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• they deliver rearward sloping baroclinic structures, which should generally be more realistic. 
  
• the spread of outcomes grows realistically.
• the code is fairly inexpensive to run (it has a low resolution (320km) and there .  There is no evidence yet that higher resolution SVs would improve ensemble skill).
  

 The disadvantages of the Singular Vectors are:

• they don’t directly take into account analysis uncertainty, nor observation coverage or accuracy.
• they produce rather localized variability (in the very short range).
• they under-develop variability in tropical regions (tropical singular vectors are employed to try to offset this problem)

Points to note:

• Average SV total energy charts can be used to identify unstable regions. 
• SVs (i.e. the SV perturbations applied) tend to be localized in areas of strong barotropic and baroclinic instability.Average
• SV total energy charts can be used to identify unstable regions. SV growth tends to be characterized by characterized during the model run by:
  • an upscale
  and
  • energy transfer.
  • an upward energy transfer (most rapid for smaller scales)
  , with
  • .
  • initial
  -time
  • potential energy being converted
  , during the model run,
  • into kinetic energy.
• Information for the final-time synoptic-scale structure is contained in the sub-synoptic scale SVs.  At initial time:
  
  • SVs with sub-synoptic-scale wavenumbers at initial time may grow very rapidly to reach synoptic scales.
    
  • SVs with large scale wavenumbers at initial time grow much more slowly than unconstrained, smaller-scale perturbations; the .  The presence or absence of large scales has little effect on SV growth. 
• The atmospheric flow structure in winter tends to be more baroclinically unstable than it does in summer (and during .  During winter the flow over Pacific and Atlantic sectors is on average more unstable than it is in other regions).

Additional Sources of Information

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