Infrared Remote Sensing of the Ocean

doi:10.1117/3.1002079.ch8

Book: Ocean Sensing and Monitoring: Optics and Other Methods

Author(s): Weilin Hou

Published: 2013

https://doi.org/10.1117/3.1002079.ch8

Author Affiliations +

Abstract

As we have seen, SST is a key parameter in the study of oceanography. This is due to the high heat capacity of seawater, with its top three meters containing as much latent heat as the entire atmosphere above it. Energy exchange between the air–sea interface is largely a function of SST, in association with surface wind speed, cloudiness, humidity, and air temperature. Understandably, such heat storage capacity influences air temperature on both smaller (local) and larger (global) scales. On the smaller side, water bodies exert their influence by regulating air temperature, humidity, and wind speed, thereby affecting local weather. This is the reason behind the mild weather of the San Francisco Bay area, thanks to the upwelling of deeper cooler water. Global temperature anomalies, such as El Niño and La Niña events, are primarily associated with SST variations or pattern changes. Longer-term climate patterns (Fig. 8.1), especially the pressing issues of global warming, require precise monitoring of the ocean surface temperature on 72% of the planet’s surface. Regional events such as hurricanes are also strongly dependent on SST, as warmer waters serve as the engines of tropical cyclones. These storms, on the other hand, increase vertical mixing and bring up deeper cooler waters, often leaving behind a cool wake. SST is also associated with the key driving mechanisms of ocean currents by the transfer of solar energy via the heat flux across the air–sea interface. Lastly, solar input is certainly the driving force of most, if not all, biological activities in the ocean.