Transcript Extremes - S2S Project

Prediction of extreme events at Sub-seasonal to
Seasonal lead times
Frédéric Vitart, Laura Ferranti, Ivan Tsonevsky
ECMWF
Slide 1
S2S Extremes Workshop Dec 2016 - IRI -
INDEX
1. S2S database
2. MJO/Weather regimes in S2S database
3. Case studies:
• 2010 Heat Wave over Russia
• Tropical Cyclone PAM
4. Extreme Forecast products and Verification
Slide 2
S2S Extremes Workshop Dec 2016 - IRI -
WWRP/WCRP Sub-seasonal to Seasonal (S2S) Prediction Project
Sub-Projects
Teleconnections (C. Stan and H. Lin)
Madden-Julian Oscillation (D. Waliser and S. Woolnough)
Monsoons (H. Hendon)
Africa (A. Robertson and R. Graham)
Extremes (F. Vitart)
Verification and Products (C. Coelho)
Research Issues
•
•
•
•
•
Slide 3
Predictability
Teleconnection
O-A Coupling
Scale interactions
Physical processes
Modelling Issues
•
•
•
•
•
•
Initialisation
Ensemble generation
Resolution
O-A Coupling
Systematic errors
Multi-model combination
S2S Database
S2S Extremes Workshop Dec 2016 - IRI -
Needs & Applications
Liaison with SERA
(Working Group on
Societal and Economic
Research Applications)
S2S database
 3-week behind real-time forecasts + re-forecasts (up to day 60)
 Common grid (1.5x1.5 degree)
 Data archived with a daily frequency (sub-daily for total precip/max
and min 2mtm) in GRIB2 at ECMWF and CMA
 About 80 parameters, including:





Slide 4
3D fields (u/v/w/z/t/q) on 10 pressure levels (up to 10 hPa)
Surface fluxes
Sea Surface temperature
Sea-ice cover (fraction)
Snow depth/density/snow fall/snow albedo
S2S Extremes Workshop Dec 2016 - IRI -
WWRP/WCRP S2S Database
Timerange
Resol.
Ens. Size
Freq.
Hcsts
ECMWF
D 0-46
T639/319L91
51
2/week
On the fly
UKMO
D 0-60
N216L85
4
daily
NCEP
D 0-44
N126L64
4
4/daily
ECCC
D 0-32
0.45x0.45 L40
21
weekly
BoM
D 0-60
T47L17
33
2/weekly
Fix
JMA
D 0-34
T319L60
25
2/weekly
Fix
KMA
D 0-60
N216L85
4
daily
CMA
D 0-45
T106L40
4
daily
Fix
1886-2014
CNRM
D 0-32
T255L91
51
weekly
Fix
1993-2014 2/monthly
15
CNR-ISAC
D 0-32
0.75x0.56 L54
40
weekly
Fix
1981-2010
6/month
1
HMCR
D 0-63
1.1x1.4 L28
20
weekly
Fix
1981-2010
weekly
10
Slide 5
S2S Extremes Workshop Dec 2016 - IRI -
Hcst length Hcst Freq
Past 20y
Hcst Size
2/weekly
11
4/month
3
1999-2010
4/daily
1
On the fly 1995-2014
weekly
4
1981-2013
6/month
33
1981-2010
3/month
5
On the fly 1996-2009
4/month
3
daily
4
On the fly 1993-2015
Fix
Sub-seasonal prediction of extreme events
 Prediction of large-scale, long lasting events (> 1 week):
• Heat/cold waves
• Droughts
• Flooding
 Prediction of statistics of small scale events, for example:
• Tropical cyclones
• Tornadoes
Slide 6
S2S Extremes Workshop Dec 2016 - IRI -
Madden Julian Oscillation
MJO PHASES
Locations of large floods during 1985–2010
MJO influences on large floods of the West
Coast of North America
From C. Zhang, BAMS 2013
Slide 7
S2S Extremes Workshop Dec 2016 - IRI -
Bivariate Correlation with ERA Interim – Ensemble Mean
1999-2010 re-forecasts
All Year
Slide 8
S2S Extremes Workshop Dec 2016 - IRI -
DJF
8
MJO Teleconnections (S2S re-forecasts)
EI 0.48
Z500 Composites
Phase 3 + 3 pentads NDJFM
BoM 0.15
CMA 0.14
CNRM 0.15
UKMO 0.28
Slide 9
HMCR 0.13
JMA 0.22
S2S Extremes Workshop Dec 2016 - IRI -
NCEP 0.32
ECCC 0.21
ISAC 0.25
ECMWF 0.31
Predicting skill associated with the Euro-Atlantic Regimes:
NAO -
NAO +
Bom
Blocking
Bom
Atlantic Ridge
Bom
Slide 10
S2S Extremes Workshop Dec 2016 - IRI -
Bom
October 29, 2014
10
Russian Heat Wave July-August 2010
 Worst heat wave on record over the past 33 years (Hoag, Nature 2014)
 Estimated 55,000 deaths
 Wildfires, smoke, worst drought in nearly 40 years, and the loss of at least
9 million hectares of crops
ERA interim 2mtm anomalies 1-7 August 2010
Slide 11
S2S Extremes Workshop Dec 2016 - IRI -
Russian Heat Wave 2010
ERA Interim
Day 1-7
Day 8-14
Day 15-21
1%
5%
4 July
1 August
15 August
WEEK1: time evolution of heat wave well predicted
WEEK2 and 3: Onset and decay predicted one week too late
Slide 12
S2S Extremes Workshop Dec 2016 - IRI Timing of maximum well predicted
2mtm anomalies over Russia – ECMWF reforecasts
1-7 August 2010
1%
5%
Lead
time
Slide 13
d26-32 d22-28 d19-25 d15-21 d12-18 d8-14 d5-11
S2S Extremes Workshop Dec 2016 - IRI -
d1-7
2mtm anomalies over Russia – S2S reforecasts
1-7 August 2010
ECMWF (18 Jul)
UKMO (17 Jul)
BOM (16 Jul)
NCEP(16 Jul)
JMA(20 Jul)
ECCC(21 Jul)
HMCR(20 Jul)
CNRM(15 Jul)
ERA Interim
Slide 14
S2S Extremes Workshop Dec 2016 - IRI -
2mtm anomalies over Russia – S2S models reforecasts
1-7 August 2010
July
Slide 15
18
17
15
18
21
S2S Extremes Workshop Dec 2016 - IRI -
20
20
16
18
20
Tropical Cyclone PAM Case Study
Formed
Dissipated
March 6, 2015
March 22, 2015
Hit Vanuatu islands on 13 March 2015
Most intense tropical cyclone of the south Pacific Ocean
in terms of sustained winds and regarded as one of the
worst natural disasters in the history of Vanuatu.
