scholarly journals The Influence of Ocean Convection Patterns on High-Latitude Climate Projections

2004 ◽  
Vol 17 (22) ◽  
pp. 4316-4329 ◽  
Author(s):  
M. Schaeffer ◽  
F. M. Selten ◽  
J. D. Opsteegh ◽  
H. Goosse
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Surface Air Temperature ◽  
Deep Ocean ◽  
Ocean Model ◽  
Climate Projections ◽  
The North ◽  
The North Atlantic ◽  
Convection Patterns

Abstract The mean state and variability of deep convection in the ocean influence the North Atlantic climate. Using an ensemble experiment with a coupled atmosphere–ocean–sea ice model, it is shown that cooling and subdued warming areas can occur over the North Atlantic Ocean and adjacent landmasses under global warming. Different “present-day” convection patterns in the Greenland–Iceland–Norway (GIN) Sea result in different future surface-air temperature changes. At higher latitudes, the more effective positive sea ice feedback increases the likelihood of changes in convection causing a regional cooling that is larger than the warming brought about by the enhanced greenhouse effect. The modeled freshening of deep ocean layers in the North Atlantic in a time period preceding a reorganization of GIN Sea convection is consistent with recent observations. Low-frequency internal variability in the ocean model has relatively little impact on the response patterns.

AMOC response to changing resolution in the Finite-volumE Sea ice–Ocean Model

2020 ◽  
Author(s):  
Dmitry Sidorenko ◽  
Sergey Danilov ◽  
Nikolay Koldunov ◽  
Patrick Scholz
Keyword(s):  
Sea Ice ◽  
Finite Volume ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ocean Model ◽  
Water Masses ◽  
Meridional Overturning Circulation ◽  
Meridional Transport ◽  
The North ◽  
The North Atlantic

<p>The Atlantic meridional overturning circulation (AMOC) is the most common diagnostics of numerical simulations. Generally it is computed as a streamfunction of zonally averaged flow along the constant depth. More rarely it is computed as zonally averaged along constant isopycnals. The latter computation, however, allows one to better distinguish between water masses and physical processes contributing to the meridional transport. We analyze the AMOC in global simulations based on the Finite-volumE Sea ice–Ocean Model (FESOM 2.0) using eddy permitting to eddy resolving configurations in the North Atlantic. We (1) split the AMOC computed in density space into the constitutes induced by surface buoyancy fluxes and cross isopycnal transformations, (2) identify the water masses which contribute to the formation of the North Atlantic Deep Water and (3) study the AMOC response to the permitting or resolving eddies in the North Atlantic ocean.</p>

scholarly journals Atlantic Ocean Influence on Middle East Summer Surface Air Temperature

2020 ◽  
Author(s):  
Muhammad Azhar Ehsan ◽  
Dario Nicolì ◽  
Fred Kucharski ◽  
Mansour Almazroui ◽  
Michael Tippett ◽  
...  
Keyword(s):  
Middle East ◽  
Atlantic Ocean ◽  
Air Temperature ◽  
North Atlantic ◽  
Surface Air Temperature ◽  
Ocean Model ◽  
Boreal Summer ◽  
Multidecadal Variability ◽  
The North ◽  
The North Atlantic

<p>Middle East surface air temperature (ME−SAT), during boreal summer (June to August: JJA), shows robust multidecadal variations for the period 1948−2016. Here using observational and reanalysis datasets as well as coupled atmosphere−ocean model simulations, we linked the observed summer ME−SAT variability to the multidecadal variability of sea surface temperature (SST) in the North Atlantic Ocean (AMV). This Atlantic−ME connection during summer involves ocean−atmosphere interactions through multiple ocean basins, with an influence from the Indian Ocean and the Arabian Sea. The downstream response to Atlantic SST is a weakening of the subtropical westerly jet stream that impacts summer ME−SAT variability through a wave−like pattern in the upper tropospheric levels. The Atlantic SST response is further characterized by positive geopotential height anomalies in the upper levels over the Eurasian region and dipole−like pressure distribution over the ME lower levels. For positive Atlantic SST anomalies, this pressure gradient initiates anomalous low−level southerly flow, which transports moisture from the neighboring water bodies toward the extremely hot and dry ME landmass. The increase in atmospheric moisture reduces the longwave radiation damping of the SAT anomaly, increasing further ME−SAT. A suite of Atlantic Pacemaker experiments skillfully reproduces the North Atlantic−ME teleconnection. Our findings reveal that in observations and models the Atlantic Ocean acts as a critical pacemaker for summer ME−SAT multidecadal variability and that a positive AMV can lead to enhanced summer warming over the Middle East.</p>

scholarly journals The sources of deep ocean infragravity waves observed in the North Atlantic Ocean

