Slide 1 Nargis 0600UTC May 2nd Progress in global tropical cyclone forecasting at ECMWF Martin...

Slide 1Nargis 0600UTC May 2nd

Progress in global tropical Progress in global tropical cyclone forecasting at cyclone forecasting at

ECMWFECMWF

Martin Miller Martin Miller

Slide 2

Outline Introduction

General performance improvements

Objective scores

Systematic errors

TC forecast skill ECMWF: Tracks, intensity and genesis

Other Centres

Forecast system improvements Physical parametrizations

Observation quality control

Resolution

Extended-range forecasting Monthly

Seasonal

Conclusions

Slide 3

Historic Evolution of Skill

Slide 4

Global extra-tropics

Slide 5

Slide 6

Slide 7

Large-scale eg MJO

Slide 8

ECMWF Systematic Error: D+3 DJF

-10

-5

-5

-5

0

0

0

0

5

5

5

510

Mean FC Error: VPOT200 FC+3 (DJF 1986-1989)

-7-6-5-4-3-2-11234567

-120

-120-120

-60-60-60

00

0

606060

120120120

Mean FC Error: STRF200 FC+3 (DJF 1986-1989)

-10.5-9-7.5-6-4.5-3-1.5

1.534.567.5910.5

5200

5200

520

0

5400

5400

5400

5400

5400

5600

5600

5600

5600

560

0

5600

5800

5800

5800

5800

5800

5800

Mean Z500 FC Error: D+3 (DJF 1986-1989)

-35

-30

-25

-20

-15

-10

-55

10

15

20

25

30

35

-10

-5

-5

-5

0

0

0

0

5

5

5

5


-7-6-5-4-3-2-11234567

-120

-120-120

-60-60-60

00

0

606060

120120120


-10.5-9-7.5-6-4.5-3-1.5

1.534.567.5910.5

5200

5200

5400

5400

5400

5400

5400

5600

5600

5600

5600

56 0

0

5600

5800

5800

5800

5800

5800

5800


-35

-30

-25

-20

-15

-10

-55

10

15

20

25

30

35

-12

-6

-6

-6

0

0

0

0

6

6

6

6


-7-6-5-4-3-2-11234567

-120

-120-120

-60-60-600

0

0

606060

120120120


-10.5-9-7.5-6-4.5-3-1.5

1.534.567.5910.5

5200

5200

5400

5400

5400

5400

5400

5600

5600

5600

5600

56

00

5600

5800

5800

5800

5800

5800

5800


-35

-30

-25

-20

-15

-10

-55

10

15

20

25

30

35

Z500 Z500Z500

Stream Function 200hPa Stream Function 200hPa Stream Function 200hPa

Velocity Potential 200hPa Velocity Potential 200hPa Velocity Potential 200hPa

1986-1989 1996-1999 2006-2009

Slide 9

ECMWF Systematic Error: D+3 JJA

Z500 Z500Z500

Stream Function 200hPa Stream Function 200hPa Stream Function 200hPa

Velocity Potential 200hPa Velocity Potential 200hPa Velocity Potential 200hPa

1986-1989 1996-1999 2006-2009

5600

5600

5600

5800

5800

5800

5800

5800

Mean Z500 FC Error: D+3 (JJA 1986-1989)

-35

-30

-25

-20

-15

-10

-55

10

15

20

25

30

35

5600

5600

5600

5800

5800

58005800

5800


-35

-30

-25

-20

-15

-10

-55

10

15

20

25

30

35

5600

5600

5600

5800

5800

5800

5800

5800


-35

-30

-25

-20

-15

-10

-55

10

15

20

25

30

35

-50-50-50

000

0

5050

50

100100100

150150150

Mean FC Error: STRF200 FC+3 (JJA 1986-1989)

-10.5-9-7.5-6-4.5-3-1.5

1.534.567.5910.5

-50-50

-50

000

0

5050

50

100100100

150150150


-10.5-9-7.5-6-4.5-3-1.5

1.534.567.5910.5

-50-50

-50

000

0

5050

50

100100100

150150150


-10.5-9-7.5-6-4.5-3-1.5

1.534.567.5910.5

-12

-12

-6

-6

- 6

0

0

0

0

6

6

6

6

Mean FC Error: VPOT200 FC+3 (JJA 1986-1989)

-7-6-5-4-3-2-11234567

-12

-12-6

-6

-6

0

0

0

0

6

6

6

6


-7-6-5-4-3-2-11234567

-18

-12

-12

-6-6

-6

0

0

0

0

6

6

6

6

12


-7-6-5-4-3-2-11234567

Slide 16

Forecast system development

The current levels of success in TC forecasting at ECMWF are due to many important changes in the forecast system in the past, In particular some changes of note include:

implementation of 4D-Var;

increases in horizontal and vertical model resolution;

better model physics;

availability and assimilation of massive amounts of data from satellites, and also the drop-sondes released in and around TCs;

EPS stochastic physics and also targeted perturbations in the vicinity of the TCs.

