scholarly journals Can the Atlantic Ocean drive the observed multidecadal variability in Northern Hemisphere mean temperature?

2007 ◽  
Vol 34 (2) ◽  
Author(s):  
Rong Zhang ◽  
Thomas L. Delworth ◽  
Isaac M. Held
Keyword(s):  
Atlantic Ocean ◽  
Northern Hemisphere ◽  
Multidecadal Variability ◽  
Mean Temperature

Northern hemisphere atmospheric response to changes of atlantic ocean SST on decadal time scales: a GCM experiment

1990 ◽  
Vol 4 (3) ◽  
pp. 157-174 ◽  
Author(s):  
Andreas Hense ◽  
Rita Glowienka-Hense ◽  
Hans von Storch ◽  
Ursula Stähler
Keyword(s):  
Atlantic Ocean ◽  
Time Scales ◽  
Northern Hemisphere ◽  
Atmospheric Response

scholarly journals The Impact of North Atlantic–Arctic Multidecadal Variability on Northern Hemisphere Surface Air Temperature

2010 ◽  
Vol 23 (21) ◽  
pp. 5668-5677 ◽  
Author(s):  
Vladimir A. Semenov ◽  
Mojib Latif ◽  
Dietmar Dommenget ◽  
Noel S. Keenlyside ◽  
Alexander Strehz ◽  
...  
Keyword(s):  
Climate Variability ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
The Arctic ◽  
Decadal Climate Variability ◽  
Multidecadal Variability ◽  
The North ◽  
Hemisphere Surface ◽  
The North Atlantic ◽  
Decadal Climate

Abstract The twentieth-century Northern Hemisphere surface climate exhibits a long-term warming trend largely caused by anthropogenic forcing, with natural decadal climate variability superimposed on it. This study addresses the possible origin and strength of internal decadal climate variability in the Northern Hemisphere during the recent decades. The authors present results from a set of climate model simulations that suggest natural internal multidecadal climate variability in the North Atlantic–Arctic sector could have considerably contributed to the Northern Hemisphere surface warming since 1980. Although covering only a few percent of the earth’s surface, the Arctic may have provided the largest share in this. It is hypothesized that a stronger meridional overturning circulation in the Atlantic and the associated increase in northward heat transport enhanced the heat loss from the ocean to the atmosphere in the North Atlantic region and especially in the North Atlantic portion of the Arctic because of anomalously strong sea ice melt. The model results stress the potential importance of natural internal multidecadal variability originating in the North Atlantic–Arctic sector in generating interdecadal climate changes, not only on a regional scale, but also possibly on a hemispheric and even a global scale.

scholarly journals Decadal-to-Multidecadal Variability of Seasonal Land Precipitation in Northern Hemisphere in Observation and CMIP6 Historical Simulations

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 195
Author(s):  
Hua Chen ◽  
Zhenchen Xu
Keyword(s):  
Northern Hemisphere ◽  
Atlantic Multidecadal Oscillation ◽  
Ensemble Empirical Mode Decomposition ◽  
Dominant Mode ◽  
Coupled Models ◽  
Multidecadal Variability ◽  
The North ◽  
Mode Decomposition ◽  
Four Seasons ◽  
Oceanic Forcing

Based on the centennial-scale observations and CMIP6 historical simulations, this paper employs the ensemble empirical mode decomposition to extract the decadal-to-multidecadal variability of land precipitation (DMVLP) in the northern hemisphere. The spatial distributions of the dominant mode from the empirical orthogonal function are different in four seasons. Regions with the same sign of precipitation anomalies are likely to be teleconnected through oceanic forcing. The temporal evolutions of the leading modes are similar in winter and spring, with an amplitude increasing after the late 1970s, probably related to the overlap of oceanic multidecadal signals. In winter and spring, the Interdecadal Pacific Oscillation (IPO) and the Atlantic Multidecadal Oscillation (AMO) play a joint role. They were in phase before late 1970s and out of phase after then, weakening/strengthening the impacts of the North Pacific and North Atlantic on the DMVLP before/after late 1970s. In summer and autumn, AMO alone plays a part and the amplitude of time series does not vary as in winter and spring. The ability of the coupled models from CMIP6 historical simulations is also evaluated. The good-models average largely captures the spatial structure in four seasons and the associated oceanic signals. The poor-models average is hardly or weakly correlated with observation.

