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.