A wide-range of improvements in seasonal forecasting systems involving both atmosphere and ocean

Slide 17

Tropical cyclones

Verification of TC predictions from the operational deterministic forecast for 12-month periods ending on 14 July. The latest period, 15 July 2008 to 14 July 2009, is shown in red.

Mean error in core pressure (left) and position (right).

Tropical cyclone position error(mean of 365 days ending 14 July)

0

100

200

300

400

500

600

0 12 24 36 48 60 72 84 96 108 120

forecast range (hours)

Err

or

(km

)

2003

2004

2005

2006

2007

2008

2009

Tropical cyclone mean intensity error(mean of 365 days ending 14 July)

0

5

10

15

20

25

30

0 12 24 36 48 60 72 84 96 108 120


Err

or

(hP

a)

2003

2004

2005

2006

2007

2008

2009

Slide 19

Tropical cyclones

Verification of tropical cyclone predictions from the operational deterministic forecast for 12-month periods ending on 14 July.

Along track error: mean error in the direction of travel of the cyclone (negative values indicate slow bias)

Cross track error: mean error at right-angles to the direction of travel

Tropical cyclone mean along track error(mean of 365 days ending 14 July)

-250

-200

-150

-100

-50

0

50

100

0 12 24 36 48 60 72 84 96 108 120


Err

or

(km

)

2003

2004

2005

2006

2007

2008

2009

Tropical cyclone mean cross track error(mean of 365 days ending 14 July)

-250

-200

-150

-100

-50

0

50

100

0 12 24 36 48 60 72 84 96 108 120


Err

or

(km

)

2003

2004

2005

2006

2007

2008

2009

Slide 20

Slide 21

Nargis 0440UTC May 1st

Slide 22

D+5 from 23 april 00z T799 D+9 from 23 april 00z

EPS probabilities from 23 april 00z at D+5

Black dots are the first official reported positions of cyclone (~april 28th)

Slide 23

August-September 2008 Atlantic Basin

Tropical Storm Genesis

Increasingly ECMWF forecasts pick up tropical cyclones before they are

officially reported

Recent Atlantic hurricanes were predicted 5-7 days before they were observed

TS/Hurricane 1st Observed date Forecast detection

Fay 16-Aug D+6 (run: 10-Aug)

Gustav 25-Aug D+5 (run: 20-Aug)

Hanna 28-Aug D+5 (run: 23-Aug)

Ike 02-Sep D+7 (run: 26-Aug)

Josephine 03-Sep D+5 (run: 29-Aug)

Slide 24

Initial Tendencies: Mean u_vdgw 925, 20080603-20080831, Expver=33R1 f2nd, Analysis=yotc. Deep colours = 5% significance

Unit = m/s

-183 -15 -9 -3 3 9 15 141 -183 -15 -9 -3 3 9 15 141

Initial Tendencies: Mean u_dyn 925, 20080603-20080831, Expver=33R1 f2nd, Analysis=yotc. Deep colours = 5% significance

Unit = m/s

-183 -15 -9 -3 3 9 15 141 -183 -15 -9 -3 3 9 15 141

Precipitation GPCP (6-8 1963-2006)

1

3

5

7

9

11

13

15

Precipitation 32R3-GPCP (6-8 1963-2006)

-10

-4

-2

-0.5

0.5

2

4

10

Analysis Increments: Mean u925, 2008 JJA, Expver=oper 1, Analysis=dcda. Deep colours = 5% significance

0.8m/s0.8m/s

Unit = 0.1m/s

-29 -5 -3 -1 1 3 5 15 -29 -5 -3 -1 1 3 5 15

Initial Tendencies: Mean u_con 925, 20080603-20080831, Expver=33R1 f2nd, Analysis=yotc. Deep colours = 5% significance

Unit = m/s

-183 -15 -9 -3 3 9 15 141 -183 -15 -9 -3 3 9 15 141

Seamless Approach to Understanding Model Error

Precipitation Climatology JJA (GPCP)

Model Climate Error JJA (32R3)

Analysis Increments U925 (JJA 2008)

Process Tendencies U925 (JJA 2008)

DYN

CON

V.DIF

For the India monsoon, momentum tendency is a residual of the sum of large terms.