A new isopod species from the abyssal South Pacific ocean: Eugerda gigantea sp. nov. (Isopoda: Asellota: Desmosomatidae)

1999 ◽  
Vol 79 (6) ◽  
pp. 1061-1067 ◽  
Author(s):  
Ja-Yang Park
Keyword(s):  
New Species ◽  
Pacific Ocean ◽  
Atlantic Ocean ◽  
Northern Hemisphere ◽  
South Pacific ◽  
First Record ◽  
The Other ◽  
Equatorial Atlantic ◽  
South Pacific Ocean ◽  
Equatorial Atlantic Ocean

The new species Eugerda gigantea sp. nov. is described from the abyssal of the equatorial eastern South Pacific. For the genus Eugerda this is the first record from the South Pacific ocean, the other known species of the genus occur in the northern hemisphere or the equatorial Atlantic ocean.

scholarly journals Multidecadal variability and climate shift in the North Atlantic Ocean

2017 ◽  
Vol 44 (10) ◽  
pp. 4985-4993 ◽  
Author(s):  
Dan Seidov ◽  
Alexey Mishonov ◽  
James Reagan ◽  
Rost Parsons
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Multidecadal Variability ◽  
Climate Shift ◽  
The North ◽  
The North Atlantic

scholarly journals The Rapid Warming of the North Atlantic Ocean in the Mid-1990s in an Eddy-Permitting Ocean Reanalysis (1982–2013)

2016 ◽  
Vol 29 (15) ◽  
pp. 5417-5430 ◽  
Author(s):  
Chunxue Yang ◽  
Simona Masina ◽  
Alessio Bellucci ◽  
Andrea Storto
Keyword(s):  
Atlantic Ocean ◽  
Heat Transport ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ocean Reanalysis ◽  
The North ◽  
Mean Temperature ◽  
The Mean ◽  
The North Atlantic ◽  
Mean State

Abstract The rapid warming in the mid-1990s in the North Atlantic Ocean is investigated by means of an eddy-permitting ocean reanalysis. Both the mean state and variability, including the mid-1990s warming event, are well captured by the reanalysis. An ocean heat budget applied to the subpolar gyre (SPG) region (50°–66°N, 60°–10°W) shows that the 1995–99 rapid warming is primarily dictated by changes in the heat transport convergence term while the surface heat fluxes appear to play a minor role. The mean negative temperature increment suggests a warm bias in the model and data assimilation corrects the mean state of the model, but it is not crucial to reconstruct the time variability of the upper-ocean temperature. The decomposition of the heat transport across the southern edge of the SPG into time-mean and time-varying components shows that the SPG warming is mainly associated with both the anomalous advection of mean temperature and the mean advection of temperature anomalies across the 50°N zonal section. The relative contributions of the Atlantic meridional overturning circulation (AMOC) and gyre circulation to the heat transport are also analyzed. It is shown that both the overturning and gyre components are relevant to the mid-1990s warming. In particular, the fast adjustment of the barotropic circulation response to the NAO drives the anomalous transport of mean temperature at the subtropical/subpolar boundary, while the slowly evolving AMOC feeds the large-scale advection of thermal anomalies across 50°N. The persistently positive phase of the NAO during the years prior to the rapid warming likely favored the cross-gyre heat transfer and the following SPG warming.

scholarly journals Impact of solar vs. volcanic activity variations on tropospheric temperatures and precipitation during the Dalton Minimum

2013 ◽  
Vol 9 (6) ◽  
pp. 6179-6220 ◽  
Author(s):  
J. G. Anet ◽  
S. Muthers ◽  
E. V. Rozanov ◽  
C. C. Raible ◽  
A. Stenke ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Solar Irradiance ◽  
Energetic Particle ◽  
Volcanic Eruptions ◽  
Hadley Cell ◽  
Particle Spectrum ◽  
Volcanic Aerosol ◽  
Mean Temperature ◽  
The Impact ◽  
Dalton Minimum

Abstract. The aim of this work is to elucidate the impact of changes in solar irradiance and energetic particles vs. volcanic eruptions on tropospheric global climate during the Dalton Minimum (DM, 1780–1840 AD). Separate variations in the (i) solar irradiance in the UV-C with wavelengths λ < 250 nm, (ii) irradiance at wavelengths λ > 250 nm, (iii) in energetic particle spectrum, and (iv) volcanic aerosol forcing were analyzed separately, and (v) in combination, by means of small ensemble calculations using a coupled atmosphere-ocean chemistry-climate-model. Global and hemispheric mean surface temperatures show a significant dependence on solar irradiance at λ > 250 nm. Also, powerful volcanic eruptions in 1809, 1815, 1831 and 1835 significantly decrease global mean temperature by up to 0.5 K for 2–3 yr after the eruption. However, while the volcanic effect is clearly discernible in the southern hemispheric mean temperature, it is less significant in the Northern Hemisphere, partly because the two largest volcanic eruptions occurred in the SH tropics and during seasons when the aerosols were mainly transported southward, partly because of the higher northern internal variability. In the simulation including all forcings, temperatures are in reasonable agreement with the tree-ring-based temperature anomalies of the Northern Hemisphere. Interestingly, the model suggests that solar irradiance changes at λ < 250 nm and in energetic particle spectra have only insignificant impact on the climate during the Dalton Minimum. This downscales the importance of top-down processes (stemming from changes at λ < 250 nm) relative to bottom-up processes (from λ > 250 nm). Reduction of irradiance at λ > 250 nm leads to a significant (up to 2%) decrease of the ocean heat content (OHC) between the 0 and 300 m of depth, whereas the changes in irradiance at λ < 250 nm or in energetic particle have virtually no effect. Also, volcanic aerosol yields a very strong response, reducing the OHC of the upper ocean by up to 1.5%. In the simulation with all forcings, the OHC of the uppermost levels recovers after 8–15 yr after volcanic eruption, while the solar signal and the different volcanic eruptions dominate the OHC changes in the deeper ocean and prevent its recovery during the DM. Finally, the simulations suggest that the volcanic eruptions during the DM had a significant impact on the precipitation patterns caused by a widening of the Hadley cell and a shift of the intertropical convergence zone.

