scholarly journals Linearity of the Atmospheric Response to North Atlantic SST and Sea Ice Anomalies

2005 ◽  
Vol 18 (12) ◽  
pp. 1986-2003 ◽  
Author(s):  
Sébastien Conil ◽  
Laurent Z-X. Li
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Geopotential Height ◽  
Winter Season ◽  
Low Frequency ◽  
Temperature Response ◽  
Low Level ◽  
The North ◽  
The North Atlantic

Abstract The observations of the ocean–atmosphere–sea ice have recently revealed that the oceanic surfaces can have a subtle but significant impact on the atmospheric long-term fluctuations. Low-frequency variations and long-term trends of the North Atlantic atmospheric circulation have been partly related to particular SST and sea ice features. In this work, the influence of typical tripolar SST and dipolar sea ice anomalies in the North Atlantic–Arctic on the atmosphere is investigated. A large ensemble of AGCM simulations forced by three different anomalous boundary conditions (SST, sea ice, and SST + sea ice) are used. The linearity of the simulated response in the winter season is particularly assessed. In these experiments, while the winter low-level temperature response is mainly symmetric about the sign of the forcing, the asymmetric part of the geopotential response is substantial. The sea ice forcing maintains a baroclinic response with a strong temperature anomaly in the vicinity of the forcing but with a weak vertical penetration. The SST maintains an NAO-like equivalent barotropic temperature and geopotential height response that extends throughout the troposphere. It is also shown that the combination of the two forcings is mainly linear for the low-level temperature and nonlinear for the geopotential height. While the SST forcing seems to be the main contributor to the total temperature and geopotential height responses, the sea ice forcing appears to introduce significant nonlinear perturbations.

scholarly journals Dynamics and Impacting Factors of Ice Regimes in Latvia Inland and Coastal Waters

2016 ◽  
Vol 70 (6) ◽  
pp. 400-408 ◽  
Author(s):  
Māris Kļaviņš ◽  
Zanita Avotniece ◽  
Valērijs Rodinovs
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
North Atlantic ◽  
Sea Water ◽  
Inland Waters ◽  
The North ◽  
The North Atlantic ◽  
Ice Regime ◽  
The Impact

Abstract The sea ice regime is considered to be a sensitive indicator of climate change. This study investigates long-term changes in the ice regimes of the Gulf of Riga along the coast of Latvia in comparison with those of inland waters. The ice regime of the studied region indicates the impact of climate change related to increasing air and sea water temperatures. Ice cover duration on both the sea and inland waters has decreased during recent decades. In addition, long-term records on ice break in the studied region exhibit a pattern of periodic changes in the intensity of ice regime, while trends of the sea ice regime are not consistent between periods of time. Alternating mild and severe winters also occur. The ice regime was shown to be strongly influenced by large-scale atmospheric circulation processes over the North Atlantic, as indicated by close correlation with the North Atlantic Oscillation index.

Preaching and Sermons

2017 ◽  
Author(s):  
Robert H. Ellison
Keyword(s):  
Eighteenth Century ◽  
North Atlantic ◽  
Religious Revival ◽  
Early Nineteenth Century ◽  
Denominational Identity ◽  
The North ◽  
The North Atlantic ◽  
The One ◽  
The Impact

Prompted by the convulsions of the late eighteenth century and inspired by the expansion of evangelicalism across the North Atlantic world, Protestant Dissenters from the 1790s eagerly subscribed to a millennial vision of a world transformed through missionary activism and religious revival. Voluntary societies proliferated in the early nineteenth century to spread the gospel and transform society at home and overseas. In doing so, they engaged many thousands of converts who felt the call to share their experience of personal conversion with others. Though social respectability and business methods became a notable feature of Victorian Nonconformity, the religious populism of the earlier period did not disappear and religious revival remained a key component of Dissenting experience. The impact of this revitalization was mixed. On the one hand, growth was not sustained in the long term and, to some extent, involvement in interdenominational activity undermined denominational identity; on the other hand, Nonconformists gained a social and political prominence they had not enjoyed since the middle of the seventeenth century and their efforts laid the basis for the twentieth-century explosion of evangelicalism in Africa, Asia, and South America.

