Transcript Subseasonal prediction of extreme heat over Australia www.cawcr.gov.au Debbie Hudson Andrew Marshall, Chris White, Oscar Alves, Harry Hendon, Matthew Wheeler, Griff Young S2S Conference 10-13

Subseasonal prediction of extreme heat over Australia
www.cawcr.gov.au
Debbie Hudson
Andrew Marshall, Chris White, Oscar Alves, Harry Hendon,
Matthew Wheeler, Griff Young
S2S Conference 10-13 February 2014
The Centre for Australian Weather and Climate Research
A partnership between CSIRO and the Bureau of Meteorology
Motivation
•
Increasing demand for subseasonal forecast guidance in Australia
•
Large-scale impacts of heat extremes e.g. health, agriculture, infrastructure
•
Trend towards more frequent and intense heat waves is projected to continue
•
Recent record-breaking Australian heat waves, e.g.
The Centre for Australian Weather and Climate Research
Summer 2009 (7 Feb)
Spring 2009 (August)
A partnership
between
Bureau of Meteorology
Summer
2013
(4 CSIRO
Jan)and theSummer
2014 (13-17 Jan)
January 2014 heatwave
Infrastructure
Bushfires
http://www.theage.com.au/victoria/anger-over-spike-indeaths-during-record-victorian-heatwave-2014012631gxb.html
Health
http://www.dailymail.co.uk/news/article-2539626/Widespreadheatwave-causes-bushfires-court-chaos-Australian-Open.html
http://www.abc.net.au/news/2014-01-16/bushfire-threat-asaustralia-south-east-suffers-heatwave/5204250
http://smh.drive.com.au/roads-andtraffic/heatwave-likely-cause-oflarge-crack-on-west-gate-bridge20140120-314w4.html
Agriculture
http://www.theage.com.au/comment
/more-power-to-the-people-asheatwave-hits-20140116-30xir.html
http://www.sbs.com.au/news/article/201
4/01/15/heatwave-conditions-prompthealth-warning
http://www.abc.net.au/news/2014-01-13/grape-growers-fearheatwave-will-destroy-crops/5197208
http://www.abc.net.au/news/2014-01-15/fire-crews-on-alert-assouth-east-australia-sizzles-in-heatwave/5200424
POAMA
Subseasonal forecasting using POAMA
Weather
forecast
Data
Assimilation
Atmos/Land
IC
Coupled climate model
Ensemble of
forecasts
Seasonal
forecast
Atmospheric Model
BAM T47L17
3hr
OASIS Coupler
Ocean
IC
Coupled breeding
method produces
perturbations for burst
ensemble
Ocean Model
ACOM2 (lat 0.5~1.5º; lon 2º; 25 lvls)
Real-time: ensemble of 33 forecasts updated twice-weekly
Hindcast set:
• 1981-2010
• Ensemble (n=33) 3x every month (1st, 11th, 21st)
• Forecasts out to 9-months
The Centre for Australian Weather and Climate Research
A partnership between CSIRO and the Bureau of Meteorology
Capturing the teleconnection: large-scale drivers
and heat extremes
Madden Julian Oscillation
MJO
IOD
ENSO
Indian Ocean Dipole
El Niño Southern Oscillation
OLR’
Marshall, Hudson et al. 2013 Clim Dyn
White, Hudson et al. 2013 Clim Dyn
U500 & MSLP’
STR high
(Tasman)
MSLP EOF1
U500 & MSLP’
SAM
Southern Annular Mode
Blocking
(split-flow)
Capturing the teleconnection: ENSO
Increased chance of heat extremes during El Niño
Heat extreme: weekly-mean Tmax anomaly in highest decile (above 90th percentile)
(observations)
POAMA: using
weeks 2 and 3 of
the forecast
Increased probability
of extreme heat
The Centre for Australian Weather and Climate Research
A partnership
between as
CSIRO
and the
Meteorology
Probability of weekly mean Tmax exceeding the 90th percentile,
expressed
ratio
toBureau
the ofmean
probability
Capturing the teleconnection: SAM
Chance of heat extremes during negative SAM
(-ve SAM: Equatorward shift of the mid-latitude westerly wind belt)
The Centre for Australian Weather and Climate Research
A partnership
between as
CSIRO
and the
Meteorology
Probability of weekly mean Tmax exceeding the 90th percentile,
expressed
ratio
toBureau
the ofmean
probability
Capturing the teleconnection: MJO
Examples:
DJF, phase 8
SON, phase 3
OBS rain
prob.
