Array Format (Native / Original)

This document describes some of the native data formats present in AMOC datasets provided by different observing arrays.

In the logic of amocarray, we will first convert to an OceanSITES compatible format. Documentation is outlined in the OceanSITES format.

Note: This is a work in progress and not all arrays are fully described. The goal is to provide a summary of the data formats and how they could be transformed into a common format. The common format is not yet defined but will ideally be able to capture most if not all of the original data.

Table of Contents

• RAPID

• OSNAP

• MOVE

• SAMBA

• FW2015

• MOCHA

OSNAP Original Data Format

The OSNAP array provides multiple observational data products including time series of overturning and heat/freshwater transport, streamfunctions in density space, and gridded fields of velocity, temperature, and salinity.

At OSNAP, we have variables like MOC_ALL, MOC_EAST and MOC_WEST which are time series (TIME), but these could be represented as MOC (N_PROF, TIME) where instead of the three different variables, N_PROF=3. This would be somewhat more difficult to communicate to the user, since LATITUDE and LONGITUDE are not single points per N_PROF but instead may represent end points of a section.

Variables MOC_ALL_ERR are also provided, which could be translated to MOC_ERR (N_PROF, TIME) with LATITUDE (N_PROF) or LATITUDE_BOUND (N_PROF, 2).

Heat fluxes also exist, as MHT_ALL, MHT_EAST and MHT_WEST, so these could be MHT (N_PROF, TIME).

OSNAP_MOC_MHT_MFT_TimeSeries_201408_202006_2023.nc

Variables

Name	Dimensions	Shape	Units	Description
TIME	TIME	(71,)	datetime	standard_name: time long_name: Start date of each monthly period units: days since 1950-01-01 comment: Start date of each month processing_level: data manually reviewed
MOC_ALL	TIME	(71,)	Sv	standard_name: Transport_anomaly long_name: Total MOC description: Maximum overturning streamfunction across full OSNAP array comment: Maximum of the overturning streamfunction in sigma_theta coordinates QC_indicatoris: good data processing_level: data manually reviewed
MOC_ALL_ERR	TIME	(71,)	Sv	standard_name: Transport_anomaly long_name: MOC uncertainty description: Uncertainty in MOC_ALL comment: Determined from a Monte Carlo analysis
MOC_EAST	TIME	(71,)	Sv	standard_name: Transport_anomaly long_name: MOC east description: Overturning streamfunction at OSNAP East comment: Maximum of the overturning streamfunction in sigma_theta coordinates QC_indicatoris: good data processing_level: data manually reviewed
MHT_ALL	TIME	(71,)	PW	standard_name: Heat_transport long_name: Heat transport description: Meridional heat transport across full OSNAP array QC_indicatoris: good data processing_level: data manually reviewed
MFT_ALL	TIME	(71,)	Sv	standard_name: Freshwater_transport long_name: Freshwater transport description: Meridional freshwater transport across full OSNAP array QC_indicatoris: good data processing_level: data manually reviewed

OSNAP_Streamfunction_201408_202006_2023.nc

Variables

Name	Dimensions	Shape	Units	Description
TIME	TIME	(71,)	datetime	standard_name: time long_name: Start date of each monthly period units: days since 1950-01-01 comment: Start date of each month processing_level: data manually reviewed
LEVEL	LEVEL	(481,)	kg m-3	standard_name: potential_density long_name: Sigma-theta levels description: Potential density surfaces (sigmatheta) processing_level: data manually reviewed
T_ALL	LEVEL, TIME	(481, 71)	Sv	standard_name: Transport long_name: Streamfunction total description: Streamfunction in sigmatheta coordinates across full OSNAP comment: Streamfunction in sigma_theta coordinates QC_indicatoris: good data processing_level: data manually reviewed
T_EAST	LEVEL, TIME	(481, 71)	Sv	standard_name: Transport long_name: Streamfunction east description: Streamfunction in sigmatheta at OSNAP East comment: Streamfunction in sigma_theta coordinates QC_indicatoris: good data processing_level: data manually reviewed
T_WEST	LEVEL, TIME	(481, 71)	Sv	standard_name: Transport long_name: Streamfunction west description: Streamfunction in sigmatheta at OSNAP West comment: Streamfunction in sigma_theta coordinates QC_indicatoris: good data processing_level: data manually reviewed