3 9 15-3-9-153 9 15-3-9-15 ms-1day-1

Unit = 0.1 ms-112hr-1

mmday-1

mmday-1

Slide 25

WGNE TC VerificationTC tracks on 2008 season

Northern-Hemisphere [2008/01/01 to 2008/12/31]

Southern-Hemisphere [2007/09/01 to 2008/08/31]Number of TCs , [best track data provider]

22 western North-Pacific [RSMC Tokyo]17 eastern North-Pacific (including Central-

Pacific) [RSMC Miami, Honolulu]

16 North Atlantic [RSMC Miami] 4 north Indian-Ocean [RSMC New-Delhi]12 south Indian-Ocean [RSMC La-Reunion] 4 around Australia [RSMC Nadi and 4

TCWCs ]

2217

16

12

4

4

Daisuke Hotta andTakuya Komori (NPD/JMA)

Slide 26

(a) Verification of western North-Pacific (WNP) domainPosition Error

22 TCs in 2008

Slide 27

(a) WNP domain Detection Rate

better

DetectionRate – PositionError map (FT +72)

Slide 28

JMAJMA ECMWFECMWF UKMOUKMO CMCCMC

DWDDWD NCEPNCEP NRLNRL Meteo FranceMeteo France

Scattering diagram of TC positions at 72 hour forecast.

Red : Before recurvature Green : During recurvature Blue : After

recurvature

Y-axis represents position errors in Along Track (AT) direction and X-

axis in the Cross Track (CT) direction. Unit: kms. ECMWF has a

small bias in all stages. CMC, DWD, NCEP,, NRL, Meteo France have

slow bias in “before recurvature” stage.

(a) WNP domain AT-CT bias map (FT +72)

Slide 29

JMAJMA ECMWFECMWF UKMOUKMO CMCCMC

DWDDWD NCEPNCEP NRLNRL Meteo FranceMeteo France

Scattering diagram of central pressure at 72 hour forecast.

Y-axis represents central pressure of forecast

and X-axis does that of analysis. Unit: hPa

Predicted central pressure of most models is higher than analysis

JMA and ECMWF has some relation ship between analysis and forecast.

Other center has very small.

(a) WNP domain Central Pressure scatter diagram (FT +72)

Slide 30

Time series of 2-day and 4-day forecast of JMA, ECM, UKM and 3 centres ensemble in WNP domain.

Slide 31

16 TCs in 2008

(b) Verification of North-Atlantic (NAT) domainPosition Error

Slide 32

(b) NAT domain Detection Rate

DetectionRate – PositionError map (FT +72)

better

Slide 33

A characteristic according to the domain of Northern Hemisphere.

Position error of each model will be compared in the next slide according to the domain.

Slide 35

(d) Verification of south Indian-Ocean (SIO) domainPosition Error

12 TCs in 2008

Slide 39

Tropical Forecast Biases Precipitation against GPCP for different cycles: from 15 year 5 months integrations for 1990-2005.

c 32r2 d 32r3

b 31r1a

Slide 40

2

2

/ 2

/ 2H x

pk x k

if |x| <= k,

if |x| > k,

Introduction of the Huber norm

Gaussian

Huber

Gaussian + flat

Slide 41

The Huber-norm and robust estimation

18 months of conventional dataFeb 2006 – Sep 2007

Normalised fit of PDF to data Best Gaussian fit

Best Huber norm fit

Slide 42

Comparing optimal observation weightsHuber-norm (red) vs. Gaussian+flat (blue)

More weight in the middle of the distribution

More weight on the edges of the distribution

More influence of data with large departures

Weights: 0 – 25%

25%

Slide 44

Implementation of the next resolution upgrade

Configuration: Deterministic model: T1279L91 (~16km) Outer loop of 4D-Var T1279L91 and inner

loops (T159/T255/T255) EPS resolution T639 (to 10 days) and T319

thereafter Wave model (25km and 36 directions)

Implementation planned for January 2010

Slide 45

OPS (35r2)

980hPa

(35r3) Use of improved QC (Huber norm)

961hPa

(36r1) High-res system (T1279 etc)

945hPa

Hurricane Bill, observed pressure~944hPa

Slide 47

ECMWF model simulations (T1279, ~15 km)compared with Satellite Observations (Met 9)

Slide 48

The MJO and tropical cyclones in the monthly forecast system

What is the state of play regarding the models MJO?What is the models TC climatology like?How does the MJO influence the model TC

15-member ensemble forecasts starting on the 15th of each month from 1989 to 2008.

