Boron Content of Sea Water of the North Atlantic Coast

Abstract. Dissolved Fe (DFe) samples from the GEOVIDE voyage (GEOTRACES GA01, May–June 2014) in the North Atlantic Ocean were analysed using a SeaFAST-picoTM coupled to an Element XR HR-ICP-MS and provided interesting insights on the Fe sources in this area. Overall, DFe concentrations ranged from 0.09 ± 0.01 nmol L−1 to 7.8 ± 0.5 nmol L−1. Elevated DFe concentrations were observed above the Iberian, Greenland and Newfoundland Margins likely due to riverine inputs from the Tagus River, meteoric water inputs and sedimentary inputs. Air-sea interactions were suspected to be responsible for the increase in DFe concentrations within subsurface waters of the Irminger Sea due to deep convection occurring the previous winter, that provided iron-to-nitrate ratios sufficient to sustain phytoplankton growth. Increasing DFe concentrations along the flow path of the Labrador Sea Water were attributed to sedimentary inputs from the Newfoundland Margin. Bottom waters from the Irminger Sea displayed high DFe concentrations likely due to the dissolution of Fe-rich particles from the Denmark Strait Overflow Water and the Polar Intermediate Water. Finally, the nepheloid layers were found to act as either a source or a sink of DFe depending on the nature of particles.

Download Full-text

Identification and quantification of the North Atlantic Deep Water pathways

10.5194/egusphere-egu21-10358 ◽

2021 ◽

Author(s):

Philippe Miron ◽

Maria J. Olascoaga ◽

Francisco J. Beron-Vera ◽

Kimberly L. Drouin ◽

M. Susan Lozier

Keyword(s):

North Atlantic ◽

Deep Water ◽

Sea Water ◽

Lower Layer ◽

North Atlantic Deep Water ◽

Meridional Overturning Circulation ◽

Labrador Sea ◽

Western Boundary ◽

The North ◽

The North Atlantic

The North Atlantic Deep Water (NADW) flows equatorward along the Deep Western Boundary Current (DWBC) as well as interior pathways and is a critical part of the Atlantic Meridional Overturning Circulation. Its upper layer, the Labrador Sea Water (LSW), is formed by open-ocean deep convection in the Labrador and Irminger Seas while its lower layers, the Iceland&#8211;Scotland Overflow Water (ISOW) and the Denmark Strait Overflow Water (DSOW), are formed north of the Greenland&#8211;Iceland&#8211;Scotland Ridge.In recent years, more than two hundred acoustically-tracked subsurface floats have been deployed in the deep waters of the North Atlantic. &#160;Studies to date have highlighted water mass pathways from launch locations, but due to limited float trajectory lengths, these studies have been unable to identify pathways connecting &#160;remote regions.This work presents a framework to explore deep water pathways from their respective sources in the North Atlantic using Markov Chain (MC) modeling and Transition Path Theory (TPT). Using observational trajectories released as part of OSNAP and the Argo projects, we constructed two MCs that approximate the lower and upper layers of the NADW Lagrangian dynamics. The reactive NADW pathways&#8212;directly connecting NADW sources with a target at 53&#176;N&#8212;are obtained from these MCs using TPT.Preliminary results show that twenty percent more pathways of the upper layer(LSW) reach the ocean interior compared to &#160;the lower layer (ISOW, DSOW), which mostly flows along the DWBC in the subpolar North Atlantic. Also identified are the Labrador Sea recirculation pathways to the Irminger Sea and the direct connections from the Reykjanes Ridge to the eastern flank of the Mid&#8211;Atlantic Ridge, both previously observed. Furthermore, we quantified the eastern spread of the LSW to the area surrounding the Charlie&#8211;Gibbs Fracture Zone and compared it with previous analysis. Finally, the residence time of the upper and lower layers are assessed and compared to previous observations.

Download Full-text

Impact of Seasonality in the North Atlantic Jet Stream and Storm Migration on the Seasonality of Hurricane Translation Speed Changes

Journal of Climate ◽

10.1175/jcli-d-20-0642.1 ◽

2021 ◽

pp. 1-38

Author(s):

Xi Guo ◽

James P. Kossin ◽

Zhe-Min Tan

Keyword(s):

North Atlantic ◽

Atlantic Coast ◽

Jet Stream ◽

Translation Speed ◽

Multidecadal Variability ◽

The Past ◽

The North ◽

Term Variation ◽

The North Atlantic

AbstractTropical cyclone (TC) translation speed (TCTS) can affect the duration of TC-related disasters, which is critical to coastal and inland areas. The long-term variation of TCTS and their relationship to the variability of the mid-latitude jet stream and storm migration are discussed here for storms near the North Atlantic coast during 1948-2019. Our results reveal the prominent seasonality in the long-term variation of TCTS, which can be largely explained by the seasonality in the covariations of the mid-latitude jet stream and storm locations. Specifically, significant increases of TCTS occur in June and October during the past decades, which may result from the equatorward displacement of the jet stream and poleward migration of storm locations. Prominent slowdown of TCTS is found in August, which is related to the weakened jet strength and equatorward storm migration. In September, the effects of poleward displacement and weakening of the jet stream on TCTS are largely compensated by the poleward storm migration, therefore, no significant change in TCTS is observed. Meanwhile, the multidecadal variability of the Atlantic may contribute to the multidecadal variability of TCTS. Our findings emphasize the significance in taking a seasonality view in discussing the variability and trends of near-coast Atlantic TCTS under climate change.

Download Full-text