Loading NetCDF datafiles

Underlying assumptions

There are NetCDF files in a folder (in what follows, argument foldername) that contain (time-dependent) scalar/velocity fields on a regular (in space and time) grid spanning the whole globe in longitude/latitude units (in particular, you do not care about the poles).
Each file corresponds to a single-time snapshot of this field (and spacing between times are constant).
The filenames are orded ascending with time.
Each file has a field with longitude and latitude coordinates as a 1d array (uniform accross files).
You have a regular expression (e.g. r"^nrt_global_allsat_phy_l4_([0-9][0-9][0-9][0-9])([0-9][0-9])([0-9][0-9])_.*.nc$") that matches only the files you want (in what follows, argument schema).

Loading velocity fields

OceanTools.read_ocean_velocities — Function

read_ocean_velocities(foldername,start_date,end_date,boundary_t, [schema,LL_space=nothing,UR_space=nothing,...])

Reads velocity fields in a space-time window. Uses the whole globe if LL_space and UR_space are nothing. Else the rectangle of points will include spatially include the rectangle bounded by LL_space and UR_space.

The first timestep loaded is the first one in the folder foldername matching the regular expression schema where the "time" variable (converted to Int via kwarg date_to_int) is not less than start_date.

Spacing of "time" is assumed to be 1 day, change date_to_int if your data is different (note that the units of the velocity fields in the files were assumed to be in m/s and are converted to deg/day, you will have to manually rescale if spacing is not 1 day ). The range will include end_date

Supports 360-periodic longitude in the sense that LL_space[1] can larger than UR_space[1]. However, it cannot extend by more than one period. If you are very close to one period use the whole globe to avoid issues.

Other keyword arguments are:

lon_label with default "longitude"
lat_label with default "latitude"
remove_nan with default true, sets missing values to 0 instead of NaN
array_ctor with default SharedArray{Float64} to specify underlying storage to use.
date_to_int with default _daysSince1950 is the method for converting DateTime objects to Int
filename_match_to_date (if not equal to nothing) converts the match of the regex schema with the filename into the (integer) date

of the contents.

Returns (res_full, Ust1, (Lon, Lat, times)) where res_full is the corresponding ItpMetdata object and Ust1 is a slice of the x-component at the first timestep without NaNs removed

source

Loading scalar fields

OceanTools.read_ocean_scalars — Function

read_ocean_scalars(args...; scalar_field_name="ssh", kwargs...)

Reads in a scalar field, otherwise like read_ocean_velocities. Resulting data field in the ItpMetdata is a 1-tuple with an array (of type given by array_ctor).

source

In each case, the end result contains an ItpMetadata that contains all of the data needed for interpolation.

Pseudocode example

p, _ = read_ocean_velocities(arguments)
uv_trilinear(u,p,t)