Category Archives: Physical Oceanography

A research vessel ploughs through the waves, braving the strong westerly winds of the Roaring Forties in the Southern Ocean in order to measure levels of dissolved carbon dioxide in the surface of the ocean. (Nicolas Metzl, LOCEAN/IPSL Laboratory).

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 reliably and at a fraction of the cost of the older Inmarsat-C platform. Since completion, the Iridium system has been adopted on a number of Expendable Bathythermographs (XBTs) observation transects and have been simultaneously tested and implemented in other AOML observing systems.

The development of this new system involved creating new transmission hardware and software. The system includes state of the art technologies combined with advanced algorithms to allow for the fast and stable transmission of digital data.  Results from the initial tests carried out in 2013 were used to optimize the system and to reduce or eliminate connection drops and data loss. The new system began its transition to operational capacity in 2015 and is currently being used on all cargo ships with XBT observation transects operated by AOML and Scripps Oceanographic Institution. The adoption of this system has resulted in a 95% reduction of the average transmission cost per XBT profile.

NOAA deploys approximately 12,000 XBTs per year as part of its contribution to the global XBT Network, a component of the Global Ocean Observing System. XBTs are probes that measure temperature profiles to a depth of 800m. This global network consists of approximately 50 fixed transects that are repeated several times a year. Historically, the real-time transmission of this data was carried out using the Inmarsat-C satellite network, which was implemented in the early 2000s, and relies on twelve geostationary telecommunications satellites. The Inmarsat-C network is costlier and does not allow for the transmission of different data types.

Although originally developed for XBT observations, the new Iridium-based transmission system is capable of transmitting various types and amounts of data. Its applicability has been expanded to data transmissions for ThermoSalinoGraph (TSG), pCO2, and marine weather observations. Other global oceanographic observational platforms such as Argo floats and drifting buoys also use the Iridium network for data transmission, however these platforms use a protocol only suitable for smaller amounts of data. With the application of the new antenna system, which can transmit files of arbitrary size, this data can be transmitted at a lower cost and at a faster rate.

In addition to Iridium transmissions, the new system can be also be configured to transmit data over telephone landlines or computer networks, potentially decreasing many other operational costs.  Future plans for the system include increasing its use along XBT transects run by other XBT partner institutions as well as its application to other types of real-time environmental data transmissions.

This work was funded by the Climate Observations Division of the NOAA Climate Program Office and by AOML, through the XBT Network and the Ship of Opportunity Program.

Left: New Iridium antenna and housing. Right: Antenna installed aboard the CMA CGM Racine cargo vessel in Miami, FL, before the start of the January 2016 AX07 (Miami to Gibraltar) XBT transect.

Originally Published in March 2015 by Shannon Jones

Deployment of a PIES mooring in the South Atlantic. Photo credit: NOAA/AOML

If you want to understand Earth’s climate and how it changes from year-to-year and decade-to-decade, look to the oceans, and follow the heat. The major driver in the redistribution of heat around the globe in the ocean-climate system is Meridional Overturning Circulation, or MOC. The MOC is a vertical circulation pattern that exchanges surface and deep waters via poleward movement of surface waters. As an example, the well known Gulf Stream on the eastern seaboard of North America carries warm water northward to the Greenland and Norwegian Seas, where it cools and sinks.

Scientists with AOML’s Physical Oceanography Division joined with partners from Argentina and Brazil in October to study the MOC at 34.5°S in the South Atlantic. On board the Argentine research vessel ARA Puerto Deseado, researchers united for the ninth joint cruise undertaken in support of the NOAA-funded Southwest Atlantic MOC (SAM) project since March 2009. Participants included researchers from the Universidade de Buenos Aires, the Servicio de Hidrografía Naval, the Instituto Nacional de Investigación y Desarrollo Pesquero, the Universidade Federal do Rio Grande, and the Universidade de Sao Paulo, as well as NOAA-AOML.

The MOC sinks at high latitudes and upwells elsewhere. Its variability is linked in numerical models to significant changes in precipitation patterns, surface air temperatures, and hurricane intensity over large portions of the Earth. NOAA-AOML serves in a leading role with its partners to collect observations of the South Atlantic portion of the global MOC system to gain a more complete understanding of its complex nature. A complete trans-basin instrument array to measure the MOC at 34.5°S is in the process of deployment, and NOAA instruments near the western boundary are the cornerstone of the full array.

