Vader Variable Changes

Each variable change that can be performed by Vader is defined by code called a “Recipe” (from a design metaphor within the Vader code.) Each recipe shares the same structure:

• Name - The name of the recipe which can be used in yaml to specify the recipe parameters. (Follows the recipe naming standard.)

• Variable Produced - The variable that will be created by the algorithm, usually called the “product”.

• Input Variables - Usually called “ingredients”, these are the variables required as input for the algorithms.

• Number of Levels - The number of levels for the Atlas Field for the product. Must be a constant or a function of the number of levels of the ingredients.

• FunctionSpace - The Atlas FunctionSpace for the Atlas Field for the product. Can be specific FunctionSpace or the same as one of the ingredients.

• hasTLAD - This is a boolean flag indicating whether the recipe has implemented the tangent linear and adjoint (TL/AD) of the transformation. (These are optional, while the non-linear transformation is required.)

• Algorithms - Put into methods called executeNL (and executeTL and executeAD if hasTLAD is true), this code performs the calculations on the inputs and produces the output.

• Required Configuration Variables - Some recipes reference values that are stored in VADER’s configuration variables. These variables must be defined in the VaderConstructConfig class that is passed to the VADER constructor.

• Parameters - Recipes can have optional parameters which can configure their behavior. These parameters should not be required.

Below is a list of the recipes that have been implemented in VADER:

• Potential Temperature from temperature and surface pressure
• Potential Temperature from temperature and pressure to kappa
• Air pressure at midpoints from air pressure at interface
• Air pressure at interface from ak/bk
• Air pressure at interface from pressure thickness
• Log of air pressure at interface from air pressure at interface
• Air pressure thickness from pressure at interface
• Air pressure to kappa from air pressure at interface
• Surface air pressure from air pressure thickness
• Temperature from potential temperature and exner
• Temperature from virtual temperature and specific humidity
• Virtual Temperature from potential temperature and exner
• Dry air density levels minus one from virtual potential temperature and pressure
• U-wind at 10m from eastward wind
• V-wind at 10m from northward wind