KSEC1 element Contents GRIB octet Recommended GRIB_API keys Coded GRIB_API keys Comments
37 
ECMWF local GRIB use definition identifier.
9 = Singular vectors and ensemble perturbations.
41 localDefinitionNumber localDefinitionNumber
38 Class 42 class marsClass
39 Type 43 type marsType
40 Stream 44-45 stream marsStream
41 
Version number or experiment identifier.
(4 ASCII characters, right justified)
 46-49 expver experimentVersionNumber
42 
If type 60, the perturbed forecast number.
If type 62 or 63, the singular vector number.
 50-51 forecastOrSingularVectorNumber
 forecastOrSingularVectorNumber
43-55 These elements are set to zero for type = 60. Otherwise: 52-92


43 Number of iterations. 52-53 numberOfIterations
 numberOfIterations
44 Number of singular vectors computed. 54-55 numberOfSingularVectorsComputed
 numberOfSingularVectorsComputed
45 Norm used at initial time. 56 normAtInitialTime
 normAtInitialTime
46 Norm used at final time. 57 normAtFinalTime
 normAtFinalTime
47 Multiplication factor to convert latitude/longitude and accuracy from real to integer. 58-61 multiplicationFactorForLatLong
 multiplicationFactorForLatLong
48 Latitude in degrees of north-west corner of LPO area multiplied by KSEC1(47). 62-65 northWestLatitudeOfLPOArea
 northWestLatitudeOfLPOArea
49 Longitude in degrees of north-west corner of LPO* area multiplied by KSEC1(47). 66-69 northWestLongitudeOfLPOArea
 northWestLongitudeOfLPOArea
50 Latitude in degrees of south-east corner of LPO* area multiplied by KSEC1(47). 70-73 southEastLatitudeOfLPOArea
 southEastLatitudeOfLPOArea
51 Longitude in degrees of south-east corner of LPO* area multiplied by KSEC1(47). 74-77 southEastLongitudeOfLPOArea
 southEastLongitudeOfLPOArea
52 Accuracy multiplied by KSEC1(47). 78-81 accuracyMultipliedByFactor
 accuracyMultipliedByFactor
53 Number of singular vectors evolved. 82-83 numberOfSingularVectorsEvolved
 numberOfSingularVectorsEvolved
54-55 
Ritz numbers.
RITZ = KSEC1(55)*EXP( LOG(10.0*KSEC1(54) )
Thus:
 -


54 NINT( LOG10(RITZ)-5 ) 84-87 NINT_LOG10_RITZ NINT_LOG10_RITZ
55 NINT( RITZ/( EXP(LOG(10.0*KSEC1(54) ) 88-91 NINT_RITZ_EXP NINT_RITZ_EXP
- Spare (set to zero) 92


*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).

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.