Notation	Name	Description	Status
'	minute (angle)	Unit of plane or phase angle, accepted for use with SI: 1 ' =...	stable
''	second (angle)	Unit of plane or phase angle, accepted for use with SI: 1 '' ...	stable
0.001	parts per thousand		superseded
1	dimensionless	Dimensionless; SI base unit equivalent: 1	stable
A	ampere	SI base unit of electric current	stable
AU	astronomical unit	Unit of length, accepted for use with SI: 1 AU = 149597870700...	stable
Bq	becquerel	SI derived unit of radioactivity; SI base unit equivalent: s-...	stable
Bq.l-1	becquerel per litre	Unit of radioactivity concentration; SI base unit equivalent:...	stable
Bq.m-2	becquerel per square metre	SI derived unit of radioactivity area concentration; SI base ...	stable
Bq.m-3	becquerel per cubic metre	SI derived unit of radioactivity concentration; SI base unit ...	stable
Bq.s.m-3	becquerel second per cubic metre	SI derived unit of time integrated radioactivity concentratio...	stable
Bq_l-1	becquerels per litre		superseded
Bq_m-2	becquerels per square metre		superseded
Bq_m-3	becquerels per cubic metre		superseded
Bq_s_m-3	becquerel seconds per cubic metre		superseded
C	coulomb	SI derived unit of electric charge; SI base unit equivalent: ...	stable
CFU.ml-1	colony-forming unit per millilitre	Unit of number concentration of viable bacteria or fungal cel...	stable
C_(100m)-1	degrees Celsius per 100 metres		superseded
C_m-1	degrees Celsius per metre		superseded
Cel	degree Celsius		superseded
DU	Dobson Unit	Unit of column abundance of molecules in the atmosphere. 1 DU...	stable
E	Eötvös	Unit of acceleration divided by distance,1 E = 1E-9 Gal/cm; S...	stable
F	farad	SI derived unit of electrical capacitance; SI base unit equiv...	stable
GHz	gigahertz	SI derived unit of frequency; SI base unit equivalent: 1E9 s-...	stable
Gy	gray	SI derived unit of absorbed dose (of ionizing radiation); SI ...	stable
H	henry	SI derived unit of electrical inductance; SI base unit equiva...	stable
HU	Hazen unit	Unit of color according to the Platinum/Cobalt or Apha-Hazen ...	stable
Hz	hertz	SI derived unit of frequency; SI base unit equivalent: s-1	stable
J	joule	SI derived unit of energy, work, heat; SI base unit equivalen...	stable
J.kg-1	joule per kilogram	SI derived unit of specific energy or specific potential enth...	stable
J.m-2	joule per square metre	SI derived unit of radiant exposure; SI base unit equivalent:...	stable
J_kg-1	joules per kilogram		superseded
J_m-2	joules per square metre		superseded
K	kelvin	SI base unit of thermodynamic temperature	stable
K.m-1	kelvin per metre	SI derived unit of spatial gradient of temperature	stable
K.m.s-1	kelvin metre per second	SI derived unit of covariance of wind speed and temperature o...	stable
K.m2.kg-1.s-1	kelvin square metre per kilogram per second	SI derived unit of potential vorticity	stable
K_m-1	kelvins per metre		superseded
K_m2_kg-1_s-1	kelvin square metres per kilogram per second		superseded
K_m_s-1	kelvin metres per second		superseded
MHz	megahertz	SI derived unit of frequency; SI base unit equivalent: 1E6 s-...	stable
MPN.ml-1	most probable number index number in 1 millilitre	Unit of expected number concentration of bacteria in the orig...	stable
Mm-1	per megametre	Unit of quantity with dimension of reciprocal length, e.g., o...	stable
Mm-1.sr-1	per megametre per steradian	SI derived unit of the scattering coefficient at a given dire...	stable
N	newton	SI derived unit of force, weight	stable
N.m-2	newton per square metre	SI derived unit of pressure or equivalent quantity	stable
NTU	nephelometric turbidity unit	Units of turbidity from a calibrated nephelometer; SI base un...	stable
