scholarly journals Stable near-surface ocean salinity stratifications due to evaporation observed during STRASSE

2014 ◽  
Vol 119 (5) ◽  
pp. 3219-3233 ◽  
Author(s):  
William E. Asher ◽  
Andrew T. Jessup ◽  
Dan Clark
Keyword(s):  
Near Surface ◽  
Surface Ocean ◽  
Ocean Salinity

Ocean Salinity Aspects of the Ningaloo Niño

2021 ◽  
pp. 1
Author(s):  
Yaru Guo ◽  
Yuanlong Li ◽  
Fan Wang ◽  
Yuntao Wei
Keyword(s):  
Fresh Water ◽  
Large Scale ◽  
Southern Oscillation ◽  
Regional Climate ◽  
Ocean Model ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Near Surface ◽  
Ocean Salinity

AbstractNingaloo Niño – the interannually occurring warming episode in the southeast Indian Ocean (SEIO) – has strong signatures in ocean temperature and circulation and exerts profound impacts on regional climate and marine biosystems. Analysis of observational data and eddy-resolving regional ocean model simulations reveals that the Ningaloo Niño/Niña can also induce pronounced variability in ocean salinity, causing large-scale sea surface salinity (SSS) freshening of 0.15–0.20 psu in the SEIO during its warm phase. Model experiments are performed to understand the underlying processes. This SSS freshening is mutually caused by the increased local precipitation (~68%) and enhanced fresh-water transport of the Indonesian Throughflow (ITF; ~28%) during Ningaloo Niño events. The effects of other processes, such as local winds and evaporation, are secondary (~18%). The ITF enhances the southward fresh-water advection near the eastern boundary, which is critical in causing the strong freshening (> 0.20 psu) near the Western Australian coast. Owing to the strong modulation effect of the ITF, SSS near the coast bears a higher correlation with the El Niño-Southern Oscillation (0.57, 0.77, and 0.70 with Niño-3, Niño-4, and Niño-3.4 indices, respectively) than sea surface temperature (-0.27, -0.42, and -0.35) during 1993-2016. Yet, an idealized model experiment with artificial damping for salinity anomaly indicates that ocean salinity has limited impact on ocean near-surface stratification and thus minimal feedback effect on the warming of Ningaloo Niño.

scholarly journals Pronounced Impact of Salinity on Rapidly Intensifying Tropical Cyclones

2020 ◽  
Vol 101 (9) ◽  
pp. E1497-E1511 ◽  
Author(s):  
Karthik Balaguru ◽  
Gregory R. Foltz ◽  
L. Ruby Leung ◽  
John Kaplan ◽  
Wenwei Xu ◽  
...  
Keyword(s):  
Positive Impact ◽  
River System ◽  
Surface Salinity ◽  
Near Surface ◽  
Salinity Stratification ◽  
Sst Cooling ◽  
Prediction Scheme ◽  
Ocean Salinity ◽  
Global Coverage ◽  
The Impact

Abstract Tropical cyclone (TC) rapid intensification (RI) is difficult to predict and poses a formidable threat to coastal populations. A warm upper ocean is well known to favor RI, but the role of ocean salinity is less clear. This study shows a strong inverse relationship between salinity and TC RI in the eastern Caribbean and western tropical Atlantic due to near-surface freshening from the Amazon–Orinoco River system. In this region, rapidly intensifying TCs induce a much stronger surface enthalpy flux compared to more weakly intensifying storms, in part due to a reduction in SST cooling caused by salinity stratification. This reduction has a noticeable positive impact on TCs undergoing RI, but the impact of salinity on more weakly intensifying storms is insignificant. These statistical results are confirmed through experiments with an ocean mixed layer model, which show that the salinity-induced reduction in SST cold wakes increases significantly as the storm’s intensification rate increases. Currently, operational statistical–dynamical RI models do not use salinity as a predictor. Through experiments with a statistical RI prediction scheme, it is found that the inclusion of surface salinity significantly improves the RI detection skill, offering promise for improved operational RI prediction. Satellite surface salinity may be valuable for this purpose, given its global coverage and availability in near–real time.

What is gradualism? Cryptic speciation in globorotaliid foraminifera

Paleobiology ◽  
1996 ◽  
Vol 22 (3) ◽  
pp. 386-405 ◽  
Author(s):  
Richard D. Norris ◽  
Richard M. Corfield ◽  
Julie Cartlidge
Keyword(s):  
Reproductive Isolation ◽  
Morphological Changes ◽  
Morphological Evolution ◽  
Reproductive Ecology ◽  
Shell Growth ◽  
Shell Shape ◽  
Planktic Foraminifera ◽  
Near Surface ◽  
Surface Ocean ◽  
Speciation Event