46-day integrations

Cycle 32R3

T399 uncoupled till day 10 and T255 coupled after day 10

(Frederic Vitart – submitted to GRL)

Slide 49

MJO Propagation

1 2 3 4 5 6 7 8MJO Phase

0

2

4

6

Num

ber o

f Day

s

Time spent in each phase of the MJO

ERA-IModel

Slide 50

Amplitude of the MJO

Era Interim - VP200 Model - VP200

Era Interim - OLR Model - OLR

Slide 51

NDJFMAObservations Model

JASON

TS GENESIS

30°S30°S

20°S 20°S

10°S10°S

0° 0°

10°N10°N

20°N 20°N

30°N30°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 10 10.. 15 15.. 20 20.. 25 25.. 30 30.. 35 35.. 40 40.. 45 45.. 50 > 50

TS GENESIS

30°S30°S

20°S 20°S

10°S10°S

0° 0°

10°N10°N

20°N 20°N

30°N30°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 10 10.. 15 15.. 20 20.. 25 25.. 30 30.. 35 35.. 40 40.. 45 45.. 50 > 50

TS GENESIS

30°S30°S

20°S 20°S

10°S10°S

0° 0°

10°N10°N

20°N 20°N

30°N30°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 10 10.. 15 15.. 20 20.. 25 25.. 30 30.. 35 35.. 40 40.. 45 45.. 50 > 50

TS GENESIS

30°S30°S

20°S 20°S

10°S10°S

0° 0°

10°N10°N

20°N 20°N

30°N30°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 10 10.. 15 15.. 20 20.. 25 25.. 30 30.. 35 35.. 40 40.. 45 45.. 50 > 50

Tropical Cyclone Genesis climatology

1989-2008

Slide 52

NDJFMAObservations

JASON

Model

TS GENESIS

80°S80°S

70°S 70°S

60°S60°S

50°S 50°S

40°S40°S

30°S 30°S

20°S20°S

10°S 10°S

0°0°

10°N 10°N

20°N20°N

30°N 30°N

40°N40°N

50°N 50°N

60°N60°N

70°N 70°N

80°N80°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 2 2.. 4 4.. 8 8.. 12 12.. 16 16.. 20 20.. 24 24.. 28 28.. 32 > 32

TS GENESIS

80°S80°S

70°S 70°S

60°S60°S

50°S 50°S

40°S40°S

30°S 30°S

20°S20°S

10°S 10°S

0°0°

10°N 10°N

20°N20°N

30°N 30°N

40°N40°N

50°N 50°N

60°N60°N

70°N 70°N

80°N80°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 2 2.. 4 4.. 8 8.. 12 12.. 16 16.. 20 20.. 24 24.. 28 28.. 32 > 32

TS GENESIS

80°S80°S

70°S 70°S

60°S60°S

50°S 50°S

40°S40°S

30°S 30°S

20°S20°S

10°S 10°S

0°0°

10°N 10°N

20°N20°N

30°N 30°N

40°N40°N

50°N 50°N

60°N60°N

70°N 70°N

80°N80°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 2 2.. 4 4.. 8 8.. 12 12.. 16 16.. 20 20.. 24 24.. 28 28.. 32 > 32

TS GENESIS

80°S80°S

70°S 70°S

60°S60°S

50°S 50°S

40°S40°S

30°S 30°S

20°S20°S

10°S 10°S

0°0°

10°N 10°N

20°N20°N

30°N 30°N

40°N40°N

50°N 50°N

60°N60°N

70°N 70°N

80°N80°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< 2 2.. 4 4.. 8 8.. 12 12.. 16 16.. 20 20.. 24 24.. 28 28.. 32 > 32

Tropical Cyclone Density climatology

1989-2008

Slide 53

TS GENESIS

30°S30°S

20°S 20°S

10°S10°S

0° 0°

10°N10°N

20°N 20°N

30°N30°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-20 -20..-10 -10.. -5 -5.. -2 -2.. 2 2.. 5 5.. 10 10.. 20 > 20

MJO Composite- ASO

Tropical storm density anomaly

Phases 2+3

Phases 4+5

Phases 6+7

Phases 8+1

ModelObservations

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-10 -10.. -5 -5.. -2 -2.. -1 -1.. 1 1.. 2 2.. 5 5.. 10 > 10

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< -7 -7.. -5 -5.. -2 -2.. -1 -1.. 1 1.. 2 2.. 5 5.. 7 > 7

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< -7 -7.. -5 -5.. -2 -2.. -1 -1.. 1 1.. 2 2.. 5 5.. 7 > 7

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< -7 -7.. -5 -5.. -2 -2.. -1 -1.. 1 1.. 2 2.. 5 5.. 7 > 7

