Temperature

Ocean temperatures vary all over the world. Measuring temperature is an important way to keep track

of climate studies and to continue research and study of earth's ocean waters. Meterological phenomena such as El Nino/La Nina or tropical hurricanes/cycles are the direct consequences of specific temperature variations at the sea-surface.

How it Works
Measuring temperature is important to determine whether the ocean is warming

or cooling down. In order to measure the temperature of ocean water one must know the three different parts: the surface layer (the top), the thermocline layer (boundary layer), and the deep ocean. Temperatures may vary depending on locations, seasons, and weather.

As the sun warms up the surface layer, wind and waves mix the warmer water up and down the ocean column. Surface water temperature does vary mostly with latitude. High latitude areas, like the polar seas, can have water temperatures as low as -2° C. High latitudes such as this can possibly produce sea ice. Warmer latitude areas like the Persian Gulf can be as warm as 36°C. The average surface water temperature of the ocean is about 17°C.

Sea Surface Temperature (sst) is the measure of the energy due to the motion of molecules at the top layer of the ocean. Depending on the sensor, spaceborne measurements give us an unprecedented global measurement of sea surface temperatures every few days to a week.[1]

Sensor Variations
Starting in the 1980s, SST (Sea Surface Temperature) had came from satellite observations. One important instrument during that time was the Moderate Resolution Imaging Spectroradiometer (MODIS). This instrument was aboard NASA's Terra and Aqua satellites that orbit Earth approximately 14 times per day.

Since the 1990s, temperature has been measured by an extensive array of buoys placed throughout the ocean. Information from these buoys are transmitted to satellites. Specifically, the ARGO  program deploys underwater robots that measure salinity and temperature throughout the surface layer of the ocean. 3,000 underwater robots are programmed to go 10 hours at the surface later drifting to a depth of 1000m continuing to move for 8-10 days until the final profiling descent of 2000m. Next, it ascents where salinity and temperature where it rests for 10 more hours. This program also transmits its data to satellites allowing the information to be accessed by the public within hours of the data collection. The ARGOs system is usually also in charge of moorings. Moorings, including surface and submerged buoys, are another way to measure the ocean's temperature.

Another alternative way to measure temperature is by using a CTD (conductivity, temperature, depth). From a ship or platform, a CTD is placed in ocean water. CTDs can be used to by programming it to sample water from different depthsby triggering a series of Niskin bottles at specified depths. From there the censors calculate the data as programmed. CTDs are a great tool to calculate ocean water temperature for mostly the whole water column. An independent marine science organization, BIOS, the Bermuda Institute of Ocean Sciences use instruments like CTDs to help measure ocean temperatures--they have been doing so for over 55 years.

In this day in age, it has become common practice for ships to record water temperatures while at sea. Depths and locations may vary but the data is there.