pemanfaatan wrf var 3

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

Pendahuluan
WRF ( 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 Laboratory
™ Oklahoma University
™ Federal 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 OPTIONS
1. 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 multiband scheme with carbon dioxide, ozone and microphysics effects (99).

PHYSIC AND DYNAMIC OPTIONS
2.2 Shortwave Radiation (ra_sw_physics)
a. Dudhia scheme: Simple downward integration allowing efficiently for
clouds and clear-sky absorption and scattering. When used in highresolution 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 OPTIONS
3.2 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 OPTIONS
4. 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. Onedimensional 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 archived
ob_format = 1
• NCAR archived observation data files
( Format Little_R via obsproc)
ob_format = 2
• NOAA / ESRL / GSD MADIS files : real-time dan
archived
0b_format =3

Data Observasi

Sumber : mmm.ucar.edu

Data Observasi Prebufr NOAA
• Real-time data
Download dari NCEP NOAA, yaitu :
gdas1.thhz.prebufr.nr dan

gdas1.thhz.gpsro.tm00.bufr_d
• Archived data
Download 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 ).

Sumber : mmm.ucar.edu

Data Observasi NCAR ( cont'd)

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

Sumber : mmm.ucar.edu


Cakupan satelit NOAA

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
temperatur
1=RTTOV (Radiative Transfer for TOVS)
EUMETSAT (European Organisation for the Exploitation of
Meteorological Satellites)

http://www.metoffice.gov.uk/research/interproj/nwpsaf/rtm/index.html
Latest 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 option
mp_physics

= 4, WSM-5 Class Scheme

ra_lw_physics

= 1, RRTM Scheme

ra_sw_physics

= 1, Dudhia Scheme

sf_sfclay_physics

= 2, Eta Similarity

sf_surface_physics

= 1, 5-Layer thermal diffusion

bl_pbl_physics

= 2, MYJ Scheme

cu_physics

= 3, Grell-Devenyi Ensemble

Resolusi Topografi

= 36 km

Resolusi Grid

= 10 '.

Resolusi Temporal

= 3 jam

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

Validasi
Suhu Permukaan, Medan
35
30
25
20
oC

WRF
OBS

15
10
5

27

20

0
20-30 April 2011

Under-estimated

%
20

0

20

40

60

80

100

120

20-30 April 2011

RH , Medan

27

Validasi

OBS

WRF

Validasi

Suhu Permukaan, Cengkareng
35
30
25
20
oC

WRF
OBS

15
10
5

28

25

22

20

0

20-30 April 2011

Under-estimated

%
20

0

20

40

60

80

100

120

22

Over-estimated

20-30 April 2011

25

RH Cengkareng

Validasi

28

OBS

WRF

Validasi
Suhu Permukaan, Makassar
35
30
25
20
oC

WRF
OBS

15
10
5

20-30 April 2011

Under-estimated

30

26

21

20

0

%
0

20

40

60

80

100

120

21

20

RH Makassar

Validasi

26
20-30 April 2011

30

OBS

WRF

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

oC
0

5

10

15

20

25

30

35

40

2

2-9 Mei 2011

Under-estimated

5

Suhu Permukaan, Medan

Validasi

9

OBS

WRF

Validasi
RH Medan
120
100

WRF

60

OBS

40
20

9

5

0
2

%

80

2-9 Mei 2011

Validasi
Suhu Permukaan, Cengkareng
40
35
30

WRF

20

OBS

15
10
5

4

0
2

oC

25

2-9 Mei 2011

Under-estimated

Validasi
RH Cengkareng
100
90
80
70
WRF

50

OBS

40
30
20
10

4

0
2

%

60

2 -9 Mei 2011

Validasi
Suhu Permukaan Makassar
35
30
25
20
%

WRF
OBS

15
10
5

2-9 Mei 2011

8

6

2

0

Validasi
RH Makassar
120
100

WRF

60

OBS

40
20

2-9 Mei 2011

8

6

0
2

%

80

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