On this fall 2014 cruise, scientists used ship-based instruments to acoustically download data from four pressure-equipped inverted echo sounder (PIES) moorings in the SAM array, as well as two similar Brazilian instruments. These instruments send sound pulses from their position near the ocean floor to the sea surface and listen for the return of the reflected sound waves. The round-trip acoustic travel time measurements are then combined with historical hydrographic data to obtain daily estimates of the temperature, salinity, and density for the full water column above the mooring. Meanwhile, the pressure gauges provide information on the variability of deep-water flows. The combination of data sets from the PIES moorings provides long-term observations of the shallow and deep western boundary currents at 34.5°S, key components in the MOC system.

The existing array is scheduled to continue through at least 2016, with annual or semi-annual cruises planned to collect new hydrographic information and acoustically download data from the array. NOAA’s contribution to this effort is funded by the Climate Program Office/Climate Observations Division and by AOML.

Originally Published in November 2014 by Shannon Jones

Scientists at NOAA’s Atlantic Oceanographic and Meteorological Laboratory are at the forefront of hurricane research to improve track and intensity forecasts. Every hurricane season they fly into storms, pour over observations and models, and consider new technological developments for how to enhance NOAA’s observing capabilities. The 2014 hurricane season will provide an opportunity to test some of the most advanced and innovative technologies, including unmanned hurricane hunter aircraft and sea gliders, which will help scientists better observe and, eventually, better predict a storm’s future activity.

The game plan: where we are and where we need to be

NOAA’s Aircraft Operations Center (AOC) maintains two P-3 Orions and a Gulfstream IV jet for hurricane observations. To collect data, NOAA’s hurricane researchers fly aboard these aircraft into and around the periphery of storms. A primary tool they use for measuring the hurricane environment is the dropsonde, a lightly weighted cylindrical tube equipped with a parachute and global positioning system technology. Dropsondes transmit their position every half second as they drift through a storm. These mini-weather stations are deployed from the belly of the aircraft and fall towards the ocean, sending data such as pressure, temperature, wind speed, wind direction, and moisture to scientists aboard the hurricane hunter aircraft.

NOAA’s P-3 Orion and G-IV jet. Photo credit: NOAA

While dropsondes are an excellent tool for measuring a storm’s atmospheric environment, their spatial coverage is limited. Dropsondes essentially obtain vertical profiles of a storm at discrete points. Other instruments on the aircraft measure storm properties at altitudes as great as 60,000 feet. However, NOAA’s hurricane hunter aircraft are unable to fly below 5,000 feet due to the extreme turbulence occurring between the ocean and atmosphere. This leaves a gap in the opportunity to collect potentially important data from the lower part of the storm, which may be essential to increasing the understanding of intensity change.

Congressional funding supports new unmanned aircraft

Post-Hurricane Sandy federal funding, the Disaster Relief Appropriations Act of 2013, provided NOAA with the opportunity to test new technology in hopes of better understanding and evaluating storm physics that drive intensity change. An unmanned weather drone, called the Coyote, will do just that.  The Navy originally designed the Coyote for maritime surveillance. NOAA plans to transition this unique platform into a “smart sonde” that can be used for hurricane science. During the 2014 hurricane season, the Small Unmanned Aircraft Vehicle Experiment will test the capability of the Coyote in storms, observing how well it handles severe winds and the harsh hurricane environment.

Scientists will deploy the seven pound unmanned aircraft from the P-3 Orion in the same way as the dropsondes. However, instead of drifting downward towards the ocean surface, the Coyote will open its six-foot wingspan and fly through the storm.  It can be controlled from miles away but will typically be piloted by scientists onboard the P-3s. Its relative lightweight design requires the Coyote to fly with the wind currents, but it will be directed up, down, and sideways to navigate specific flight patterns to measure the inner core and lowest altitudes of the storm.

Hurricanes are fueled by warm ocean water, and vital information needed to better understand and predict intensity change may rest close to the sea surface where manned aircraft cannot fly and the dropsondes only pass through for a few seconds. With its ability to fly for two hours in this region, the Coyote provides the opportunity for much more complete data collection, in comparison to the traditional dropsonde.

Adding a new twist to existing technology The traditional dropsonde itself will also receive an upgrade for the 2014 season with the addition of a sensor to measure sea surface temperature at splashdown. This additional last data point will provide a critical piece of information at the air-sea interface, the environment where energy transfer occurs and is most challenging to observe in a hurricane environment. (image credit: NCAR)

Diving into the ocean to improve hurricane forecasts

The 2014 season will also feature two sea gliders, remotely operated profiling instruments that dive below the ocean surface and then resurface to transmit observations of temperature and salinity. NOAA is testing two ocean gliders in critical hurricane regions of the Caribbean north and south of Puerto Rico. The gliders were deployed in July and will be recovered at the end of hurricane season.  The gliders will profile the upper ocean about 10 times daily, diving to a depth of 1,000 feet and collecting data as they ascend. When a sea glider breaks the surface, its data will be transmitted to AOML and made available in near-real time via the web.