Slide 16
S2S Extremes Workshop Dec 2016 - IRI -
March 2015 MJO
Forecasts starting on 26 Feb 2015
Slide 17
S2S Extremes Workshop Dec 2016 - IRI -
Modulation of tropical cyclone density anomaly by MJO
MJO Phase 2-3
MJO Phase 4-5
OBS
ECMWF
NCEP
JMA
BoM
Multi
Slide 18
S2S Extremes Workshop Dec 2016 - IRI -
MJO Phase 6-7
MJO Phase 8-1
Prediction from ECMWF
Probability of a TC strike within 300 km
09 March 2015 Day 1-7
23 February 2015 Day 15-21
Slide 19
S2S Extremes Workshop Dec 2016 - IRI -
02 March 2015 Day 8-14
16 February 2015 Day 22-28
Tropical Cyclone Pam case study
Multi-model prediction of TC strike
probability anomalies- 9-15 March 2015
(NCEP/ECMWF/BoM/JMA/CMA)
2015/02/19 day 19-25
Slide 20
S2S Extremes Workshop Dec 2016 - IRI -
2015/02/26 day 12-18
Impact of Resolution - Tropical cyclone PAM - 9-15 March 2015
Probability of a TC strike within 300 km
Day 12-18
64km
32km
16km
110km+
SP
Verification
Slide 21
S2S Extremes Workshop Dec 2016 - IRI -
Day 19-25
Verification of extreme events in S2S
database
Main issues:
 Rarity of extreme events in observations
 Low number of ensemble members in most S2S
re-forecasts
 Low frequency of ensemble reforecasts in some
S2S models
 Short common re-forecast period 1999-2010
S2S real-time forecasts are more suitable for verification of
extreme events, but period covered is small (archived only
from 1st Jan 2015)
Slide 22
S2S Extremes Workshop Dec 2016 - IRI -
Relative Operating Characteristics (ROC) score
Decile Probabilities – May 2015- April 2016 - NH
ECMWF real-time forecasts Day 12-18
Probability to be in lower decile
Forecast
Slide 23
S2S Extremes Workshop Dec 2016 - IRI -
Probability to be in upper decile
Persistence of
previous week
23
2m temp Cumulative Distribution Function
ensemble predictions for 29 June - 5 July 2015
Climate
15 June 2015
(15-21d)
Slide 24
18 June 2015
(12-18d)
S2S Extremes Workshop Dec 2016 - IRI -
22 June 2015
(8-14d)
25 June 2015
(5-11d)
Observed
anomaly
2m temp Extreme Forecast Index
forecast range:12-18days verifying 8-14 August 2016
Ncep
Ecmwf
JMA
Ukmo
http://www.ecmwf.int/en/research/projects/s2s/charts/s2s/
Slide 25
S2S Extremes Workshop Dec 2016 - IRI -
EFI skill assessment
Preliminary results based on ECMWF system:
Slide 26
S2S Extremes Workshop Dec 2016 - IRI -
Example of Attribution: March 2013 Cold wave over Europe
2mtm anomalies ERA Interim
ECMWF - strong MJOs
ECMWF - Weak MJOs
Slide 27
NCEP - strong MJOs
NCEP - Weak MJOs
S2S Extremes Workshop Dec 2016 - IRI -
27
Conclusions
• The S2S database can be a useful resource for case studies, skill
assessment and also attribution of extreme events
• S2S models display skill to predict MJO up to 3-4 weeks. However impact
on NAO is weaker than in re-analysis and skill to predict European blocking
(important for summer heat wave prediction) and NOA- (important with
winter cold waves) is limited to 2 weeks.
• Russian heat wave 2010: S2S model forecasts provided indications of an
exceptional warm anomaly more than 10 days in advance.
• Tropical cyclone PAM: High probabilities of TC strike 2-3 weeks in
advance, most likely because of the impact of the strongest MJO on record
on TC activity
• Preliminary verification of ECMWF model suggests some useful skill for
decile and EFI extended-range
prediction
Slide 28
S2S Extremes Workshop Dec 2016 - IRI -
Regimes based on clustering of daily anomalies for 29 cold
seasons (1980-2008)
500 hPa geopotential
• Obtain well-known Euro-Atlantic regime
patterns
‘k means’ clustering applied
to EOF pre-filtered data
(retaining 80% of variance)
m 2s 2
Slide 29
S2S Extremes Workshop Dec 2016 - IRI -
October 29, 2014
29
Heat Wave Prediction in ECMWF re-forecasts
ERA Interim
Monthly Forecast Day 12-18
Slide 30
S2S Extremes Workshop Dec 2016 - IRI -