Jennifer Fry, July 28, 2009


NOAA Teacher at Sea
Jennifer Fry
Onboard NOAA Ship Miller Freeman (tracker)
July 14 – 29, 2009 

Mission: 2009 United States/Canada Pacific Hake Acoustic Survey
Geographical area of cruise: North Pacific Ocean from Monterey, CA to British Columbia, CA.
Date: July 28, 2009

Map of the world showing longitude and latitude lines

Map of the world showing longitude and latitude lines

Weather Data from the Bridge 
Wind speed:  17 knots
Wind direction: 345° from the north
Visibility: 8 nautical miles /clear
Temperature: 16.8°C (dry bulb); 11.6°C (wet bulb)
Sea water temperature: 15.5°C
Wave height: 3-5 ft.
Air pressure: 1012.9 millibars
Weather note: Millibars is a metric unit used to measure the pressure of the air.

Science and Technology Log 

Weather Instruments and Predicting Weather 

Lt Oliver Brown, surrounded by navigational tools, and Fishery Scientist Steve DeBlois make observations on the bridge of the Miller Freeman.

Lt Oliver Brown, surrounded by navigational tools, and Fishery Scientist Steve DeBlois make observations on the bridge of the Miller Freeman.

Everything that happens out at sea is dependent upon the weather forecasts.  Throughout history man has used a variety of instruments to acquire accurate weather information.  The Miller Freeman is equipped with state of art weather reporting instruments. Every 3 hours weather data is sent to the National Weather Service to help predict the weather at sea.  Once again accuracy in reporting data is paramount.

Global Position: The Miller Freeman has several methods by which to determine longitude and latitude, which is our position in the ocean or on land.  There are 2 G.P.S. systems on the bridge, a magnetic compass, a gyro compass, and radar. These instruments help determine the ship’s position.

True north: The actual location of a point on the earth related to the north pole.

A Gyrocompass with cardinal headings including north, south, east, and west

A Gyrocompass with cardinal headings including north, south, east, and west

Magnetic north: Caused by the magnetic pull on the earth.  Magnetic north heading is different depending on where you are on the earth, for instance, Magnetic north in Oregon has a variation of 16.45°east from true north. Southern California has a variation of 13.3° east from true north.

Temperature: Measured by a thermometer, units used are Celsius. Dry bulb: Measures air temperature.  Wet bulb:  Uses a thermometer wrapped in a wet cloth. The dry and wet temperatures together give the dew point and help to determine humidity.

Wind Speed: Measured in knots using an anemometer, or estimated by using the Beaufort scale. The Beaufort scale uses observations of the sea surface, and the effects of wind on people or objects aboard ship to estimate the wind speed.

Wind Direction: Is measured by what direction in which the wind is coming.

Cloud Height/Type: Is measured visually.

Cloud Type: Is measured visually using a variety of names of clouds depending on their patterning and altitude.

Magnetic compass

Magnetic compass

Visibility: Is measured by estimating how much of the horizon can be seen.

Wave Direction: measured visually from the direction the wave comes.

Wave Height: The vertical distance between trough (bottom of the wave) and crest (top of the wave) and is usually measured in feet.

Swell Direction/ Height: Measured visually usually in feet.

Personal Log 

I have enjoyed my time on the bridge of the Miller Freeman immensely.  I have a better understanding of the weather instruments used onboard and am getting better at spotting whales and identifying birds. I want to thank the entire NOAA Corps Officers who have taught me so much about how navigation and weather work aboard the Miller Freeman.

Crewmember John Adams uses on-board weather instruments to record hourly weather readings that are then sent to National Weather Service.

Crewmember John Adams uses on-board weather instruments
to record hourly weather readings that are then sent to National
Weather Service.

An anemometer, which measures wind speed

An anemometer, which measures wind speed

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