Products of the JMA Ensemble Prediction System (EPS)

for Seasonal Forecast

Shuhei MaedaClimate Prediction Division

smaeda@naps.kishou.go.jp

Contents1. Introduction

2. Products of the EPS for one-month prediction

3. Products of the EPS for three-month outloo

k

4. Remarks

TCC Web pagehttp://cpd2.kishou.go.jp/tcc/

One-month prediction

Three-month outlook

2. Products of the EPS for one-month prediction

1) Outline of the EPS 2) Performance of the system 3) Examples of products

The EPS　 for one-month prediction

Atmospheric Model

(Atmosphere-Land)

SSTpersisted SST

anomaly

Initial

Atm

osp

here

Land

Oce

an

Products• Map• Verification・ GPV

Analysis

Boundary

C

ondit

ion

Horizontalresolution

T106 (about 1.125 º Gaussian grid ~110km)

Time integrationrange

34 days

Executingfrequency

Once a week

Ensemble size 26 membersSST persisted anomalyPhysicalprocesses

The same as those of short-and medium- range forecastmodel

7 day running mean Z500 normalized anomaly over the western North Pacific (40N,140E-170E)

Ensemble mean

Spread

Each member

Example of ensemble prediction

Initial

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ProductsKind Forecast

rangeParameter

Ensemble mean map

2-8day

9-15day

16-29day

2-29day

(NH)

Z500,Z500A

T850,T850A

PSEA

PSEAA

(60N-60S and Asia)

Z500,Z500A

SLP,SLPA

PSI200,PSI200A

PSI850,PSI850A

CHI200,CHI200A

T2m,T2mA

RAIN,RAINA,SSTA

＊○○○ A: 　 anomalies of 　　○○○

(continue) ProductsForecast range

Parameter

Spread map 2-8 day

9-15 day

16-29 day

2-29 day

Z500A

Large anomaly index* map

Time series

(each member)

7-day running mean

Circulation indices (Z500A)

Area averaged T850A

Area averaged spread (Z500A)

CHI200 in the equatorial region*Ratio of number of members whose anomaly is higher than 0.5SD to total number of ensemble menber at each grid point

2) Performance of the system

Example of one-month prediction verification charts

Anomaly correlation scores of ensemble mean forecast in 2001

28 day (2-29) mean 500hPa height fields over the Northern Hemisphere. Initial: 2001/1/4-2001/12/27

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RMSE of ensemble mean forecast in 2002

28 day (2-29) mean 500hPa height fields over the Northern Hemisphere. Initial: 2002/1/3-2002/12/27

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Example of verification of probabilistic one-month prediction

Reliability diagram for 7 day mean 500hPa field: day 9-15

2003 Spring (2003/2/27-5/29)

Frequency of occurrences where E was forecast within each of the probability category bins

Event (E)

Z500 anomaly is greater than 0

Forecast frequency distribution

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3) Examples of products

Prediction of

・ Arctic Oscillation

・ Rossby waves along Asia jet

・ Intra Seasonal Oscillation in the tropics (Madden Julian Oscillation (MJO))

Ensemble　 average forecast　map ( Initial: 2002/10/24)

Northern Hemisphere Z500 and T850 ; 28day mean

Ｚ５００

analysis

Ｚ５００

forecast

T850

analysis

T850

forecast

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AO!

Example of one-month prediction products(1)

Large anomaly index map

Init:2002.10.24 28 day mean ( day:2-29)

Many members predict large Z500 anomaly (above 0.5*standard deviation)

Many members predict large Z500 anomaly (below 0.5*standard deviation)

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7 day running mean Z500 normalized anomaly over North western Pacific (40N,140E-170E)

Analysis and ensemble average

Analysis

Each member

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Normalized　temperature anomalies

2002.1.11-15

Time sequences of temperature anomalies in Japan　 (5 day running mean)

2001.10-2002.1

Oct Nov Dec Jan

Example of one-month prediction products(2)

WWhat?

Ensemble　 average forecast　map ( Initial: 2002/1/3)

PSI200 ; 7day mean (9-15 day forecast range)

PSI200

analysis

PSI200

forecast

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Prediction of the Rossby wave along Asia jet

1/12-1/18

Rossby wave guide along Asia jetDispersion relation of barotropic Rossby wave in U(y) is

ω ＝ Uk-β ＊ k/K2, here, β ＊ ＝ β-∂2U/ ∂y2 , K2 ＝ k2+l2.

Therefore, total wave number of a stationary Rossby wave is

K ＝ Ks ＝（ β ＊ /U)1/2.

Hoskins and Ambrizzi(JAS,1993,1661-) showed that if Ks has maximum at some latitude as figure 1, it works as “Rossby wave guide”

Schematic figure of Rossby wave guide

Climatological Ks in DJF (shade)

and

Analyzed stream function anomaly at 200hPa (2002.1.11-15)

latitude

Temperature anomalies, and Rossby wave along Asia jet

Normalized　temperature anomalies

Longitude and height cross section of 20N-30N averaged stream function anomaly

2002.1.11-15

Stream function (200hPa) anomalies

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Time-longitude cross-section of stream function anomaly (20N-30N) at 200 hPa initial 2002.1.3

(left) analysis (right) ensemble mean forecast

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Spread among ensemble members

Spread among ensemble members ( Initial: 2003/10/16) Z500 ; 7day mean (9-15 day )

Predicted stream function (200hPa) anomalies and wave activity flux of two of 26 ensemble member

1 10 20 30

Example of one-month prediction products(3)

MAY　2003

Observed amount of daily precipitation in MAY 2003

96015

97430

98618

91425What ??

Eastward propagation of MJO

1-5 May

2003

6-10 May

11-15 May

16-20 May

OLR Velocity potential (200hPa)

longitude

da

y 1 May

20 MayW

Velocity potential (200hPa) in the equatorial region

Rui and Wang(1990)

Schematics of MJO 3-D structure over the Indian Ocean

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Prediction of MJO in May 2003

Observation 2nd week prediction ( 7 day mean)

Velocity potential anomalies (200hPa)

Stream function anomalies (200hPa)

Ensemble mean

Initial:2003/4/24

2003/5/3-5/9

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Velocity potential anomalies (200hPa)

Stream function anomalies (200hPa)

Observation 2nd week prediction

Ensemble mean

Initial:2003/5/1

2003/5/10-5/16

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Velocity potential anomalies (200hPa)

Stream function anomalies (200hPa)

2nd week predictionObservation

Ensemble mean

Initial:2003/5/8

2003/5/17-5/23

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Prediction of MJO in Oct. 2003

Velocity potential at 200hPa (CHI200)

Longitude

day

20 Sep

10 Oct

Obs.

Fcst

Init:10/9 2nd week

CHI200a

PSI850a

PSI200a

Prediction of MJO in July 1984-1993OBS FCST

CHI200A in the equatorial region

84

86

88

92

1

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