scholarly journals Increasing Knowledge of Biodiversity on the Orphan Seamount: A New Species of Tedania (Tedaniopsis) Dendy, 1924

2021 ◽  
Vol 8 ◽  
Author(s):  
Pilar Ríos ◽  
Javier Cristobo ◽  
Emily Baker ◽  
Lindsay Beazley ◽  
Timothy Culwick ◽  
...  
Keyword(s):  
New Species ◽  
Atlantic Ocean ◽  
Northern Hemisphere ◽  
Fisheries Management ◽  
External Morphology ◽  
Labrador Sea ◽  
Horizon 2020 ◽  
Additional Information ◽  
Northern Atlantic ◽  
A New Species

A new Tedania species (Porifera) was collect using remotely operated vehicles during the Canadian mission HUD2010-029 and the British RRS Discovery Cruise DY081, on the Orphan Seamount near the Orphan Knoll, northwest Atlantic, between 2999.88 and 3450.4 m depth. Orphan Knoll is an isolated, drowned continental fragment 550 km northeast Newfoundland in the Labrador Sea. This region is biologically rich and complex and in 2007, the regional fisheries management organization operating in the area regulated that no vessel shall engage in bottom-contact fishing activities until reviewed in 2020 with a review slated at the end of this year. Members of the genus Tedania are uncommon in the temperate northern hemisphere with only six species known previously: Tedania (Tedania) anhelans; Tedania (Tedania) pilarriosae; Tedania (Tedania) suctoria; Tedania (Tedania) urgorrii; Tedania (Tedaniopsis) gurjanovae; and Tedania (Tedaniopsis) phacellina. The particular features of the new sponge we describe are the very peculiar external morphology which is tree-like with dichotomous branching—a morphology not previously described in this subgenus; and the combination of spicules found: long styles, the typical tornotes of the subgenus and two sizes of onychaetes. Additional information is provided on other species of Tedaniopsis described from the Atlantic Ocean. Based on the characteristics reported, we propose a new species, Tedania (Tedaniopsis) rappi sp. nov. in honor of Prof. Hans Tore Rapp (1972–2020), University of Bergen, Norway, a renowned sponge taxonomist and coordinator of the Horizon 2020 SponGES project. The holotype of T. (T.) phacellinaTopsent, 1912 from the Azores, the only other northern Atlantic species in the subgenus Tedaniopsis, was reviewed for comparison.

scholarly journals Climate of the last millennium: ensemble consistency of simulations and reconstructions

2012 ◽  
Vol 8 (3) ◽  
pp. 2409-2444 ◽  
Author(s):  
O. Bothe ◽  
J. H. Jungclaus ◽  
D. Zanchettin ◽  
E. Zorita
Keyword(s):  
Northern Hemisphere ◽  
Temperature Fields ◽  
Data Sets ◽  
Last Millennium ◽  
Max Planck ◽  
Simulation Data ◽  
Central European ◽  
Spatial And Temporal Scales ◽  
Mean Temperature ◽  
Ensemble Mean

Abstract. Are simulations and reconstructions of past climate and its variability comparable with each other? We assess if simulations and reconstructions are consistent under the paradigm of a statistically indistinguishable ensemble. Ensemble consistency is assessed for Northern Hemisphere mean temperature, Central European mean temperature and for global temperature fields for the climate of the last millennium. Reconstructions available for these regions are evaluated against the simulation data from the community simulations of the climate of the last millennium performed at the Max Planck Institute for Meteorology. The distributions of ensemble simulated temperatures are generally too wide at most locations and on most time-scales relative to the employed reconstructions. Similarly, an ensemble of reconstructions is too wide when evaluated against the simulation ensemble mean. Probabilistic and climatological ensemble consistency is limited to sub-domains and sub-periods. Only the ensemble simulated and reconstructed annual Central European mean temperatures for the second half of the last millennium demonstrates consistency. The lack of consistency found in our analyses implies that, on the basis of the studied data sets, no status of truth can be assumed for climate evolutions on the considered spatial and temporal scales and, thus, assessing the accuracy of reconstructions and simulations is so far of limited feasibility in pre-instrumental periods.

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