Analysis of the evolution of the Globorotalia (Fohsella) lineage of planktic foraminifera suggests that reproductive ecology and shell shape have evolved independently in this group. The silhouette of fohsellid shells displays a nearly unbroken anagenetic trend, yet isotopic data show that the fohsellids changed their depth of reproduction during the anagenetic evolution of their skeletons. Remarkably, there are no correlations between anagenesis in skeletal shape and the establishment of reproductive isolation. Apparently, anagenesis masks at least one speciation event that is apparent only in the isotopic evidence for a change in reproductive ecology. Although anagenetic trends have been widely cited as evidence for gradual speciation in planktic foraminifera and other microfossil groups, our data suggest that they should not always be considered to record either the tempo or mode of speciation.Speciation was apparently uncoupled from morphological evolution in fohsellids because these evolutionary phenomena occurred in different phases of ontogeny. Gradual morphological changes were associated with the main phase of shell growth of both the ancestor and descendant species in the near-surface ocean. Reproductive isolation occurred when ancestral and descendant populations became established at different depths near the end of the life cycle. Morphological evolution may also be uncoupled from reproductive isolation in other organisms that experience very different selection pressures over the duration of their ontogenies, such as parasites with many hosts, species with multiple phases of metamorphosis, and organisms that broadcast their gametes.

Two-sided turbulent boundary layer parameterizations for assessing ocean – atmosphere fluxes

2020 ◽  
Author(s):  
Florian Lemarie ◽  
Charles Pelletier ◽  
Pierre-Etienne Brilouet ◽  
Eric Blayo ◽  
Jean-Luc Redelsperger ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
Ocean Surface ◽  
Near Surface ◽  
Surface Ocean ◽  
Turbulent Closure ◽  
Surface Fields ◽  
Ocean Surface Layer ◽  
Vertical Level ◽  
Layer Solution

<p><span>Standard </span><span>methods for determining air – sea fluxes typically rely on bulk algorithms derived from the Monin-Obukhov stability theory (MOST), </span><span>using ocean surface fields and atmosphere near-surface fields. In the context of coupled ocean – atmosphere simulations, </span><span>the </span><span>shallowest ocean vertical level is usually assimilated to </span><span>the surface, and the turbulent closure is one-sided: it aims at extrapolating atmosphere near-surface solution profiles (for wind speed, temperature and humidity) to the prescribed ocean surface values. </span><span>Assimilating near-surface ocean fields as surface ones is equivalent to considering that in the ocean surface layer, solution profiles are constant instead of also being determined by a turbulent closure. Here we introduce a method for extending existing turbulent parameterization</span><span>s</span><span> to a two-sided </span><span>context, by including the ocean surface layer and the viscous sublayers, which are also generally neglected in </span><span>standard air – sea fluxes computation. </span><span>The formalism we use for this method is derived from that of classical turbulent closure, so that our novelties can easily be implemented within existing formulations.</span> <span>Special care is taken to </span><span>ensure the smoothness of </span><span>resulting solution profiles. </span><span>We</span> <span>investigate the </span><span>impact of such two-sided bulk formulations on air - sea fluxes and </span><span>discuss further implications such as resulting bulk formulation retuning. We also present leads on incorporating </span><span>other mechanisms impacting air – sea fluxes within our framework, such as waves and radiation penetration.<br></span></p>

scholarly journals On the effect of sea-ice dynamics on oceanic thermohaline circulation

1995 ◽  
Vol 21 ◽  
pp. 361-368
Author(s):  
W. D. Hibler ◽  
Jinlun Zhang
Keyword(s):  
Sea Ice ◽  
Thermohaline Circulation ◽  
Ocean Model ◽  
Flat Bottom ◽  
Ice Dynamics ◽  
Surface Ocean ◽  
The North ◽  
Air Temperatures ◽  
Sea Ice Dynamics ◽  
Ocean Salinity

An idealized planetary flat-bottom geostrophic ice–ocean model is constructed with boundaries at latitudes 5° and 65° N and longitudes 50° W and 10° E in order to approximate the North Atlantic. The model is driven by fixed zonally averaged wind, surface air temperatures and surface ocean salinity. A dynamic thermodynamic sea-ice model is coupled to the ocean model. Only the thermodynamic insulating effects of the sea ice are considered, and no salt fluxes due to melting and freezing are included. Four equilibrium simulations of about 5000 years each are performed: two with interactive sea ice with and without ice dynamics, and two control simulations with either a fixed or no ice cover.In the two simulations including interactive sea ice, characteristic oscillations in the ice thickness and ocean temperature are found to occur. The oscillations are smaller when sea-ice dynamics are included. The dominant oscillation occurs at about a 5 year period, with the key feature being that the presence of sea ice tends to insulate the ocean and hence allows an oceanic warming. This warming in turn eventually causes a melt-back of the ice and a subsequent cool-down of the ocean. Oscillations at longer periods of about 20 years in the thermohaline circulation are also observed. These longer-period oscillations are particularly pronounced in the northward surface water transport.

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