4. Conversion to OS format

This document outlines the standardised conversion step from raw or partially processed instrument data to the AC1 format. This format builds on the OceanSITES specification but provides additional structure and vocabulary enforcement to support AMOC array interoperability.

1. Overview

The AC1 format is produced by the amocarray.convert.to_AC1() function and is designed to ensure consistency across RAPID, OSNAP, MOVE, and SAMBA arrays.

It is based on OceanSITES NetCDF conventions (see OceanSITES reference manual), with adaptations for AMOC-specific use.

See also: format_oceanSITES.

2. File Format

  • Format: NetCDF4

  • Structure: xarray.Dataset

  • Dimensions: TIME, N_LEVELS, N_PROF, N_COMPONENT (optional)

  • Coordinates: TIME, optionally DEPTH or PRESSURE, LATITUDE, LONGITUDE

  • Encoding: float32, compressed NetCDF, optionally chunked

CF conventions recommend dimensions ordered as: T, Z, Y, X.

3. Variables

Required and Optional Variables

Name

Dimensions

Units

Description

RS

TIME

(TIME,)

seconds since 1970-01-01

Timestamps in UTC

M

LONGITUDE

scalar or (N_PROF,)

degrees_east

Mooring or array longitude

S

LATITUDE

scalar or (N_PROF,)

degrees_north

Mooring or array latitude

S

DEPTH or PRESSURE

(N_LEVELS,)

m

Depth levels if applicable

S

TEMPERATURE

(TIME, …)

degree_Celsius

In situ or potential temperature

S

SALINITY

(TIME, …)

psu

Practical or absolute salinity

S

TRANSPORT

(TIME,)

Sv

Overturning transport estimate

S

4. Global Attributes

Required Global Attributes

Attribute

Example

Description

RS

title

“RAPID-MOCHA Transport Time Series”

Descriptive dataset title

M

platform

“moorings”

Platform type

M

featureType

“timeSeries”

NetCDF featureType

M

id

“RAPID_20231231_<orig>.nc”

File identifier

M

contributor_name

“Dr. Jane Doe”

Dataset PI

M

contributor_email

“jane.doe@example.org”

Contact email

M

contributor_role

“principalInvestigator”

Controlled vocab role

M

contributing_institutions

“University of Hamburg”

Data owners

M

source_doi

“https://doi.org/…”

Original data DOI

M

amocarray_version

“0.2.1”

Software version

M

date_created

“20240419T130000”

UTC file creation timestamp

M

5. Validation Rules

  • Must include TIME.

  • Must include one scientific variable (e.g. TEMP, SAL).

  • Must define global attributes listed above.

  • File should pass CF-checks where applicable.

6. Usage Example

from amocarray.convert import to_AC1
ds_ac1 = to_AC1(ds_std)

This function:

  • Validates inputs

  • Applies variable attributes

  • Adds global metadata

  • Returns CF-compliant AC1 dataset

7. Notes

This format is extensible and version-controlled. All AC1 files should include provenance fields like source, source_doi, source_acknowledgement, amocarray_version, and history.

For full definitions and examples, see the format_AC1.rst file.