AMV usage in the JMA NWP model

Use of AMVs in the JMA model

Physical characteristics

Global Model

  • Spectral model
  • Horizontal resolution:
    • Model: TL959 (0.1875° (20 km) Reduced Gaussian Grid).
    • Analysis: outer loop is TL959, inner loop is TL319 (0.5625° (55 km) Reduced Gaussian Grid).
  • Vertical resolution: Surface + 100 levels up to
    0.01 hPa.

  • Analysis times (T): 00, 06, 12, 18 Z

Data assimilation method

Global Model

  • 4D-Var, 6 hr time window
  • Time window: T ± 3 hr
  • Time constraints (model runtime):
    • Early analysis: 40 min before time window ends
    • Cycle analysis: 8 hr 50 min after time window
      ends(T=00,12), 4 hr 50 min after time window
      ends(T=06,18)

AMV types assimilated

Global Model

  • Meteosat-11 BUFR IR10.8, VIS0.8, cloudy WV(6.2,7.3)
  • Meteosat-8 BUFR IR10.8, VIS0.8, cloudy WV(6.2,7.3)
  • Himawari-8 BUFR IR(3.9,10.4), VIS(0.64), cloudy WV(6.2,6.9,7.3)
  • GOES-15 BUFR IR, VIS, cloudy WV
  • CIMSS MODIS Terra A/N IR, cloudy WV
  • CIMSS MODIS Aqua A/N IR, cloudy WV
  • NESDIS and direct broadcast CIMSS MODIS Terra IR, cloudy WV,
    clear sky WV
  • NESDIS and direct broadcast CIMSS MODIS Aqua IR, cloudy WV,
    clear sky WV
  • CIMSS and NESDIS AVHRR NOAA-15
  • CIMSS AVHRR NOAA-16/-18/-19,Metop-A,-B
  • CIMSS LEOGEO

Global quality control

Blacklisting in space

  • MODIS IR winds for NH above 300 hPa or below 900 hPa
  • MODIS WV and CSWV winds for NH above 300 hPa or below 550 hPa
  • MODIS IR and WV winds for SH above 300 hPa or below 550 hPa
  • MODIS CSWV winds for SH above 350 hPa or below 550 hPa
  • MODIS IR and WV winds for SH above 300 hPa or below 550 hPa
  • MODIS CSWV winds for SH above 350 hPa or below 550 hPa
  • ALL AVHRR winds below 700 hPa
  • NESDIS AVHRR winds above 400 hPa
  • LEOGEO winds above 300 hPa or below 900 hPa
  • LEOGEO winds between 600 hPa and 640 hPa
  • LEOGEO winds at the extratropics poleward of 70N or 70S
  • LEOGEO winds at the extratropics poleward of 60S between 640 hPa and 900 hPa
  • All polar winds (MODIS/AVHRR/LEOGEO) at the extratropics poleward of 88N or 88S
  • All geostationary winds above 175 hPa or below 975 hPa except Himawari-8 winds
  • All geostationary winds between 400 hPa and 825 hPa except Himawari-8 winds
  • All geostationary IR winds above 275 hPa at the extratropics poleward of 20N or
    20S except Himawari-8 winds
  • All geostationary WV winds above 225 hPa at the extratropics poleward of 20N or
    20S except Himawari-8 winds
  • Himawari-8 IR and VIS winds over land below 700 hPa.
  • Meteosat-8 IR and VIS winds over land below 700 hPa.

Blacklisting by wind speed in Japan and surrounding area (Area of super-observation processing)
wind speed 15 m/s and over 15 m/s and large u-component wind speed
compared with v-component wind speed and O-B over 3 m/s or under -2 m/s

QI thresholds

  extratropics tropics
HL (NH/SH) ML (NH/SH) LL (NH/SH) HL ML LL
Meteosat-8 QI1 IR 94/90 90/90 80/80 82 88 85
VIS -/- -/- 82/82 82
WV 94/94 -/- -/- 84
Meteosat-11 QI1 IR 94/90 90/90 80/80 82 88 85
VIS -/- -/- 82/82 82
WV 94/94 -/- -/- 84
GOES-15 QI1 IR 60/60 60/60 60/60 60 60 60
VIS -/- -/- 60/60 60
WV 60/60 -/- -/- 60
Himawari-8 QI1 IR 85/92 94/91 88/93 85 85 88
VIS 88/96 95/96 85/85 95 90 85
WV 85/95 85/85 -/- 85 85
Polar orbit satellites (except
LEOGEO)
QI1 IR 60/60 60/60 60/60
VIS -/- -/- -/-
WV 60/60 60/60 -/-
LEOGEO QI1 IR 70/70 70/70 70/70
VIS -/- -/- -/-
WV -/- -/- -/-

tropics:
20S-20N
extratropics: polewards of 20S/N

HL:
10-400 hPa
ML: 400-700 hPa
LL: 700-1000 hPa
NH: Northern Hemisphere
SH: Southern Hemisphere

QI1 – EUMETSAT QI with first guess check
QI2 – EUMETSAT QI without first guess check
RFF – Recursive
Filter Function (CIMSS/NESDIS)

For information on how
the quality indicators are formulated see Holmlund (1998, Weather
Forecasting
13 1093-1104) and Hayden and Purser
(1995, Journal of Applied Meteorology 34 3-15).

Thinning

  • All geostationary winds thinned in 2° by 2° by 100 hPa boxes.
    A minimum horizontal distance is 200km.
  • Wind selected by highest QI and proximity to analysis time and
    centre of thinning boxes for all geostationary winds
  • All polar winds thinned in 1.5° by 1.5° by 100 hPa boxes.
  • Wind selected by proximity to analysis time and centre of
    thinning boxes for all polar winds
  • Only one wind selected per box in the 6 hour time window for
    all winds.
Super-observation processing

  • The super-observation data are produced by averaging hourly Himawari-8 winds in 1° by 1° by 100 hPa boxes.
  • The data are only produced over Japan and the surrounding areas (20N-45N, 120E-150E).

Background check

  • Pass for |O-B| <= a+1.5*sigma
  • Reject for |O-B| <= a+3*sigma
  • Between these criteria, the data undergoes consistency check.

where
“a” is predefined criteria
calculated from averaged O-B, dependent on wind level
sigma is predefined observation error, dependent on wind level.
O-observation, B-first guess

Observation errors

Level (hPa) 1000 850 700 500 400 300 200 100 50 30 10
Error (m/s) 4.5 4.5 4.5 4.5 4.3 5.3 5.8 6.8 7.0 7.2 7.6