WRF - Developmental Testbed Center

15. DOMINANT_CATEGORY : When specified as a character string, the effect is tocause geogrid to compute the dominant category from the fractional categorical field, andto output the dominant category field with the name specified by the value ofdominant_category. This option can only be used for fields withdest_type=categorical. Default value is null (i.e., no dominant category will becomputed from the fractional categorical field).16. DOMINANT_ONLY : When specified as a character string, the effect is similar tothat of the dominant_category keyword: geogrid will compute the dominant categoryfrom the fractional categorical field and output the dominant category field with the namespecified by the value of dominant_only. Unlike with dominant_category, though,when dominant_only is used, the fractional categorical field will not appear in thegeogrid output. This option can only be used for fields with dest_type=categorical.Default value is null (i.e., no dominant category will be computed from the fractionalcategorical field).17. DF_DX : When df_dx is assigned a character string value, the effect is to causegeogrid to compute the directional derivative of the field in the x-direction using a centraldifference along the interior of the domain, or a one-sided difference at the boundary ofthe domain; the derivative field will be named according to the character string assignedto the keyword df_dx. Default value is null (i.e., no derivative field is computed).18. DF_DY : When df_dy is assigned a character string value, the effect is to causegeogrid to compute the directional derivative of the field in the y-direction using a centraldifference along the interior of the domain, or a one-sided difference at the boundary ofthe domain; the derivative field will be named according to the character string assignedto the keyword df_dy. Default value is null (i.e., no derivative field is computed).19. Z_DIM_NAME : For 3-dimensional output fields, a character string giving the nameof the vertical dimension, or z-dimension. A continuous field may have multiple levels,and thus be a 3-dimensional field, and a categorical field may take the form of a 3-dimensional field if it is written out as fractional fields for each category. No defaultvalue.Description of index OptionsRelated to the GEOGRID.TBL are the index files that are associated with each static dataset. An index file defines parameters specific to that data set, while the GEOGRID.TBLfile describes how each of the data sets should be treated by geogrid. As with theGEOGRID.TBL file, specifications in an index file are of the form keyword=value.Below are possible keywords and their possible values.WRF-NMM V3: User’s Guide 3-40