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.
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.
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.
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.
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 .
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.
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.
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.
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.
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.
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.
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.
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.
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.
01/21/2011 - 02/28/2011
Collaborative Research between PhOD and SEFSC Presented at Bluefin Tuna Workshop
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.