Erratum to: An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation

2017 ◽  
Vol 50 (1-2) ◽  
pp. 443-443 ◽  
Author(s):  
Mihaela Caian ◽  
Torben Koenigk ◽  
Ralf Döscher ◽  
Abhay Devasthale
Keyword(s):  
Sea Ice ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The North ◽  
Arctic Sea ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

scholarly journals Climate impacts on multidecadal <i>p</i>CO<sub>2</sub> variability in the North Atlantic: 1948–2009

2015 ◽  
Vol 12 (17) ◽  
pp. 15223-15244
Author(s):  
M. L. Breeden ◽  
G. A. McKinley
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Dissolved Inorganic Carbon ◽  
Atlantic Multidecadal Oscillation ◽  
Climate Impacts ◽  
Co2 Uptake ◽  
Subpolar Gyre ◽  
The North ◽  
The North Atlantic

Abstract. The North Atlantic is the most intense region of ocean CO2 uptake. Here, we investigate multidecadal timescale variability of the partial pressure CO2 (pCO2) that is due to the natural carbon cycle using a regional model forced with realistic climate and pre-industrial atmospheric pCO2 for 1948–2009. Large-scale patterns of natural pCO2 variability are primarily associated with basin-averaged sea surface temperature (SST) that, in turn, is composed of two parts: the Atlantic Multidecadal Oscillation (AMO) and a long-term positive SST trend. The North Atlantic Oscillation (NAO) drives a secondary mode of variability. For the primary mode, positive AMO and the SST trend modify pCO2 with different mechanisms and spatial patterns. Warming with the positive AMO increases subpolar gyre pCO2, but there is also a significant reduction of dissolved inorganic carbon (DIC) due primarily to reduced vertical mixing. The net impact of positive AMO is to reduce pCO2 in the subpolar gyre. Through direct impacts on SST, the net impacts of positive AMO is to increase pCO2 in the subtropical gyre. From 1980 to present, long-term SST warming has amplified AMO impacts on pCO2.

scholarly journals LONG-TERM VARIABILITY OF CURRENTS IN THE SUBARCTIC FRONT OF THE ATLANTIC OCEAN

2019 ◽  
Vol 47 (2) ◽  
pp. 246-265
Author(s):  
A. K. Ambrosimov ◽  
N. A. Diansky ◽  
A. A. Kluvitkin ◽  
V. A. Melnikov
Keyword(s):  
North Atlantic ◽  
Ocean Surface ◽  
North Atlantic Current ◽  
Reykjanes Ridge ◽  
The North ◽  
Subarctic Front ◽  
Average Water ◽  
The North Atlantic ◽  
Atlantic Current

Based on time series of near-bottom current velocities and temperatures obtained in the period June, 2016 to July, 2017, at three points in the Atlantic Subarctic Front, along with the use of multi-year (since 1993 up to now) satellite ocean surface sounding data, multi-scale fluctuations of ocean surface and near-bottom flows over the western and eastern flanks of the Reykjanes ridge, as well as near Hatton Rise, on the Rokoll plateau, are studied. Hydrological profiles were carried out from the ocean surface to the bottom with readings every 10 m, when setting and retrieving the buoy stations. Using data from the Bank of hydrological stations (WOD13), SST satellite arrays (Pathfinder), long-term sea level and geostrophic velocities time series (AVISO), and bottom topography (model ETOPO-1), features of longterm cyclical fluctuations of SST, sea level, geostrophic currents on the ocean surface were defined in the sub-polar North Atlantic. It is shown that, in accordance with the large-scale thermohaline structure of the Subarctic front, two branches of the North Atlantic Current are detected on the ocean surface.One is directed from the Hatton towards the Icelandic-Faroese Rise, and the other – alomg the western flank of the Reykjanes Ridge toward Iceland. For the first branch, which is the main continuation of the North Atlantic Current, the average (for 25 years) water drift at a speed of 9.1±0.1 cm/s is determined to the northeast. The second branch, which forms the eastern part of the Subarctic cyclonic gyre, has the average water drift at a speed of 4.0±0.1 cm/s is directed north-northeast, along the western flank of the Reykjanes Ridge. In the intermediate waters of the frontal zone, an average water flow is observed at a speed of 2.7±0.1 cm/s to the north-northeast, along the eastern slope of the Reykjanes ridge.Due to the multy-scale components of the total variability, the average kinetic energy densities(KED) of total currents (109, 45, 97, (±3) erg/cm3, at station points from east to west) are much greater than the mean drift KED. The near-bottom flows on the Reykjanes ridge flanks are opposite to the direction of the North Atlantic Current. Outside the Subarctic gyre, the direction of average transport is maintained from the ocean surface to the bottom. The average (per year) KED of near-bottom currents are 31, 143, 27 (±3 erg/cm3), for three stations from east to west, respectively. In the intermediate waters of the frontal zone, above the eastern slope of the Reykjanes Ridge, there is a powerful reverse (relative to the North Atlantic Current) near-bottom water flow to the south-west, with a high average speed of ~ 15 cm/s. The KED of the currents during the year varies widely from zero to ~ 600 erg/cm3. The overall variability is due to cyclical variations and intermittency (“flashes”) of currents. Perennial cycles, seasonal variations, synoptic fluctuations with periods in the range of 30–300 days, as well as inertial oscillations and semi-diurnal tidal waves are distinguished. The intermittency of oscillations is partly due to changes in low-frequency flows, which can lead to a dopler frequency shift in the cyclic components of the spectrum. The amplitude of temperature fluctuations in the bottom layer for the year was (0.07–0.10) ± 0.01°C by the standard deviation. The seasonal changes of the bottom temperature are not detected. However, a linear trend with a warming of ~ (0.10–0.15) ± 0.01°С per year is noticeable.

