Probability of Detection averaged over
30 kyds vs. a threat at 150 ft
Probability of Detection averaged over
20 kyds vs. a threat at 510 ft
Probability of detecting a target somewhere between the sensor
a range of 30 kyds distant when the target is in the surface duct (maximum depth ~400 ft).
Probability of detecting a threat somewhere between the sensor and
a range of 20 kyds distant when the target is at an operating depth below the surface duct.
NOTE: “Good” performance against a deep target occurs on the
side of the poor performance shallow-duct areas
(Gridlines included for reference purposes only).
by George Lammons
New developments in ocean forecasting at the Naval Oceanographic Office (NAVOCEANO) are revolutionizing the way warfighters look at oceanography and how it enhances their ability to conduct Anti-Submarine Warfare (ASW).
The newly-established Ocean Forecast Group now forecasts ocean conditions in much the same way meteorologists forecast atmospheric conditions – a discipline the team developed from scratch.
“We have built a capability from ground zero—developing procedures, tools and methods based on our experience probing the ocean and collecting data from it,” said Capt. Jim Berdeguez, NAVOCEANO commanding officer.
The culmination of this data yields an ocean forecast that ultimately provides commanders with enhanced means to make tactical decisions. As varying ocean conditions affect the way acoustic sensors perform, the forecasters predict those conditions and describe the impact on acoustics in a particular setting.
“Ocean forecasters provide integral support to ASW by taking model output and turning it into tactically relevant information that helps warfighters decide where and how to best use their sensors,” said Cmdr. Tony Miller, commanding officer of the Naval Oceanography Anti-Submarine Warfare Center at NAVOCEANO.
The Ocean Forecast Group was established to enhance the growing ASW activities of the Naval Meteorology and Oceanography Command (NMOC). The Navy uses a variety of tools to discern acoustic performance: ocean data from several sources, numerical ocean models, acoustic models—and now ocean forecasters, who provide additional analysis as weather forecasters provide analysis to weather models and atmospheric data.
By analyzing how ocean variables affect sound speed and sonar performance, the ocean forecasters verify where data and the resulting models work, and how to weigh the data in a particular operational area.
“They are the ones who are analyzing and adding real value to the model output,” said Berdeguez.
Jay Wallmark, Ocean Forecast Team Leader, added: “We are able to filter out all the irrelevant data, based on the oceanography of a particular area and the way sensors work.”
Full-field plots of duct leakage leading to below-duct detection potential. Areas where the duct
shallows are directly linked to areas where there is significant energy below duct due to duct leakage.
Graphic representations provided by the Naval Meteorology and Oceanography Command.
NAVOCEANO has long used models and data graphics that show general ocean conditions, but oceanographers in the field typically did not have the time or scientific expertise to apply the degree of analysis in the field to support the operational commanders at this level. NMOC realigned to warfighting missions in 2004 and instituted a concept of operations that relies on reachback to operational production centers for products that incorporate this higher level of analysis and application to warfare decision-making. Military oceanographers at key decision nodes then use these products to advise and facilitate warfighting decisions based on the operational situation.
“We do the analysis here at NAVOCEANO, where we have all of the data and knowledge, then send it forward. We are the experts,” Wallmark said. “When we release our product, the forward guy can immediately turn around and brief the commander. It saves them the time it would take to generate a less accurate ocean forecast.”
Because less is known about ocean science than atmospheric science, ocean forecasting is still a developing discipline.
“Overall, ocean forecasters have less experience than weather forecasters. There are a lot more unknowns in forecasting the ocean,” said John Blaha, technical lead for the Ocean Forecast Group. “The goal is that ocean forecasters will one day be as proficient at forecasting in their environment as meteorologists are at forecasting atmospheric conditions.”
In the four years since its inception, Capt. Berdeguez says the group has proved its value and is “extremely important” to the Navy’s ASW operations.
The Ocean Forecast Group has a strict operational focus, the vast majority of which is ASW-related. To stay prepared, the forecasters daily monitor locations with high ASW activity or with the potential for such. Wallmark said that by monitoring potential hotspots they are nimble enough to respond to requests for products and analysis at any time.
Said Blaha: “We’re a conduit that helps the Fleet to see farther and shoot better.”
He described how operational ocean forecasters are able to provide this service with such proficiency.
First, the ocean forecasters know the limits of the models and the capabilities of the observation system. The models use a variety of data collection systems—satellites, ships at sea, historical data, expendable probes, towed arrays and more—and the ocean forecasters know some data sources can be more dependable than others.
Second, the forecasters possess intimate knowledge of the particular area of the ocean they are forecasting, and the characteristics like currents and eddies, depth, water temperature range and variability, bottom profile, etc. A naval operation could potentially occur in any part of the world, so the forecasting team must know the unique character of almost every part of the oceans.
Third, they know how to tailor their products based on the operational application. For example, the differing parameters between ASW and mine warfare call for ocean forecasters to know which factors are pertinent for each type of operational application.
The vast amount of knowledge required to generate their products means that the Ocean Forecast Group must behave in complete cohesion.
“There are no loners here,” Blaha said. “It is a true integrated, multi-disciplinary process.”
Wallmark said that the new discipline of ocean forecasting and the reinvigoration of oceanography in the Navy makes for exciting times to be a professional oceanographer. Researchers are working to make the models more dependable and finer scale, and operational oceanographers and acousticians are learning more about the ocean as they monitor and analyze conditions.
But the reason for the advancements and improvements—and the new discipline of ocean forecasting—remains ASW today.
“We try to find out what’s going on in the ocean and how it applies to ASW,” Wallmark said. “It’s important that it be tactically focused.”
NMOC provides tactical, operational and strategic support to all five Warfare Enterprises. The Naval Oceanography Program consists of the operationally-applied sciences of oceanography, meteorology, hydrography, and precise time and astrometry.
The Ocean Forecast Group is a prime example of NMOC’s larger strategy, called Battlespace On Demand (BonD). BonD is the process by which NMOC translates its knowledge of the current and predicted physical environment—its inherent variability and its impact on sensors, platforms and people—into warfighting decision-making.
Lt. Cmdr. Neil Smith, an oceanographer previously assigned to the Forward Deployed Naval Forces at CTF 74, tested the implementation of ocean models and analytical tools that are now a reality for warfighters around the world. “One of the first lessons we learned in a major exercise utilizing these new forecasting tools was the dynamic nature of ASW conditions and the value of accurate acoustic models.” He recalls that task force commanders immediately saw the value in these new products. The ability to accurately predict future conditions provides an effective tool for planning ASW missions.
Mr. Lammons works in the Public Affairs Office at the Naval Meteorology and Oceanography Command. He is a graduate of the University
of Tennessee and Millsaps College. His articles
have appeared in a variety of Navy, technical,
professional and general interest publications.