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1. Introduction The Atlantic multidecadal variability (AMV) is a mode of basinwide sea surface temperature (SST) variability over the North Atlantic Ocean with pronounced signals at decadal-to-multidecadal time scales ( Schlesinger and Ramankutty 1994 ; Kerr 2000 ). The AMV significantly affects global and regional climate [see review by Zhang et al. (2019) ] through its impact on the global-mean temperature ( Ting et al. 2009 ), the position of the Atlantic intertropical convergence zone
1. Introduction The Atlantic multidecadal variability (AMV) is a mode of basinwide sea surface temperature (SST) variability over the North Atlantic Ocean with pronounced signals at decadal-to-multidecadal time scales ( Schlesinger and Ramankutty 1994 ; Kerr 2000 ). The AMV significantly affects global and regional climate [see review by Zhang et al. (2019) ] through its impact on the global-mean temperature ( Ting et al. 2009 ), the position of the Atlantic intertropical convergence zone
1. Introduction a. The Nordic seas in the climate system The Nordic seas (i.e., Greenland, Iceland, and Norwegian Seas; Fig. 1 ), a transitional region between the Arctic Ocean north of Fram Strait and the North Atlantic Ocean, are a site of key climate processes. Deep convective mixing, a driver of the thermohaline circulation, takes place in the Nordic seas where wintertime air–sea heat fluxes destabilize the stratification and produce deep mixed layers ( Nilsen and Falck 2006 ); further
1. Introduction a. The Nordic seas in the climate system The Nordic seas (i.e., Greenland, Iceland, and Norwegian Seas; Fig. 1 ), a transitional region between the Arctic Ocean north of Fram Strait and the North Atlantic Ocean, are a site of key climate processes. Deep convective mixing, a driver of the thermohaline circulation, takes place in the Nordic seas where wintertime air–sea heat fluxes destabilize the stratification and produce deep mixed layers ( Nilsen and Falck 2006 ); further
1. Introduction Warming of the North Atlantic over the past 50 years has not been uniform (e.g., Levitus et al. 2000 , 2005a ; Lozier et al. 2008 ). For example, using data from hydrographic stations, Lozier et al. (2008) found in the North Atlantic that the tropics and subtropics have warmed but the subpolar ocean has cooled (see also Levitus et al. 2000 ). These observations suggest that, instead of a diffusive process from the surface, ocean heat content change is largely a consequence
1. Introduction Warming of the North Atlantic over the past 50 years has not been uniform (e.g., Levitus et al. 2000 , 2005a ; Lozier et al. 2008 ). For example, using data from hydrographic stations, Lozier et al. (2008) found in the North Atlantic that the tropics and subtropics have warmed but the subpolar ocean has cooled (see also Levitus et al. 2000 ). These observations suggest that, instead of a diffusive process from the surface, ocean heat content change is largely a consequence
, leading to the upper oceans of larger depth to uptake surface heat ( Liu et al. 2016 ). The other focuses on the vertical heat redistributing to the deeper oceans on decadal or multidecadal time scales ( Meehl et al. 2011 ; Chen and Tung 2014 ). It was calculated that the surface warming hiatus has been accompanied by more than 30% of the total increment of ocean heat content in deep oceans below 750 m in the Atlantic and Southern Oceans and below 300 m in the Pacific and Indian Oceans ( Meehl et al
, leading to the upper oceans of larger depth to uptake surface heat ( Liu et al. 2016 ). The other focuses on the vertical heat redistributing to the deeper oceans on decadal or multidecadal time scales ( Meehl et al. 2011 ; Chen and Tung 2014 ). It was calculated that the surface warming hiatus has been accompanied by more than 30% of the total increment of ocean heat content in deep oceans below 750 m in the Atlantic and Southern Oceans and below 300 m in the Pacific and Indian Oceans ( Meehl et al
Atlantic from Mercator Océan. This system assimilates both in situ (temperature and salinity) and satellite data (sea level and sea surface temperature) in a multivariate way. Hence, the extrapolation over undetermined variables is less a problem here, and the paper focuses on the control of the spinup effects and the systematic biases. To this purpose, a new variant of the IAU with two sharp time weighting functions is introduced. This system is described in section 2 . The assimilation cycling
Atlantic from Mercator Océan. This system assimilates both in situ (temperature and salinity) and satellite data (sea level and sea surface temperature) in a multivariate way. Hence, the extrapolation over undetermined variables is less a problem here, and the paper focuses on the control of the spinup effects and the systematic biases. To this purpose, a new variant of the IAU with two sharp time weighting functions is introduced. This system is described in section 2 . The assimilation cycling