2015 ◽  
Vol 120 (7) ◽  
pp. 5120-5133 ◽  
Author(s):  
Wayne Crawford ◽  
Valerie Ballu ◽  
Xavier Bertin ◽  
Mikhail Karpytchev
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Deep Ocean ◽  
Infragravity Waves ◽  
The North ◽  
The North Atlantic

scholarly journals Twenty-first century wave climate projections for Ireland and surface winds in the North Atlantic Ocean

2016 ◽  
Vol 13 ◽  
pp. 75-80 ◽  
Author(s):  
Sarah Gallagher ◽  
Emily Gleeson ◽  
Roxana Tiron ◽  
Ray McGrath ◽  
Frédéric Dias
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Global Climate ◽  
Wave Climate ◽  
Climate Projections ◽  
The North ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Wind Climate ◽  
The North Atlantic

Abstract. Ireland has a highly energetic wave and wind climate, and is therefore uniquely placed in terms of its ocean renewable energy resource. The socio-economic importance of the marine resource to Ireland makes it critical to quantify how the wave and wind climate may change in the future due to global climate change. Projected changes in winds, ocean waves and the frequency and severity of extreme weather events should be carefully assessed for long-term marine and coastal planning. We derived an ensemble of future wave climate projections for Ireland using the EC-Earth global climate model and the WAVEWATCH III® wave model, by comparing the future 30-year period 2070–2099 to the period 1980–2009 for the RCP4.5 and the RCP8.5 forcing scenarios. This dataset is currently the highest resolution wave projection dataset available for Ireland. The EC-Earth ensemble predicts decreases in mean (up to 2 % for RCP4.5 and up to 3.5 % for RCP8.5) 10 m wind speeds over the North Atlantic Ocean (5–75° N, 0–80° W) by the end of the century, which will consequently affect swell generation for the Irish wave climate. The WAVEWATCH III® model predicts an overall decrease in annual and seasonal mean significant wave heights around Ireland, with the largest decreases in summer (up to 15 %) and winter (up to 10 %) for RCP8.5. Projected decreases in mean significant wave heights for spring and autumn were found to be small for both forcing scenarios (less than 5 %), with no significant decrease found for RCP4.5 off the west coast in those seasons.

scholarly journals Impacts of Changed Ice-Ocean Stress on the North Atlantic Ocean: Role of Ocean Surface Currents

2021 ◽  
Vol 8 ◽  
Author(s):  
Yang Wu ◽  
Zhaomin Wang ◽  
Chengyan Liu
Keyword(s):  
Atlantic Ocean ◽  
Sea Ice ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ocean Surface ◽  
Surface Currents ◽  
Stress Calculation ◽  
The North ◽  
Ocean Surface Currents ◽  
The North Atlantic

The importance of considering ocean surface currents in ice-ocean stress calculation in the North Atlantic Ocean and Arctic sea ice is investigated for the first time using a global coupled ocean-sea ice model. Considering ocean surface currents in ice-ocean stress calculation weakens the ocean surface stress and Ekman pumping by about 7.7 and 15% over the North Atlantic Ocean, respectively. It also significantly reduces the mechanical energy input to ageostrophic and geostrophic currents, and weakens the mean and eddy kinetic energy by reducing the energy conversion rates of baroclinic and barotropic pathways. Furthermore, the strength of the Atlantic Meridional Overturning Circulation (AMOC), the Nordic Seas MOC, and the North Atlantic subpolar gyre are found to be reduced considerably (by 14.3, 31.0, and 18.1%, respectively). The weakened AMOC leads to a 0.12 PW reduction in maximum northward ocean heat transport, resulting in a reduced surface heat loss and lower sea surface temperature over the North Atlantic Ocean. This reduction also leads to a shrink in sea ice extent and an attenuation of sea ice thickness. These findings highlight the importance of properly considering both the geostrophic and ageostrophic components of ocean surface currents in ice-ocean stress calculation on ocean circulation and climate studies.

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