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Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium- Range Weather Forecasts

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Page 1: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Systematic Errors

Thomas Jung

European Centre for Medium-Range Weather Forecasts

Page 2: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Scope of the Lecture

Question: “Do we still have significant systematic errors in the ECMWF forecasting system?”

If so, what are the main problems? How do systematic errors grow? How did systematic errors evolve over the years? How well do we simulate specific phenomena (e.g., blocking, extratropical cyclones)? Does increasing resolution help? Which techniques can be used to understand systematic error?

Page 3: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Introduction

Two principal sources of forecast error:

Uncertainties in the initial conditions (“observational error”)

Model error

Two kinds of forecast error

Random error (model+initial error)

Systematic error (model error*)

Page 4: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Concept of Systematic Error

)(ˆ)(ˆ),(ˆ ttttse odfdofd

Relatively straightforward to compute

BUT can be difficult to identify the origin of errors

Moreover there are pitfalls:• finite length (significance tests help partially)• apparent systematic error for short time series (loss of predictability) • observations might be biased

Page 5: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Loss of Predictability and “Systematic Error”

-6 -4 -2 0 2 4 6Temperature

0.00

0.01

0.02

0.03

0.04

0.05

0.06P

DF

Observed Anomaly“Systematic Error” when predictability

is lost

Fingerprint of loss of predictability: “Systematic error” resembles the opposite of the observed anomaly

“Observed”

“Forecast”

Page 6: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Example: Z500 DJF 2005/06

5120

5280

5280

5280

5440

5440

5440

5440

5600

56

00

5600

5600

5600

5760

5760

5760

5760

5760

5760

Mean Z500 Anomaly DJF 2006

-200

-140

-100

-80

-60

-40

-20

20

40

60

80

100

140

200

Observed Anomaly

5120

5280

5280

5280

5440

5440

5440

5440

5600

5600

5600

5600

5600

5760

5760

5760

5760

5760

5760

Mean Z500 Anomaly DJF 2006

-200

-140

-100

-80

-60

-40

-20

20

40

60

80

100

140

200

Mean Error @ D+10

Spatial correlation=-0.78

Page 7: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Uncertainty of our “Truth”

Precipitation GPCP (12-2 1990-2005)

-0.5

1

3

5

7

9

11

13

Precipitation ex51-GPCP (12-2 1990-2005)

-10

-4

-2

-0.5

0.5

2

4

10

Page 8: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Data

• Medium-range forecasts Primarily hindcasts from ERA-40 and ERA-Interim (robust

statistics).

• Seasonal integrations: 13 month long integrations started on 1st November of each of the

years 1962-2005 (or a subset of this period). Diagnosis of standard seasons DJF, MAM, JJA, SON (errors had at

least 1 month to grow, asymptotic errors). Most experiments at TL159 with 91 levels in the vertical.

Observed lower boundary conditions (uncoupled integrations).

• Observational data: ERA-40 Other “observational” data sets.

Page 9: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Systematic Error Growth

How do systematic errors grow throughout the forecast?

Page 10: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Systematic Z500 Error Growth from D+1 to D+10

520

540

560

560

580

580

580

(a) Z500 Difference D+1 FC-AN (DJF 1990-2001 ERA Interim)

-1-0.8-0.6-0.4-0.3-0.2-0.1

0.10.20.30.40.60.81

520

540

560

560

580

580

580

(b) Z500 Difference D+3 FC-AN (DJF 1990-2001 ERA Interim)

-3-2.4-1.8-1.2-0.9-0.6-0.3

0.30.60.91.21.82.43

520

540

560

560

580

580

580

(c) Z500 Difference D+5 FC-AN (DJF 1990-2001 ERA Interim)

-5-4-3-2-1.5-1-0.5

0.511.52345

520

540

560

560580

580

580

(d) Z500 Difference D+10 FC-AN (DJF 1990-2001 ERA Interim )

-10-8-6-4-3-2-1

12346810

Page 11: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Systematic Z500 Errors: Medium-Range and Beyond

