Output

We write output to HDF5. In the Input struct the user can specify a dictionary of OutputSpec, specifying how much and at which interval to write output. Typically, you'd want a full topographic output with lower time resolution, and choose a transect with full time resolution. For example, on the ALCAP model:

const INPUT = ALCAP.Input(
    box = Box{Coast}(grid_size = (300, 150), phys_scale = 50.0u"m"),
    time = TimeProperties(Δt = 50.0u"yr", steps = 20_000),
    output = Dict(
        :topography => OutputSpec(write_interval = 200),
        :profile => OutputSpec(slice = (:, 75))),

    ...)  # add more options

Saving the full output of this simulation would take several hundreds of gigabytes, not gargantuan, but a bit unwieldy if you want to save many simulation runs. With this output specification, we cut down on this significantly.

@kwdef struct Input <: AbstractInput
    output = Dict(:full => OutputSpec((:, :), 1))
end

The default is to write all output, which is fine for smaller runs. The slice argument of OutputSpec will accept three different forms:

• (:, :) (default) output the full area of the model.
• (<n>, :) or (:, <n>) output a slice of the model, either with a fixed $x$ or a fixed $y$ coordinate. In our examples we always have the $x$ axis orthogonal to the shoreline, so slicing with a fixed $y$ (the second form) is what we use.
• (<m>, <n>), output a column of the model. If you have a very precise experiment workflow, this could be of use. You'll have to specify each column as a separate output. Most of the time though, we can extract columns from slice data in a post-processing stage, so if all your columns have the same $y$ coordinate, taking a slice is the preferred option.

If an output with a write_interval that does not divide the total number of timesteps is specified, the output array will contain div(time.steps, write_interval) values and the value for the remainder of the steps at the end of the model will not be recorded (since this will not cover an equal interval of time as the rest of the values).

@compose module Output
using ..Common

<<output-spec>>
end