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makeNcmlDataset

Description

Generates a NcML file from a collection of netCDF files.

Usage

makeNcmlDataset(source.dir, ncml.file) 

Arguments

The output is a NcML file named as file.name which will be stored in the output.dir.

Details

Value

Creates a NcML file at the specified location

Notes

A NcML file is a ?XML representation of netCDF metadata. This is approximately the same information one gets when dumping the header of a netCDF file (e.g. by typing on the terminal the command ncdump -h). By means of NcML it is possible to create virtual datasets by modifying and aggregating other datasets, thus providing maximum flexibility and ease of access to data stored in collections of files containing data from different variables/time slices. The function makeNcmlDataset is intended to deal with reanalysis, forecasts and other climate data products, often consisting of collections of netCDF files corresponding to different variables and partitioned by years/decades or other time slices. It operates by applying to types of ?aggregation operations:

  1. Union: Performs the union of all the dimensions, attributes, and variables in multiple NetCDF files
  2. JoinExisting: Variables of the same name (in different files) are connected along their existing, outer dimension, called the aggregation dimension. In this case the aggregation dimension is time.

dataInventory

Description

Provides summary information about the main characteristics of a NcML dataset.

Usage

dataInventory(ncml.file)

Arguments

Value

The output of the function consists of a list of variable length, depending on the number of variables contained in the dataset, following this structure:

Details

A common need prior to data analysis is to get an overview of all data available and their structure (variables, dimensions, units, geographical extent, time span ...). Note that the function provides an overview of the raw data as they are stored in the original data files. The units may change after loading the function if conversions are applied via dictionary.

loadSystem4

Description

Loads hindcast/forecast data from ECMWF's System4 model by remotely accessing the SPECS-EUPORIAS THREDDS Data Server.

Usage

loadSystem4(dataset, var, members, lonLim, latLim, season, years, leadMonth)

Arguments

Details

Currently, accepted values for the argument var are tas, tasmin, tasmax, pr or mslp, as internally defined in the vocabulary of System4 following the nomenclature displayed in the table below. However, note that new variables and datasets will be progressively included. Further details regarding the nature and temporal aggregation of these variables can be obtained through the dataInventory function.

Short NameLong nameUnitsInstantaneous
tasmaxMaximum temperature at 2 metresdegCNo
tasminMinimum temperature at 2 metresdegCNo
tasMean temperature at 2 metresdegCYes
prTotal precipitation accumulatedmmNo
mslpMean sea level pressurePaYes

Value

The output returned by the function consists of a list with the following elements providing the necessary information for data representation and analysis:

Note

A worked example describing a multi-model selection of a dataset is presented in the tutorial, which can be downloaded ?here, or in the section Examples?.