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

< -7 -7.. -5 -5.. -2 -2.. -1 -1.. 1 1.. 2 2.. 5 5.. 7 > 7

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-20 -20..-10 -10.. -5 -5.. -2 -2.. 2 2.. 5 5.. 10 10.. 20 > 20

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-20 -20..-10 -10.. -5 -5.. -2 -2.. 2 2.. 5 5.. 10 10.. 20 > 20

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-20 -20..-10 -10.. -5 -5.. -2 -2.. 2 2.. 5 5.. 10 10.. 20 > 20

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-20 -20..-10 -10.. -5 -5.. -2 -2.. 2 2.. 5 5.. 10 10.. 20 > 20

Slide 54

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-20 -20..-10 -10.. -5 -5.. -2 -2.. 2 2.. 5 5.. 10 10.. 20 > 20

TS GENESIS

10°N10°N

20°N 20°N

30°N30°N

40°N 40°N

160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

<-20 -20..-10 -10.. -5 -5.. -2 -2.. 2 2.. 5 5.. 10 10.. 20 > 20

Phases 6+7 – Phase 2+3

Observations

Model

MJO Composite- ASO

Tropical storm density anomaly

Slide 55

Example of Tropical Storm Seasonal Forecast

80°S80°S

70°S 70°S

60°S60°S

50°S 50°S

40°S40°S

30°S 30°S

20°S20°S

10°S 10°S

0°0°

10°N 10°N

20°N20°N

30°N 30°N

40°N40°N

50°N 50°N

60°N60°N

70°N 70°N

80°N80°N

20°E

20°E 40°E

40°E 60°E

60°E 80°E

80°E 100°E

100°E 120°E

120°E 140°E

140°E 160°E

160°E 180°

180° 160°W

160°W 140°W

140°W 120°W

120°W 100°W

100°W 80°W

80°W 60°W

60°W 40°W

40°W 20°W

20°W

8.1 12.18.5 12.323.2 21.82.62.53.8

Not Significant Significant at 5%

Ensemble size = 41,climate size =176Forecast start reference is 01/06/2009Tropical Storm FrequencyECMWF Seasonal Forecast

Climate = 1990-2005JASOND 2009

System 3

Forecast mean Standard deviation Climate mean

Slide 57

Interannual variability of Atlantic tropical storm ACE

Forecasts issued in June for the period July-December 1990-2009 Correlation: 0.72 RMS error: 0.40

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Year (start of verification period)

0.10.20.30.40.50.60.70.80.9

11.11.21.31.41.51.61.71.81.9

22.12.22.32.42.52.62.72.82.9

NO

RM

ALI

ZE

D A

CE

0.10.20.30.40.50.60.70.80.911.11.21.31.41.51.61.71.81.922.12.22.32.42.52.62.72.82.9

Ensemble size = 11 (real time = 41)Calibration period = 1990-2005Forecast start reference is 01/06/YYYYNorth Atlantic Accumulated Cyclone EnergyECMWF Seasonal Forecast

JASONDSystem 3

RMS Error= 0.40( 0.58)Correlation= 0.72( 1.00)

Forecast Observations +/- 1 Std. Deviation

Slide 58

Interannual variability of the frequency of Typhoons

Forecasts issued in April for the period May-October 1990-2009 Correlation: 0.66 RMS error: 3.29

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Year (start of verification period)

4

6

8

10

12

14

16

18

20

22

24

26

28

Typ

hoon

Num

ber

4

6

8

10

12

14

16

18

20

22

24

26

28

Ensemble size = 11 (real time = 41)Calibration period = 1990-2005Forecast start reference is 01/04/YYYYWestern North Pacific Typhoon FrequencyECMWF Seasonal Forecast

MJJASOSystem 3

RMS Error= 3.29( 3.49)Correlation= 0.66( 1.00)

Forecast Observations +/- 1 Std. Deviation

Slide 59

Closing remarks Steady improvements in skill in traditional measures such as 500hPa

geopotential (~1 day per decade for deterministic forecasts and ~1 day per 7

years for ensemble systems). Forecasts of weather parameters such as

precipitation, cloud etc. are ~ 1 day per 7 years.

Skill of tropical cyclone forecasting is improving at a similar rate with

emerging skill in intensity and genesis. ECMWF generally the best available

especially in the most recent years

Advanced assimilation methods enable better use of storm-related data

Progressive increases in resolution and improved physics are improving

realism of structures and intensity and hence improvements in tracking

Links to MJO activity provide some sub-seasonal skill in forecasting TC

statistics

Seasonal forecasting shows (surprisingly?) good skill in multi-basin statistics

Slide 1 Nargis 0600UTC May 2nd Progress in global tropical cyclone forecasting at ECMWF Martin...

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