Tag: Renellys Perez

First-ever Daily Time Series Reveals the Strength of the Deep Ocean Circulation in the South Atlantic

In a recent study published in the journal Science Advances, oceanographers at AOML and the Cooperative Institute for Marine and Atmospheric Studies for the first time describe the daily variability of the circulation of key deep currents in the South Atlantic Ocean that are linked to climate and weather. The study found that the circulation patterns in the upper and deeper layers of the South Atlantic often vary independently of each other, an important new result about the broader Meridional Overturning Circulation (MOC) in the Atlantic.

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TACOS Program Hits 25,000th Profile Milestone!

TACOS has added 10 acoustic current meters to the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) buoy, moored at 4N, 23W.  Profile measurements are taken every 1-10 minutes, depending on depth.  Prior to the addition of the TACOS upper ocean observations in March 6, 2017 velocity profiles were only collected at this location during shipboard surveys.  These measurements are important because ocean currents influence temperature, salinity, and air-sea fluxes in the tropical North Atlantic, which affect weather, climate, and fisheries of the surrounding continents.

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PIRATA Array

New Data Set to Improve Tropical Atlantic Ocean and Atmospheric Research

Researchers at NOAA AOML have released a new tropical Atlantic data set that includes several enhancements to improve data accuracy and data collection in the tropical Atlantic. The new data set is called enhanced PIRATA, or ePIRATA, and provides continuous records of upper-ocean temperature, salinity, and currents, together with meteorological data such as winds, humidity, and solar radiation. ePIRATA should prove valuable in better analyzing ocean and atmospheric processes in the tropical Atlantic.

PIRATA, the Prediction and Research Moored Array in the Tropical Atlantic, is a multinational observation network, established to improve knowledge and understanding of ocean-atmosphere variability in the tropical Atlantic. It is a joint project of Brazil, France and the United States of America, motivated by fundamental scientific issues and by societal needs for improved prediction of climate variability and its impact on the countries surrounding the tropical Atlantic basin. PIRATA provides measurements at 18 locations throughout the tropical Atlantic

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Partial CLIVAR sections demonstrating the spread of NADW eastward into the central South Atlantic Ocean. Vertical axis is depth in meters. Panel a) partial A16S section of CFC-11 from 15 ° -30 ° S along about 25 ° W from 1000-5000 m. The lowest contour for CFC-11 concentration is 0.01 pmol kg -1 . Color scale given on the right; two neutral density surfaces are 27.9 and 28.1 kg m -3 are identified as white lines . Panel b) Same as panel a) except for oxygen concentration in m mol kg -1 . Panel c) Same as panel a) except for salinity. Panel d) partial A13 section of CFC-11 from 15 ° -30 ° S along about 5 ° -10 ° E from 1000-5000 m. The lowest contour for CFC-11 concentration is 0.005 pmol/kg. Panel e) full cross-basin section of CFC-11 along A10, 30 ° S from 1000-5000 m. Note for a, d, and e that 0.3 pmol kg -1 is the highest concentration CFC-11 contoured and higher concentrations will appear in the same shades as for 0.3 pmol kg -1.

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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AOML Scientists Featured in Special Women’s History Month Issue of Oceanography Magazine

Women’s History Month is celebrated annually in March and pays tribute to the generations of women whose contributions made a historical impact on society. It is also a month to honor women who are currently working hard to make positive innovations and impressions on the world.

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Distribution of long-term mean observed (a)-(b) and simulated (c)-(d) meridional velocity along 23°W and 10°W. Gray dots in (a)-(b) indicate statistically significant values. Contour interval is 2.5 cm s-1. Figure reproduced from Perez et al., (2013). Image Credit: NOAA AOML.

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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The evolution of the tropical Pacific ocean/atmosphere system concurrent with and following atmospheric variability in the SLPI region in the year preceding an El Nino event. Shading: Composite of normalized monthly-mean heat content anomalies in the upper 300m. Shading interval is from 0.4 (yellow) to 1.0 (maroon) in increments of 0.1. Black contours: Composite of normalized monthly mean near-surface temperature anomalies at 5 m depth. Contour interval is 0.1; minimum contour is ±0.4. White contours: Composite of normalized monthly mean zonal wind stress anomalies. Positive (negative) values have solid (dashed) contours. See Anderson et al. (2013) for more details. Image Credit: NOAA AOML.

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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(a) Correlation between the NEUC transport and the SST and pseudo-wind stress in the Tropical Atlantic. The boxes are regions of high magnitude of correlation, where a SST index (SST2) and a meridional wind index (y-wind2) are taken (b). (c) Lagged correlation between the indices timeseries and the NEUC transport index. Image Credit: NOAA AOML.

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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