Water mass definition workshop

Arild Sundfjord
RF1 leader
Norwegian Polar Institute


The project’s research focus on the northern Barents Sea and the adjacent Nansen Basin has highlighted a need for common reference terms when discussing water mass origins and modification processes.

Several relevant water mass definitions have been proposed and applied over the years, but these often focus either on water masses in the southern and central part of the Barents Sea, or on the deep interior Arctic Ocean. In a series of small workshops, oceanographers from the Nansen Legacy project analyzed existing data from the Nansen Legacy study area, and discussed different approaches for common water mass definitions.

The outcome from the workshops is a set of quite broad water mass definitions that can be applied throughout the Nansen Legacy study region – supplied by additional, more specific definitions as needed.

Water mass

Nansen Legacy definition

PW (Polar Water)

CT <= 0.0°C, s0 <= 27.97 kg m-3

(q <= 0.0°C, s0 <= 27.97 kg m-3)

wPW (warm Polar Water)1

CT > 0.0°C, SA < 35.06 g kg-1

(q > 0.0°C, S < 34.9)

AW (Atlantic Water)

CT > 2.0°C, SA >= 35.06 g kg-1

(q > 2.0°C, S >= 34.9)

mAW (modified Atlantic Water)

0.0°C < CT <= 2.0°C, SA >= 35.06 g kg-1

(0.0°C < q <= 2.0°C, S >= 34.9)

IW (Intermediate Water)

-1.1°C < CT <= 0.0°C, s0 > 27.97 kg m-3

(-1.1°C < q <= 0.0°C, s0 > 27.97 kg m-3)

CBSDW (Cold Barents Sea Dense


CT <= -1.1°C, s0 > 27.97 kg m-3

(q <= -1.1°C, s0 > 27.97 kg m-3)

EBDW (Eurasian Basin Deep Water)

Note: to be used for data from North

of the Barents Sea (e.g. > 500 m


-1.1°C < CT <= 0.0°C, SA > 35.06 g kg-1

(-1.1°C < q <= 0.0°C, S > 34.9)