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ECMWF medium-range/monthly ensemble. Roberto Buizza European Centre for Medium-range Weather Forecasts. Atmospheric model. Wave model. The ECMWF Integrated Forecasting System (IFS) . EDA 25 T L 399L137. HRES T L 1279L137 (d 0-10). ENS 51 T L 639L91 (d0-10) T L 319L91 (d10-15/32).

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slide1

ECMWF medium-range/monthly ensemble

Roberto Buizza

European Centre for Medium-range Weather Forecasts

the ecmwf integrated forecasting system ifs

Atmospheric model

Wave model

The ECMWF Integrated Forecasting System (IFS)

EDA25

TL399L137

HRES

TL1279L137 (d0-10)

ENS51

TL639L91 (d0-10)

TL319L91 (d10-15/32)

Seasonal S451

TL255L91 (m0-7/12)

Atmospheric model

Wave model

Ocean model

ORTAS4 Real Time Ocean Analysis ~8 hours

ORAS4 Delayed Ocean Analysis ~12 days

the ens re forecast suite to estimate the m climate
The ENS re-forecast suite to estimate the M-climate

…28 6 13 20 27 March …

Following Thomas Hamill work, a re-fc suite is part of all ECMWF ensemble systems. Each day, the M-climate is estimated using 500 EPS re-forecasts:

  • 20 years (1994 – 2013)
  • 5 ICs (-14d,-7d,0,+7d, +14d)
  • 5 members

Some of the ENS products (e.g. the Extreme Forecast Indices) are bias corrected and/or calibrated using the model climate.

2014

2013

5

5

5

5

5

5

5

5

5

5

51

T639

L91

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

51

T319

L91

5

5

5

5

5

5

5

5

5

2012

20y

2011

…..

1994

slide5

ENS to identify rare events

80%

Mcli

t+84-108h

t+0-72h

t+36-60h

TP24 CDFs for Boulder

(From Ivan Tsonevski)

Boulder, 12-13 Sep 2013.

This plot shows EFI fcs for TP24 valid for the 24-hours between 00 UTC of 12 and 13 September 2013.

EFI was increasing approaching the date.

how do they perform ensembles must be reliable
How do they perform? Ensembles must be reliable

Reliability is a key property that probabilistic forecasts must have.

T850

24TP

10WS

how do they perform ensembles must be reliable1
How do they perform? Ensembles must be reliable

NH T500 – fc v analysis

NH T500 – fc v radiosondes

NH T500 – fc v AMSUA

ENS reliability is sensitive to verification field (analysis or obs).

t+24h

t+24h

t+24h

w/o stoch. phys.

with stoch. phys

w/o stoch. phys.

with stoch. phys

w/o stoch. phys.

with stoch. phys.

t+120h

t+120h

t+120h

w/o stoch. phys.

with stoch. phys

w/o stoch. phys.

with stoch. phys.

w/o stoch. phys.

with stoch. phys.

(From M Yamaguchi)

slide8

ENS to predict anomalies weeks ahead

Day 12-18

Day 19-25

9D 23D 6J 20J 3F 17F 3M

This plot shows ENS weekly anomaly forecasts over North America in D13-JFM13 (the right panels show average 2mT over (120-60W;40-70N).

how do ensembles perform scores trends crpss z500 nh
How do ensembles perform? Scores’ trends CRPSS Z500 NH

Scores’ trends can be used to monitor progress.

This plot shows that for upper-level fields over the NH extra-tropics , performance has been improving continuously.

Results indicate predictability gains of 1.5-2.0 days per decade.

how do ensembles perform scores trends crpss tp24 eu
How do ensembles perform? Scores’ trends CRPSS TP24 EU

Similar, although smaller in size, improvements can be seen by looking at 24h total precipitation, with skill gains of about 1.75 days between 2001 and 2012.

The plot shows the forecast lead time when CRPSS crosses a 10% value.

how do they perform ensembles must be reliable2
How do they perform? Ensembles must be reliable
  • 4 TIGGE ENS: ECMWF JMA NCEP UKMO
  • Verification Areas

TIGGE-based results for Jul-Oct 2012. TC tracking data have been created with the ECMWF vortex tracker (Vitart et al. 1997, JC). Verified TCs are storms with a ‘Tropical Storm’ intensity or stronger (>35 knots).

  • BSS
  • 10 deg. X 10 deg.
  • BSS
  • 20 deg. X 10 deg.

(From M Yamaguchi)

slide17

How do the ensembles perform? ROCA[PR(2mT>U3)] NH

ROC score for prob. Fc of 2-meter temperature in the upper tercile.

Day 19-32

Day 12-18

Pers. d12-19

Pers. d5-11

slide18

Nov 2013: ENS coupling from d0 to a better marine model …

Work is progressing to introduce a better, unified wave-currents-sea-ice model (LIM). The new model based on NEMO is under testing at higher resolution, ORCA_025_Z75.

In 2014 we will complete a ¼ degree NEMOVAR re-analysis, and we will then implement the ¼ model first in ENS, and then in the seasonal system (S5, planned for 2016/17).

(From F Vitart)

Nov 2013: coupling from initial-time to a new version of the ocean model (NEMO), with 1-way wave-currents coupling, improved skill, especially in the monthly time-range.

slide19

Nov 2013: ENS coupling d0, L62>L91, new physics+SKEB

Results based on 61 cases (JFM12, JJA12); 38r2 analyses and EDA perturbations.

(From M Leutbecher)

slide20

Nov 2013: EDA-based land-surface pert. in ENS ICs

SWVL1 – std(t=48h)

Nov 2013: EDA-based surface initial perturbations introduced in ENS.

Preliminary results indicate increased reliability in the short forecast range, due to small spread improvements.

EDA[sf]

NOSPPT

EDA[ua]

NOSPPT

EDA[sf,ua]

NOSPPT

EDA[sf]

Initial perturbations improved by coupling more the ensemble of analyses and forecasts.

slide21

The future: moving towards a more integrated approach

Today

The future

EDA25

ERA

4DV

ENS51

S451

HRES

EnsembleN

coupled analysis

and re-analysis

EnsembleN

coupled

forecasts

ORAS45

PDF(0) << coupled analysis and

re-analysis (past) stream

PDF(T) << medium/long range stream

PDF(0) << 4DV+EDA+ORAS4

PDF(0) << ERA+ORAS4 (past)

PDF(T) << HRES+ENS/S4