National Oceanic and Atmospheric Administration

Atlantic Oceanographic and Meteorological Laboratory

Physical Oceanography Division

Research Highlights

03/25/2016 - 03/25/2016

Global Characteristics of Coherent Vortices from Surface Drifter Trajectories

In a recent study by Lumpkin (2016) looping trajectories of surface drifting buoys were extracted from the global drifter dataset and analyzed in order to examine the distribution of submesoscale to mesoscale vortices. Over 15,000 looping trajectory segments were identified worldwide.

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02/25/2016 - 02/25/2016

A recent paper published in the Journal of Climate led by PHOD researchers Hosmay Lopez, Shenfu Dong, Sang-Ki Lee, and Gustavo Goni provides a physical mechanism on how low frequency variability of the South Atlantic Meridional Heat Transport (SAMHT) associated with the Atlantic Meridional Overturning Circulation ( AMOC) may influence decadal variability of atmospheric circulation and monsoons. This is the first attempt to link the South Atlantic Overturning Circulation variability to weather and climate.

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01/28/2016 - 01/28/2016

The Meridional Overturning Circulation (MOC) plays a critical role in global and regional heat and freshwater budgets. Recent studies have suggested the possibility of a southern origin of the anomalous MOC and meridional heat transport (MHT) in the Atlantic, through changes in the transport of warm/salty waters from the Indian Ocean into the South Atlantic basin.

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10/22/2015 - 10/22/2015

Underwater gliders observations reveal the importance of salinity effects

during passage of Hurricane Gonzalo (2014)

Hurricanes are known to drive the cooling of surface waters as they travel over the ocean, leaving a cooling swath where they pass. The sea surface cooling is mostly caused by mixing forced by the strong winds of the hurricane, which occurs as the mixture of warm surface waters with colder waters that can be as deep as 100 m below the surface.

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09/21/2015 - 09/21/2015

Pathways and hydrography in the Mesoamerican Barrier Reef System

The results of two oceanographic cruises conducted in the Mexican and Belizean shelf waters over the Mesoamerican Barrier Reef during 2006 and 2007 show that the circulation can be divided into two distinct regimes: a northern region dominated by the strong, northward-flowing Yucatan Current, and a southern region with weaker southward coastal currents and the presence of the Honduras Gyre.

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09/10/2015 - 09/10/2015

Research Shows Indian Ocean Plays Key Role in Global Warming Hiatus

The earth is warming, but atmospheric and oceanic temperatures that rose steadily over the last half century have leveled off and slowed this past decade, causing the appearance of an imbalance in the Earth's heat budget.

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07/23/2015 - 07/23/2015

The fate of the Deep Western Boundary Current in the South Atlantic

The pathways of recently ventilated North Atlantic Deep Water (NADW) are part of the lower limb of the Atlantic Meridional Overturning Circulation (AMOC). In the South Atlantic these pathways have been the subject of discussion for years, mostly due to the lack of observations. Knowledge of the pathways of the AMOC in the South Atlantic is a first order prerequisite for understanding the fluxes of climatically important properties.

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02/18/2015 - 02/18/2015

NOAA Scientific Publications Report - February 18, 2015

A collaboration paper between SEFSC and AOML/PhOD scientists “Potential impact of climate change on the intra-Americas sea: Part 2. Implications for Atlantic bluefin tuna and skipjack” was selected as a NOAA research highlight.

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12/01/2014 - 12/31/2014

A new approach provides a holistic view of ENSO variability during the onset, peak and decay phases

From its onset to the decay, El Niño-Southern Oscillation (ENSO) plays an important role in forcing climate variability around the globe. A new study led by Sang-Ki Lee, a PhOD/CIMAS scientist, provides an efficient approach to explore the differences in the evolution of space-time patterns of sea surface temperature observed during El Niño events.

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06/15/2014 - 07/16/2014

A global perspective on CMIP5 climate model biases

A recent paper published in Nature Climate Change by PhOD researchers, in collaboration with researchers at the Ocean University of China and at the University of California, found a common pattern of global SST biases in 22 climate models. The global SST biases for different regions are commonly linked with a weak AMOC simulated by these models. The paper suggests that an improvement of the simulated AMOC in climate models is needed for better climate predictions and projections.

