Debbie Stringham, July 11, 2005

NOAA Teacher at Sea
Debbie Stringham
Onboard NOAA Ship Fairweather
July 5 – 15, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific, Alaska
Date: July 11, 2005

Weather Data

Shumagin Islands, AK --on shore in Eagle Harbor.
Shumagin Islands, AK –on shore in Eagle Harbor.

Location: Shumagin Islands, AK
Latitude: 55 17.7’ N
Longitude: 160 32.1’ W
Visibility: 8 n.m.
True Wind Speed: 12 kts.
True Wind Direction: 190
Sea Wave Height: 1 ft.
Swell Wave Height: none
Swell Wave Direction: none
Sea Water Temperature: 11.7 C
Sea Level Pressure: 1014.0 mb
Sky Description: Cloudy, Drizzle
Dry Bulb Temperature: 11.5 C
Wet Bulb Temperature: 10.0 C

Daily Log 

Returning to ship due to stormy seas.
Returning to ship due to stormy seas.

Last night, some of the crew, including myself, went ashore while anchored in Eagle Harbor. I was eager to learn of the geology of the Shumagin Islands, but have had no opportunity to take samples from shore. It is not so much the composition of the rocks that I’m interested in as the process and time frame of which they formed. I collected both rounded pebbles from the beach and oxidized, angular fragments from a cliff face. I’m extremely impressed by the magnitude of folding, faulting, and glaciation process that are apparent–even from the deck of the ship many miles away. Upon inquiring, I have discovered that there is only one crew member who has any geologic text on the area and she is not on board for this leg.

This morning, I was once again assigned to a launch that would collect bottom samples, but the unfortunate event of well-developed seas and high winds drove us back to the ship. Our sunny weather for the past two days is definitely at an end and our bottom sampling is postponed until further notice.

On this leg, the ship does not have any tide stations to install, but I inquired as to how that affects data collection anyway. Tide stations are used as vertical control on water depths. The Chief Survey Technician said that local tidal data is collected from a primary station on Sand Point and vertical corrections are made to the hydrographic survey data as it is collected. If the data were not corrected to the Mean Lower Low Water (MLLW), the depths displayed on hydrographic charts could mislead ships navigating in shallow waters.

Question of the Day 

Why is knowledge of atmospheric sciences helpful in navigating ships?

Answer from Previous Day 

SONAR stands for Sound Navigation and Radar. Essentially, the purpose is to emit sound waves and capture their echo as they bounce off of the sea floor or other objects to determine shape, position, and/or location. Marine organisms use a similar type feature to detect prey.

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