Annual mean sea surface temperature for the World Ocean. Data from the World Ocean Atlas 2001.

Sea surface temperature (SST) is the water temperature at the surface. In practical terms, the exact meaning of "surface" will vary according to the measurement method used. A satellite infra-red radiometer indirectly measures the temperature of a very thin layer (about 10 micrometres thick) or skin of the ocean (leading to the phrase skin temperature) representing the top millimeter; a thermometer attached to a moored or drifting buoy in the ocean would measure the temperature as a specific depth (e.g. the top 1 meter below the sea surface); the measurements routinely made from ships are often from the engine water intakes and may be at various depths in the upper 20 m of the ocean. Note that the depth of measurement in this case will vary with the cargo aboard the vessel. Image File history File links Download high-resolution version (1550x1075, 265 KB) Annual mean sea surface temperature from the World Ocean Atlas 2001. ... Image File history File links Download high-resolution version (1550x1075, 265 KB) Annual mean sea surface temperature from the World Ocean Atlas 2001. ... The term World Ocean refers to the interconnected system of the planet Earths marine waters. ... The World Ocean Atlas (WOA) is a data product of the Ocean Climate Laboratory of the National Oceanographic Data Center (USA). ... Fig. ... The metre, or meter (symbol: m) is the SI base unit of length. ... Sea as seen from jetty in Frankston, Australia Look up maritime in Wiktionary, the free dictionary. ...

Measuring SST

There are a variety of techniques for measuring this parameter that can potentially yield different results because different things are actually being measured.

The earliest technique for measuring SST was dipping a thermometer into a bucket of water manually drawn from the sea surface. The first automated technique for determining SST was accomplished by measuring the temperature of water in the intake port of large ships. This measurement is not always consistent, however, as the depth of the water intake as well as exactly where the temperature is taken can vary from vessel to vessel. Probably the most exact and repeatable measurements come from fixed buoys where the depth of water temperature measurement is approximately 1 meter. Many different drifting buoys exist around the world which vary in design and the location of reliabile temperature sensors varies. Furthermore, once deployed, it is very difficult to obtain information that reliably monitors the temperature sensor calibration. These measurements are sometimes beamed to satellites for automated and immediate data distribution. A large network of coastal buoys in U.S. waters is maintained by the National Data Buoy Center (NDBC). Since about 1990, there has also been an extensive array of moored buoys maintained across the equatorial Pacific Ocean designed to help monitor and predict the El Niño phenomenon. However, much more data is required for SST studies than El Niño studies and only a fraction of the data set required by numerical weather prediction and ocean forecasting models for SST is available from buoys. Only satellite SST data sets can provide this information. A common mercury thermometer A thermometer is a device which measures temperature or temperature gradient, using a variety of different principles. ... A typical deep-sea NDBC discus buoy in the Gulf of Mexico. ... Chart of ocean surface temperature anomaly [°C] during the last strong El Niño in December 1997 El Niño and La Niña (also written in English as El Nino and La Nina) are major temperature fluctuations in surface waters of the tropical Eastern Pacific Ocean. ...

Since the 1980s satellites have been increasingly utilized to measure SST and have provided an enormous leap in our ability to view the spatial and temporal variation in SST. Satellite measurements of SST are far more consistent and, in some cases, accurate than the in situ temperature measurements described above. The satellite measurement is made by sensing the ocean radiation in two or more wavelengths in the infrared part of the electromagnetic spectrum which can be then be empirically related to SST. These wavelengths are chosen because they are, An Earth observation satellite, ERS 2 For other uses, see Satellite (disambiguation). ... The word space has many meanings, including: Physics The definition of space in physics is contentious. ... For alternate uses of time, see Time (disambiguation) or see TIME (magazine). ... Radiation in physics is the process of emitting energy in the form of waves or particles. ... Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High...

1. within the peak of the blackbody radiation expected from the earth, and
2. able to transmit well through the atmosphere

The satellite measured SST provides both a synoptic view of the ocean and a high frequency of repeat views, allowing the examination of basin-wide upper ocean dynamics not possible with ships or buoys. For example, a ship traveling at 10 knots (20 km/h) would require 10 years to cover the same area a satellite covers in two minutes. The Global Ocean Data Assimilation Project (GHRSST-PP see [1] provides operational access to nearly all satellite SST data sets in a common format and within 6 hours of acquisition by the satellite instrument. As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... Layers of Atmosphere - not to scale (NOAA)[2] Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... The worlds oceans as seen from the South Pacific Ocean, before the definition of the Southern Ocean in 2000 For other uses, see Ocean (disambiguation). ... A knot is a unit of speed, abbreviated kt or kn. ...

However, there are several difficulties with satellite based absolute SST measurements. First, because all the radiation emanates from the top "skin" of the ocean, approximately the top 0.01 mm or less, it may not represent the bulk temperature of the upper meter of ocean due primarily to effects of solar surface heating in the daytime, and back radiation and sensible heat loss at night as well as from the effects of surface evaporation. This makes it difficult to compare to measurements from buoys or shipboard methods, complicating ground truth efforts. Secondly, the satellite cannot look through clouds, creating a "fair weather bias" in the long term trends of SST. Nonetheless, these difficulties are small compared to the benefits in understanding gained from satellite SST estimates. A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ...

As an aside, away from the immediate sea surface, general temperature measurements are accompanied by a reference to the specific depth of measurement (e.g. SST1m refers to an SST measurement made at a depth of 1m). This is because of significant differences encountered between measurements made at different depths, especially during the daytime when low wind speed and high sunshine conditions may lead to the formation of a warm layer at the ocean's surface and strong vertical temperature gradients (a diurnal themocline).

SST and tropical cyclones

See also: Tropical cyclogenesis

SSTs above 26.5 degrees C are generally favorable for the formation and sustaining of tropical cyclones. Generally the higher the SST, the stronger the storm. However, there are many factors affecting the strength of such storms. Global Tropical Cyclone Tracks Cyclogenesis is the technical term describing the development or strengthening of a surface low pressure system, or cyclone, in the atmosphere. ... Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004 Hurricane and Typhoon redirect here. ...

Remotely sensed SST can be used to detect the surface temperature signature due to hurricanes. In general, a SST cooling is observed after the passing of a hurricane primarily as the result of mixed layer deepening and surface heat losses. In some cases upwelling caused by a surface wind field divergence perhaps in conjunction with bathymetric effects can also be a source of cooling. The seafloor topography near the Puerto Rico Trench Bathymetry is the underwater equivalent to topography. ...

The SST changes primarily have important biological implications for hospitable/inhospitable conditions for many organisms including species of plankton, seagrasses, shellfish, fish and mammals. Although the SST changes are short-lived their ramifications are still not well understood. A biological process is a process of a living organism. ... This article or section does not adequately cite its references or sources. ... Photomontage of plankton organisms This page is about microscopic sea creatures. ... Halophila johnsonii (Johnsons seagrass) in the coast of Florida Seagrass (or sea-grass in British English) are flowering plants from four plant families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae) that grow in the marine saline environment. ... Cooked mussels Shellfish is a term used to describe shelled molluscs and crustaceans used as food. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary...

See also

• Loop Current, with plots of sea temperature in the Gulf of Mexico

External links

• GHRSST-PP, an international project dealing with the production and application of SST data products
• NOAA Sea Surface Temperature (SST) Contour Charts
• Data Buoy Cooperation Panel