Version 13 (modified by Jin Lee, 2 years ago) (diff)


Assess possible degradation of TC forecasts by ACCESS-G caused by not assimilating some observation types

Additional observation types

Following table shows a comparison of observations which are currently used operationally in ACCESS-G3 and those used in OSNN,

Obstype Usage in ACCESS-G3 Usage in UKMO OS42 Comment
METAR, SYNOP used used
Sonde used used
AIREPS, AMDARS used used
ATOVS used NOAA-15, NOAA-18, NOAA-19, MetOp-1, MetOp-2
AIRS used Aqua
IASI used
CrIS used S-NPP
SSMIS used used
FY3C/MWS (?) not used used
FY3B/????instrument???? not used FY-3B
Satwind used used
Scatwind used used
GPSRO used MetOp-1, MetOp-2, TerraSAR-X, TanDEM-X, FY-3C, COSMIC-6
Ground GPS used used
MT/SAPHIR not used used
SEVIRI CSR not used used
AHI CSR ???? H-8
GOES CSR not used GOES-13, GOES-15

Experimental set-up

For each TC case we will use a control and a test. The control will have only the observation types used operationally whereas the test will assimilate additional observation types that we currently do not assimilation but are used by UKMO.

We will mainly assess the difference in track forecasts between control and test. However a question arises as to how robust the difference in track forecasts is. It's possible that the difference arose because of the inherent chaotic nature of the data assimilation system and the forecast model. To allow us to approximately the effect of this randomness we will also create an initial condition by adding global, random perturbations to the control.

Trial periods

The following is a list of TC's used in this experiment and the trial periods,

TC First cycle of trial last cycle of trial lon/lat when first declared Category Comments
KAI-TAK 2017120400 2017122318
TEMBIN 2017121100 2017122518 straight track
HILDA 2017121700 2017122318
BOLAVEN 2017122400 2018010318
IRVING 2017122700 2018010618 Cat 1
JOYCE 2018010100 2018011318 Cat 1
CEBILE 2018011800 2018020818
FEHI 2018011900 2018013018
GITA 2018013100 2018022218 Cat 4
SANBA 2018020100 2018021618
KELVIN 2018020700 2018021918

Starting cycletimes are chosen 10 days prior to the dates when TC's were declared ("Start date"). ???? might need to go a little further to allow analysis of pre-storm environment ????

Obstore files

Obstore files were retrieved from the update runs of UKMO operational OS,

  • all obstypes are tar'ed in a single tarball
  • 6 GB of data per day



  • non-hybrid 4DVar . alternatively hybrid uncouple 4DVar with error modes from an archive of a single run


  • PC2 cloud scheme
  • ????


  • Jim Fraser's List of TCs in West Pacific & Eastern Indian Ocean from G3 trial periods
    • Note "First Lat" and "First Lon" columns show lat/lon when TC's were first named; they are the TC locations on the dates under the column, "Start date"
  • JTWC bogus central pressure observations are available from Dec, 2017
    • the central pressure data are converted to text files and then these text files are read in by OPS

Things to do

  • For Ops_ExtractAndProcess tasks work out how to read UKMO obstore files
    • Do we use exclusively obstores from UKMO - both for control and test?
  • Need initial varstats files

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