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NWP SAF Scatterometer Monitoring

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Use in Numerical Weather Prediction (NWP)

Scatterometer use in NWP at
JMA

Last updated Jul 2015

Back to use in NWP table

Physical characteristics
Deterministic modelling system: Global Spectral Model (GSM) and Meso-Scale Model (MSM) (JMA 2013).
Global Spectral Model (GSM)
  • Spectral model
  • Horizontal resolution: TL959 (0.1875° (20 km), Reduced Gaussian Grid)
  • Vertical resolution: 100 vertical levels, sigma-p hybrid coordinate, lid at 0.01 hPa
Meso-Scale Model (MSM)
  • Grid-point model (817 E-W x 661 N-S), grid centred on Japan
  • Horizontal resolution: 5km at 60N and 30N
  • Vertical resolution: 50 vertical levels, hybrid terrain-following coordinate, lid ~ 22km
Data assimilation method
Global Spectral Model (GSM - Global Analysis)
  • 4D-Var, 6-hr data assimilation window, increment resolution TL319 (~55 km)
  • Analysis times (T): 00, 06, 12, 18 Z
  • Time window: T ± 3 hrs
  • Time constraints (model runtime):
    • Early analysis: 40 min before time window ends
    • Cycle analysis: 8 hr 50 min after time window ends at 00,12 Z, and 4 hr 50 min after time window ends at 06,18 Z
Meso-Scale Model (MSM - Meso-scale Analysis)
  • 4D-Var, 3-hr data assimilation window, increment resolution 15km, 50 vertical levels
  • Analysis times (T): 00, 03, 06, 09, 12, 15, 18, 21 Z
  • Time window: ( T - 3hrs ) - T
  • Time constraints (model runtime):
    • 50 min after time window ends
Scatterometers assimilated
WindSat (if assimilated) should also be included here
Scat name Product Models assimilated
ASCAT-A/B

OSI-SAF Level 2 BUFR 25-km equivalent-neutral wind product produced by KNMI.

GSM
*Note: ASCAT not used in MSM (under development)
 
Monitoring
External monitoring web pages
Generic Quality Control
Blacklisting
  • All wind speeds outside range 0-15 m/s
  • All observations made over ice according to the JMA sea ice analysis
  • All observations with SST less than 274.15 K according to Merged satellite and in-situ data Global Daily Sea Surface Temperature (MGDSST)
Ambiguity removal
  • Performed a-priori by using solution identified as most probable by the GSM first guess
Bias correction
  • None
Thinning
  • Thinning distances are about 110 km (1 degree longitude at the equator) in GSM
Background check
  • Observation of which first guess departure is larger than 5 m/s is rejected.
  • A specialized quality control named 'Group QC' (Ohhashi 2004) is performed for the wind direction.
Specific Quality Control
Scat name ASCAT-A/B
Operational since July 2009 (Metop-A) and November 2013 (Metop-B)
Observation error U/V 4.0m/s (6.0m/s below 30S)
Wind speed range 0-15 m/s
Bias corrected? No
Crosstrack cells used All nodes 1-21 and 22-42
QC thresholds Check supplied wind vector QC flag
 
Observation Operator
Lowest model level
  • Height of lowest model level: ~10m in GSM
Interpolation
  • 10m real wind components are calculated using the stability functions of Louis et al. (1982). Model wind fields are horizontally interpolated to the observation location using standard linear interpolation of the surrounding 4 grid points.
Analysis Increments
  • Observations are considered as real winds.
History of Changes
The list includes the main scatterometer or model changes implemented operationally at JMA.

18/03/14 GSM upgrade from TL959L60 to TL959L100 and raise of the model top level from 0.1hPa to 0.01hPa
28/11/13 ASCAT-B data assimilated in GSM
28/03/13 MSM forecast area extended from 721(E-W) x 577(N-S) to 817(E-W) x 661(N-S) with same grid length
28/07/09 ASCAT-A data assimilated in GSM
 
References

JMA, 2013: 'Outline of the operational numerical weather prediction at the Japan Meteorological Agency'. Appendix to WMO Numerical Weather Prediction Progress Report. Japan Meteorological Agency, Tokyo, Japan. Available on http://www.jma.go.jp/jma/jma-eng/jma-center/nwp/outline2013-nwp/index.htm
Louis, J. F., M. Tiedtke, and J.-F. Geleyn, 1982: A short history of the PBL parameterization at ECMWF. Workshop on planetary boundary layer parameterization, November 1981, ECMWF, Reading, England.
Ohhashi, Y. 2004: Assimilation of QuikSCAT/SeaWinds Ocean Surface Wind Data into the JMA Global Data Assimilation System. RSMC Tokyo Typhoon Center Technical Review, NO. 7, Japan Meteorological Agency, pp 22-27. Available on http://www.jma.go.jp/jma/jma-eng/jma-center/rsmc-hp-pub-eg/techrev.htm