Level 1 data (velocity point-measurements)

Page status: Draft
Author(s):	Cynthia
Reviewer(s):
Comment:

Dimensions

The number of velocity instruments [N_VEL_INSTRUMENT] is here for completeness, but the benchmarks examples will have measurements only from one instrument stored.

Short name	Standard name	Dimensions	Comments
TIME	time	time	Units in Days since 1950-01-01T00:00:00Z
TIME_HPR	time_of_heading_pitch_roll	TIME_HPR	Heading, pitch and roll (tilt) sensors measure always at 1Hz for Vector ADV
N_VEL_COMPONENT	number_of_velocity_component	N_VEL_COMPONENT	Maximum of 3 for u,v, w (east,north, up) velocities
N_VEL_INSTRUMENT	number_of_unique_velocity_instruments	N_VEL_INSTRUMENT	Required only if storing multiple synchronized instruments in the same file

Variables

Required variables

Short name	Standard name	Dimensions	Comments
ABSIC	backscatter_intensity_from_acoustic_beam	TIME, N_VEL_COMPONENT, N_VEL_INSTRUMENT
CORRN	noise_correlation_percent_from_each_acoustic_beam	TIME, N_VEL_COMPONENT, N_VEL_INSTRUMENT
[math]\displaystyle{ \ddagger }[/math] XYZ_VEL (or ENU_VEL/BEAM_VEL)		TIME, N_VEL_COMPONENT, N_VEL_INSTRUMENT
[math]\displaystyle{ \dagger }[/math] HEIGHT or DEPTH		TIME, N_VEL_INSTRUMENT
HEADING		TIME_HPR, N_VEL_INSTRUMENT
PITCH		TIME_HPR, N_VEL_INSTRUMENT
ROLL		TIME_HPR, N_VEL_INSTRUMENT
[math]\displaystyle{ \ddagger }[/math] Some manufacturers record quality-control variables (e.g., CORRN) in the instrument coordinate system. For example, Nortek records these variables in the instrument XYZ frame of reference. It's best to record the data in that coordinate system. [math]\displaystyle{ \dagger }[/math] A variable situating the instruments in the water column is required. This may be a nominal depth (or height) or a time-varying depth or height above the bottom.

Required height variable

Height or depth-related variables (only 1x is required). These variables locate the instrument vertically from a boundary (e.g, surface or ice). A negative value implies it's below the boundary. Units are always in meters.

Short name	Standard name	Dimensions
HEIGHT_AB	height_above_bottom	TIME, N_VEL_INSTRUMENT
DEPTH	depth_below_surface	TIME, N_VEL_INSTRUMENT

Optional variables

Short name	Standard name	Dimensions
PRES		TIME, N_VEL_INSTRUMENT
SNR		TIME, N_VEL_COMPONENT
TEMP, and other scalars*		TIME
*Data from concurrent sensors may be optionally included e.g., temperature, dissolved oxygen (e.g., eddy-correlation system)

Group attributes (metadata)

This section describes attributes that may provide additional information about how the data was processed and manipulated at this stage.

Attribute name	Purpose	Suggested content
processing_level	Boilerplate about the ATOMIX Level 1 content.	This group includes the raw measurements from the recorder and ancillary measurements required for quality-controlling them using the manufacturer's recommendations.	comment (optional)	Information is pertinent to problems in the raw data files during collection.	Examples: Stitching of files, corruption of binary files that were recovered by the manufacturer, etc.