Proposing Standard Names for data from Current Meters and Profilers

From Earth Science Information Partners (ESIP)
            draft draft draft draft

This is workspace for developing a DRAFT list of terms and definitions to be proposed to the Climate and Forecast standard names committee. Please consider adding your ideas!

Working principles

  • CF is unconcerned with methodologies, and wants to include terms that convey a concept; so e.g. the instrument_heading field should represent the same concept whether the data is from a shipboard ADCP or a current meter attached to a mooring line. In the former case, the value is derived from external sensors (ships gyro, among others) and known constants that describe the instrument's alignment with respect to the ship's hull; in the latter case, it's recorded by the instrument. Broadly applicable terms will be most useful.
  • Likewise, it might be possible to define a term like echo_amplitude and re-use it for any number of beams; using variable names and long_name attributes to distinguish between them (EAMP1: long_name='echo_amplitude_beam_1"). This takes a lot of the complexity out of the project, because we don't need names for the outputs of differently configured instruments.
  • We can't request standard names for every output of every type of instrument, at least not if we hope to get anything approved, so let's concentrate on instrument alignment first, and then some common outputs (percent good, error velocity ...). Where possible, we should use earth coordinate systems, not relative-to-platform terms.
  • The most useful terms will be for processed data that's got earth-relative velocities; this is the data most often shared and so most in need of standard names (and definitions).


Existing Vocabularies

  • From CODAS NetCDF "Short form" :
u:long_name = "Zonal velocity component" ; (velocity over the ground)
v:long_name = "Meridional velocity component" ;
amp:long_name = "Received signal strength" ; (averaged raw signal strength as reported by the instrument on a 0-255 scale)
pg:long_name = "Percent good pings" ;
heading:long_name = "Ship heading" ;
tr_temp:long_name = "ADCP transducer temperature" ;
uship:long_name = "Ship zonal velocity component" ;
vship:long_name = "Ship meridional velocity component" ;
depth:long_name = "Depth"; (not adjusted for actual sound speed profiles)
  • From IOOS parameter vocabulary (selected terms related to currents)
northward_current_speed: North/South component of ocean current. Northward is positive.
bin_direction: Current direction of bin (?)
vertical_current: Upward/Downward component of ocean current. Upward is positive.
current_to_direction: Direction towards which ocean current is going
number_profile_bins: Number of uniformly spaced depth cells where data is collected
bin_size: Width distance between bins
number_of_transducer_beams: Number of directionally independent beams of the ADCP
bin_velocity: Current velocity of bin
sound_velocity: Magnitude of velocity of sound in water
transducer_height: Height of transducer above bottom or from surface
transducer_frequency: Operating frequency of ADCP
beam_velocity: Current velocity measured parallel to the path of beam 1
current_speed: Magnitude of velocity of ocean current
beam_echo_intensity: Measure of the echo intensity returning to beam 1 from the ADCP transmit pulse
eastward_current_speed: East/West component of ocean current. Eastward is positive.
blanking_height: Distance from instrument to first bin measurement
bottom_track_heading: no definition
bottom_tracking_depth: Distance to sea floor determined by a series of long pulses sent out from ADCP
  • From IMOS
sea_surface_wave_directional_spread (degrees, clockwise from true north)
sea_surface_wave_direction_spectral_density(degrees, clockwise from true north)
volumetric_backscatter_coefficient (m-1 sr-1)
frequency (Hz)