Met Office Perspective and Activities

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Met Office Perspective and ActivitiesRuth McDonald TEMPEST meeting 8th February 2011


Validation of model winter BPF MSLP storm track wrt ERA40

HadCM3 A1B 11 membersCMIP3 AR4 multi-model ensemble

units = hPa

TQUMP perturbed physics ensemble

Errors in simulation of present day storms adds to uncertainty of future predictions


Uncertainty in future changes in storms: winter 2080s wrt 1961-1990

TQUMP HadCM3 A1B 11 members CMIP3

Cyclones (%) BPF MSLP Storm Track (hPa)

4.3% fewer over NH Southward shift Intensification


RCM tracks and mean sea level pressure

18Z 0Z

06Z 12Z

Shading is MSLP in hPa (colours are at 4 hPa intervals)

Lines show tracks

Features at time of MSLP fields are indicated by *s

Tracking smaller scale features than in GCM


Future changes in UK storms

RQUMP HadRM3 A1B perturbed physics 11 member ensemble

% changes in cyclone track density DJF 2071-2099 minus 1961-1990 DJF

% c

hang

e

UK Storms Autumn 30y mean % changes

All storms – no change

% c

hang

e

850 hPa wind speed > 17.5 ms-1

moreFewer UK storms no change in intensity


Strength of UK storms in ERA40RCM

Max strength of storm (vorticity)

• 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


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


Changes in winter UK BPF storm track – TQUMP and AR4

Cha

nge

in la

titud

e ov

er U

K (

degr

ees)

Climate Sensitivity (K)

ABI report Fig 4

3 conditions provided

1.45º southward shift

Low prob shifts of: 4.4º north 7.28º south


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 100-year 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.


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.


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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