Since this blog has main focused on air temperature measurement, and has not done any discussion of manual measurement techniques of Sea Surface Temperature measurements, I thought it would be good to first review some of the instrumentation used.
Sea Surface Temperature Measurement Instruments:
Measures: Temperature in degrees, typically used in the bucket thermometer
Operates: At any depth by cable or line or by hand
Notes: Mercury in original thermometer has been replaced in many standard
thermometers by less toxic materials
Measures: Water temperature near the surface
Operates: At the surface by hand or line
Notes: Typically lowered about 1 meter into the water, left there for one
minute, and then retrieved deck side for reading.
Reversing Thermometer (for Nansen Bottle)
Measures: Water temperature at a specific predetermined depth
Operates: Only when turned 180 degrees (the mercury breaks in the special loop
and will not get back together until reset) Temperature at depth can be recorded
with a 180 degree flip (as is done with the Nansen Bottle) and there will be no
change on the way up.
Notes: A Nansen bottle
is a device for obtaining samples of seawater at a specific depth. It was
designed in 1910 by the early explorer and oceanographer Fridtjof Nansen.
The bottle, a metal or plastic cylinder, is lowered on a cable into the sea, and
when it has reached the required depth, a brass weight called a “messenger” is
dropped down the cable. When the weight reaches the bottle, the impact tips the
bottle upside down and trips a spring-loaded valve at the end, trapping the
water sample inside. The bottle and sample are then retrieved by hauling in the
Measures: Water temperature over a range of depth
Operates: Over any depth with a cable or line by hand or with a hydraulic winch
Notes: This model records the information inside and is retrieved however there
are expendable models (XBTs) that free fall on a copper line and transmit the
temperature and depth information through the copper wire before dropping to the