-6-2 -2

-2

-2

-2

-2

-2-2

2

2

2

2

6

Z500 Difference 32R1-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

520

540

560

560

580

580

580

(a) Z500 Difference D+1 FC-AN (DJF 1990-2001 ERA Interim)

-1-0.8-0.6-0.4-0.3-0.2-0.1

0.10.20.30.40.60.81

520

540

560

560

580

580

580

(b) Z500 Difference D+3 FC-AN (DJF 1990-2001 ERA Interim)

-3-2.4-1.8-1.2-0.9-0.6-0.3

0.30.60.91.21.82.43

520

540

560

560

580

580

580

(c) Z500 Difference D+5 FC-AN (DJF 1990-2001 ERA Interim)

-5-4-3-2-1.5-1-0.5

0.511.52345

520

540

560

560

580

580

580

(d) Z500 Difference D+10 FC-AN (DJF 1990-2001 ERA Interim )

-10-8-6-4-3-2-1

12346810

D+10 ERA-Interim Asymptotic: 31R2

Page 12: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Evolution of Systematic Error

How did systematic errors evolve throughout the years?

Page 13: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Evolution of D+3 Systematic Z500 Errors

1983-1987 1993-1997 2003-2007

5120

5280

5280

5280

5440

5440

5440

5440

5600

5600

5600

56

00

5600

5760

5760

5760

5760

5760

5760

Mean Z500 Error DJF 1983-1987

-50

-35

-25

-20

-15

-10

-55

10

15

20

25

35

50

5120

5280

5280

5440

5440

5440

5440

5600

56

00

5600

5600

5600

5760

5760

5760

5760

57

60

5760

Mean Z500 Error DJF 1993-1997

-50

-35

-25

-20

-15

-10

-55

10

15

20

25

35

50

5120

5280

5280

5280

5440

5440

5440

5440

5600

5600

5600

56

00

5600

5760

576

0

5760

5760

57

60

5760

Mean Z500 Error DJF 2003-2007

-50

-35

-25

-20

-15

-10

-55

10

15

20

25

35

50

Page 14: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Evolution of Systematic Z500 Errors: Model Climate

-2

-2

-2

-2

-2

2

2

2

2

Z500 Difference 35R1-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-2

-2

2

2

2

Z500 Difference 33R1-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-2

-2

2

2

2

2

2

2

Z500 Difference 32R3-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-6

-6

-6

-6

-2

-2

-2

-2

-2

-2

-2

-2

-2

2

2

2

2

2

2

6

6

Z500 Difference 32R2-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-6

-2 -2

-2

-2

-2

-2

-2-2

2

2

2

2

6

Z500 Difference 32R1-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-10

-6

-6

-6

-6

-2

-2

-2

-2

-2

-2

-2

-2

2

2

22

2

2

Z500 Difference 31R1-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-6

-6

-6

-6

-6

-2

-2

-2

-2

-2

-2

-2

-2

2

2

2

2

6

Z500 Difference 30R1-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-6

-6

-6

-6

-6

-2

-2

-2-2

-2

-2

-2

-2

-2

2

2

2

2

2

6

Z500 Difference 29R2-er40 (12-2 1963-2006)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

35R1 33R1 32R3 32R2

32R1 31R1 30R1 29R2

Page 15: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Systematic Z500 Errors: Impact of Recent Changes

-2

-2

-2

-2

-2

2

22

2

2

2

Z500 Difference f127-er40 (12-2 1990-2005)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-6

-2

-2-2

-2

-2

-2

2

2

2

2

2

2

6

Z500 Difference f3wt-er40 (12-2 1990-2005)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14-2

-2

-2

2

2

2

2

2

2

2

2

2

Z500 Difference f251-er40 (12-2 1990-2005)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-2

-2

-2

2

2

2

2

2

2

2

2

Z500 Difference f3y0-er40 (12-2 1990-2005)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-2

-2

-2

-2

-2

-2

-2

2

2

Z500 Difference f3y1-er40 (12-2 1990-2005)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

-2

-2

-2

-2

-2

-2-2

2

2

2

Z500 Difference f3y2-er40 (12-2 1990-2005)

