Water masses in the Atlantic Ocean: characteristics and distributions

Abstract

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.

Neural Ordinary Differential Equation Model for Evolutionary Subspace Clustering and Its Applications

“…The pattern and shape of the clusters are relatively similar, where the red, yellow and orange clusters distribute from 0 • to 60 • E and from 25 • S to 45 • S, from the west to the east. This finding is consistent with the discoveries in environmental science [39]. The NODE-ESCM is able to capture the complicated clustering patterns which are observed from the shapes of the clusters.…”

Biological Carbon Pump Sequestration Efficiency in the North Atlantic: A Leaky or a Long‐Term Sink?

“…35.3% of re‐entrained particles released at 2,000 m were re‐entrained into the mixed layer in the Southern Ocean (35‐90S), compared to only 0.2% and 1.5% for the 500 and 1,000 m releases. Particles released at 2,000 m traverse different pathways compared to the shallower releases, with a major pathway, likely North Atlantic Deep Water (NADW; 2,000 m particles were released at potential densities between 1,027.73 and 1,028.09 kg m −3 , with a mean density of 1,027.86 kg m −3 , consistent with upper NADW water mass definitions 1,027.85–1,028.10 kg m −3 ; Liu & Tanhua, 2021), which flows along the Western Atlantic and into the Southern Ocean, where REC may be upwelled (Figures 2 and 3). This different behavior is supported by the greater distances traveled by re‐entrained Lagrangian particles released at 2,000 m in Figure 2i, compared to subplots 2g and 2h, and the shallower re‐entrainment depth between 0 and 50N in Figure 3f, compared to subplots 3d and 3e.…”

Dissolved Methane in the World's Largest Semi‐Enclosed Estuarine System: The Estuary and Gulf of St. Lawrence (Canada)

“…This might also be the case for our estimation here, since we did not account for the potential mixing of the NACW with “older” water during its passage from the formation site to Cabot Strait. Another factor likely contributing to this discrepancy is the enhanced microbial methane oxidation due to the warmer temperature of the NACW (11.1°C, Table S4 in Supporting Information ) compared to the “young” NADW (mostly 2–5°C, Liu & Tanhua, 2021; Puerta et al., 2020). Q 10 values, which describe the temperature dependence of metabolic rates (Genovesi et al., 2011), for aerobic microbial methane oxidation in seawater are unknown but are 3.4–4.4 in waters of two Arctic Alaskan lakes (Lofton et al., 2014), 1.4–2.1 in subarctic peat soils (Dunfield et al., 1993), and ∼2.6 in a sandy landfill cover soil (Park et al., 2005).…”