N_m-2	newtons per square metre		superseded
N_units	N units	Unit of atmospheric refractivity, the refractivity, N, is rel...	stable
Ohm	ohm	SI derived unit of electrical resistance, impedance, reactanc...	stable
Pa	pascal	SI derived unit of pressure/stress; SI base unit equivalent: ...	stable
Pa.s-1	pascal per second	SI derived unit of temporal derivative of pressure/stress; SI...	stable
Pa_s-1	pascals per second		superseded
S	siemens	SI derived unit of electrical conductance; SI base unit equiv...	stable
S.m-1	siemens per metre	SI derived unit of spatial gradient of electric conductance	stable
S_m-1	siemens per metre		superseded
Sv	sievert	SI derived unit of equivalent dose (of ionizing radiation); S...	stable
T	tesla	SI derived unit of magnetic induction, magnetic flux density;...	stable
THz	terahertz	SI derived unit of frequency; SI base unit equivalent: 1E12 s...	stable
V	volt	SI derived unit of voltage, electrical potential difference, ...	stable
W	watt	SI derived unit of power, radiant flux; SI base unit equivale...	stable
W.m-1.sr-1	watt per metre per steradian	SI derived unit of spectral intensity, a directional quantity...	stable
W.m-2	watt per square metre	SI derived unit of heat flux density or irradiance; SI base u...	stable
W.m-2.sr-1	watt per square metre per steradian	SI derived unit of radiance; SI base unit equivalent: kg.s-3	stable
W.m-2.sr-1.Hz-1	watt per square metre per steradian per hertz	SI derived unit of spectral radiance per unit frequency; SI b...	stable
W.m-2.sr-1.cm	watt per square metre per steradian per inverse centimetre	SI derived unit of spectral radiance per unit wavenumber, wav...	stable
W.m-2.sr-1.m	watt per square metre per steradian per inverse metre	SI derived unit of spectral radiance per inverse metre; SI ba...	stable
W.m-3.sr-1	watt per square metre per steradian per metre	SI derived unit of spectral radiance per unit wavelength; SI ...	stable
W_m-1_sr-1	watts per metre per steradian		superseded
W_m-2	watts per square metre		superseded
W_m-2_sr-1	watts per square metre per steradian		superseded
W_m-2_sr-1_cm	watts per square metre per steradian centimetre		superseded
W_m-2_sr-1_m	watts per square metre per steradian metre		superseded
W_m-3_sr-1	watts per cubic metre per steradian		superseded
Wb	Weber	SI derived unit of magnetic flux; SI base unit equivalent: kg...	stable
a	year	Conventional unit of time duration, ranging from 365 days to ...	stable
cb.(12h)-1	centibar per 12 hours	Conventional unit of time derivative of pressure, pressure te...	stable
cb.s-1	centibar per second	Conventional unit of time derivative of pressure, pressure te...	stable
cb_-1	centibars per 12 hours		superseded
cb_s-1	centibars per second		superseded
cd	candela	SI base unit of luminous intensity	stable
cm	centimetre	SI prefixed unit of length; SI base unit equivalent: 0.01 m	stable
cm-3	per cubic centimetre	SI derived unit of specific volume; SI base unit equivalent: ...	stable
cm.h-1	centimetre per hour	SI derived unit of speed; SI base unit equivalent: 1/360000 m...	stable
cm.s-1	centimetre per second	SI derived unit of speed; SI base unit equivalent: 0.01 m.s-1	stable
cm2	square centimetre	SI derived unit of area; SI base unit equivalent: 1E-4 m2	stable
cm3.m-3	cubic centimetre per cubic metre	SI derived unit of volumetric mixing ratio, equivalent to ppm...	stable
cm_h-1	centimetres per hour		superseded
cm_s-1	centimetres per second		superseded
d	day	Unit of time, accepted for use with SI: 1 d = 86400 s	stable
dB	decibel	Unit of sound intensity, accepted for use with SI	stable
dB.deg-1	decibel per degree (angle)	Unit of angular gradient of sound intensity	stable
