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extracts values from complex BUFR messages where coordinate descriptors are required to locate particular data. Briefly, when a BUFR element descriptor described as F'XX'YYY has an F of 0 and an XX of less than 10, it is a 'coordinate descriptor', which means that it retains its current value until redefined. In this way, a set of observations 'inherit' the same value for such a descriptor without it appearing explicitly for each observation. The purpose of this icon is to extract data that can only be described by using coordinate descriptors; for more complete BUFR data extraction, it can be used with BUFR output from the Observation Filter icon. The output is a geopoints file.

generates plots of spectra as a function of Legendre polynomial order.

The macro language equivalent is

bufr

spec_

picker

graph().


The

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Spectra Editor

The Spectra editor belongs to a type of editor known as family editor which allows related sets of input specifications to be grouped in the same icon editor, each in its own tabbed pane. The available working input pane is :

Spec Graph - To plot a graph of amplitude against N, where N is the Legendre polynomial order using the first field in the input data.

Data

Specifies the data required for the application. The assist button provides a tailor made MARS request in case you need some guidance in the data specification.

Truncation

 Specifies the highest wave number in spectra plots.

Data

Drop any icon containing or returning BUFR data. This may be, for example, a MARS Retrieval (of observations) icon, a BUFR file icon or an Observation Filter icon (provided it outputs BUFR, not geopoints).

Output

Specifies the output format you want. Specify one of the geopoints formats (Geographical Points, Geographical Polar Vectors or Geographical X Y Vectors).

Parameter

To specify a parameter enter its unique BUFR descriptor value (a numerical code). Geographical Polar Vectors and Geographical X Y Vectors require two descriptors, separated by a slash (/). The descriptor value is of the form XXYYY, where XX defines the class (e.g. 12 = Temperature class) and YYY the parameter within that class (e.g. 12004 = Dry bulb Temperature at 2m). These descriptor values are different from the ones of the GRIB format. If you do not know the descriptor value, click-left on the assist button to obtain a check list of parameters and associated descriptors. This list only contains the most common parameters. If the one you need is not on the list you can use the BUFR Examiner (right-click, Examine the BUFR file) to see what is there, or up its descriptor value in the "BUFR Reference Manual" (available from http://www.ecmwf.int/products/data/software/bufr.html#description) - see "BUFR Table B", pages 6-19. The significance of code and flag values for non-quantitative parameters are given in the same manual, in "BUFR code table", pages 22-70.

Missing Data

If set to Ignore, missing data is not included in the output file; this is the default behaviour. If set to Include, missing data will be output to the geopoints file, its value being set to that specified by Missing Data Value. Note that when the output format is one of the two geopoints vector formats, the observation is considered missing if one or both of the parameters are missing.

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