The Practical Salinity Scale 1978 (PSS-78) has been considered by the Joint Panel on Oceanographic Tables and Standards and recommended by all oceanographic organizations as the scale in which to report future salinity data.
S=a0 + a1K1/2 + a2 K + a3K3/2 + a4K2 + a5K5/2 where K is K15
formulated and adopted by the UNESCO/ICES/SCOR/IAPSO Joint Panel on Oceanographic tables and Standards,
a0 = 0.008 b0 = 0.0005
R= C(S, T68, P) / C(35,1568,0)
C(35,1568,0) = 42.914 mS/cm = 4.2914 S/m
T68 = 1.00024×T90
RT= R / rTRP
Rp= 1 + (A1p + A2p2 + A3p3 ) / (1 + B1T + B2T2 + B3R + B4TR)
rT = c0 + c1T + c2T2 + c3T3 + c4T4
c0 = 0.6766097
These equations enable the practical salinity S in a range 2 to 42 to be calculated from conductivity C (mS/cm or S/m) measured at temperature T (ºC) and hydrostatic pressure p(dBar) and is valid in the temperature range -2°C to +35°C and hydrostatic pressure 0-10000 dBar.
Practical salinity should be expressed by dimensionless number only and should be written as, e.g. S = 35.034.