dB.m-1	decibel per metre	Unit of spatial gradient of sound intensity	stable
dB_deg-1	decibels per degree		superseded
dB_m-1	decibels per metre		superseded
dPa.s-1	decipascal per second (microbar per second)	SI derived unit of time derivative of pressure, pressure tend...	stable
dPa_s-1	decipascals per second (microbar per second)		superseded
daPa	dekapascal	SI derived unit of pressure/stress; SI base unit equivalent: ...	stable
deg	degree (angle)	Unit of plane or phase angle, accepted for use with SI: 1 deg...	stable
deg.s-1	degree (angle) per second	Unit of angular speed, accepted for use with SI	stable
deg2	square degree (angle)	Unit of square of phase or plane angle, accepted for use with...	stable
degC	degree Celsius (°C)	SI derived unit of temperature, as defined by ITS-90; SI base...	stable
degC.hm-1	degree Celsius per 100 metres	SI derived unit of spatial gradient of temperature per 100 me...	stable
degC.m-1	degree Celsius per metre	SI derived unit of spatial gradient of temperature per metre;...	stable
deg_s-1	degrees per second		superseded
degree_(angle)	degree (angle)		superseded
degrees_true	degrees true		superseded
dm	decimetre	SI prefixed unit of length; SI base unit equivalent: 0.1 m	stable
eV	electron volt	Unit of energy, accepted for use with SI; SI base unit equiva...	stable
fmol.kg-1	femtomole per kilogram	SI derived unit of amount per unit mass; SI base unit equival...	stable
ft	foot	Imperial/US unit of length, equal to 1200/3937 metre or 0.304...	stable
g	acceleration due to gravity		superseded
g.cm-3	gram per cubic centimetre	SI derived unit of density, equivalent to kilograms per litre...	stable
g.kg-1	gram per kilogram	SI derived unit of mass fraction, dimensionless; SI base unit...	stable
g.kg-1.s-1	gram per kilogram per second	SI derived unit of time derivative of mass fraction; SI base ...	stable
g0	standard acceleration due to gravity	Conventional unit of gravity acceleration; g0 = 9.80665 m.s-2	stable
g_kg-1	grams per kilogram		superseded
g_kg-1_s-1	grams per kilogram per second		superseded
gpm	geopotential metre	The height of a given point in the atmosphere in units propor...	stable
h	hour	Unit of time, accepted for use with SI: 1 h = 3600 s	stable
hPa	hectopascal	SI derived unit of pressure/stress; SI base unit equivalent: ...	stable
hPa.(3h)-1	hectopascal per 3 hours	SI derived unit of time derivative of pressure; SI base unit ...	stable
hPa.h-1	hectopascal per hour	SI derived unit of time derivative of pressure; SI base unit ...	stable
hPa.s-1	hectopascal per second	SI derived unit of time derivative of pressure; SI base unit ...	stable
hPa_-1	hectopascals per 3 hours		superseded
hPa_h-1	hectopascals per hour		superseded
hPa_s-1	hectopascals per second		superseded
ha	hectare	Unit of area, accepted for use with SI: 1 ha = 1E4 m2	stable
in	inch	Imperial/US unit of length, equal to 25.4 millimetres	stable
inapplicable	inapplicable	There is no value (categorical data)	stable
kHz	kilohertz	SI derived unit of frequency; SI base unit equivalent: 1000 s...	stable
kPa	kilopascal	SI derived unit of pressure/stress, equal to 1000 Pa; SI base...	stable
kcal.cm-2	kilocalory per square centimetre	Unit of radiant exposure, equal to 4.184E7 J.m-2	stable
kg	kilogram	SI base unit of mass	stable
kg-2.s-1	per square kilogram per second	SI derived unit of quantity with dimension of M-2.T-1	stable
kg-2_s-1	per square kilogram per second		superseded
kg.kg-1	kilogram per kilogram	SI derived unit of mass fraction; SI base unit equivalent: 1	stable
kg.kg-1.s-1	kilogram per kilogram per second	SI derived unit of time derivative of mass fraction; SI base ...	stable
