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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 that was 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 that vary in design and the location of reliable 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 Nio phenomenon. However, much more data is required for SST studies than El Nio 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. Since the 1980s satellites have been increasingly utilized to measure SST and have provided an enormous leap in the 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 or other parts of the spectrum which can then be empirically related to SST. These wavelengths are chosen because they are, within the peak of the blackbody radiation expected from the earth, and 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 Group for High resolution SST Ghrsst-pp see provides operational access to nearly all satellite SST data sets in a common format and within 6 hours of acquisition by the satellite instrument. The National Oceanic and Atmospheric Administration (NOAA) has been providing research quality SST data continuously since 1981. As of 2009, version 5 of the Pathfinder project contains re-processed global SST data from 1981 through April 2009 at 4km resolution. This is the longest continuous data set of its kind. NASA's (National Aeronautic and Space Administration) Moderate Resolution Imaging Spectroradiometer (MODIS) SST satellites have been providing global SST data since 2000. These gridded products are available with a one-day lag. NOAA's GOES (Geostationary Orbiting Earth Satellites) satellites are geo-stationary and always fly above the Western Hemisphere. This enables to them to deliver SST data on an hourly basis with only a few hours of lag time. GHRSST, Pathfinder, MODIS and GOES data can all be obtained from NASA's Physical Oceanography Distributed Active Archive Center (PO.DAAC). However, there are several difficulties with satellite based absolute SST measurements. First, in infrared remote sensing methodology 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, reflected radiation, as well as sensible heat loss and surface evaporation. All these factors make it somewhat 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. However, some microwave techniques can measure SST and "see" through clouds. 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 1 m). 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).There are 3 layers to the ocean one is the surface layer the next on is the thermocline,and the last is the deep ocean. 75 percent of the ocean is made up of the deep ocean area/layer. Annual mean sea surface temperature for the World Ocean. Data from the World Ocean Atlas 2005. SST and tropical cyclones See also: Tropical cyclogenesis SSTs above 26.5C (80F), 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. Remotely sensed SST can be used to detect the surface temperature signature due to hurricanes. In general, an 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 SST changes primarily have important biological implications for hospitable/inhospitable conditions for many organisms including species of plankton, seagrasses, shellfish, fish and mammals. SST changes are short-lived and their ramifications are still not well understood. Atlantic Multidecadal Oscillation (AMO) Loop Current, with plots of sea temperature in the Gulf of Mexico Ghrsst-pp the Group for High Resolution SST GHRSST-PP, an international project dealing with the production and application of SST data products NASA's Physical Oceanography Distributed Active Archive Center (PO.DAAC) Provider of historic and near real time SST data from 14 satellites, spanning 1981 through yesterday NOAA Sea Surface Temperature (SST) Contour Charts Data Buoy Cooperation Panel SQUAM, SST Quality Monitor (A near real-time Global QC Tool for monitoring time-series stability & cross-platform consistency of satellite SST) iQuam, in situ SST Quality Monitor (A near real-time quality control & monitoring system for in situ SST measured by ships and buoys) MICROS, Monitoring of IR Clear-sky Radiances over Oceans for SST Meteorological data and variables Adiabatic processes Lapse rate Lightning Surface solar radiation Surface weather analysis Visibility Vorticity Wind Cloud Cloud condensation nuclei Fog Precipitation Water vapor Convective available potential energy (CAPE) Convective inhibition (CIN) Convective instability Convective temperature (Tc) Helicity Lifted index (LI) Bulk Richardson number (BRN) Dew point (Td) Equivalent temperature (Te) Forest fire weather index Haines Index Heat index Humidex Humidity Potential temperature () Equivalent potential temperature (e) Sea surface temperature (SST) Wet-bulb temperature Wet-bulb potential temperature Wind chill Atmospheric pressure Baroclinity Barotropicity Earth-based meteorological observation systems and weather stations Aircraft report (AIREP) Automatic weather station (AWS) Automated airport weather station Dropsonde Hurricane Hunters Binary Universal Form for the Representation of meteorological data (BUFR) Meteorological Aerodrome Report (METAR) Pilot report (PIREP) SST buoys Tide gauge Weather balloon Weather buoy Weather ship Argo Global Atmosphere Watch (GAW) Aircraft Communication Addressing and Reporting System (ACARS) Aircraft Meteorological Data Relay (AMDAR) Global Sea Level Observing System (GLOSS) FluxNet Project (FluxNet) Citizens Weather Observer Program (CWOP) Coastal-Marine Automated Network (C-MAN) NEXRAD radar Remote Automated Weather Station (RAWS) Tropospheric Airborne Meteorological Data Reporting (TAMDAR) Abyssal fan Abyssal plain Atoll Bathymetric chart Cold seep Continental shelf Continental margin Contourite Hydrography Guyot Oceanic basin Oceanic plateau Oceanic trench Passive margin Seabed Seamount Submarine canyon Coastal geography More... 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