Units Reference: for AC1

This document summarizes unit definitions relevant to the amocarray project, based on udunits2-base.xml.

Check out udunits.

SI base units (XML) are here.

Derived units (XML) are here.

Non-SI units including sverdrup, where apparently we cannot use Sv because it also means “sievert” in the SI unit-system.

Variables

Mass/Volume Units

Name	Symbol	Definition
gram_per_cubic_meter	g/m³, g m-3	0.001 kg/m³
kilogram_per_cubic_meter	kg/m³, kg m-3	base SI unit

Length Units

Name	Symbol	Definition
meter	m	base SI unit
centimeter	cm	0.01 m
kilometer	km	1000 m

Temperature Units

Name	Symbol	Definition
degree_Celsius	°C, Celsius	1 K offset by -273.15
kelvin	K	base SI unit

Conductivity Units

Name	Symbol	Definition
siemens_per_meter	S/m, S m-1	base SI unit
millisiemens_per_centimeter	mS/cm	0.1 S/m

Pressure Units

Name	Symbol	Definition
decibar	dbar	10,000 Pa
kilopascal	kPa	1,000 Pa
pascal	Pa	base SI pressure
bar	bar	100,000 Pa

Velocity Units

Name	Symbol	Definition
centimeter_per_second	cm/s, cm s-1	0.01 m/s
meter_per_second	m/s, m s-1	base SI unit

Angle Units (Accepted Non-SI)

These units are accepted for use with SI and commonly used in geophysical data.

Name	Symbol	Conversion to radians
degree	°, degrees	π / 180
arcminute	′	(1/60) degree
arcsecond	″	(1/60) arcminute

Notes: - Degrees are commonly used for geographic coordinates (latitude and longitude). - These are dimensionless units in the SI sense but critical for interpreting spatial data.

Transport Units

Name	Symbol	Definition
sverdrup, Sverdrup	Sv*	1e6 m³/s alias for Sv
cubic_meter_per_second	m³/s, m3 s-1	Ocean volume transport

*Not recommended since it conflicts with SI “sievert”.

Energy and Power Units

Name	Symbol	Definition
watt	W	J/s = kg·m²/s³
kilowatt	kW	1000 W
megawatt	MW	1e6 W
petawatt	PW	1e15 W
joule	J	N·m = kg·m²/s²

Name	Symbol	Definition
kilojoule	kJ	1000 J
gigajoule	GJ	1e9 J

Surface Heat Flux Units

Name	Symbol	Definition
watt_per_square_meter	W/m², W m-2	Heat flux density

Mapping of Custom Conversions

Original Unit	Canonical Unit	Factor	Notes
cm/s, cm s-1	m s-1	0.01	Velocity
S/m	mS cm-1	0.1	Conductivity
dbar	Pa, kPa	10000, 10	Pressure
degrees_Celsius	Celsius	1	Temperature
m	cm, km	100, 0.001	Length
g m-3	kg m-3	0.001	Density
Sverdrup	Sv*	1	Transport
W, J	watt, joule	base units	Energy and Power

*Not recommended since it conflicts with SI “sievert”.

SI Unit Prefixes

Standard prefixes supported by UDUNITS-2 for scaling base and derived units.

Prefix	Symbol	Factor
yotta zetta exa peta tera giga mega kilo hecto deca deci centi milli micro nano pico femto atto zepto yocto	Y Z E P T G M k h da d c m µ (u) n p f a z y	1e24 1e21 1e18 1e15 1e12 1e9 1e6 1e3 1e2 1e1 1e-1 1e-2 1e-3 1e-6 1e-9 1e-12 1e-15 1e-18 1e-21 1e-24

Notes: - Prefixes can be applied to compatible base/derived units (e.g., kW, cm, µS/cm). - µ is often typed as u in ASCII-only environments.