Sea Surface Temperature (SST) Quiz

Introduction to SST - Sea Surface Temperature

The sea surface temperature (SST) refers to the temperature of the ocean's surface layer called the mixed layer, which is typically 0-100 meters deep. This measurement plays a crucial role in understanding climate and weather patterns because it influences many atmospheric processes such as hurricane formation and marine life migration. Here, we will discuss the history of SST measurements, their significance, and how they are used today.

Historical Background

The first attempts at measuring SST can be traced back thousands of years ago when Phoenicians observed the freezing or melting of water to get a sense of the temperature. However, organized efforts to measure the temperature of oceans began during the Age of Exploration around the late 17th century when mariners would note changes in the thickness of ice sheets as an estimate of air temperatures from the nearby landmasses. It wasn't until the mid-19th century with the advent of thermometers and the development of ships suitable for scientific expeditions that systematic observations of the ocean's surface temperature became possible.

In the early 1800s, Alexander von Humboldt made a series of measurements by lowering buckets into the ocean from his ship while traveling between Europe and South America. These were among the first set of quantitative data on ocean temperature. In the following decades, more instruments were developed for collecting temperature data, including the hydrometer invented by James Cossar Ewart in 1852, which was later adapted for marine use by James Glaisher aboard the British flagship Victory in 1860. The introduction of thermometers specifically designed for oceanographic work came in 1884 with the so-called 'oceanographers' thermometer', an instrument originally designed by William Thomson (Lord Kelvin), although other scientists had previously devised methods for measuring ocean temperature.

By the end of the 19th century, recording devices for SST included the mainmast thermometer, which was attached to the mast of a sailing ship or floating structure; the bucket method, where seawater is collected and its temperature measured; and finally, electrical conductivity thermometry. Instruments like the 'oceanographers' thermometer' were considered too fragile for open-sea use and relied heavily on human readings, resulting in inconsistencies and errors in the recorded values.

The instrument most commonly used today for SST measurement is the Sealed Engine Room Thermometer, which provides high accuracy by being housed within a sealed housing unit and connected to a depth gauge, allowing for consistent and accurate readings. With these advancements, modern SST measurements have become increasingly reliable over time, providing valuable insights into ocean dynamics and global climate trends.

Significance of SST

Sea Surface Temperature is significant because it affects various aspects of our planet's climate system, both locally and globally:

1. Weather Patterns: Changes in SST affect localized atmospheric conditions and help predict weather events such as hurricanes and storms.
2. Ocean Circulation: Ocean currents and circulation are driven by temperature differences across the surface layers, making SST an important factor in determining global ocean circulation patterns.
3. Marine Life: Many species of fish and marine animals rely on specific temperature ranges for survival, reproduction, and migration, thus alterations in SST can impact entire ecosystems.
4. Tropical Cyclones: A low SST is associated with reduced chances of tropical cyclones forming, whereas higher SST generally promotes cyclone development.
5. Climate Change: An increase in SST has been linked to global warming due to the release of greenhouse gases into the atmosphere.

Present Day Usage and Measurement Techniques

Today, satellites play a critical role in obtaining global coverage of SST through sensors that detect the intensity of sunlight reflected off the ocean's surface, which correlates with SST. Other remote sensing techniques include active microwave systems, which emit energy and detect the amount absorbed and returned, also giving information about SST. Additionally, buoys equipped with SST sensors are deployed throughout the world's oceans, providing continuous real-time monitoring of SSTs.

Furthermore, climate models now incorporate SST data to simulate past, present, and future global climates, further enhancing our understanding of the Earth's complex climate system. As a result, SST continues to serve as a vital indicator of climate change and ocean health, influencing studies spanning multiple disciplines from marine biology to meteorology.