observing system experiments of mtsat-2 rapid scan atmospheric motion vector...

February 22 - 26, 2010 KKR Tokyo, Japan

Tenth International Winds Workshop 11

Observing system experiments of MTSAT-2 Rapid Scan Atmospheric Motion Vector

for T-PARC 2008 using the JMA operational NWP system

Koji Yamashita

Japan Meteorological Agency

[email protected]



Outline

• T-PARC 2008

• Global and Meso-scale Experiments Specification

• Experimental design

–Trial of 2-step thinning scheme

• Results of OSE

• Summary and Future plan

2



THORPEX Pacific Asian Regional Campaign (T-PARC 2008)

• Objectives

– Research the mechanism of genesis, recurvature

and extratropical transition for tropical cyclones in the northwestern Pacific.

– Assess the effectiveness of Global Interactive Forecasting System (GIFS) for tropical cyclones.

– Improve the performance of numerical weather prediction for tropical cyclones.


Tenth International Winds Workshop

THORPEX Pacific Asian Regional Campaign (T-PARC 2008)

• International Cooperation– Project by the Asian, North American and European

THORPEX Regional Committees.

– JMA contributed to the provision of forecast sensitivity analysis and special observations.

4

Aircraft Aircraft

DropsondeDropsondeUpperUpper--Sounding Sounding

By ObservatoriesBy Observatories

UpperUpper--SoundingSounding

By JMA VesselsBy JMA Vessels

MTSATMTSAT--2 2

RapidRapid--scanscan

Sep. 11 (36 Dropsondes)

Sep. 17 (29)

Sep. 28 (21)

Aug. 19 12UTC – 20 12UTC

Sep. 10 12UTC – 12 12UTC

Sep. 27 12UTC – 28 12UTC

Aug. 19 12UTC – 20 12UTC

Sep. 10 12UTC – 14 06UTC

Sep. 27 12UTC – 28 00UTC

Sep. 10 12UTC – 13 06UTC

Sep. 17 12UTC – 18 12UTC

Sep. 27 12UTC – 28 12UTC



Global and Meso-scale Experiments Specification

5

GSMHydrostatic Global

Spectral Model

MSMNon-hydrostatic Meso-

scale Model

Horizontal rez./ Vertical rez. 20 km / 60 level 5 km / 60 level

Top 0.1 hPa 21,800 m

Inner-loop model rez. for DA 80 km 15 km

Assimilation method 4D-Var 4D-Var

Time windows 6 hour 3 hour

Forecasts 84 hours (00,06,12,18UTC) 15 hours (00,06,12,18UTC)

33 hours (03,09,15,21UTC)

�Target Tropical Cyclone (TC)

– SINLAKU and Tropical depression (TD)

From 18UTC 10/09/2008 to 06UTC 13/09/2008

From 18UTC 17/09/2008 to 12UTC 18/09/2008



SINLAKU and TD Track map

6

9/9 990hPa

10/9 965hPa

11/9 935hPa12/9 940hPa

13/9 945hPa14/9 975hPa

15/9 985hPa

16/9 990hPa

17/9 990hPa

18/9 985hPa

19/9 980hPa

20/9 990hPa

10/9 1008hPa

11/9 1008hPa

12/9 1004hPa

TD

SINLAKU



Experimental Design• TEST – MTSAT-2 rapid scan AMVs are assimilated.

• CNTL – No MTSAT-2 rapid scan AMVs are assimilated.

Utilization of special of special of special of special observationsobservationsobservationsobservations

TEST CNTLMTSAT-2-RS-AMVs ○ (use) ×Dropsonde and Special

upper sounding (3-hourly)

×（no use) ×

TC BOGUS × ×The other

observations ○ ○



Trial of 2-step thinning scheme for MTSAT-2 rapid scan AMVs

• Step 1 – Equal-distance thinning with 200km (one AMV in 2deg. x

2deg. x 100hPa box ）– One AMV selected per box in the 6 hour time window.

• Step 2– Equal-distance thinning with 100km (one AMV in 1deg. x

1deg. x 100hPa box ）• For MTSAT-2 rapid scan AMVs (IR and WV, 4 or 7 min. intervals)

– One AMV selected per box in the hourly time window.

– Small observation error correlation

※ MTSAT-2 Rapid Scan AMVs have as almost same accuracy as MTSAT-1R.

Presented by K. Shimoji and S. HOSHINO



Example of MTSAT-1R AMVs （CNTL）after QC at 300hPa in 17-19UTC 17th September

9


Tenth International Winds Workshop 10Example of MTSAT AMVs （TEST）after

QC at 300hPa in 17-19UTC 17th September

Red barb :

MTSAT-2-RS-47MIN

Yellow barb :

MTSAT-2-RS-15MIN

Blue barb: MTSAT-1R



Experimental results for GSM-DA

11



Analysis and First-guess against radiosonde observations

• BIAS and RMAE of wind analysis for GSM-DA using MTSAT-2 rapid scan AMVs reduced.

U-comp. wind speed BIAS and RMSE, and Z500 difference from 11 to 13 Sep.