(Wheeler et al. 2009)
OBS
extreme
heat prob.
POAMA
extreme
heat prob.
The Centre for Australian Weather and Climate Research
A partnership between CSIRO and the Bureau of Meteorology
Capturing the teleconnection: persistent STR
Tasman High
U500 & MSLP’
Chance of heat extremes with a persistent high
in the Tasman
The Centre for Australian Weather and Climate Research
A partnership
between as
CSIRO
and the
Meteorology
Probability of weekly mean Tmax exceeding the 90th percentile,
expressed
ratio
toBureau
the ofmean
probability
Forecast skill: Windows of forecast opportunity
associated with ENSO
Skill (SEDI score) for forecasting extreme heat
Tmax above the upper decile in JJA in weeks 2 and 3 of the forecast
Skill when ENSO is strong
Skill when ENSO is weak/neutral
Skill better than for
random forecasts
The Centre for Australian Weather and Climate Research
A partnership
between CSIRO and the Bureau of Meteorology
Symmetric Extremal Dependence Index (SEDI; Ferro and Stephenson,
2011)
Forecast skill: Windows of forecast opportunity
associated with the SAM
Skill (SEDI score) for forecasting extreme heat
Tmax above the upper decile in weeks 2 and 3 of the forecast
Skill when negative SAM
Skill when SAM is weak/neutral
Teleconnection
SON
Teleconnection
DJF
Skill better than for
The Centre for Australian Weather and Climate Research
A partnership between CSIRO and the Bureau of Meteorology
random
forecasts
Forecast skill: Windows of forecast opportunity
associated with the MJO
Skill (SEDI score) for forecasting extreme heat
Tmax above the upper decile in weeks 2 and 3 of the forecast
Skill when MJO phase 2
Skill when MJO is weak
Teleconnection
JJA
Teleconnection
SON
Overall forecast skill
ROC area: Tmax in upper quintile
Fortnight 1 (week1+2)
DJF
MAM
JJA
MAM
JJA
Fort 1 SON
SON
Fortnight 1.5 (week2+3)
DJF
SON
Fort 2 SON
Fortnight 2 (week3+4)
DJF
MAM
JJA
SON
Heat extremes case studies (Hudson et al 2014, in prep)
3-16 JAN 2013
OBSERVED
SEP 2013
OBSERVED
FORECASTS for 3 Jan-16 Jan (initialised on the 27th Dec i.e. weeks 2 and 3)
Tercile
Upper quintile
FORECASTS for 1 Sep-30 Sep (initialised on the 22nd Aug)
Tercile
Upper quintile
Heat extremes case studies (Hudson et al 2014, in prep)
Attribution of heat extremes: case studies
Example: Observations 8-21 Nov 2009
Teleconnection
with extreme heat
at this time of year
El Nino
MJO
Blocking index
(inverted)
SAM index
(inverted)
MJO
phase 2
SAM (-ve)
Persistent Tasman High
(STRH)
phase 3
Blocking (-ve)
(i.e. no blocking)
STRH
Summary
 Increasing demand for subseasonal forecasts of heat extremes in Australia
 Approach is to
• Understand the large-scale climatic processes (e.g. state of the SAM) that
lead to episodes of extreme heat over Australia
• Examine the ability of POAMA to simulate the teleconnection and predict
these large-scale processes
• Explore and define skill of POAMA for making predictions of heat extremes,
including identifying windows of forecast opportunity
• Trialling different heat extreme indices for forecast products
 POAMA shows promising skill in subseasonal prediction of heat extremes
 There are windows of forecast opportunity related to state of the large-scale
drivers. Skill is related to how well the model can predict the driver and capture the
teleconnection.
The Centre for Australian Weather and Climate Research
A partnership between CSIRO and the Bureau of Meteorology