1980 2000 202025.8

26

26.2

26.4

26.6

26.8

27

Year

SS

T (

C)

1900 1920 1940 1960 1980 2000 2020

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of T

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Total Tropical Cycones vs East Atlantic SST

TC's Forming <20 Lat

Est Atlantic SST

R=0.659-y Running Mean


Importance of AEW DevelopmentImportance of AEW Development

0

1

2

3

4

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6

0 10 20 30 40 50

Genesis Latitude

Ca

teg

ory

Equatorial90%

92%

81%

55%

36%

42%

(Data 1945-2004)

>85% of all Major Hurricanes develop from Easterly Waves!!!


East/West Atlantic and Gulf SSTsEast/West Atlantic and Gulf SSTs

(0.60)

(0.40)

(0.20)

-

0.20

0.40

0.60

1850 1900 1950 2000

EA 9-Y

WA 9-Y

GM 9-Y


Global Surface Temperature VariabilityGlobal Surface Temperature VariabilityVolcano

Ozone

Sulfate

Solar

There is no known natural forcing mechanism that can explain the surface temperature increases since 1960 (Meehl et al 2004, 2006)

Notice the warm 1940-50 period in the “natural cycle”

1970

(0.60)

(0.40)

(0.20)

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0.20

0.40

0.60

1850 1900 1950 2000

Year

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EPAC 9-Y

The NAO


So what is happening?So what is happening?Compare the record 2005 season with a mean of 1991-1993:

• 2005: 27 Storms, 12 hurricanes, 5 cat 4-5;• 1991-1993: 22 storms (total), 12 hurricanes, 2 cat 4-5

• 2995 30% of all AEWs became named storms (normally 10%);

• AEWs produced 10 of the 14 hurricanes in 2005, all category 3-5 hurricanes, all tropical cyclones in July and August, and 8 of the 11 tropical cyclones in September and October. Two AEWs also generated two tropical cyclones each, a rare event that last occurred in 1988;

• For 1991-1993 only one hurricane developed from AEWs, there were no July storms and only one in October.


2005 vs 1991-19932005 vs 1991-1993


NAT SST-Hurricane RelationshipsNAT SST-Hurricane Relationships

Max SST

7000 km

Min OLR

North Atlantic oceanic and atmospheric response North Atlantic oceanic and atmospheric response to global warming.to global warming.

S S S 5 4 S 1 5 3 5 4 S S 2 1 S 3

Tropical cyclone formation locationsTropical cyclone formation locations


Vorticity Changes; du/dx<0Vorticity Changes; du/dx<0

July 2005July 2005


Assessing Potential Climate Change Impact on Tropical Cyclones:

Requirements

Assessing Potential Climate Change Impact on Tropical Cyclones:

Requirements

• Resolve hurricane structure• Simulate tropical atmospheric response to

oceanic heat changes• Simulate tropical modes accurately• Simulate feedback between hurricanes and

ocean/atmospheric circulations

Coupling CCSM/CAM with WRF and a GOM/ROM Coupling CCSM/CAM with WRF and a GOM/ROM

enables thisenables this


SummarySummary

• The weather and climate scales are part of a continuum of action across scales;

• We have the tools in CAM/CCSM and WRF to open up new frontiers in understanding and predicting these 2-way interactions;

• The Petascale Computing Facility provides the capacity;

So Lets Do ItSo Lets Do It

Thank YouThank You

Predicting the Earth System Across Scales: Both Ways

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