OSNAP_Gridded_201408_202006_2023.nc

Variables

Name	Dimensions	Shape	Units	Description
TIME	TIME	(71,)	datetime	standard_name: time long_name: Start date of each monthly period units: days since 1950-01-01 comment: Start date of each month processing_level: data manually reviewed
LATITUDE	LATITUDE	(256,)	degrees_north	standard_name: latitude long_name: Latitude description: Latitude in degrees axis: Y
LONGITUDE	LONGITUDE	(256,)	degrees_east	standard_name: longitude long_name: Longitude description: Longitude in degrees axis: X
DEPTH	DEPTH	(199,)	m	standard_name: depth long_name: Depth description: Depth in meters positive: down axis: Z
VELO	TIME, DEPTH, LONGITUDE	(71, 199, 256)	m s-1	standard_name: sea_water_velocity long_name: Velocity description: Cross-sectional velocity along OSNAP QC_indicator: good data processing_level: Data manually reviewed
TEMP	TIME, DEPTH, LONGITUDE	(71, 199, 256)	degC	standard_name: sea_water_temperature long_name: Temperature description: In-situ temperature along OSNAP QC_indicator: good data processing_level: Data manually reviewed
SAL	TIME, DEPTH, LONGITUDE	(71, 199, 256)	psu	standard_name: sea_water_practical_salinity long_name: Salinity description: Practical salinity along OSNAP QC_indicator: good data processing_level: Data manually reviewed

RAPID Original Data Format

The RAPID array at 26°N produces a range of observational and derived products:

• 1D time series of AMOC transport

• Time series profiles of temperature, salinity, and velocity at specific locations (moorings)

• Gridded sections of hydrographic and velocity fields

• Layer transport estimates based on defined vertical boundaries

• Streamfunction evaluations in depth or density space

moc_vertical.nc

Variables

Name	Dimensions	Shape	Units	Description
depth	depth	(307,)	m	Vertical coordinate in meters
time	time	(13779,)	datetime	Time coordinate, 12-hour intervals
stream_function_mar	depth, time	(307, 13779)	Sv	Overturning streamfunction at 26°N

ts_gridded.nc

Variables

Name	Dimensions	Shape	Units	Description
pressure	depth	(242,)	dbar	Pressure coordinate
time	time	(13779,)	datetime	Time coordinate, 12-hour intervals
TG_west	depth, time	(242, 13779)	°C	Temperature west 26.52N/76.74W
SG_wb3	depth, time	(242, 13779)	psu	Salinity WB3 26.50N/76.6W
TG_marwest	depth, time	(242, 13779)	°C	Temperature MAR west 24.52N/50.57W
TG_mareast	depth, time	(242, 13779)	°C	Temperature MAR east 24.52N/41.21W
TG_east	depth, time	(242, 13779)	°C	Temperature east 26.99N/16.23W
TG_west_flag	depth, time	(242, 13779)	1	Data quality flag for TG_west

moc_transports.nc

Variables

Name	Dimensions	Shape	Units	Description
time	time	(13779,)	datetime	Time coordinate, 12-hour intervals
t_therm10	time	(13779,)	Sv	Thermocline recirculation 0–800 m
t_aiw10	time	(13779,)	Sv	Intermediate water 800–1100 m
t_ud10	time	(13779,)	Sv	Upper NADW 1100–3000 m
t_ld10	time	(13779,)	Sv	Lower NADW 3000–5000 m
t_bw10	time	(13779,)	Sv	AABW >5000 m
t_gs10	time	(13779,)	Sv	Florida Straits transport
t_ek10	time	(13779,)	Sv	Ekman transport
t_umo10	time	(13779,)	Sv	Upper Mid-Ocean transport
moc_mar_hc10	time	(13779,)	Sv	Overturning transport MOC index

