Category: Physical Oceanography

New Antenna System Design Improves Reliability and Significantly Reduces Cost

Scientists and engineers from NOAA have successfully designed, built, and tested a new antenna system that dramatically increases data transmission reliability while drastically reducing operating costs. The new Iridium-based transmission system, developed by NOAA’s Atlantic Oceanographic & Meteorological Laboratory (AOML) & the Cooperative Institute for Marine & Atmospheric Studies (CIMAS), has no restrictions on data format or size, allowing data from various ocean and land-based observation platforms to be transmitted more securely and at a fraction of the cost of the older Inmarsat-C platform.

Read Full Article
(left column) Seasonality of precipitation and 850mb winds for the monsoon regions as measured by the difference between June-July-August-September (JJAS) minus annual mean precipitation and winds. (middle-column) shows the composite difference of JJAS precipitation (shaded) and 850mb wind for each monsoon region with respect to weak minus strong SAMHT at lead-time 20 years after the anomalous SAMHT. Blue stipples indicates regions where precipitation differences are significant at 95% confidence level based on a non-parametric Kolmogorov-Smirnov test. (right-column) Lag-lead Spearman ranked correlation between SAMHT and NH monsoon index. The blue dashed lines depict the 95% significance level based on a non-parametric Kendall-t test. Negative lag indicates periods when SAMHT leads the NH monsoon index. Periods with significant correlation between the SAMHT and monsoon are shaded blue. Image Credit: NOAA AOML.

Meridional heat transport in the South Atlantic reveals links with global monsoons

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.

Read Full Article
Interannual variations of the MOC (black) and contributions from the geostrophic (red) and Ekman (green) components at 20°S, 25°S, 30°S, and 34.5°S, respectively. The gray shading denotes the range where anomalies are not significantly different from zero. The red and green shading denote the periods of the dominance of the geostrophic and Ekman components on the MOC, respectively. Image Credit: NOAA.

Dominance of the Geostrophic and Ekman Transports on the MOC in the South Atlantic

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. This possibility clearly manifests the importance of understanding the South Atlantic MOC (SAMOC). Observations in the South Atlantic have been historically sparse both in space and time compared to the North Atlantic. To enhance our understanding of the MOC and MHT variability in the South Atlantic, a new methodology is recently published to estimate the MOC/MHT by combining sea surface height measurements from satellite altimetry and in situ measurements (Dong et al., 2015).

Read Full Article
NOAA's Ship of Opportunity Program coordinates a fleet of vessels that collect surface ocean CO2 measurements across the world's oceans. Image credit: NOAA

AOML-led Carbon Dioxide Sampling Effort Helps Quantify the Ocean’s Role in Global Carbon Budget

Researchers with the Global Carbon Budget released their annual update for the global carbon budget in December 2015, revealing carbon dioxide (CO2) emissions from fossil fuels increased slightly in 2014 (+0.6%), but are projected to decline slightly (by est. -0.6%) in 2015. The global oceans serve as a natural buffer, offsetting increased emissions by absorbing an estimated 27% of human-produced CO2 from the atmosphere in 2014. Data collected, in part, from long-term surface ocean CO2 monitoring efforts, funded by NOAA’s Climate Program Office and the Ocean Acidification Program, indicate that the oceans removed about 10.7 billion tons of CO2 from the atmosphere in 2015.

Read Full Article
An image of the successfully retrieved glider, including puncture marks from an encounter with a shark. Image credit: NOAA

Underwater Gliders Retrieved After Successful Third Mission

On November 16th-18th, AOML physical oceanographers partnered with the University of Puerto Rico to successfully recover two underwater gliders from the Caribbean Sea aboard the M/V La Sultana of the University of Puerto Rico Mayaguez. Over the course of the summer, the gliders successfully transected a region in the eastern Caribbean providing approximately 3000 profile observations of temperature, salinity, oxygen, and surface as well as depth-average current velocities.

Read Full Article
AOML scientists work with members of the ships' crew to recover the CTD rosette at the end of a 3 hour hydrographic cast. Image credit: NOAA

October 2015 Western Boundary Time Series Cruise

AOML oceanographers are participating in a joint research cruise to study the Meridional Overturning Circulation onboard the R/V Endeavor during October 3-20. The team will sail from Fort Lauderdale, FL to collect roughly 55 full-depth conductivity-temperature-depth (CTD) profiles in the Florida Current and the Deep Western Boundary Current east of the Bahamas. The scientists will also work with their partners from the University of Miami to recover, redeploy, and maintain three tall moorings and nine smaller moored instruments during this cruise in support of the NOAA Western Boundary Time Series project and its partner National Science Foundation project.

Read Full Article
Figure 3 Glider approximate location (black diamond) superimposed on Infrared image of Hurricane Gonzalo on October 14, 1500 UTC, when it travelled the closest to the location of the underwater glider. Credit: image obtained from the Cooperative Institute for Meteorological Satellite Studies.

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.

Read Full Article
AOML oceanographer Andy Stefanick deploys the dropsonde at one of the stations during the 100th successful dropsonde cruise on October 15, 2015.

100th Successful Dropsonde Cruise for the Western Boundary Time Series Project

In October, AOML scientists, technicians and engineers involved in the Western Boundary Time Series (WBTS) project completed the 100th successful dropsonde cruise in the Florida Current since the project’s inception in 2000. The dropsonde cruises measure volume transport in the Florida Current using an out-of-service telephone cable between Florida and Grand Bahama Island.

Read Full Article