Temperature surface, oceans

Coast of the United States, in Sweden, and at Bariloche, Argentina [6-10], but such variations are not primarily related to ocean surface temperatures. 

Incident solar energy is absorbed by the surface water of the oceans. Ocean surface temperatures in excess of 26°C occur near the equator. Pure water has a maximum density at a temperature of 4°C. The chilled water tends to settle to the depths of the ocean. The combination of the warmed ocean surface water and cold deep ocean water provides the thermodynamic condition needed to operate a heat engine called ocean thermal energy conversion (OTEC). A typical closed-cycle OTEC Rankine cycle using a working fluid such as ammonia or a freon is suggested. 

OTEC is limited to regions where differences between ocean surface temperatures and deepwater temperatures are greatest. Fleets of floating offshore rigs have been proposed, with the electricity generated used to produce transportable hydrogen fuel made from seawater. Onshore OTEC plants are best suited for islands, such as Hawaii, Guam, and Puerto Rico, where deep waters are relatively... 

Ocean surface temperature AYHRR, ATSR-2/ERS-2, AATSR/ENYISAT, MODIS/ EOS-Terra/Aqua, AMSR-E/EOS-Aqua, OCTS/ADEOS. Spaceborne system EOS/Terra is equipped with radiometer ASTER to measure thermal radiation and its reflection from the ocean surface, spectrometers MODIS and MISRC, as well as MOPITT and CERES instruments to record pollutant and energy fluxes, respectively. 

Ward B, Wanninkhof R, McGillis WR, Jessup AT, DeGrand-pre MD, Hare JE, Edson JB (2004) Biases in the air-sea flux of C02 resulting from ocean surface temperature gradients. J Geophys Res-Oceans 109 Article no. C08S08... 

As should become clear, the U37 index appears nevertheless to provide a remarkably faithful estimate of paleotemperamres near the sea surface. At the same time, difficulties in matching the space and timescales of modem process studies to the information contained in sediments mean that the caveats raised above remain significant. Field studies provide only snapshots of haptophyte abundance and alkenone unsaturation parameters, sediment traps provide only a few years of data at only a few locations in the global ocean, and it is unclear how well laboratory cultures replicate the natural environment. I have endeavored to treat different lines of evidence systematically, but I have found it difficult to discuss each aspect in a purely serial way. The reader will therefore be asked to digest a review in which very diverse measurements and paradigms are woven together to answer the central question of how to reconstmct past ocean surface temperatures with the U37 proxy. 

Figure 10 Compilation of all available alkenone estimates of cooling of ocean surface temperatures at the LGM relative to the late Holocene. The estimates have been projected onto the sine of latitude to approximately compensate for the distribution of ocean surface area from the equator to the poles. Note that the Ice Age anomalies are much stronger at mid and high latitudes than in the tropics. Scatter at any given latitude reflects variability in the quality of the chronological control used to assign the LGM level in alkenone time series, but also includes an important contribution from real heterogeneity of cooling at the LGM.

A very simple demonstration of the importance of ocean temperature, marine biology and ocean d5mamics to atmospheric/coj is achieved by using a three-box model (Fig. 11.2) of the ocean and atmosphere that is similar to the two-layer model introduced in Ghapter 6. This construct can be used to show the sensitivity of atmospheric/coj to ocean surface temperature, biological processes... 

MacLeish W (1970) Spatial spectra of ocean surface temperatures. J Geophys Res 75 6872-6877... 

This type of dynamics is used, for example, in models of oceanic surface temperature distribution (Abraham and Bowen, 2002), with To(x) representing an imposed atmospheric temperature field. 

Equilibrium isotopic-fractionation factors for O and D during evaporation and condensation are temperature-dependent, but the main control on degree of fractionation of precipitation 0 and D from the source composition is the fraction of water extracted from an air mass before condensation of the precipitation of interest (e.g. Dansgaard 1964). This in turn is controlled primarily by the difference between the temperature at which condensation first begins for an air mass, and the temperature at which the precipitation of interest condenses. The first-condensation temperature in turn is tied closely to the ocean surface temperature by the high and more-or-less constant relative humidities over most ocean surfaces (Vimeux et al. 2001). Hence, and 5D of precipitation depend in part on the temperatures at all contributing moisture sources, and not just on the temperature at the site. 

Changes in surface temperature elsewhere in the globe are likely to have a lesser impact on carbon or DMS production. For example, the warming that a doubling of atmospheric COj could produce in the Southern Ocean has been modelled to lead to decreased carbon uptake, but enhanced biological productivity, due to the temperature effect on phytoplankton growth." This would lead to an approximately 5% increase in DMS production and a lesser increase in CCN. There is thus a negative feedback here, but only of minor impact. 

As a hurricane travels over warm ocean water, it lowers the sea surface temperature by about 3°C m a 100 km swath. When a hurricane is stationaiy, this surface ocean cooling weakens the storm intensity. Hurricanes also rapidly lose strength when they move over cold water or land. 

Ocean thermal energy conversion (OTEC) power plants generate electricity by exploiting the difference in temperature between warm water at the ocean surface and colder waters found at ocean depths. To effectively capture this solar energy, a temperature difference of 35°F or more between surface waters and water at depths of up to 3,000 feet is required. This situation can be found in most of the tropical and subtropical oceans around the world that are in latitudes between 20 degrees north and 20 degrees south. 

There are three potential types of OTEC power plants opcii-cyclc, closed-cycle, and hybrid systems. Open-cycle OTEC systems exploit the fact that water boils at temperatures below its normal boiling point when it is under lower than normal pressures. Open-cycle systems convert warm surface water into steam in a partial vacuum, and then use this steam to drive a large turbine connected to an electrical generator. Cold water piped up from deep below the oceans surface condenses the steam. Unlike the initial ocean water, the condensed steam is desalinated (free of salt) and may be collected and used for drinking or irrigation. 

Table 2.15 Average surface temperature of the oceans between parallels of latitude (°C)...

Recent revisions to the boundary conditions (ice-sheet topography and sea surface temperatures) have added uncertainty to many of the GCM calculations of the past two decades. Moreover, all of these calculations use prescriptions for at least one central component of the climate system, generally oceanic heat transport and/or sea surface temperatures. This limits the predictive benefit of the models. Nonetheless, these models are the only appropriate way to integrate physical models of diverse aspects of the Earth systems into a unified climate prediction tool. 

Thus, the global thermal pollution will at steady state have increased the sea surface temperature by 1.9 °C, the land area temperature by 3.9 °C and the global mean temperature by 2.5 °C. Since part of this heating has already begun, further temperature increases of 1.4 °C (Ocean), 2.7 °C (Land), and 1.8 °C (Mean) should be expected (Figure 11). 

In the following chapter model refinements are described and compared with the setup used by Gughelmo (2008). The focus is given on the represention of marine organic matter. In a sensitivity study the impact of organic matter on long-range transport is explored. Additionally, a study is included that clarifies the relative importance of sea surface temperature, wind speed, and pollutant concentration for volatilisation of DDT from the ocean. 

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