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05/16/2014 - 06/15/2014

Wind forced variability of the Antarctic Circumpolar Current south of Africa between 1993 and 2010

Researchers from PhOD and from the University of Cape Town used temperature data from the AX25 repeat XBT transect (from South Africa to Antarctica) in combination with other hydrographic and satellite observations to report a mechanism by which local winds alter the structure of the Antarctic Circumpolar Current flow south of Africa.

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04/16/2014 - 05/15/2014

Impact of canonical and Modoki El Niño on tropical Atlantic SST

Results from research performed by Dillon Amaya, an undergraduate Hollings Scholar from Texas A&M University, were published recently in Journal of Geophysical Research. Dillon's work was carried out in the Physical Oceanography Division of AOML during the summer of 2013 and focused on understanding the impacts of different types of El Niño events ("canonical" and "Modoki") on sea surface temperatures in the tropical Atlantic. The main result from the research is that Modoki El Niños fail to produce significant warming in the tropical North Atlantic, in contrast to the well known warming following canonical events.

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02/01/2014 - 03/01/2014

Oceanographic conditions in the Gulf of Mexico in July 2010, during the Deepwater Horizon oil spill

Results from collaborative research conducted by AOML and NOAA's Southeast Fisheries Science Center (SEFSC) in response to the 2010 Deepwater Horizon oil spill, were recently published in Continental Shelf Research (December, 2013). PhOD oceanographers R. Smith, E. Johns, G. Goni, J. Trinanes, and R. Lumpkin, in collaboration with other researchers at AOML (M. Wood, C. Kelble, and S. Cummings) and SEFSC (J. Lamkin and S. Privoznik) report on the surface and subsurface connectivity across the eastern Gulf of Mexico (GOM) during July 2010.

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12/15/2013 - 01/15/2014

Mean meridional currents in the central and eastern equatorial Atlantic

In an article recently published in Climate Dynamics ( Perez et al., 2013 ) , scientists in PhOD (R. Perez, R. Lumpkin, C. Schmid) described for the first time the mean vertical and cross-equatorial structure of the upper-ocean meridional currents in the Atlantic cold tongue region, using in situ observations including drifters, Argo, shipboard/lowered ADCP, and moored ADCP. This study involves collaborations with scientists from the University of Miami, Scripps Institution of Oceanography, and several international institutions and makes use of data from several major tropical Atlantic field programs including NOAA's PIRATA Northeast Extension .

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11/01/2013 - 11/31/2013

Interhemispheric influence of the northern summer monsoons on the southern subtropical anticyclone

In a recent article accepted for publication in the Journal of Climate, scientists in PhOD, S.-K. Lee (CIMAS) and C. Wang collaborated with R. Mechoso and D. Neelin, both at UCLA, to explore why the southern subtropical anticyclones are notably stronger in the austral winter than in summer, which is in contrast with the Northern Hemisphere (NH) in which subtropical anticyclones are more intense in summer according to the monsoon heating paradigm. They performed model experiments to show that during the boreal summer enhanced tropical convection activity in the NH plays important roles in strengthening the southern subtropical anticyclones.

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07/01/2013 - 07/15/2013

Triggering of El Nino through trade-wind induced charging of the equatorial Pacific

In a recent study by scientists at Boston University, PHOD, and NCAR, a new mechanism was uncovered for initiating ENSO events wherein SLP-generated North Pacific trade winds induce subsurface heat content changes that serve as precursors to El Ninos. This trade-wind charging mechanism of the equatorial Pacific is fundamentally different from any previously diagnosed, and studies examining the surface and subsurface ocean dynamics associated with this mechanism are underway.

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06/15/2013 - 06/30/2013

Relationship between the off-equatorial current system and the tropical Atlantic variability

Scientists at PHOD developed a synthetic method, which combines high-density expendable bathythermograph (XBT) temperature data along the AX08 XBT transect (which runs between Cape Town and NYC) with altimetric sea level anomalies, to estimate the variability of the off-equatorial currents, such as the North Equatorial Countercurrent and the North Equatorial Undercurrent, on seasonal to interannual timescales. Understanding how the ocean dynamics is liked to anomalies of temperature and wind-stress in the tropical Atlantic is critical to understand the climate and weather variability in the adjacent continental areas.

