Custom SingleLevel variables

The Climate Data Store provides a very large number of SingleLevel variables. As such, we only predefine a small subset of the variables available on CDS in ERA5Reanalysis.jl. However, only SingleVariable type variables can be downloaded from the Climate Data Store - SingleCustom type variables are not defined on CDS. Therefore, we allow the user the option to define if the custom SingleLevel variable they are defining exists on the Climate Data Store, and store it as a SingleVariable type.

Defining a new SingleVariable or SingleCustom

To define both SingleVariable and SingleCustom variables, we use the funciton SingleVariable(). To create a SingleCustom variable, the keyword argument inCDS must be set to false.

ERA5Reanalysis.SingleVariable — Type
SingleVariable(
    ST = String;
    varID :: AbstractString,
    lname :: AbstractString = "",
    vname :: AbstractString,
    units :: AbstractString,
    inCDS :: Bool = true
) -> evar :: SingleLevel

Create a custom Single-Level variable that is not in the default list exported by ERA5Reanalysis.jl. These variables are either available in the CDS store (whereby they can be both downloaded analyzed), or not (in which case means that they were separately calculated from other variables and analyzed).

Keyword Arguments

  • varID : variable ID (in string format) used in the NetCDF file
  • lname : long-name for variable (used in specifying variable for CDS downloads)
  • vname : user-defined variable name
  • units : user-defined units of the variable
  • inCDS : Boolean that indicates if this variable is available on the CDS store. True if available.

Removing Custom PressureLevel Variables

To remove a SingleLevel variable, we can use the rmSingle() function:

ERA5Reanalysis.rmSingle — Method
rmSingle( varID :: AbstractString ) -> nothing

Remove the Single-Level Variable with the ID varID from the lists.

Arguments

  • RegID : The keyword ID that will be used to identify the Single-Level Variable that is to be removed

An Example!

In this example, we add two SingleLevel variables to the list:

  • hvc, for High Vegetation Cover, which is a downloadable variable in the CDS
  • eke, for Eddy Kinetic Energy, which is not downloadable and must be calculated using other variables

The Eddy Kinetic Energy is calculated by the following:

\[E = \frac{1}{2g} \int_0^{p_s} \overline{u'^2} + \overline{v'^2} \>dp\]

And it is often used as a measure of storm-track intensity.

julia> using ERA5Reanalysis
julia> SingleVariable(
           varID = "cvh",
           units = "0-1",
           vname = "High Vegetation Cover",
           lname = "high_vegetation_cover",
       )ERROR: 2023-04-03T03:55:13.205 - ERA5Reanalysis.jl - The SingleVariable "cvh" has already been defined,please use another identifier.
julia> SingleVariable(
           varID = "eke",
           units = "J m**-2",
           vname = "Eddy Kinetic Energy",
           lname = "eddy_kinetic_energy",
           inCDS = false
       )The Single-Level Variable "eke" has the following properties:
    Variable ID    (varID) : eke
    Long Name      (lname) : eddy_kinetic_energy
    Variable Name  (vname) : Eddy Kinetic Energy
    Variable Units (units) : J m**-2
julia> tableSingles()ERROR: MethodError: no method matching pretty_table(::Matrix{Any}, ::Vector{String}; alignment=[:c, :c, :l, :c, :l], crop=:none, tf=PrettyTables.TextFormat(' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', '-', [:begin, :header, :end], :all))
Closest candidates are:
  pretty_table(!Matched::IO, ::Any; kwargs...) at ~/.julia/packages/PrettyTables/pZvTh/src/print.jl:705
  pretty_table(!Matched::Type{String}, ::Any; color, kwargs...) at ~/.julia/packages/PrettyTables/pZvTh/src/print.jl:707
  pretty_table(!Matched::Type{HTML}, ::Any; kwargs...) at ~/.julia/packages/PrettyTables/pZvTh/src/print.jl:713
  ...
julia> rmSingle.(["eke","hvc"])[ Info: 2023-04-03T03:55:13.319 - ERA5Reanalysis.jl - Successfully removed the Single-Level variable defined by "eke"
┌ Warning: 2023-04-03T03:55:13.321 - ERA5Reanalysis.jl - "hvc" is not a valid SingleVariable identifier, use the function SingleVariable() or SingleCustom() to add this ERA5Variable to the list.
└ @ ERA5Reanalysis ~/.julia/packages/ERA5Reanalysis/o6ANm/src/variable/single.jl:200
┌ Warning: 2023-04-03T03:55:13.321 - ERA5Reanalysis.jl - No Single-Level variable defined by "hvc" exists, please make sure you specified the correct variable ID
└ @ ERA5Reanalysis ~/.julia/packages/ERA5Reanalysis/o6ANm/src/variable/single.jl:230
2-element Vector{Nothing}:
 nothing
 nothing
julia> isSingle("eke",throw=false) # don't throw error, just show warning┌ Warning: 2023-04-03T03:55:13.395 - ERA5Reanalysis.jl - "eke" is not a valid SingleVariable identifier, use the function SingleVariable() or SingleCustom() to add this ERA5Variable to the list.
└ @ ERA5Reanalysis ~/.julia/packages/ERA5Reanalysis/o6ANm/src/variable/single.jl:200
false