Category: Physical Oceanography

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 4.6x1017J 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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30 Years of Drifter Data Allow Scientists to Create a Visual Climatology of Ocean Currents

Using over 30 years of observations from satellite-tracked surface drifting buoys, NOAA oceanographers derived a global climatology of seasonally-varying ocean surface currents at one-half degree resolution. This data set can be used to better understand how the ocean transports properties like heat, salt, and passive tracers, and as a reference to study changes in ocean […]

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Incidents of intense (Fujita scale F3-F5) U.S. tornadoes in April-May for (a) the top ten positive Trans-Niño years, (b) ten neutral Trans-Niño years, and (c) the top ten negative Trans-Niño years during 1950-2010 obtained from Severe Weather Database (SWD). Green color is for F3, blue color for F4 and red color for F5 tornadoes. Image Credit: NOAA AOML.

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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Upper Ocean Heat content during the intensification of Hurricanes Katrina (left) and Isaac (right) Image Credit: New York Times

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 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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(a) Simulated pathways of the northward heat transport (contours) and heat transport vector (vectors) in the upper 3000 m for 1979-2008 obtained from the control experiment (EXP_CTR). The unit is 1x109 W/m. (b) Differences in the simulated northward heat transport (contours) and heat transport vector (vectors) between 1979-2008 and 1871-1900 periods, obtained from EXP_CTR. Red color indicates northward heat transport, while blue color indicates southward heat transport. (c) Globally averaged zonal wind stress for 1871-1900 and for 1979-2008 periods, obtained from the 20th Century Reanalysis. Image Credit: NOAA AOML.

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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IPCC projected changes of bluefin tuna’s spawning habitat in the Gulf of Mexico due to anthropogenic global warming for three time frames: top (late 20th century), (middle) mid 21st century and (bottom) late 21st century. The colors indicate preferred spawning habitat, with yellow/orange for favored locations and blue/purple for non-ideal regions. Liu and Lee’s research indicates that the area of spawning habitat for the bluefin tuna may not be as drastically reduced as in the IPCC results shown in these figures. Image Credit: NOAA AOML.

Collaborative Research between PhOD and SEFSC Presented at Bluefin Tuna Workshop

A joint workshop hosted by NOAA and the National Aeronautics and Space Administration (NASA) for bluefin tuna research was held at the University of Miami on December 6-7th. Researchers with AOML’s Physical Oceanography Division (PhOD) presented the results of their collaborative efforts with NOAA’s Southeast Fisheries Science Center (SEFSC), which have focused on the link between the ocean and stock assessment species of relevant commercial importance.

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