Anl TEST

Anl CNTL

Guess TEST

Guess CNTL

Ex.



Normalized score against initial forecast ( FT=0 )

• Significantly positive impacts (average ~3%) on three-day GSM forecast in Japan area.

Forecast Improvement Rate wrt RMSE for 1-3 day forecasts (CNTL-TEST)/CNTL from 11 to 13 Sep. in Japan area.

Forecast Improvement Rate wrt RMSE for 1-3 day forecasts (CNTL-TEST)/CNTL from 11 to 13 Sep. in Japan area.

Ex.

BetterWorse

Statistically significant

Psea T850 Z500 Wsp850 Wsp250

Forecast time (hour)



Mean TC Track Forecast Error• SINLAKU track predictions were worse in the late-forecast

time. But TD predictions were better.

CNTL

TEST

From 11 to 13 Sep.

10 samples

From 17 to 18 Sep.

4 samples

From 11 to 12 Sep.

Below 7 samples

SINLAKU

TD



Experimental results

for MSM-DA

15



Initial forecasts against radiosonde observations

• RMSE above 500hPa level were reduced, where many MTSAT-2-RS-AMVs were assimilated.

ME (m/s)RMSE (m/s)

RMSE and ME against Japan Radiosonde Wind speeds both 10-13 and 17-18 September 2008 ( FT: Forecast time )Ex.

2.0 3.02.5 4.03.51.5

1000

900

800

700

600

500

400

300

200

hP

a

FT=0Init. 00，06，12，18UTC

－－－－0.4－－－－0.8 0.2－－－－0.6 0.0

1000

900

800

700

600

500

400

300

200

hP

a

－－－－0.2

FT=0

TEST

CNTL

TEST

CNTL



Equitable Threat Score against Precipitation• There was a improvement of rain in one-day forecasting for

precipitation over 1-15 mm per three hours around Japan.

0 5 10 15 20 25 30 35 40 45 500.05

0.10

0.15

0.20

0.25

0.30

mm/3hour

Equitable Threat Score against Radar-Rainfall composite precipitation data in Japan both 10-13 and 17-18 September 2008（Init. 03,09,15,21UTC : Error bar : 95% confidence interval)

Ex.

30.15

Forecast time (hour)

6 9 12 15 18 21 24 30 3327

0.20

0.25

0.30

0.35

0.40

0.45

Ex. threshold 10mm/3hour

TEST

CNTL TEST

CNTL



Mean TC Track Forecast Error• SINLAKU track predictions were slightly better in the after-

recuvature stage. Another TD predictions were better.

CNTL

TEST

From 11 to 13 Sep.

7 samples.

From 17 to 18 Sep.

3 samples

From 11 to 12 Sep.

Below 7 samples.

SINLAKU

TD



Summary• OSEs for MTSAT-2 rapid scan AMVs using the global

and meso-scale NWP system were conducted.

• The trial of 2-step thinning scheme for MTSAT-2 rapid scan AMVs was performed.

• This scheme contributed to the increase of AMVs in the vicinity of Japan where AMVs data was sparse heretofore.

• BIAS and RMSE of wind analysis in GSM and MSM reduced against radiosonde observations using AMVs.

• This better wind analysis brought the improvement of forecasts in GSM and MSM.

• SINLAKU track predictions were improved or neutral in GSM and MSM except the late-forecast time of GSM.



Future Plan

• We will investigate the reason why SINLAKU track predictions were worse in GSM.

• We will perform more OSEs for MTSAT Rapid Scan AMVs to validate accuracy 2-step thinning scheme.

• Considering usage of the other satellite rapid scan AMVs ( METEOSAT-8 etc.)



Thank you for your attention

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Back up slide

22



Mean TC Intensity Forecast Error (GSM)• SINLAKU intensity predictions were worse in the beginning-

forecast time in the after-recurvature stage. TD predictions were newtral.

CNTL

TEST

From 11 to 13 Sep.

10 samples

From 17 to 18 Sep.

4 samples

From 11 to 12 Sep.

Below 7 samples

SINLAKU

TD



Mean TC Intensity Forecast Error (MSM)• Mean TC intensity predictions were almost neutral impact.

CNTL

TEST

From 11 to 13 Sep.

7 samples.

From 11 to 12 Sep.

Below 7 samples.

SINLAKU

TD

From 17 to 18 Sep.

3 samples



MTSAT-2 Rapid Scan AMV comparison

25



Case study with initial time of 18UTC 17/09/2008

26

TC track forecast

18

19

20

19

TESTCNTLTESTCNTL

Track Forecast Error

Slightly

improvement of

slow bias speed

for TC track forecasts



Case study with initial time of 18UTC 17/09/2008

• Impact of MTSAT-2-RS-AMVs in the north or north-west side on 300 – 400 hPa.

27

W

S

N

E

TEST-CNTLAnl.- Guess



Case study with initial time of 15UTC 11/09/2008 for MSM

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CNTL TEST Rader-Rainfall

observing system experiments of mtsat-2 rapid scan atmospheric motion vector...

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