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What’s With the Heat!?

ARABIAN GULF (Aug. 3, 2017) U.S. Navy Sailors on the rigging team work and cool off during an underway replenishment-at-sea between the aircraft carrier USS Nimitz (CVN 68) and the dry cargo and ammunition ship USNS Carl Brashear (T-AKE 7), Aug. 3, 2017, in the Arabian Gulf. Nimitz is deployed in the U.S. 5th Fleet area of operations in support of Operation Inherent Resolve. While in this region, the ship and strike group are conducting maritime security operations to reassure allies and partners, preserve freedom of navigation, and maintain the free flow of commerce. (U.S. Navy photo by Mass Communication Specialist 3rd Class Ian Kinkead)

Visible heat spans across the flight deck under the smoldering sun in the Arabian Gulf. A blanket of haze surrounds the ship and the minimal cloud coverage makes next to no difference. The Sailors and Marines working aboard the aircraft carrier USS Nimitz (CVN 68) can’t seem to escape the heat, sometimes even within the skin of the ship. With an average heat index of 125 degrees Fahrenheit, the Arabian Gulf is one of the hottest operating areas for the U.S. Navy.

Nimitz caught a deployment in the middle of the hottest time of year: summer. The heat in this region can have its effects on the ship and, obviously, the crew.

“The Arabian Gulf is as hot as it is due to a number of factors,” said Aerographer’s Mate 2nd Class Cyrel Claudio, from San Diego. “The ratio of land to water favors land; land heats up a lot faster than water does and the lack of moisture continues to produce drier conditions.”

Average air temperatures range from 100 to 105 degrees Fahrenheit with an average heat index of 125 degrees Fahrenheit. Heat index is the apparent temperature relative to the human body which takes into account the ambient air temperature and humidity.MAP“In the summer, something called Southwest Monsoon takes place and has a direct effect on the Arabian Gulf,” said Claudio. “High pressure sets up south of the equator pushing winds northwest towards Somalia.”

The winds by the equator get shifted to the right due to the Coriolis effect. The Coriolis effect is the outcome of Earth’s rotation on weather patterns and ocean current. In the northern hemisphere, objects move clockwise, as in the southern hemisphere, objects move counter-clockwise.

“Winds along the coast of Somalia will cause seas at the surface to deflect to the right,” said Aerographer’s Mate 1st Class Rodney Bruno, from Miami. “This brings cooler subsurface water to the surface, which causes a thermal gradient that will then form a low-level jet, called the Somali Jet.”

A low-level jet is a stream of relatively strong winds in the lower part of the atmosphere.

“The stronger the Southwest Monsoon is, the more moisture will be pushed into the Arabian Gulf,” said Bruno. “This, in turn, will have an effect on the heat index.”

Sailors Read Weather

Dust and sand from the surrounding land are also suspended into the air from the wind causing the rustic haze to the air and can restrict vision up to 3-5 miles depending on wind speed.

Many Sailors and Marines may not be used to the heat in the Arabian Gulf. It not only has an effect on the crew, but the equipment may have a hard time coping with the heat as well.

“The heat of the sea surface can also affect our operations aboard the ship,” said Claudio.

The average water depth in the Arabian Gulf is roughly 300 feet and sits at about 95 degrees Fahrenheit during the summer. These shallow waters heat rapidly and remain hot throughout the summer, which may have a lasting effect on Nimitz.

“The air conditioning and refrigeration systems use sea water to cool the refrigerant,” said Machinist’s Mate 2nd Class Ryan Tavares, from Eureka, California. “Our equipment was designed for a maximum of 90 degree salt water inlet temperature. Perfect conditions would be about 85 degrees, so right now, we’re about 10 degrees over that and it’s causing a lot of problems.”

Sailors Perform Maintenance

Due to the heat of the sea water, the equipment used to cool the refrigerant works harder and takes much longer to cool than usual. If the equipment itself gets too hot, it will shut down and other air conditioning units would have to pick up the slack.

“This is caused by high heat loads from not maintaining air conditioning boundaries, running equipment that doesn’t need to be ran, etc.,” said Tavares. “When an air conditioning unit shuts down, the other air conditioners that are running pick up the load; almost like a domino effect, one goes down, then two go down, and so on and so forth until we can get it under control.”

Although personnel around the ship may be uncomfortable due to the heat, the primary purpose of the air conditioning on the ship is to cool vital equipment and radars.

“The secondary purpose is comfort of the crew,” said Tavares. “We have to keep the radars spinning and the weapons systems cool so that we know where we’re going and have a means to defend ourselves.”

As Tavares mentioned before, high heat loads are caused by not maintaining air conditioning boundaries; a simple solution that has a significant impact on not only the crew’s comfort, but the air conditioners as well.

Sailor Wipes Sweat

“If you open a hatch, you should probably shut it,” said Tavares. “Something simple like shutting a door behind you can easily be a 10 or 15 degree temperature difference in your space. I’ve seen it on this ship, as well as my last. Air conditioning boundaries are vital to keeping your spaces cool.”

Although this may be the first time in the Arabian Gulf for many of Nimitz’ crew, many service members have worked tirelessly in this region for many years before them, at sea and on land.

The Nimitz Carrier Strike Group is deployed in the U.S. 5th Fleet area of operations in support of Operation Inherent Resolve. While in the region, the strike group is conducting maritime security operations to reassure allies and partners, preserve freedom of navigation and maintain the free flow of commerce.

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Story by Mass Communication Specialist 3rd Class Leon Wong

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