. In past years, an amount of Lagrangian data about the South Atlantic Ocean (SAO) was collected thanks to the First Global Atmospheric Research Program (GARP) Global Experiment (FGGE) drifters, released following the major shipping lines; the Southern Ocean Studies (SOS) drifters, deployed in the Brazil–Malvinas Confluence (BMC); and the Programa Nacional de Bóias (PNBOIA) drifters [Brazilian contribution to the Global Oceans Observing System (GOOS)], released in the Southeastern Brazilian Bight
. In past years, an amount of Lagrangian data about the South Atlantic Ocean (SAO) was collected thanks to the First Global Atmospheric Research Program (GARP) Global Experiment (FGGE) drifters, released following the major shipping lines; the Southern Ocean Studies (SOS) drifters, deployed in the Brazil–Malvinas Confluence (BMC); and the Programa Nacional de Bóias (PNBOIA) drifters [Brazilian contribution to the Global Oceans Observing System (GOOS)], released in the Southeastern Brazilian Bight
the North Pacific ( Zhang et al. 1996 ; Lau 1997 ; Zhang et al. 1998 ; Wang 2002 ), North tropical Atlantic ( Enfield and Mayer 1997 ), North Atlantic ( Hoerling et al. 2001 ; Lu et al. 2004 ), and Indian Oceans ( Yu and Rienecker 1999 ) on interannual to decadal time scales. The extratropical climate can also affect the tropics through both the atmospheric bridge and oceanic tunnel ( Gu and Philander 1997 ; Kleeman et al. 1999 ; Barnett et al. 1999 ; Pierce et al. 2000 ), generating
the North Pacific ( Zhang et al. 1996 ; Lau 1997 ; Zhang et al. 1998 ; Wang 2002 ), North tropical Atlantic ( Enfield and Mayer 1997 ), North Atlantic ( Hoerling et al. 2001 ; Lu et al. 2004 ), and Indian Oceans ( Yu and Rienecker 1999 ) on interannual to decadal time scales. The extratropical climate can also affect the tropics through both the atmospheric bridge and oceanic tunnel ( Gu and Philander 1997 ; Kleeman et al. 1999 ; Barnett et al. 1999 ; Pierce et al. 2000 ), generating
1. Introduction Because of its large heat capacity and slow movement the ocean plays a central role in low-frequency climate variability. The role of the Atlantic Ocean is of particular interest because the North Atlantic is host to one of the few regions of deep-water formation on the planet, and therefore plays a vital role in the overturning circulation, which is responsible for a large fraction of the poleward heat transport accomplished by the oceans. There is evidence from palaeoclimate
1. Introduction Because of its large heat capacity and slow movement the ocean plays a central role in low-frequency climate variability. The role of the Atlantic Ocean is of particular interest because the North Atlantic is host to one of the few regions of deep-water formation on the planet, and therefore plays a vital role in the overturning circulation, which is responsible for a large fraction of the poleward heat transport accomplished by the oceans. There is evidence from palaeoclimate
Clustering of Climate Change Impacts on Ocean Waves in the Northwest Atlantic-temporal correlations of wave parameters, the optimal number of clusters, training the Geo-SOM method and visualizations, wave regime assessment, and extreme-value analysis (EVA). Section 4 provides discussion and conclusions. 2. Method a. Study area The northwestern Atlantic Ocean is bounded by the east coast of the United States and Canada and, on the north, by the Arctic Ocean. As shown in Fig. 1 , the study domain is located between −74° and −40° east longitude and between 25° and 65° north latitude
-temporal correlations of wave parameters, the optimal number of clusters, training the Geo-SOM method and visualizations, wave regime assessment, and extreme-value analysis (EVA). Section 4 provides discussion and conclusions. 2. Method a. Study area The northwestern Atlantic Ocean is bounded by the east coast of the United States and Canada and, on the north, by the Arctic Ocean. As shown in Fig. 1 , the study domain is located between −74° and −40° east longitude and between 25° and 65° north latitude
western North Atlantic Ocean is the Subtropical Mode Water (STMW), a vertically homogeneous water mass between the seasonal thermocline and the permanent thermocline. The STMW is formed by deep convection just south of the Gulf Stream (GS) during winter and contains the memory of its interaction with the atmosphere. After its formation, the STMW is advected by the GS and its recirculation gyre. The net heat loss to the atmosphere has been considered an important factor for forming and sustaining the
western North Atlantic Ocean is the Subtropical Mode Water (STMW), a vertically homogeneous water mass between the seasonal thermocline and the permanent thermocline. The STMW is formed by deep convection just south of the Gulf Stream (GS) during winter and contains the memory of its interaction with the atmosphere. After its formation, the STMW is advected by the GS and its recirculation gyre. The net heat loss to the atmosphere has been considered an important factor for forming and sustaining the
