Looking at Sea Salt from Space
Here is an introductory chemistry mantra: freezing point depression, boiling point elevation.
Tomorrow, NASA’s JPL will launch Aquarius, a satellite outfitted to collect sea surface salinity data. The salinity data will allow for us to gain a better understanding of the global water cycle, ocean circulation and the effects of these on our climate. Even with all of the routine ship and buoy observations, there is only salinity data for 24% of the ocean’s surface. This is a significant gap in our understanding of the ocean and the current models for ocean circulation. Recently, for World Ocean’s Day, there was a great guest blog post in Scientific American mentioning that perhaps the “Ocean Conveyor Belt” picture for our understanding of heat flow in the ocean is an oversimplification. This concept has dominated the field of oceanography and what is exciting is that Aquarius has the potential to help researchers track processes such as precipitation, evaporation, ice melting, and river runoff that influence the global water cycle in order to develop better models. Aquarius will provide sea salinity surface data for the entire Earth’s surface every 7 days.
Salinity of the ocean may seem like a simple and obvious concept for many of us who have experienced the coast. But knowing salt concentrations to 0.2 g/kg (about 1 ppt) can reveal what salinity changes can disrupt ocean circulations. Drastic changes in salinity (ocean circulations) has the potential to lead to changes in the Earth’s climate. The dry regions of the ocean (more evaporation, less precipitation) are the regions of highest salinity. Creating and understadning patterns for future climate/precipitation conditions will be important for agriculture or the stability of ocean fronts for fisheries.
It is all connected. Pictured is an excellent demonstration done by Josh Willis at the JPLtweetup June 7, wherein he illustrates water’s ability to store heat. This ability to store heat effects the temperature of our oceans, which has a direct effect on salinity. And what happens in places with strong variations in salinity? Drastic changes in evaporation and precipitation from season-to-season. Which in turn impacts the global water cycle and ocean circulation.
Global warming is perhaps changing the way in which the ocean is adapting. And isn’t it fascinating that a simple compound like NaCl, with the help of a satellite can help us understand the connection between our climate and the ocean better?
*Edit (06/10/2011) Aquarius is about to launch (t-minus 15 min.) How exactly is Aquarius able to measure salt from space? Through microwave emissions! From an interview with Gary Lagerloef, Principle Investigator, just before the launch: Aquarius will measure the electrical conductivity (directly correlated to the salt concentration – greater the salt concentration, higher the electrical conductivity) which modulate the microwave emissions off the surface of the ocean.
**Edit (06/10/2011. 10:4o am) successful launch of Aquarius/SAC-D!