PEMANFAATAN WRF-VAR 3.2.1 UNTUK PRAKIRAAN CUACA

FATKHUROYAN, ST.PUSAT PENELITIAN DAN PENGEMBANGAN

BMKG

POKOK BAHASAN

• PENDAHULUAN• PHYSIC AND DYNAMIC OPTIONS• INPUT DATA• HASIL • KESIMPULAN

PendahuluanWRF ( Weather Research and Forecasting ) ialah

model NWP ( numerical Weather Prediction ) yang dipakai baik untuk kebutuhan operasional forecasting maupun untuk riset atmosfer ( real data dan idealized case ).

WRF dikembangkan oleh :National Center for Atmospheric Research (NCAR)The National Centers for Environmental Prediction (NCEP)Forecast Systems Laboratory (FSL)Air Force Weather Agency (AFWA)Naval Research LaboratoryOklahoma UniversityFederal Aviation Administration (FAA)

History of WRF Model

– 2000: V1.0 (beta release of EH core)– 2001: V1.1– 2002: V1.2 (beta release of EM core)– 2003: V1.3– 2004: V2.0 (first official release)� Current version: 3.3 (released in april 2011)

Core WRF

Model yang berbeda dengan arsitektur sama tapi berbeda core-code nya.

– ARW (Advanced Research WRF) at NCAR– NMM (Non-Hydrostatic Mesoscale Model) at NCEP

• Based on Eta Model’s code– WRF-Var

Alur WRF-Var

Sumber : mmm.ucar.edu

PHYSIC AND DYNAMIC OPTIONS1. Microphysics (mp_physics)

a. Kessler scheme: A warm-rain (i.e. no ice) scheme used commonly in idealized cloud modeling studies (mp_physics = 1).b. Lin et al. scheme: A sophisticated scheme that has ice, snow and graupel processes, suitable for real-data high-resolution simulations (2).

2.1 Longwave Radiation (ra_lw_physics)a. RRTM scheme: Rapid Radiative Transfer Model. An accurate scheme using look-up tables for efficiency. Accounts for multiple bands, trace gases, and microphysics species (ra_lw_physics = 1).b. GFDL scheme: Eta operational radiation scheme. An older multi- band scheme with carbon dioxide, ozone and microphysics effects (99).

PHYSIC AND DYNAMIC OPTIONS2.2 Shortwave Radiation (ra_sw_physics)a. Dudhia scheme: Simple downward integration allowing efficiently for clouds and clear-sky absorption and scattering. When used in high- resolution simulations, sloping and shadowing effects may be considered (ra_sw_physics = 1).b. Goddard shortwave: Two-stream multi-band scheme with ozone from climatology and cloud effects (2).

3.1 Surface Layer (sf_sfclay_physics)a.MM5 similarity: Based on Monin-Obukhov with Carslon-Boland viscous sub-layer and standard similarity functions from look-up tables (sf_sfclay_physics = 1).b. Eta similarity: Used in Eta model. Based on Monin-Obukhov with Zilitinkevich thermal roughness length and standard similarity functions from look-up tables(2).

PHYSIC AND DYNAMIC OPTIONS3.2 Land Surface (sf_surface_physics)a. 5-layer thermal diffusion: Soil temperature only scheme, using five layers (sf_surface_physics = 1).b. Noah Land Surface Model: Unified NCEP/NCAR/AFWA scheme with soil temperature and moisture in four layers, fractional snow cover and frozen soil physics. New modifications are added in Version 3.1 to better represent processes over ice sheets and snow covered area.

3.3 Urban Surface (sf_urban_physics – replacing old switch ucmcall)a. Urban canopy model (1): 3-category UCM option with surface effects for roofs, walls, and streets.b. BEP (2). Building Environment Parameterization: Multi-layer urban canopy model that allows for buildings higher than the lowest model levels. Only works with Noah LSM and Boulac and MYJ PBL options. New in Version 3.1.

PHYSIC AND DYNAMIC OPTIONS4. Planetary Boundary layer (bl_pbl_physics)a. Yonsei University scheme: Non-local-K scheme with explicit entrainment layer and parabolic K profile in unstable mixed layer (bl_pbl_physics = 1).b. Mellor-Yamada-Janjic scheme: Eta operational scheme. One- dimensional prognostic turbulent kinetic energy scheme with local vertical mixing (2).

5. Cumulus Parameterization (cu_physics)a. Kain-Fritsch scheme: Deep and shallow convection sub-grid scheme using a mass flux approach with downdrafts and CAPE removal time scale (cu_physics = 1).b. Betts-Miller-Janjic scheme. Operational Eta scheme. Column moist adjustment scheme relaxing towards a well-mixed profile (2).

Input Data

Sumber : mmm.ucar.edu

Alur WRF

Sumber : mmm.ucar.edu

System requirement

Required libraries (WRF and WPS):• FORTRAN 90/95 compiler• C compiler• Perl• netCDF• NCAR Graphics (optional, but recommended – used by

graphical utility programs)Optional libraries* for GRIB2 support (in WPS):• JasPer (JPEG 2000 “lossy” compression library)• PNG (“lossless” compression library)• zlib (compression library used by PNG

Data Hasil WRF-ARW

• Disebut Fg ( first Guess )• Wrfinput_d01 dan wrfbdy_d01 yang akan diproses di

WRF-Var

Sumber Data Observasi

• NCEP prebufr files : real- time dan archivedob_format = 1

• NCAR archived observation data files( Format Little_R via obsproc)ob_format = 2

• NOAA / ESRL / GSD MADIS files : real-time dan archived0b_format =3

Data Observasi

Sumber : mmm.ucar.edu

Data Observasi Prebufr NOAA

• Real-time dataDownload dari NCEP NOAA, yaitu : gdas1.thhz.prebufr.nr dan gdas1.thhz.gpsro.tm00.bufr_d

• Archived dataDownload dari dss.ucar.edu

Observation Pre-processor

• Tujuannya :Mengubah data observasi yang berbentuk format Little_R agar dapat dipakai kedalam WRF-Var.