2d_gridded.nc

Variables

Name	Dimensions	Shape	Units	Description
time	time	(689,)	datetime	Time (10-day intervals)
longitude	longitude	(254,)	degrees_east	Longitude coordinate
depth	depth	(307,)	m	Depth coordinate
CT	time, longitude, depth	(689, 254, 307)	°C	Conservative Temperature (ITS-90)
SA	time, longitude, depth	(689, 254, 307)	g/kg	Absolute Salinity
V_insitu	time, longitude, depth	(689, 254, 307)	m/s	Meridional velocity
V_ekman	time, longitude, depth	(689, 254, 307)	m/s	Ekman velocity
V_net	time	(689,)	m/s	Depth-integrated meridional velocity

meridional_transports.nc

Variables

Name	Dimensions	Shape	Units	Description
time	time	(689,)	datetime	Time (10-day intervals)
depth	depth	(307,)	m	Depth coordinate
sigma0	sigma0	(489,)	kg/m³ – 1000	Potential density anomaly (σ₀)
amoc_depth	time	(689,)	Sv	Maximum overturning from depth-streamfunction
amoc_sigma	time	(689,)	Sv	Maximum overturning from density-streamfunction
heat_trans	time	(689,)	PW	Northward heat transport
frwa_trans	time	(689,)	Sv	Northward freshwater transport
press	depth	(307,)	dbar	Pressure coordinate
stream_depth	time, depth	(689, 307)	Sv	Overturning streamfunction in depth space
stream_sigma	time, sigma0	(689, 489?)	Sv	Overturning streamfunction in density space

MOVE Original Data Format

MOVE provides the TRANSPORT_TOTAL which corresponds to the MOC, but also things like transport_component_internal (TIME,), transport_component_internal_offset (TIME,), and transport_component_boundary (TIME,). This would be similar to RAPID’s version of “interior transport” and “western boundary wedge”, but it’s not so clear how to make these similarly named.

OS_MOVE_TRANSPORTS.nc

Variables

Name	Dimensions	Shape	Units	Description
TIME	TIME	(6756,)	datetime	type: datetime time coverage: 2000-01-01 to 2018-06-30
TRANSPORT_TOTAL	TIME	(6756,)	Sverdrup	standard_name: ocean_volume_transport_across_line long_name: Total ocean volume transport across the MOVE line between Guadeloupe and Researcher Ridge in the depth layer defined by pressures 1200 to 4950 dbar valid_min: -100.0 valid_max: 100.0
transport_component_internal	TIME	(6756,)	Sverdrup	long_name: Internal component of ocean volume transport across the MOVE line valid_min: -100.0 valid_max: 100.0
transport_component_internal_offset	TIME	(6756,)	Sverdrup	long_name: Offset to be added to internal component of ocean volume transport across the MOVE line valid_min: -100.0 valid_max: 100.0
transport_component_boundary	TIME	(6756,)	Sverdrup	long_name: Boundary component of ocean volume transport across the MOVE line valid_min: -100.0 valid_max: 100.0

SAMBA Original Data Format

Note that the longer datasets (e.g., MOC_TotalAnomaly_and_constituents.asc) is from Meinen et al. (2018) and the shorter dataset (e.g., Upper_Abyssal_Transport_Anomalies.txt) is from Kersalé et al. (2020).

Upper_Abyssal_Transport_Anomalies.txt

Variables in Upper_Abyssal_Transport_Anomalies.txt

Name	Dimensions	Shape	Units	Description
TIME	TIME	(1404,)	datetime	type: datetime
UPPER_TRANSPORT	TIME	(1404,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Upper-cell volume transport anomaly (relative to record-length average of 17.3 Sv)
ABYSSAL_TRANSPORT	TIME	(1404,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Abyssal-cell volume transport anomaly (relative to record-length average of 7.8 Sv)