kg.m-1	kilogram per metre	SI derived unit of linear mass density or quantity with dimen...	stable
kg.m-2	kilogram per square metre	SI derived unit of area density	stable
kg.m-2.s-1	kilogram per square metre per second	SI derived unit of time derivative of mass area density	stable
kg.m-3	kilogram per cubic metre	SI derived unit of density, mass density	stable
kg_kg-1	kilograms per kilogram		superseded
kg_kg-1_s-1	kilograms per kilogram per second		superseded
kg_m-1	kilograms per metre		superseded
kg_m-2	kilograms per square metre		superseded
kg_m-2_s-1	kilograms per square metre per second		superseded
kg_m-3	kilograms per cubic metre		superseded
km	kilometre	SI prefixed unit of length; SI base unit equivalent: 1000 m	stable
km-1	per kilometre	SI derived unit of quantity with dimension of reciprocal leng...	stable
km-1.sr-1	per kilometre per steradian	SI derived unit of the scattering coefficient at a given dire...	stable
km.d-1	kilometre per day	SI derived unit of speed; SI base unit equivalent: 1000/86400...	stable
km.h-1	kilometre per hour	SI derived unit of speed; SI base unit equivalent: 1000/3600 ...	stable
km_d-1	kilometres per day		superseded
km_h-1	kilometres per hour		superseded
kt	knot	Conventional unit of speed, equal to 1 nmi/h; SI base unit eq...	stable
kt.km-1	knot per 1000 metres	Conventional unit of spatial gradient of speed; SI base unit ...	stable
kt_km-1	knots per 1000 metres		superseded
l	litre	SI derived unit of volume; SI base unit equivalent: 0.001 m3	stable
lm	lumen	SI derived unit of luminous flux; SI base unit equivalent: 1 ...	stable
lx	lux	SI derived unit of illuminance; SI base unit equivalent: cd.m...	stable
m	metre	SI base unit of length	stable
m(2.3-1).s-1	metre to the two thirds power per second	SI derived unit of the quantity with dimension of L^(2/3) T-1	stable
m(2_3)_s-1	metres to the two thirds power per second		superseded
m-1	per metre	SI derived unit of quantity with dimension of reciprocal leng...	stable
m-1.sr-1	per metre per steradian	SI derived unit of the scattering coefficient at a given dire...	stable
m-3	per cubic metre	SI derived unit of specific volume	stable
m.a-1	metre per year	Conventional unit of velocity	stable
m.s-1	metre per second	SI derived unit of speed	stable
m.s-1.km-1	metre per second per 1000 metres	SI derived unit of spatial gradient of speed; SI base unit eq...	stable
m.s-1.m-1	metre per second per metre	SI derived unit of spatial gradient of speed	stable
m.s-2	metre per second squared	SI derived unit of acceleration	stable
m2	square metre	SI derived unit of area	stable
m2.s	square metre second	SI derived unit of sea surface wave variance spectral density	stable
m2.s-1	square metre per second	SI derived unit of kinematic viscosity, thermal diffusivity, ...	stable
m2.s-2	square metre per square second	SI derived quantity with dimension of squared speed	stable
m2.s.rad-1	square metre second per radian	SI derived unit of sea surface wave directional variance spec...	stable
m2_Hz-1	square metres per hertz		superseded
m2_rad-1_s	square metres per radian second		superseded
m2_s	square metres second		superseded
m2_s-1	square metres per second		superseded
m2_s-2	square metres per second squared		superseded
m3	cubic metres	SI derived unit of volume	stable
m3.m-3	cubic metre per cubic metre	SI derived unit of volume fraction; SI base unit equivalent: ...	stable
m3.s-1	cubic metre per second	SI derived unit of volume flow rate or time derivative of vol...	stable
m3_m-3	cubic metres per cubic metre		superseded
m3_s-1	cubic metres per second		superseded
