Use of AMVs in the JMA model
Physical characteristics
Global Model
- Spectral model
- Horizontal resolution:
- Model: TQ959 (∼0.1250° (13 km), Reduced Gaussian Grid).
- Analysis: Outer loop is TQ959, inner loop is TL319 (∼0.5625° (55 km), Reduced Gaussian Grid).
- Vertical resolution: Surface + 128 levels up to 0.01 hPa.
- Analysis times (T): 00, 06, 12, 18 Z
Data assimilation method
Global Model
- Hybrid LETKF/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=00,12Z) and 4 hr 50 min after time window ends (T=06,18Z)
AMV types assimilated
Global Model
- Meteosat-9,10 BUFR IR10.8, VIS0.8, cloudy WV(6.2, 7.3)
- Himawari-9 BUFR IR(3.9, 10.4), VIS(0.64), cloudy WV(6.2, 6.9, 7.3)
- GOES-16,18 BUFR IR(3.9, 11.2), VIS0.64, cloudy/clear sky WV(6.2, 6.9, 7.3)
- CIMSS MODIS Terra A/N IR, cloudy WV
- CIMSS MODIS Aqua A/N IR, cloudy WV
- NESDIS and direct broadcast CIMSS MODIS Aqua IR, cloudy WV, clear sky WV
- CIMSS and NESDIS AVHRR NOAA-15
- CIMSS AVHRR NOAA-18,-19, Metop-B
- NESDIS VIIRS Suomi-NPP,NOAA-20
- CIMSS LEOGEO
- EUMETSAT AVHRR Dual-Metop
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 and VIIRS winds below 700 hPa
- NESDIS AVHRR winds above 400 hPa
- VIIRS winds above 300 hPa
- VIIRS winds over land below 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
- Dual-Metop winds between 50S and 50N
- Dual-Metop winds above 300 hPa
- Dual-Metop winds over land below 700 hPa
- All polar winds at the extratropics poleward of 88N or 88S
- All geostationary winds above 175 hPa or below 975 hPa except Himawari-9 winds
- All geostationary winds between 400 hPa and 825 hPa except Himawari-9 winds
- All geostationary IR winds above 275 hPa at the extratropics poleward of 20N or 20S except Himawari-9 winds
- All geostationary WV winds above 225 hPa at the extratropics poleward of 20N or 20S except Himawari-9 winds
- Himawari-9 IR and VIS winds over land below 700 hPa
- Meteosat-9 IR and VIS winds over land below 700 hPa
Blacklisting by wind speed
- 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
- Reject for O-B vector difference > 14.1 m/s for GOES winds
QI thresholds
extratropics | tropics | |||||||
HL (NH/SH) | ML (NH/SH) | LL (NH/SH) | HL | ML | LL | |||
Meteosat-9,10 | QI1 | IR | 94/90 | 90/90 | 80/80 | 82 | 88 | 85 |
VIS | -/- | -/- | 82/82 | – | – | 82 | ||
WV | 94/94 | -/- | -/- | 84 | – | – | ||
GOES-16,18 | QI2 | IR | 90 | 90 | 90 | 87 | 87 | 87 |
VIS | – | – | 90 | – | – | 87 | ||
WV | 90 | – | – | 87 | – | – | ||
Himawari-9 | 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 and Dual-Metop) |
QI1 | IR | 60 | 60 | 60 | – | – | – |
VIS | – | – | – | – | – | – | ||
WV | 60 | 60 | – | – | – | – | ||
LEOGEO | QI1 | IR | 70 | 70 | 70 | – | – | – |
Dual-Metop | QI1 | IR | 85 | 85 | 85 | – | – | – |
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 200 km.
- 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.
- 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 * σ
- Reject for |O-B| > a + 3 * σ
- Between these criteria, the data undergoes consistency check.
where “a” is predefined criteria calculated from averaged O-B and σ 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 |