/convertR

A climate4R package for unit conversion and variable derivation

Primary LanguageRGNU General Public License v3.0GPL-3.0

convertR: A climate4R package for unit conversion and variable derivation

convertR is an R package performing unit conversion and variable derivation using the climate4R Common Data Model.

Installation and requirements

Physical quantity handling is done via the Unidata's UDUNITS-2 software libraries, tailoring the functionalities of the R package udunits2 to the climate4R framework. Thus, the C-based UDUNITS-2 package must be installed in your system prior to package installation (link to installation instructions).

Then, install_github can be used:

devtools::install_github("SantanderMetGroup/convertR")

Unit conversion

The function udConvertGrid is used for unit conversion. An example follows:

library(convertR)
data("ps.iberia")
transformeR::getGridUnits(ps.iberia)
## [1] "Pascals"
range(ps.iberia$Data)
## [1]  86657.5 105690.0
ps.mmHg <- udConvertGrid(ps.iberia, new.units = "mmHg")
transformeR::getGridUnits(ps.mmHg)
## [1] "mmHg"
range(ps.mmHg$Data)
## [1] 649.9846 792.7401

Derivation of physical quantities

In the following table the available variable derivations are summarized, including the input variables. The nomenclature of the input variables to calculate the derivations is according to the climate4R vocabulary (see loadeR::c4R.vocabulary())

The (*) symbol indicates that the function is planned but not yet available.

function Definition psl ps tas dpds tdps zgs huss hurs rsds rlds
psl2ps Sea-level pressure to surface pressure X X X
ps2psl Surface pressure to sea-level pressure X X X
rad2cc Radiation to cloud cover X X
huss2hurs Specific humidity to relative humidity X X X
hurs2huss Relative humidity from specific humidity X X X
tas2ws Saturation vapor pressure from temperature X X
hurs2w Water vapor mixing ratio from relative humidity X X X
dpds2hurs* Relative humidity from dew-point depression X X X
tdps2hurs Relative humidity from dew-point temperature X X
hurs2tdps Dew-point temperature from relative humidity X X
huss2pvp Partial vapor pressure from specific humidity X X

The input variables do not require to be in specific units, as all the necessary unit conversions are internally undertaken by the unit converter utility.