Two gliders ready for deployment from the R/V Sultana,

off the coast of Puerto Rico (credit: NOAA/AOML)

In addition to these new technologies, the Disaster Relief Appropriations Act of 2013 also provided funding to assess the impact of data from these and other instruments in hurricane forecast models. AOML will make use of its Observing System Simulation Experiment expertise to evaluate how such ocean observations can best improve hurricane forecasts of track and intensity change.

The Hurricane Research Division is one of AOML’s three scientific research divisions. Scientists with HRD, and its precursors, have been flying into hurricanes for almost 60 years and regularly collaborate with other federal, university, and international  partners to leverage that expertise to advance hurricane science and forecasting globally. Follow the latest HRD activities during this research season on Twitter or by visiting the division website.

Originally Published August 2014 by Shannon Jones

Gliders Patrol Ocean Waters with a Goal of Improved Prediction of Hurricane Intensity

 (This feature represents an ongoing mission or event. Most recent updates can be found by scrolling to the bottom of the page)

2014 Glider Mission:

Scientists at NOAA’s Atlantic Oceanographic and Meteorological Laboratory are in the Caribbean to launch two underwater gliders from a vessel off Puerto Rico to collect temperature and other weather data to improve hurricane forecasting.

One of the gliders will collect observations in the Caribbean Sea, and another in the North Atlantic Ocean. They are positioned to operate over the next six months (June-November) collecting data in areas where hurricanes are common and areas where there is a lack of environmental data.

“The goal of the research is to see how these unmanned tools can help us to gather unique observations initialize and evaluate ocean models used for hurricane predictions,” said Gustavo Goni, director of AOML’s Physical Oceanography Division and lead investigator on the project. “This experiment will also help assess the impact of these types of ocean observations in hurricane forecasts using observing system simulation experiments.”

Preparing to Deploy the First Glider  

The gliders will collect data on temperature and salinity from the surface of the ocean down to 1000 meters over the next six months through the rest of the Atlantic hurricane season.

The two gliders are being deployed with the help of scientists and students from the University of Puerto Rico, who are partners in the project along with the Maritime Authority of the Dominican Republic. The university contributed its research vessel, La Sultana, for the deployments. University students assisted with the deployment and will assist with data collection.

The underwater gliders are durable, autonomous, and powered by battery.  Scientists from AOML, with support from NOAA’s National Data Buoy Center, steer the gliders remotely using computers. They will traverse the two regions (identified in the image below), making repetitive dives as they descend and ascend back and forth, weaving through the upper 1000 meters of the ocean.  As the gliders reach the ocean surface at the end of each dive cycle they will transmit their data in real-time to be used by scientists all over the through the Global Telecommunications System.

These observations are a component of AOML’s Hurricane Research Division’s field program and will be used to analyze thermal conditions of the upper ocean and to evaluate existing ocean models, with the goal of improving our understanding of the role the ocean plays in the formation and intensification of tropical cyclones.

The project is funded through the Disaster Relief Appropriations Act of 2013 and AOML. It is a partnership between NOAA’s AOML, NDBC, and Environmental Modeling Center, the University of Miami’s Cooperative Institute of Marine and Atmospheric Studies, University of South Florida, the University of Puerto Rico at Mayaguez, and the Maritime National Authority of the Dominican Republic.

Update: October 2014

AOML’s two underwater gliders recently completed their one thousandth dive.

Since late July, both gliders have provided temperature and salinity profiles down to 1000 meters from the Caribbean Sea and Tropical North Atlantic Ocean. The data collected by these gliders include observations made during Tropical Storm Bertha and Hurricane Gonzalo. The gliders will continue to record temperature and salinity profiles until their planned recovery during the week of November 17th.

The glider located in the Tropical North Atlantic, north of Puerto Rico, was situated close to the path of Hurricane Gonzalo.  During Gonzalo’s passage, the glider obtained information on how the storm’s winds altered local ocean temperature and salinity conditions. Observations show changes in salinity and temperature in the upper 100m due to mixing. Two days after the passage of the storm, the glider moved northward to obtain more information from areas traveled by Hurricane Gonzalo.

