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 ).
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 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
Validasi RH , Medan 120 100
WRF
60
OBS
40 20
27
0 20
%
80
20-30 April 2011
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
Validasi RH Cengkareng 120 100
WRF
60
OBS
40 20
20-30 April 2011
Over-estimated
28
25
22
0 20
%
80
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
Validasi RH Makassar 120 100
WRF
60
OBS
40 20
20-30 April 2011
30
26
21
0 20
%
80
Validasi • Resolusi 36 km. • Mp-Physics = 4 ( WSM-5 Class Scheme ).
Validasi Suhu Permukaan, Medan 40 35 30
WRF
20
OBS
15 10 5
5
9
0 2
oC
25
2-9 Mei 2011
Under-estimated
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
