ocean_currents

Provides nodes useful for integrating ocean currents into simulation.

Nodes

ocean_currents

Provides ocean current information for given a time, latitude, longitude and depth. Defaults to downloading the most recent information from NASA's OSCAR dataset [1], which provides ocean surface current information. One can also provide a local file in the OSCAR file format to bypass the download step.

Subscribed Topics

gps_fix (sensor_msgs/NavSatFix)

• Provides time, latitude, longitude and altitude (depth) to retrieve ocean current from. Each message prompts a call to the set_current_velocity service if the current has changed. This is not a recommended interface to use, but is useful for debugging.

Service Clients

set_current_velocity (uuv_world_ros_plugins_msgs/SetCurrentVelocity)

• Only fills out the velocity magnitude and horizontal angle fields.

Service Servers

get_ocean_current ocean_currents/GetOceanCurrent

• Given a time, latitude, longitude and altitude (depth) returns a geometry_msgs/Twist representing the ocean current at that time and location. This is the recommended interface.

Parameters

~catalog_url (string, default: https://podaac-opendap.jpl.nasa.gov/opendap/allData/oscar/preview/L4/oscar_third_deg/)

• THREDDS Data Server url for an ocean currents database. Defaults to NASA's OSCAR dataset. Used when downloading a file at runtime.

~oscar_filename (string, default: ``)

• Used to specify a local file previously downloaded from NASA's OSCAR dataset instead of downloading one at runtime.

~reference_datetime (string, default: ``)

• If blank, downloads the most recent OSCAR data. Otherwise, finds the OSCAR file closest in time to this datetime string.

~reference_datetime_format_str (string, default: %Y-%m-%d)

• Used when converting a given reference_datetime to a python datetime object.

~time_unit (string, default: days since 1992-10-05T00:00:00Z)

• Time units to use for converting times to help find the appropriate ocean currents file in a dataset. Defaults to units for NASA's OSCAR dataset. String format is from the python-netcdf4 library.

~use_maximum_velocity (bool, default: false)

• If true, uses the maximum mask fields of OSCAR files, otherwise uses the regular velocity fields. This field is intended for testing purposes only according to the OSCAR file description.

References

[1] ESR. 2009. OSCAR third deg. Ver. 1. PO.DAAC, CA, USA. Dataset accessed at https://doi.org/10.5067/OSCAR-03D01.