Background for Light Vessel/ Light Station Oceanographic Observations

East Coast of the United States

U.S. Coast Guard Reports

For over 15 years (late 1955-1970) the Woods Hole Oceanographic Institution (WHOI) conducted a Government contracted oceanographic program aboard Coast Guard light vessels and offshore light stations (LV'S and LTSTA'S) along the East Coast of the United States. The objectives were (Bumpus, 1971):

1. "To establish a program of observations to detect changes in oceanic circulation."
2. "To analyze climate and weather records to determine the cause of such changes."

Activities undertaken by WHOI in support of the program were

1. "To maintain oceanographic posts at lightships/light stations from Portland to Frying Pan Shoals."
2. "To analyze and report the data in relation to climatic and other oceanographic data."
3. "To study the non-tidal drift at the surface and bottom on the continental shelf off the east coast of the United States."
4. "To cooperate -with a number of agencies interested in the waters of the shelf. ..."

In early 1970 the direct use of these LV'S and LTSTA'S in the study of nontidal drift ended while the release of drift bottles was phased out. Considerable drift bottle data were collected and have been presented elsewhere (Bumpus, 1969a and Bumpus and Lauzier, 1965).
The U.S. Fish and Wildlife Service published temperature and salinity data from 1956-1965. The U.S. Coast Guard published data from 1966-1970.
On 1 January 1971 the U.S. Coast Guard Oceanographic Unit (CGOU) assumed responsibility for this continuing program of salinity and temperature observations.

Data Collection and Processing
The data collected once daily, included temperatures taken at depth by mechanical bathythermograph (BT), surface reference temperature and surface water salinity sample obtained by thermometer bucket and weather recorded at time of observation. Bottom water salinity samples were obtained twice weekly by Nansen bottle.

The Coast Guard handled all logistics for LOSAMP in 1971. The data were analyzed and processed at the Coast Guard Oceanographic Unit.

Salinity samples were analyzed on inductive salinometers, and salinity values were determined by computer at CGOU. The mechanical bathythermograph traces were read with handheld grids. The BT temperatures at selected depths were corrected by the following procedures:

  1. Subtract daily surface BT temperatures from corresponding surface reference temperatures for each BT each month (BT-month).
  2. Compute the mean and standard deviation for the differences for each BT-month from 1. Above.
  3. Compute the average value for those differences within the standard deviation of the mean for each BT-month.
  4. Take the average from 3. As the temperature correction factor and add it to the temperatures at all selected depths for the BT-month.

Separate corrections were computed within any BT-month when obvious shifts in BT calibration occurred.

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