Thomas Savage: Which radars are used on the bridge? August 6, 2018

NOAA Teacher at Sea

Tom Savage

NOAA Ship Fairweather

August 6 – 23, 2018

 

Mission: Arctic Access Hydrographic Survey

Geographic Area of Cruise: Point Hope, northwest Alaska

Date: August 6, 2018

Weather data from the Bridge

Wind speed 14 knots
Visibility: 5 nautical  miles
Barometer: 1007.5 mB
Temp:  8.5 C     47 F
Cloud Height: 10,000 ft
Type: Alto Stratus
Sea Height 2 feet

Science and Technology 

The focus of the NOAA ship Fairweather is to generate and update existing maps of the ocean floor called hydrography. The ship is outfitted with state of the art mapping equipment which uses single and multibeam sonar in capturing the physical topography of the ocean floor (more on this in a future blog).  The region we are mapping is located off the coast of Point Hope in north west Alaska.  It takes an amazing amount of technology especially navigational tools located in the bridge to navigate the ship within this challenging region called the Chukchi Sea.  There are two types of radar on the bridge used to navigate the ship using different radio frequencies, the X band and S band.

The X Band radar generates radio waves with 3 cm and 9 GHz, respectively. The radar is positioned high above the bridge and has the ability to pick up ships up to 40 miles in the distance. During the best weather conditions, officers on the bridge can see the horizon at a distance of 6 miles with the highest powered binoculars and make out other vessels out to about 14 miles. This radar extends the visual range of officers especially identifying ships that are not visible through the use of binoculars. This radar is useful for detecting smaller objects such as small boats in the vicinity of the ship, due to its ability to better resolve smaller objects.

The S Band radar generates radio waves with 9cm and 3 GHz … for context, a microwave oven operates at around 2.5 GHz; a car radio receives at 0.1 GHz (though most people think in MHz… e.g. “You’re listening to The Mountain on 105.9 (MHz)”… the lower frequency of the radio means it’s even less affected by rain and can travel even farther – both good things if you’re running a radio station). This type sound wave have longer distances between each crest. As a result, the sound wave can better track larger objects than the X band and objects at greater distances. In addition, this radar can be used to detect ships through walls of rain. This radar is used by weather forecasters to track types of precipitation, direction and severity and to identify possible rotations that could develop tornado. Another unique property of this radar is its ability to track precipitation on the other side of mountains. In this region of Point Hope, the Brooks Range is visible to the east and knowing the precipitation and direction is important for planning ship operations.

 

Another vital role of these radars is to track current position of the ship when anchored. By using four known coordinates of physical objects on land, in our case, the Brooks Range, located to our east, and known peninsulas are targeted. Officers will use the alidade (and compass rose) located outside the bridge to get their bearings and confirm the ships geographic coordinates. This information reveals whether the ship’s anchor is being dragged.

 

Geography – Point Hope is located just above the Arctic Circle; why is NOAA mapping this region?  The sea ice in this region of Point Hope continues to disappear as a reflection of increased global temperatures. This has generated an opportunity for merchant ships to sail north of Canada instead of using the Panama Canal. The mapping of the ocean floor will provide mariners accurate maps resulting in safer passage.

Personal Log

My journey began at 6 am as my plane from the Asheville airport departed. Traveling over Alaska viewing the Rockies and glaciers from the window has been inspiring and reveals how big Alaska really is.  As soon as I landed in Nome, Alaska, around 1 am eastern time, I was reminded again how important it is to be flexible when participating in any NOAA research. After meeting up with the junior officer at the airport, he informed me that the ship is leaving in two hours due to an approaching storm. Scientists conducting research on board a ship at sea are always at the mercy of mother nature. Everyone on board NOAA’s hydrographic ship Fairweather has been exceptionally welcoming and nice which made my transition to life at sea smooth. The tradition of excellent food on board NOAA ships continues!!

 

I am looking forward to learning as much as I can during this three week adventure and bring back inspiring lessons and labs to the classroom. It is always my hope and vision to provide real world science in action to excite and encourage our students to explore and possible explore careers in science.

Until next time, happy sailing !

~ Tom