MOC_TotalAnomaly_and_constituents.asc

Variables in MOC_TotalAnomaly_and_constituents.asc

Name	Dimensions	Shape	Units	Description
TIME	TIME	(2964,)	datetime	type: datetime
MOC	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: MOC Total Anomaly (relative to record-length average of 14.7 Sv)
RELATIVE_MOC	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Relative (density gradient) contribution description: Relative (density gradient) contribution to MOC anomaly
BAROTROPIC_MOC	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Reference (bottom pressure gradient) contribution to MOC anomaly
EKMAN	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Ekman (wind) contribution to the MOC anomaly
WESTERN_DENSITY	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Western density contribution to the MOC anomaly
EASTERN_DENSITY	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Eastern density contribution to the MOC anomaly
WESTERN_BOT_PRESSURE	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Western bottom pressure contribution to the MOC anomaly
EASTERN_BOT_PRESSURE	TIME	(2964,)	Sv	standard_name: Transport_anomaly long_name: Transport anomaly description: Eastern bottom pressure contribution to the MOC anomaly

FW2015

This is a different beast but similar to RAPID in that it has components which represent transport for different segments of the array (like Gulf Stream, Ekman and upper-mid-ocean) where these sum to produce MOC. This is vaguely like OSNAP east and OSNAP west, except I don’t think those sum to produce the total overturning. And Ekman could be part of a layer transport but here is has no depth reference. Gulf Stream has longitude bounds and a single latitude (LATITUDE, LONGITUDE_BOUND) and limits over which the depths are represented (DEPTH_BOUND?) but no N_LEVELS. It doesn’t quite make sense to call the dimension N_PROF since these aren’t profiles. Maybe N_COMPONENT?

Summary of FW2015 files: ~~~~~~~~~~~~~~~~~~~~~~~~~~` - MOCproxy_for_figshare_v1.mat

• TIME: dimension TIME (264,), type datetime

• MOC_PROXY: dimension TIME, units Sv

• EK: dimension TIME, units Sv

• GS: dimension TIME, units Sv

• UMO_PROXY: dimension TIME, units Sv

Potential reformats: ~~~~~~~~~~~~~~~~~~~~~~~~~~`

• Overturning:

  • MOC: time series (dimension: TIME)

• Component transports:

  • Dimensions: TIME, N_COMPONENT (1404, 7)

  • Coordinates: LATITUDE, LONGITUDE_BOUNDS (scalar, x2), TIME in datetime. N_COMPONENT for the number of components.

  • Variables: TRANSPORT (TIME, N_COMPONENT) - This would also have TRANSPORT_NAME (N_COMPONENT, string) to indicate what the component is (e.g. EK, GS, LNADW, MOC, MOC_PROXY, UMO_GRID, UMO_PROXY, UNADW_GRID, etc). Note that some of these were just copies of what the RAPID time series was at the time.

MOCHA

Summary of MOCHA files:

The heat transports at RAPID-MOCHA are provided with N_LEVELS, TIME, and variables:

• Q_eddy

• Q_ek

• Q_fc

• Q_gyre

• Q_int.

Again, we have a situation where N_PROF isn’t really appropriate. Maybe N_COMPONENT? WE should double check that things called N_COMPONENT then somehow sum to produce a total? Then we would have something like MHT_COMPONENTS (N_COMPONENT, TIME) and MHT (TIME)

But we also have things like:

• T_basin (TIME, N_LEVELS)

• T_basin_mean (N_LEVELS)

• T_fc_fwt (TIME)

• V_basin (TIME, N_LEVELS) –> is this identical to new RAPID velo sxn?

• V_basin_mean (N_LEVELS)

• V_fc (TIME, N_LEVELS)

Potential reformats:

So this might be suggested as a TEMPERATURE (TIME, N_LEVELS) but unclear how to indicate that this is a zonal mean temperature as compared to the ones which are TEMPERATURE (N_PROF, TIME, N_LEVELS) for the full sections.

• Heat Transport Components:

  • Q_eddy, Q_ek, Q_fc, Q_gyre, Q_int → suggest MHT_COMPONENT (N_COMPONENT, TIME)

  • Total: MHT (TIME)

• Additional Variables:

  • T_basin, V_basin, T_fc_fwt, etc.

  • These suggest basin-mean properties: TEMPERATURE (TIME, N_LEVELS)

• Note: N_COMPONENT should indicate summable components if applicable