Abstract. A large number of water masses are presented in the Atlantic Ocean,
and knowledge of their distributions and properties is important for
understanding and monitoring of a range of oceanographic phenomena. The
characteristics and distributions of water masses in biogeochemical space
are useful for, in particular, chemical and biological oceanography to
understand the origin and mixing history of water samples. Here, we define
the characteristics of the major water masses in the Atlantic Ocean as
source water types (SWTs) from their formation areas, and map out their
distributions. The SWTs are described by six properties taken from the
biased-adjusted Global Ocean Data
Analysis Project version 2 (GLODAPv2) data product, including both conservative
(conservative temperature and absolute salinity) and non-conservative
(oxygen, silicate, phosphate and nitrate) properties. The distributions of
these water masses are investigated with the use of the optimum
multi-parameter (OMP) method and mapped out. The Atlantic Ocean is divided
into four vertical layers by distinct neutral densities and four zonal
layers to guide the identification and characterization. The water masses in
the upper layer originate from wintertime subduction and are defined as
central waters. Below the upper layer, the intermediate layer consists of
three main water masses: Antarctic Intermediate Water (AAIW), Subarctic
Intermediate Water (SAIW) and Mediterranean Water (MW). The North Atlantic
Deep Water (NADW, divided into its upper and lower components) is the
dominating water mass in the deep and overflow layer. The origin of both the
upper and lower NADW is the Labrador Sea Water (LSW), the Iceland–Scotland
Overflow Water (ISOW) and the Denmark Strait Overflow Water (DSOW). The
Antarctic Bottom Water (AABW) is the only natural water mass in the bottom
layer, and this water mass is redefined as Northeast Atlantic Bottom Water
(NEABW) in the north of the Equator due to the change of key properties,
especially silicate. Similar with NADW, two additional water masses,
Circumpolar Deep Water (CDW) and Weddell Sea Bottom Water (WSBW), are
defined in the Weddell Sea region in order to understand the origin of AABW.
Local Coastal Water Masses Control Heat Levels in a West Greenland Tidewater Outlet Glacier Fjord