• Fungsi dasar :Menyaring data observasi konvensional ( time window, domain, duplikasi, dll ) untuk keperluan asimilasi Wrf-Var.Koreksi terhadap kesalahan data obs.Melakukan Quality kontrol

Data Observasi NCAR

• Data udara atas sejak 1972• Data Observasi permukaan sejak 1975• Lalu di konversi kedalam bentuk format Little_R.• Kemudian di proses kedalam observation pre-processor

( obsproc.exe ).• Ada 18 type data observasi yang diproses ( synop, ship,

metar, airep, pilot, dll ).

Data Observasi NCAR ( cont'd)

Sumber : mmm.ucar.edu

Data Observasi MADIS

• Perlu software konverter.• Belum sepenuhnya di tes.• Data Observasi sejak 2001, yaitu Metar, ACARS,

satwnd, marine, radiosonde.• madis.noaa.gov

Data Satelit

Sumber : mmm.ucar.edu

Cakupan satelit NOAA

Sumber : mmm.ucar.edu

Sumber : mmm.ucar.edu

Data yang dipakai

• Data radiasi satelit NCEP global bufr format ( total 15 sensor dari 6 satelit )

• 4 HIRS dari NOAA 16, 17, 18, metop-2• 5 AMSU-A dari NOAA 15,16,18, EOS-Aqua, metop-2• 3 AMSU-B dari NOAA 15, 16, 17.• 2 MHS dari NOAA 18, metop-2• 1 AIRS dari EOS-Aqua

Radiative Transfer Model• Berfungsi untuk menghitung radiasi dan tingkat kecerahan

temperatur1=RTTOV (Radiative Transfer for TOVS)EUMETSAT (European Organisation for the Exploitation of

Meteorological Satellites)http://www.metoffice.gov.uk/research/interproj/nwpsaf/rtm/index.htmlLatest released version: RTTOV_9_3,Version used in WRF-Var: RTTOV_8_7 (no plan/resource to update to

RTTOV_9)2=CRTM (Community Radiative Transfer Model)JCSDA (Joint Center for Satellite Data Assimilation)ftp://ftp.emc.ncep.noaa.gov/jcsda/CRTM/Latest released version: CRTM REL-2.0.2,

Kondisi saat ini

• Single Computer, Fedora 12• physics and dynamic optionmp_physics = 4, WSM-5 Class Schemera_lw_physics = 1, RRTM Scheme ra_sw_physics = 1, Dudhia Schemesf_sfclay_physics = 2, Eta Similaritysf_surface_physics = 1, 5-Layer thermal diffusionbl_pbl_physics = 2, MYJ Scheme cu_physics = 3, Grell-Devenyi EnsembleResolusi Topografi = 36 kmResolusi Grid = 10 '.Resolusi Temporal = 3 jam

Validasi

• Resolusi 60 km• Mp-Physics = 1 ( Kessler Scheme )

Validasi

Suhu Permukaan, Medan

0

5

10

15

20

25

30

3520 27

20-30 April 2011

oC

WRFOBS

Under-estimated

ValidasiRH , Medan

0

20

40

60

80

100

120

20 27

20-30 April 2011

%

WRFOBS

Validasi

Suhu Permukaan, Cengkareng

0

5

10

15

20

25

30

35

20 22 25 28

20-30 April 2011

oC

WRFOBS

Under-estimated

Validasi

RH Cengkareng

0

20

40

60

80

100

120

20 22 25 28

20-30 April 2011

%

WRFOBS

Over-estimated

Suhu Permukaan, Makassar

0

5

10

15

20

25

30

3520 21 26 30

20-30 April 2011

oC

WRFOBS

Validasi

Under-estimated

Validasi

RH Makassar

0

20

40

60

80

100

12020 21 26 30

20-30 April 2011

%

WRFOBS

Validasi

• Resolusi 36 km.• Mp-Physics = 4 ( WSM-5 Class Scheme ).

Validasi

Suhu Permukaan, Medan

0

5

10

15

20

25

30

35

40

2 5 9

2-9 Mei 2011

oC

WRFOBS

Under-estimated

RH Medan

0

20

40

60

80

100

120

2 5 9

2-9 Mei 2011

%

WRFOBS

Validasi

Suhu Permukaan, Cengkareng

0

5

10

15

20

25

30

35

40

2 4

2-9 Mei 2011

oC

WRFOBS

Validasi

Under-estimated

RH Cengkareng

0

10

20

30

40

50

60

70

80

90

100

2 4

2 -9 Mei 2011

%

WRFOBS

Validasi

Suhu Permukaan Makassar

0

5

10

15

20

25

30

35

2 6 8

2-9 Mei 2011

%

WRFOBS

Validasi

RH Makassar

0

20

40

60

80

100

120

2 6 8

2-9 Mei 2011

%

WRFOBS

Validasi

Hasil Running

Hasil Running

Hasil Running

Kesimpulan

• Data hasil Observasi baik synop, pilot, rason, dll dapat dipakai sebagai inputan WRF-Var

• Data hasil Observasi satelit juga dapat dipakai untuk input WRF-Var

• WRF_Var dapat dipakai untuk memprediksi cuaca beberapa hari kedepan

Saran

• Perlu dibangun Cluster untuk instalasi WRF-Var• Validasi model dengan MET ( Model Evaluation Tool )• Pemilihan Fisik dan dinamik yang tepat untuk wilayah

Indonesia.

Terima kasih