Transcript Met Office Perspective and Activities - TEMPEST

Met Office Perspective and Activities
Ruth McDonald TEMPEST meeting 8th February 2011
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Validation of model winter BPF
MSLP storm track wrt ERA40
HadCM3 A1B 11 members
TQUMP perturbed physics ensemble
CMIP3 AR4 multi-model ensemble
Errors in simulation of present day storms
adds to uncertainty of future predictions
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units = hPa
Uncertainty in future changes in
storms: winter 2080s wrt 1961-1990
Cyclones (%)
BPF MSLP Storm Track (hPa)
TQUMP HadCM3 A1B 11 members
CMIP3
4.3% fewer over NH
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Southward shift
Intensification
RCM tracks and mean sea
level pressure
18Z
0Z
Shading is MSLP in
hPa (colours are at 4
hPa intervals)
Lines show tracks
06Z
12Z
Features at time of
MSLP fields are
indicated by *s
Tracking smaller scale
features than in GCM
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% changes in cyclone track density
DJF 2071-2099 minus 1961-1990 DJF
% change
Future changes in UK storms
UK Storms Autumn 30y mean
% changes
All storms – no change
850 hPa wind speed > 17.5 ms-1
more
% change
Fewer UK storms
no change in
intensity
RQUMP HadRM3 A1B perturbed physics 11 member ensemble
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Strength of UK storms in ERA40RCM
• Example of strength distribution of UK
storms in RCM
• Can also use rainfall, gusts, mean
sea level pressure and wind speed as
storm intensity
• AXA RACEWIN project will look at
combined perils of wind and rainfall
• Results from perturbed physics
ensembles provide uncertainty
estimates of distributions
Max strength of storm (vorticity)
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Consultancy work:
ABI The Financial Risks of Climate
Change
• AIR Worldwide Corp. and Met Office Report
• UK Windstorms (also UK floods and China
Typhoons)
• Wanted changes in frequency and intensity of UK
windstorms for High, Medium and Low
• Literature review inconclusive for UK windstorms
• Provided changes in latitude of storm track over UK
from 17 HadCM3 A1B Transient QUMP ensemble
and AR4 CMIP3 models
• Input into CAT model
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3 conditions
provided
1.45º
southward
shift
Low prob
shifts of:
4.4º north
7.28º south
ABI
report
Fig 4
Change in latitude over UK (degrees)
Changes in winter UK BPF storm
track – TQUMP and AR4
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Climate Sensitivity (K)
ABI The Financial Risks of Climate
Change: UK windstorms Main
Findings
• Assuming a 1.45° southward shift in storm track across the UK:
• The average annual insured wind losses in the UK could
rise by 25% to £827 million.
• The wind-related insured loss from winter season windstorms in
the UK occurring once every 100 years could rise by 14% to
£7.3 billion, and the loss occurring once every 200 years could
rise by 12% to £9.7 billion.
• Regional variations range from below 10% to 16% for the 100year loss and below 10% to 17% for the 200-year loss.
• The wind component of insurance premiums could increase by
around 37% across the UK if a southward shift in storm tracks
is assumed.
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Current work on storms
• HadGEM2-CC high top v low top models
• High top models are vertically extended and have improved
representation of the stratosphere compared to low top model. Better
able to simulate the stratosphere-troposphere interaction
• Results show that future changes in the North Atlantic storm track are
shifted south in some high top models compared to low top models
• Theory is that the northward shift in storm tracks under climate change
may be overestimated in low top models
• HadCM3 has a southward shift in eastern North Atlantic
• Aim is to test the theory by comparing changes in storms in HadGEM2
high (L60) and low top (L38) models
• HadGEM2-ES and CMIP5 (maybe?)
• Changes in storms in RCP4.5 and RCP8.5 experiments, compared to
historical experiment. Use picontrol to assess natural variability. May
just use simple diagnostics.
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Aims and links to other
projects
• Paper on drivers of changes in North Atlantic storms
• Bringing together TQUMP, RQUMP, CMIP3, HadGEM2 and
maybe CMIP5 results.
• CS-RE
• Joint perils of North Atlantic tropical cyclones and European
windstorms – literature review recently completed
• AXA RACEWIN
• Use tracks from TQUMP and RQUMP
• NERC TEMPEST
• WP1 – related to HadGEM2 work
• WP2 – related to TQUMP work
• WP3 – related to HadGEM3 MORPH3 and CAPTIVATE
projects. Also of interest for “seamless prediction”
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Questions and answers
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