oxford (cape town) programme on the attribution of … (cape town) programme on the attribution of...

Oxford (Cape Town) programme on the attribution of weather risk

Oxford (Cape Town) programme on theattribution of weather risk

Daithı Stone, Neil Massey, Tolu Aina, Pardeep Pall, Myles Al len,

Peter Stott

Daithı A. Stone ([email protected]) 1


Cape Town, September 2008

I had been told the weather in Cape Town was nice!!



Can I blame Bruce or anthropogenic emissions?

=⇒ ⇐=



Subcontinental detection and attribution



Datasets

Source Number of members

OBS ALL GHG NAT CTL

HadCRUT3/CRUTEM3/HadSST2 1

ECHO-G 5 3 3 652 years

MIROC3.2(medres) 10 4 10 3500 years

MIROC3.2(medres-HS) 4 4 4 3500 years

MRI-CGCM2.3.2 5 3 4 500 years

PCM 4 4 4 1490 years

UKMO-HadCM3 4 4 4 1049 years

Total 1 32 23 29 10691 years



Regional OLS analysis



Estimating fraction attributable risks



What the world is like and what is would have been like



Selecting the 1/10 year return threshold

0.0

0.5

1.0

1.5

2.0

oC

ALA

CG

IC

NA

ENA

WN

AAM

ZC

AM SSA

NEU

SEM

EAF

SAF

SAH

WAF

CAS

EAS

NAS

SAS

SEA

TIB

NAU

SAU



The regional fraction attributable risk ( 1 −P0

P1

)



Summer 2007 UK precipitation and an operational

weather risk attribution programme



A pilot “operational” attribution project

• Intended to examine:

– The attribute risk of the wet UK summer of 2007

– Historical trends in the risk of wet UK summers



• Use two climate model versions:

– HadAM3P (∼1.5◦ resolution)

– HadAM3-N144 (∼1.0◦ resolution)

– Both to be run through the climateprediction.net/BOINC distributed

computing platform



• Generate large ensembles of simulations:

– About 100 for each of last 50 years

– Several hundred of 2006-2007

– Several 1000 of hypothetical non-GHG 2006-2007

• Data output:

– Monthly global SAT, precipitation, 500hPa height, SLP, 200 and

850hPa winds, soil moisture, 1.5m dewpoint, net solar radiation,

max 5 day precipitation, evaporation

– Monthly net longwave, 10m winds over Europe; monthly monsoon

indices

– Daily SAT, precipitation over Europe, South Africa, NW USA,

India/China; daily 250hPa height, SLP over Europe



• Base run completed to 2000

• Alpha test launched yesterday

• Hopefully beta launch in a couple of weeks, then full launch in a

couple of months



South African attribution programme



South African attribution programme

Motivation

• Priority of adaptation to climate and climate change

– What is the baseline climate?

– How are risks expected to change in the coming decade?

Plans

• Analyse southern African output of cpdn experiments

• Maybe incorporate simple event risk attribution into current seasonal

forecast system

• Maybe examine implications of downscaling on event risk attribution


oxford (cape town) programme on the attribution of … (cape town) programme on the attribution of...

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