Skip to contents

Gradients and fronts

A front is where a field changes sharply, not where it is large. These compute the change and then locate it.

distance_to_contour()
Distance to a contour of a covariate
distance_to_front()
Distance to the nearest front
distance_to_isobath()
Distance to isobaths
distance_to_shore()
Distance to the nearest shoreline
front_frequency()
How often a place is frontal
horizontal_gradient()
Horizontal spatial gradient of a covariate
temporal_gradient()
Temporal gradient of a covariate
vertical_gradient()
Vertical temperature gradient

Flow and mixing

Quantities derived from velocity fields: how fast, how deformed, how strongly stratified, and how long water stays.

buoyancy_frequency()
Buoyancy frequency between two depths
current_speed()
Current speed from velocity components
eady_growth_rate()
Eady growth rate of baroclinic instability
eke()
Eddy kinetic energy
flow_deformation()
Velocity gradient diagnostics: vorticity, divergence, strain, Okubo-Weiss
potential_density()
Potential density of seawater
residence_time()
How long water stays in a place
water_mass_fraction()
Water-mass fraction from two endmembers

Coherent structures

Eddies, and the Lyapunov exponents that reveal the transport barriers between them.

detect_eddies()
Find eddies as objects, not just as a field
distance_to_eddy()
Distance to the nearest eddy
fsle()
Finite-Size Lyapunov Exponent
ftle()
Finite-Time Lyapunov Exponent

Time treatments

The same field asked about over a different window: lagged by calendar units, integrated, rolled, or expressed as an anomaly.

box_anomaly()
Anomaly of a covariate averaged over a box
cell_anomaly()
Anomaly of a covariate against each cell's own history
decompose_covariate()
Split a covariate into trend, seasonal cycle, and what is left
integrate_covariate()
Time-integrated covariate
lag_covariate()
Lagged covariate values
marine_heatwave()
Marine heatwaves and cold spells
rolling_covariate()
Rolling summary of a covariate over a trailing window

Named regions and sections

Standing definitions for the Gulf of Maine features this work returns to, so a section is computed the same way every time.

eastern_gom_box()
The eastern Gulf of Maine box
eastern_gom_salinity()
Eastern Gulf of Maine salinity index
northeast_channel_inflow()
Northeast Channel inflow
scotian_shelf_inflow()
Scotian Shelf inflow at Cape Sable
scotian_shelf_inflow_section() northeast_channel_section()
Endpoints of the named sections
section_transport()
Volume transport across a section

Indices and metadata

Series assembled from the above, and the EML pieces that travel with them.

derived_indices() print(<derivoce_index_table>)
Regional indices this package can derive
eml_attributes()
Describe derived columns as EML metadata
eml_col_classes()
Column classes for EML, in the order the attributes are given
eml_custom_units()
Declarations for the units EML does not know
index_series()
Pull a per-time-step index back out as a series