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05/30/2013 - 06/15/2013

A Fingerprint for the AMOC: Multidecadal Ocean Temperature Variability in the Tropical North Atlantic

In an article recently accepted for publication by the Journal of Climate, PHOD scientists show that the variation of surface and subsurface ocean temperatures in the tropical North Atlantic (TNA) is important to and linked with the Atlantic meridional overturning circulation (AMOC). Results presented here suggest that the subsurface ocean temperature variation in the TNA can be taken as a fingerprint for the AMOC variability, and it also has an important implication for interpreting hurricane acticity in terms of multidecadal ocean temperature variation in the TNA.

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05/07/2013 - 05/28/2013

Global Ocean Surface Velocities from Drifters: Mean, Variance, ENSO Response, and Seasonal Cycle

Using over 30 years of observations from drogued, satellite-tracked surface drifting buoys, Lumpkin and Johnson (2013) developed a methodology to map seasonally-varying surface currents at 1/2 degree resolution. Results from this study can be used to better understand how the ocean transports properties like heat, salt, and passive tracers, and serves as a reference to study changes in ocean currents over time. One key result from this study is the global distribution of mean, seasonal and eddy kinetic energy, which totals 4.6x10 17 J in the upper 30 m of the ocean and reveals the presence of three large eddy "deserts", one in the Atlantic Ocean and the other two in the Pacific.

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09/01/2012 - 10/01/2012

Is there an optimal ENSO pattern that enhances large-scale atmospheric processes conducive to tornado outbreaks in the U.S?

The record-breaking U.S. tornado outbreaks in the spring of 2011 prompt the need to identify long-term climate signals that could potentially provide seasonal predictability for U.S. tornado outbreaks. A new research led by scientists in the Physical Oceanography Division of NOAA-AOML used both observations and model experiments to show that a positive phase Trans-Niño may be one such climate signal.

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09/01/2012 - 11/01/2012

Satellite-derived Heat Content Product Developed at AOML Helps to Understand The Differences in Intensity Between Tropical Storm Isaac and Hurricane Katrina

A news article that appeared in The New York Times on August 27 shows the ocean conditions in the Gulf of Mexico during hurricanes Katrina (August 2005) and Isaac (August 2012). The ocean conditions are depicted by the upper ocean heat content derived from satellite altimetry using a methodology developed at NOAA/AOML. The upper ocean heat content had larger values during Katrina mainly due to an anticyclonic warm ring and an extended Loop Current. These conditions, not found during the passage of Hurricane Isaac, partly contributed to the intensification of Katrina.

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11/01/2011 - 12/01/2011

Relationship Identified Between Atlantic "Warm Pool" and U.S. Landfalling Hurricanes

In this study highlighted in the Editors' Choice of Science Magazine ( issue of Oct. 21, 2011 ), NOAA scientists have identified a relationship between large–scale climate factors, the Atlantic warm pool, and hurricanes making landfall in the U.S. This relationship indicates that a large warm pool is an unfavorable condition for hurricanes to landfall on the United States coast.

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09/01/2011 - 10/15/2011

What Caused the Significant Increase in Atlantic Ocean Heat Content Since the mid-20th Century?

A new study led by researchers from University of Miami, NOAA-AOML, IFM-GEOMAR, and NCAR explores why the Atlantic Ocean has warmed substantially more than any other ocean basin since the 1950s. The research article published in the Geophysical Research letters evidences that the observed large warming of the Atlantic Ocean since the 1950s is largely induced by an increase in the inter-ocean heat transport from the Indian Ocean via the Agulhas leakage. The study points to an important role played by the Atlantic meridional overturning circulation (AMOC) in the South Atlantic in enhancing the secular warming of the Atlantic Ocean.

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03/01/2010 - 04/15/2010

Study Highlights Out-of-phase Relationship Between Tropical Cyclones in the North Atlantic and Eastern Pacific

In articles published in the scientific journal of Geophysical Research Letters and the AGU Newspaper of EOS, AOML’s scientists Chunzai Wang and Sang-Ki Lee show that tropical cyclone activity in the North Atlantic varies out-of-phase with that in the eastern North Pacific on both interannual and multidecadal timescales. That is, when tropical cyclone activity in the North Atlantic increases (decreases), tropical cyclone activity in the eastern North Pacific decreases (increases). Both vertical wind shear and convective instability contribute to the out-of-phase relationship, whereas relative humidity and vorticity variations at the lower troposphere do not seem to cause the relationship.

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