Local definition 9: Singular vectors and ensemble perturbations

Local definitions

Octets Key Type Contents
41 localDefinitionNumber unsigned ECMWF local GRIB use definition identifier. 9 = Singular vectors and ensemble perturbations.
42 class codetable Class
43 type codetable Type
44-45 stream codetable Stream
46-49 experimentVersionNumber ksec1expver Version number or experiment identifier. (4 ASCII characters, right justified)
50-51 forecastOrSingularVectorNumber unsigned If type 60, the perturbed forecast number. If type 62 or 63, the singular vector number.
52-92 These elements are set to zero for type = 60. Otherwise:
52-53 numberOfIterations unsigned Number of iterations.
54-55 numberOfSingularVectorsComputed unsigned Number of singular vectors computed.
56 normAtInitialTime unsigned Norm used at initial time.
57 normAtFinalTime unsigned Norm used at final time.
58-61 multiplicationFactorForLatLong unsigned Multiplication factor to convert latitude/longitude and accuracy from real to integer.
62-65 northWestLatitudeOfLPOArea signed Latitude in degrees of north-west corner of LPO area multiplied by KSEC1(47).
66-69 northWestLongitudeOfLPOArea signed Longitude in degrees of north-west corner of LPO* area multiplied by KSEC1(47).
70-73 southEastLatitudeOfLPOArea signed Latitude in degrees of south-east corner of LPO* area multiplied by KSEC1(47).
74-77 southEastLongitudeOfLPOArea signed Longitude in degrees of south-east corner of LPO* area multiplied by KSEC1(47).
78-81 accuracyMultipliedByFactor unsigned Accuracy multiplied by KSEC1(47).
82-83 numberOfSingularVectorsEvolved unsigned Number of singular vectors evolved.
- Ritz numbers. RITZ = KSEC1(55)*EXP( LOG(10.0*KSEC1(54) ) Thus:
84-87 NINT_LOG10_RITZ signed NINT( LOG10(RITZ)-5 )
88-91 NINT_RITZ_EXP signed NINT( RITZ/( EXP(LOG(10.0*KSEC1(54) )
92 Spare (set to zero)
Notes:

( 1) LPO = Local Projection Operator, an operator applied during the singular vector computation to confine the area where the final time norm is computed (eg Northern Hemisphere extra-tropics).

( 2) A negative Ritz number or a negative latitude/longitudes value is stored as positive number and its the most significant bit is set to 1.