Sea-Surface Temperature

The temperature of the water near to the ocean’s surface is known as sea surface temperature (SST). Surface varies depending on the measurement method, but it is between 1 millimetre (0.04 in) to 20 metres (70 feet) below the sea surface. Within a short distance of the shore, sea surface temperatures significantly alter air masses in the Earth’s atmosphere. Within an otherwise cold air mass, localised regions of heavy snow can occur in bands downwind of warm water bodies. Tropical cyclogenesis over the Earth’s oceans is known to be caused by warm sea surface temperatures. Tropical cyclones can also produce a chilly wake due to turbulent mixing of the ocean’s upper 30 metres (100 feet). SST fluctuates during the day, similar to the air above it, but to a smaller extent. On windy days, the SST varies less than on calm days. Furthermore, ocean currents such as the Atlantic Multidecadal Oscillation (AMO) can alter SSTs on multi-decadal time scales, with the global thermohaline circulation having a considerable impact on average SST across most of the world’s oceans.

Temperature of the Oceans

Ocean temperatures typically vary from -2 to 30 degrees Celsius (28-86o F). Surface water in low latitude locations tends to be the hottest, whilst surface water near the poles is obviously much colder. Water on the eastern side of the ocean basins is colder than water on the western side at equal latitudes. Despite the fact that surface water in the seas can be incredibly hot, the bulk of the water in the oceans is deeper, colder water, thus the average temperature of the entire ocean is roughly 4° C, which is about the same as the temperature inside your refrigerator.

Surface water is warmer near the equator and cooler in the poles, therefore profiles differ at different latitudes. The sea surface is substantially warmer in low latitude tropical locations, resulting in a strong thermocline.

There is little variation between the surface and deep water temperatures in high latitude (polar) locations, and temperature is largely steady (and cold) at all depths. As a result, unlike tropical water, polar seas lack a strong thermocline. Mid-latitude temperate regions see higher seasonal temperature swings than the poles or the tropics, with an 8-15o C difference between summer and winter in temperate zones compared to only 2o C in polar and tropical areas. The surface water in temperate regions is substantially warmer in the summer and the thermocline is more pronounced compared to the winter months

Tropical cyclones Relative humidity

The radius of maximum winds in tropical cyclones (TCs) can vary by an order of magnitude, according to observations; comparable size disparities can be seen in various geographical metrics of the wind field, as well as cloud and precipitation fields. Although many TC impacts are linked to storm size, the physical factors that govern storm size are poorly understood and attract little study attention. A hypothesis is presented here that suggests one element determining TC size is ambient relative humidity, to which the intensity and coverage of precipitation outside the TC core is highly sensitive. The size and strength of the related cyclonic PV anomalies are linked to the lateral expanse of the TC wind field from the perspective of potential vorticity.

The diabatic lateral expansion of the cyclonic PV distribution and balanced wind field can occur from latent heat release in outer rainbands. The growth of the lateral wind field in the outer portion of computationally generated tropical cyclones is dependent on the development of diabatic PV in spiral bands. In the wet environment simulation, breaking vortex Rossby waves in the eyewall causes the eye to expand and the inner-core PV gradients to weaken.

Conclusion

SST is and has been one of the most studied variables in the ocean, attracting a lot of scientific attention. We characterised the worldwide and seasonal trends of SST using a mix of ship SSTs, moored and drifting buoy SSTs, and satellite infrared SSTs. Recognizing that only satellite infrared SSTs can accurately represent the SST of the ocean’s 10 m thick skin layer, future studies should focus on distinguishing the satellite skin SSTs from the 1–5 m deep bulk SSTs reported by buoys and ships. Simply said, the skin layer is the molecular layer that connects a turbulent ocean to a turbulent atmosphere. The difference in temperature between the skin and the bulk is proportional to the wind speed and net air–sea heat transfer. As a result, a better understanding of this relationship can aid in the resolution of net heat and momentum fluxes between the ocean and the atmosphere. The construction of a network of’ship of opportunity’ based skin SST radiometers collecting worldwide and continuous samples of skin SST ‘ground truth’ data is necessary for this understanding and the change to skin SST calculation from satellite infrared data (i.e., without an intervening atmosphere).