-14

-12

-10

-8

-6

-4

-22

4

6

8

10

12

14

Control Old Convection Old TOFD

Old Vertical Diff Old Radiation Old Soil Hydrology

Page 16: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Phenomena

Page 17: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

510

510

510

510

520

520

520

520

520

530

530

530

530

540

540

540

540

550

550

550

550

560

560

560

560

560

570

570

570

570

570

570

570

580

580

ECMWF Analysis VT:Saturday 23 December 2006 12UTC 500hPa Geopotential

Blocking Methodology

L

H

L

Page 18: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

-180 -120 -60 0 60 120 180Latitude

0

10

20

30

40

Blo

ckin

g F

req

uenc

y (%

)

Blocking Frequency Errors (23r4)

DJF 1990-2001

ERA-40D+1D+4D+7D+10

Page 19: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Blocking Frequency Errors (31R2)

DJF 1990-2001

ERA-40D+1D+4D+7D+10

-180 -120 -60 0 60 120 180Latitude

0

10

20

30

40

Blo

ckin

g F

req

ue

ncy

(%

)

Page 20: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Blocking Frequencies: DJF 1990-2005

-180 -120 -60 0 60 120 180Longitude

0

10

20

30

40B

lock

ing

Fre

qu

en

cy (

%)

ERA4033R132R329R2-32R2

Page 21: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

New Blocking Diagnostic

• Feature tracking software from Kevin Hodges

• Track positive stream function anomalies at 1000 hPa

• Some filtering: T3-T12

• Diagnostics: Number, frequency, lifetime, …

Page 22: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Frequency of Z1000 Maxima (er40 DJFM 1962-2005)

1

2

3

4

5

6

7

8

9

10

12

15

20

25

30

Frequency of Z1000 Maxima (f18l-er40 DJFM 1962-2005)

-7.5

-5

-4

-3

-2

-1

-0.5

0.5

1

2

3

4

5

7.5

Frequency of Z1000 Maxima (f127-er40 DJFM 1962-2005)

-7.5

-5

-4

-3

-2

-1

-0.5

0.5

1

2

3

4

5

7.5

Frequency of Z1000 Maxima (f127-f18l DJFM 1962-2005)

-7.5

-5

-4

-3

-2

-1

-0.5

0.5

1

2

3

4

5

7.5

Frequency of Anti-cyclones (1962-2005 DJF)

ERA40

33R1-ERA40

31R1-ERA40

33R1-31R1

Long-lived anticyclones only

(> 2 days)

Page 23: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Average Lifetime Z1000 Maxima (er40 DJFM 1962-2005)

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

6

7

8

9

10

Average Lifetime Z1000 Maxima (f18l-er40 DJFM 1962-2005)

-6

-4.5

-3.5

-3

-1.5

-1

-0.5

0.5

1

1.5

2.5

3.5

4.5

6

Average Lifetime Z1000 Maxima (f127-er40 DJFM 1962-2005)

-6

-4.5

-3.5

-3

-1.5

-1

-0.5

0.5

1

1.5

2.5

3.5

4.5

6

Average Lifetime Z1000 Maxima (f127-f18l DJFM 1962-2005)

-6

-4.5

-3.5

-3

-1.5

-1

-0.5

0.5

1

1.5

2.5

3.5

4.5

6

Average Lifetime of Anticyclones (1962-2005 DJF)

ERA40

33R1-ERA40

31R1-ERA40

33R1-31R1

Page 24: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Extratropical Synoptic Systems

Two appoaches:

• Compute standard deviation of highpass or bandpass filtered time series (“Eulerian” approach).

• Track individual systems (“Lagrangian” approach).