Near-surface wind speeds in ERA5: Climatology, decadal variability and long-term trends

2021 ◽  
Author(s):  
Terhi K. Laurila ◽  
Victoria A. Sinclair ◽  
Hilppa Gregow
Keyword(s):  
Iberian Peninsula ◽  
North Atlantic ◽  
Decadal Variability ◽  
Surface Wind ◽  
Northern Europe ◽  
Near Surface ◽  
Wind Speeds ◽  
The North ◽  
The North Atlantic

&lt;p&gt;The knowledge of long-term climate and variability of near-surface wind speeds is essential and widely used among meteorologists, climate scientists and in industries such as wind energy and forestry. The new high-resolution ERA5 reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF) will likely be used as a reference in future climate projections and in many wind-related applications. Hence, it is important to know what is the mean climate and variability of wind speeds in ERA5.&lt;/p&gt;&lt;p&gt;We present the monthly 10-m wind speed climate and decadal variability in the North Atlantic and Europe during the 40-year period (1979-2018) based on ERA5. In addition, we examine temporal time series and possible trends in three locations: the central North Atlantic, Finland and Iberian Peninsula. Moreover, we investigate what are the physical reasons for the decadal changes in 10-m wind speeds.&lt;/p&gt;&lt;p&gt;The 40-year mean and the 98th percentile wind speeds show a distinct contrast between land and sea with the strongest winds over the ocean and a seasonal variation with the strongest winds during winter time. The winds have the highest values and variabilities associated with storm tracks and local wind phenomena such as the mistral. To investigate the extremeness of the winds, we defined an extreme find factor (EWF) which is the ratio between the 98th percentile and mean wind speeds. The EWF is higher in southern Europe than in northern Europe during all months. Mostly no statistically significant linear trends of 10-m wind speeds were found in the 40-year period in the three locations and the annual and decadal variability was large.&lt;/p&gt;&lt;p&gt;The windiest decade in northern Europe was the 1990s and in southern Europe the 1980s and 2010s. The decadal changes in 10-m wind speeds were largely explained by the position of the jet stream and storm tracks and the strength of the north-south pressure gradient over the North Atlantic. In addition, we investigated the correlation between the North Atlantic Oscillation (NAO) and the Atlantic Multi-decadal Oscillation (AMO) in the three locations. The NAO has a positive correlation in the central North Atlantic and Finland and a negative correlation in Iberian Peninsula. The AMO correlates moderately with the winds in the central North Atlantic but no correlation was found in Finland or the Iberian Peninsula. Overall, our study highlights that rather than just using long-term linear trends in wind speeds it is more informative to consider inter-annual or decadal variability.&lt;/p&gt;

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

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.

Sign in / Sign up

Export Citation Format

Share Document