Output Grids for Transects

Several tasks for producing transects use a common methodology for producing the comparison grid for each transect:

# The approximate horizontal resolution (in km) of each transect.  Latitude/
# longitude between observation points will be subsampled at this interval.
# Use 'obs' to indicate no subsampling.
horizontalResolution = obs

# The name of the vertical comparison grid.  Valid values are 'mpas' for the
# MPAS vertical grid, 'obs' to use the locations of observations or
# any other name if the vertical grid is defined by 'verticalComparisonGrid'
# verticalComparisonGridName = obs
verticalComparisonGridName = uniform_0_to_4000m_at_10m
#verticalComparisonGridName = mpas

# The vertical comparison grid if 'verticalComparisonGridName' is not 'mpas' or
# 'obs'.  This should be numpy array of (typically negative) elevations (in m).
verticalComparisonGrid = numpy.linspace(0, -4000, 401)

The horizontalResolution of all transects can be either obs or a number of kilometers. If obs, model data are sampled at latitute and longitude points corresponding to WOCE stations. It a number of kilometers is given, linear interpolation between observation points is performed with approximately the requested resolution. The distance between stations is always divided into an integer number of segments of equal length so the resolution may be slightly above or below horizontalResolution.

The vertical grid is determined by two parameters, verticalComparisonGridName and verticalComparisonGrid. If verticalComparisonGridName = mpas, the MPAS-Ocean vertical coordinate will be interpolated horitontally from grid cell centers to the latitude and longitude of each point along the transect, and the observations will be interpolated vertically to the resulting grid. If verticalComparisonGridName = obs, the vertical grid of the observations is used instead. If verticalComparisonGridName is anything else, it is taken to be the name of a user-defined vertical grid (best to make it descriptive and unique, e.g. uniform_0_to_4000m_at_10m) and verticalComparisonGrid should be assigned a valid array of positive-up depth values (in the form of a python list or numpy array), e.g.:

verticalComparisonGrid = numpy.linspace(0, -4000, 401)

produces points between 0 and -4000 m sampled every 10 m.

Note

Some types of transects (e.g. those produce with geojson files) do not have a vertical grid associated with them (just horizontal latitude/longitude points), meaning that verticalComparisonGridName = obs is not a valid option for tasks with these transects.