Page 25: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

“Observed” Tracks of Long-lived Cyclones

ETC ECMWF Analysis (DJFM 05/06)

940 950 960 970 980 990 1000 1010 1020

n= 515

>2 days

Page 26: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Sensitivity to Horizontal Resolution: 29R1

Wintertime Cyclones over the Northern Hemisphere

1980 1985 1990 1995 2000 2005Time

100

150

200

250

300

350

400N

um

be

r o

f Cyc

lon

es

ERA-40EC-T95EC-T159EC-T255

Page 27: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Sensitivity to Horizontal Resolution: 31R1

Wintertime Cyclones over the Northern Hemisphere

1990 1995 2000 2005Time

200

300

400

500

600

700

800

Nu

mb

er

of C

yclo

ne

s

ERA-40T95T159T255T511

Page 28: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Number of Extratropical Cyclones (DJFM)

Lifetime > 1day

Page 29: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Computational Effort

• 12% of all CPUs on HPCE cluster

• Wall clock time about 20 hours• About 70 times more expensive than TL95!

1 Integration (151 days) @ TL511L91:

Page 30: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Synoptic Activity Error: Evolution

2222

22 2 2

44

4

4

4444

44 4 4

6

6 66

6666

66

6

6

6

8

8 88

88

8

8

8

8

8

8

8

8

10

10

10 1010

10

10

10

10

10

1212

12

12

Synoptic Z500 Activity: Difference 33R1-ERA40 (12-2 1962-2005)

-4-3-2.5-2-1.5-1-0.50.511.522.534

2222

22 2 2

44

4

4

4444

44 4 4

6

6 66

6666

66

6

6

6

8

8 88

88

8

8

8

8

8

8

8

8

10

10

10 1010

10

10

10

10

10

1212

12

12

Synoptic Z500 Activity: Difference 32R3-ERA40 (12-2 1962-2005)

-4-3-2.5-2-1.5-1-0.50.511.522.534

2222

22 2 2

44

4

4

4444

44 4 4

6

6 66

6666

66

6

6

6

8

8 88

88

8

8

8

8

8

8

8

8

10

10

10 1010

10

10

10

10

10

1212

12

12

Synoptic Z500 Activity: Difference 32R2-ERA40 (12-2 1962-2005)

-4-3-2.5-2-1.5-1-0.50.511.522.534

2222

22 2 2

44

4

4

4444

44 4 4

6

6 66

6666

66

6

6

6

8

8 88

88

8

8

8

8

8

8

8

8

10

10

10 1010

10

10

10

10

10

1212

12

12

Synoptic Z500 Activity: Difference 31R1-ERA40 (12-2 1962-2005)

-4-3-2.5-2-1.5-1-0.50.511.522.534

2222

22 2 2

44

4

4

4444

44 4 4

6

6 66

6666

66

6

6

6

8

8 88

88

8

8

8

8

8

8

8

8

10

10

10 1010

10

10

10

10

10

1212

12

12

Synoptic Z500 Activity: Difference 30R1-ERA40 (12-2 1962-2005)

-4-3-2.5-2-1.5-1-0.50.511.522.534

2222

22 2 2

44

4

4

4444

44 4 4

6

66

6

6666

66

6

6

6

8

8 88

88

8

8

8

8

8

8

8

8

10

10

10 1010

10

10

10

10

10

1212

12

12

Synoptic Z500 Activity: Difference 35R1-er40 (12-2 1963-2006)

-4-3-2.5-2-1.5-1-0.50.511.522.534

35R1

32R3

31R1

32R2

30R1

33R1

Page 31: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

The Madden-and Julian Oscillation

Page 32: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Schematic of the MJO

From Madden and Julian (1994)

Page 33: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Near Global Impact of the MJO (Precipitation)

Conv.: Indian Ocean Conv.: Maritime Continent

Conv.: Central Pacific Conv.: WH/Africa

Page 34: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

The Madden and Julian Oscillation

ERA-40

ECMWF Model

Page 35: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Conclusions (1)

Main systematic errors: Concept of systematic error is very straightforward.

But there are pitfalls:

• Short time series (sampling issues + loss predictability).

• Uncertainty about the true state of the atmosphere.

Systematic error are a clear sign of model error.

Understanding systematic error is challenging.

Page 36: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Conclusions (2)

Main systematic errors:Do we still have systematic errors in the ECWMF model?

• Yes, we do.

• Most systematic errors have been substantially reduced in recent years.

• Some key-challenges remain, however!