m4	metre to the fourth power	SI derived unit of the second moment of area, area moment of ...	stable
mBq.m-3	millibecquerel per cubic metre	SI derived unit of volumetric radioactivity concentration; SI...	stable
mBq_m-3	millibecquerels per cubic metre		superseded
mGal	milligal	CGS unit of acceleration, equal to one thousandth of a Gal (1...	stable
mS.cm-1	millisiemens per centimetre	SI derived unit of spatial gradient of electrical conductance...	stable
mSv	millisievert	SI derived unit of equivalent dose (of ionizing radiation); S...	stable
mV	millivolt	SI derived unit of voltage, electrical potential difference, ...	stable
m_s-1	metres per second		superseded
m_s-1_km-1	metres per second per 1000 metres		superseded
m_s-1_m-1	metres per second per metre		superseded
m_s-2	metres per second squared		superseded
mbar	millibar	Conventional unit of pressure, equal to 1 hPa; SI base unit e...	stable
mg.cm-3	milligram per cubic centimetre	SI derived unit of mass concentration; SI base unit equivalen...	stable
mg.kg-1	milligram per kilogram	SI derived unit of mass fraction, equivalent to ppmm (parts p...	stable
mg.l-1	milligram per litre	SI derived unit of density or mass concentration; SI base uni...	stable
mg.m-3	milligram per cubic metre	SI derived unit of density or mass concentration; SI base uni...	stable
mg_N_l-1	milligram N per litre		superseded
mg_S_l-1	milligram S per litre		superseded
mg_m-3_25C	milligrams per cubic metre at 25 degrees		superseded
min	minute (time)	Unit of time, accepted for use with SI: 1 min = 60 s	stable
missing	missing	The correct value is not readily available to the sender of t...	stable
mm	millimetre	SI prefixed unit of length; SI base unit equivalent: 0.001 m	stable
mm.h-1	millimetre per hour	SI derived unit of speed; SI base unit equivalent: 1/3.6E6 m....	stable
mm.s-1	millimetre per second	SI derived unit of speed; SI base unit equivalent: 0.001 m.s-...	stable
mm3.m-3	cubic millimetre per cubic metre	SI derived unit of volumetric mixing ratio, equivalent to ppb...	stable
mm6.m-3	millimetre to the sixth power per cubic metre	SI derived unit of quantity with dimension of L3; SI base uni...	stable
mm6_m-3	millimetres to the sixth power per cubic metre		superseded
mmHg	millimetre of mercury	Conventional unit of pressure, equal to 133.322387415 Pa	stable
mm_h-1	millimetres per hour		superseded
mm_s-1	millimetres per second		superseded
mmol.mol-1	millimole per mole	SI derived unit equivalent to expressing mole fraction in par...	stable
mmol_mol-1	millimoles per mole		superseded
mol	mole	SI base unit of amount of substance	stable
mol.mol-1	mole per mole	SI derived unit of mole fraction; SI base unit equivalent: 1	stable
mol_mol-1	moles per mole		superseded
mon	month	Conventional unit of time duration of between 28-31 days wher...	stable
nautical_mile	nautical mile		superseded
nbar	nanobar	Conventional unit of pressure; SI base unit equivalent: 1E-4 ...	stable
ng.kg-1	nanogram per kilogram	SI derived unit of mass fraction, equivalent to pptm (parts p...	stable
ng.m-3	nanogram per cubic metre	SI derived unit of mass concentration; SI base unit equivalen...	stable
ng_m-3	nanograms per cubic metre		superseded
nm	nanometre	SI prefixed unit of length; SI base unit equivalent: 1E-9 m	stable
nmi	nautical mile	Conventional unit of length; SI base unit equivalent: 1852 m	stable
nmol.kg-1	nanomole per kilogram	SI derived unit of amount per unit mass; SI base unit equival...	stable
nmol.mol-1	nanomole per mole	SI derived unit of mole fraction; SI base unit equivalent: 1E...	stable
nmol_mol-1	nanomoles per mole		superseded
okta	eights of sky covered by cloud	Unit of cloud amount, expressed as number of eighths of the s...	stable