Data from this underwater glider were used in real-time numerical model intensity forecasts.  In addition, this data will be analyzed in combination with those obtained during Hurricane Bertha, which also traveled over this same glider. Oceanographers will assess the impact of this data on the Tropical Cyclone intensification forecasts.  The main goal of this project is to provide ocean observations to help assess the impact of these observations on tropical cyclone intensity forecast, and of seasonal forecasts.

Update: November 2014

On November 18-19th, researchers with AOML’s Physical Oceanography Division (PhOD) successfully recovered their two underwater gliders in the North Atlantic Ocean and Caribbean Sea from the RV La Sultana of the University of Puerto Rico Mayaguez (see map below for recovery locations). These recoveries marked the end of the first underwater glider mission for AOML, which started in mid July 2014.

The recovery involved a field team at sea retrieving the gliders and a pilot team at AOML controlling the gliders and steering them to an area where they could be safely recovered. PhOD-University of Miami Cooperative Institute personnel Grant Rawson and Kyle Seaton participated in their at-sea recovery, while PhOD personnel Francis Bringas and Gustavo Goni provided the piloting support from AOML.

2015 Glider Mission:

AOML’s 2015 underwater glider campaign started successfully with the deployment of two gliders in the Caribbean Sea off Puerto Rico. AOML and partners deployed the underwater gliders on February 6, 2015. The gliders’ second mission will transect a region in the eastern Caribbean Sea providing approximately 3000 profile observations of temperature and salinity until their planned recovery in April 2015.

 

Professor Julio Morell and Luis Pomales of The University of Puerto Rico at Mayaguez deploy the underwater glider. Photo Credit: NOAA/AOML

What’s new? During this mission, in addition to temperature and salinity data, the gliders now feature oxygen sensors that can measure dissolved oxygen during the ocean profiles. This new addition will help scientists learn about changes in oxygen in the upper ocean which might impact ecosystems in the Caribbean Sea. During hurricane season, the oxygen sensor will be used by scientists to monitor how dissolved oxygen is affected by the passage of a storm. Scientists also completed a firmware update which allows collection of pH profile data by using the sensors already installed in the gliders. Data from this mission will allow scientists to observe upper ocean conditions in this area to help seasonal forecasts of the Atlantic Warm Pool.

More information about the locations of gliders, data, and a summary of objectives can be found at AOML’s glider program page.

The AOML technology test of a system to autonomously retrieve data from subsurface moored instruments has had a major success. The Adaptable Bottom Instrument Information Shuttle System (ABIISS) is in the midst of its first 4000+ meter test, and on November 6th, 2015 the first data pod surfaced and successfully transmitted its daily data record from the ocean bottom pressure-equipped inverted echo sounder. This data pod, which is the first of four that will surface during the 18-month deployment of the ABIISS, has demonstrated that the new system is working properly in the deep ocean environment.  Continued success will reduce the need for manned research cruises to retrieve and download data from these subsurface moored instruments and will help NOAA redistribute its limited ship resources to other important ocean-based projects.

AOML began the deep water field test of the “ABIISS” data pod system in 2014. The ability to retrieve data from deep ocean instruments at regular intervals via a data pod system greatly reduces observing system costs, which currently requires ship time to retrieve data every 6-12 months. Scientists deployed the data pod package off the Florida shelf in approximately 750 meters of water in December 2014. The submerged system rests on the ocean floor where it collects measurements during the 6-month field test period. At predetermined intervals, data pods are released and floated to the ocean surface to transmit their recorded data via satellite. If proven successful, the data pod system will be deployed as part of existing ocean observing networks in the Atlantic and around the globe.

Read more about the ABIISS system here.

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 currents over time.

The seasonal climatology is available on our Data page, indicating near-surface currents and sea surface temperatures (SST’s) for the world, at monthly and one-half degree resolution.

Satellite-tracked drifting buoys provide observations of near-surface circulation at unprecedented resolution. In September 2005, the Global Drifter Array became the first fully realized component of the Global Ocean Observing System when it reached an array size of 1250 drifters. A drifter is composed of a surface float which includes a transmitter to relay data and a thermometer that reads temperature a few centimeters below the air/sea interface. The surface float is tethered to a holey sock drogue, centered at 15 m depth. The drifter follows the surface current flow integrated over the drogue depth. Drifter velocities are derived from finite differences of their position fixes. These velocities, and the concurrent SST measurements, are archived at AOML’s Drifting Buoy Data Assembly Center where the data are quality controlled and interpolated to 1/4-day intervals.