Page 37: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Conclusions (3)

Main systematic errors:

Tropical circulation + hydrological cycle

Madden-Julian Oscillation

Indian Summer Monsoon

Quasi-Biennial Oscillation

Euro-Atlantic blocking

Synoptic activity (severe wind storms)

Others (surface related fields)

Key-challenges:

Page 38: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Further Reading

Bechtold, P., M Koehler, T. Jung, M. Leutbecher, M. Rodwell and F. Vitart, 2008: Advances in simulating atmospheric variability with the ECMWF model: From synoptic to decadal time scales. Quart. J. Roy. Meteor. Soc., 134, 1337-1351.

Jung, T. and A.M. Tompkins, 2003: Systematic Errors in the ECMWF Forecasting System. ECMWF Technicial Memorandum 422. http://www.ecmwf.int/publications/library/do/references/list/14

Jung, T., A.M. Tompkins, and R.J. Rodwell, 2004: Systematic Errors in the ECMWF Forecasting System. ECMWF Newsletter, 100, 14-24.

Jung, A.M. Tompkins, and R.J. Rodwell, 2005: Some Aspects of Systematic Errors in the ECMWF Model. Atmos. Sci. Lett., 6, 133-139.

Jung, T. and co-authors, 2009: The ECMWF model climate: Recent progress through improved physical parametrizations. ECMWF Seminar Proceedings on Parameterization of Subgrid-scale Processes, 233-249. Available from the ECMWF website.

Jung, T., 2005: Systematic Errors of the Atmospheric Circulation in the ECMWF Model. Quart. J. Roy. Meteor. Soc., 131, 1045-1073.

Jung, T., S.K. Gulev, I. Rudeva and V. Soloviov, 2006: Sensitivity of extratropical cyclone characteristics to horizontal resolution in the ECWMF model. Quart J. Roy. Meteor. Soc., 132, 1839-1857.

Hoskins, B.J. and K.I. Hodges, 2002: New Perspectives on the Northern Winter Storm Tracks. J. Atmos. Sci., 59, 1041-1061.

Koehler, M., 2005: ECMWF Technicial Memorandum 422. http://www.ecmwf.int/publications/library/do/references/list/14

Palmer, T.N., G. Shutts, R. Hagedorn, F. Doblas-Reyes, T. Jung, and M. Leutbecher, 2005: Representing Model Uncertainty in Weather and Climate Prediction. Ann. Rev. Earth. Planet Sci., 33, 163-193.

Rodwell, MJ and T Jung, 2008: Understanding the local and global impacts of model physics changes: An aerosol example. Quart. J. Roy. Meteor. Soc., 134, 1479-1497.

Page 39: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Recent Model Changes

29R2 28 Jun 2005 Modifications to convection

30R1 1 Feb 2006 Increased resolution (L60 to L91)

31R1 12 Sep 2006 Revised cloud scheme (ice supersaturation + numerics); implicit computation of convective transports; introduction of orographic form drag scheme; revised GWD scheme

32R1 not operational

New short-wave radiation scheme; introduction of McICA cloud-radiation interaction; MODIS aerosol; revised GWD scheme; retuned ice particle size

32R2 5 Jun 2007 Minor changes to forecast model

32R3 6 Nov 2007 New formulation of convective entrainment and relaxation time scale; reduced vertical diffusion in the free atmosphere; modification to GWD scheme (top of the model); new soil hydrology scheme

33R1 3 Jun 2008 Slightly increased vertical diffusion; increased orographic form drag; retuned entrainment in convection scheme; bugfix scaling of freezing term in convection scheme; changes to the surface model

Page 40: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Sensitivity to Model Formulation

Page 41: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Systematic Errors: AMIP Models

Page 42: Training Course Presentation, 16 th March 2009 – Thomas Jung: Systematic Model Errors. Systematic Errors Thomas Jung European Centre for Medium-Range Weather

Training Course Presentation, 16th March 2009 – Thomas Jung: Systematic Model Errors.

Demeter Models (DJF Precipitation)

CERFACS LODYC

MPIMetOfficeMeteo-France

ECMWF