pH_unit	pH unit	Negative decimal logarithm of the hydrogen ion activity ('eff...	stable
pc	parsec	Astronomical unit of length, 1 pc = 64800/Π AU	stable
percent	per cent	Dimensionless number, expressed as a fraction of 100; SI base...	stable
permeg	per meg	Dimensionless number, expressed as a fraction of 1000000; SI ...	stable
permil	per mille	Dimensionless number, expressed as a fraction of 1000; SI bas...	stable
pmol.kg-1	picomole per kilogram	SI derived unit of amount per unit mass; SI base unit equival...	stable
pmol.mol-1	picomole per mole	SI derived unit equivalent of mole fraction; SI base unit equ...	stable
pmol_mol-1	picomoles per mole		superseded
ppbv	parts per billion by volume	Unit of volume fraction, equivalent to SI derived unit: 1E-9	stable
ppmv	parts per million by volume	Unit of volume fraction, equivalent to SI derived unit: 1E-6	stable
pptv	parts per trillion by volume	Unit of volume fraction, equivalent to SI derived unit: 1E-12	stable
psu	practical salinity unit	Conventional unit, equivalent to per mille; SI based unit equ...	stable
rad	radian	SI derived unit of plane angle; SI base unit equivalent: 1	stable
rad.m-1	radian per metre	SI derived unit of spatial gradient of plane angle	stable
rad.s-1	radian per second	SI derived unit of angular velocity; SI base unit equivalent:...	stable
rad_m-1	radians per metre		superseded
rad_s-1	radian per second		superseded
s	second	SI base unit of time	stable
s-1	per second (same as hertz)		superseded
s-2	per second squared	SI derived unit of second order time derivative	stable
s.m-1	second per metre	SI derived unit of quantity with dimension of T.L-1	stable
s_m-1	seconds per metre		superseded
sr	steradian	SI derived unit of solid angle; SI base unit equivalent: 1	stable
t	tonne	Unit of mass, accepted for use with SI; SI base unit equivale...	stable
t.ha-1	(metric) ton per hectare	Unit of area density, equal to 0.1 kg.m-2	stable
t_ha-1	(metric) ton per hectare		superseded
u	unified atomic mass unit	Conventional unit of mass; 1 u = 1 Da (Dalton) = 1.6605390666...	stable
uS.cm-1	microsiemens per centimetre	SI derived unit of spatial gradient of electrical conductance...	stable
ug.kg-1	microgram per kilogram	SI derived unit of mass fraction, equivalent to ppbm (parts p...	stable
ug.l-1	microgram per litre	SI derived unit of mass concentration; SI base unit equivalen...	stable
ug.m-3	microgram per cubic metre	SI derived unit of mass concentration; SI base unit equivalen...	stable
ug_C_m-3	microgram C per cubic metre		superseded
ug_Cl_m-3	microgram CI per cubic metre		superseded
ug_N_m-3	microgram N per cubic metre		superseded
ug_S_m-3	microgram S per cubic metre		superseded
ug_m-3_20C	micrograms per cubic metre at 20 degrees		superseded
ug_m-3_25C	micrograms per cubic metre at 25 degrees		superseded
um	micrometre	SI prefixed unit of length; SI base unit equivalent: 1E-6 m	stable
um3.cm-3	cubic micrometre per cubic centimetre	SI derived unit of volume fraction, equivalent to pptv (parts...	stable
umol.kg-1	micromole per kilogram	SI derived unit of amount per unit mass; SI base unit equival...	stable
umol.l-1	micromole per litre	SI derived unit of amount concentration; SI base unit equival...	stable
umol.mol-1	micromole per mole	SI derived unit of mole fraction; SI base unit equivalent: 1E...	stable
umol_kg-1	micromoles per kilogram		superseded
umol_l-1	micromoles per litre		superseded
umol_mol-1	micromoles per mole		superseded
unknown	unknown	The correct value is not known to, and not computable by, the...	stable
week	week	Conventional unit of time, equivalent to 604800 s	stable