Aquarius: NASA's First Ocean Salinity Observations

Aquarius: NASA's First Ocean Salinity Observations

Hello Everyone! Today we are talking about one of the first missions of NASA to observe ocean surface salinity. 😊 Did you know that an Aquarius is a constellation and a zodiac sign (My zodiac sign is an Aquarius!!!)? Let's dive in! 🌊

Introduction

The Aquarius/SAC-D mission was an instrument for mapping ocean surface salinity, providing important information into Earth's water cycle and ocean circulation. Scientists can better understand how freshwater moves between the ocean and the atmosphere by studying ocean surface salinity. The Aquarius mission was launched from Vandenberg Air Force Base in California on June 10, 2011, and placed into a 657 km (408 mi) Sun-synchronous orbit. The mission was a collaboration between NASA and CONAE, with participation from Brazil, Canada, France, and Italy. The data collected by Aquarius during its mission provided a clearer picture of how the ocean works, how it's linked to climate, and how it may respond to climate change. 🌊🛰️

Mission's Purpose

The mission's purpose was to provide the world's first global observations of sea surface salinity from space. These mission goals are:

• Understand ocean dynamics 🌊

• Observe and model how salinity variations affect ocean circulation and the global water cycle, and how these changes relate to climate 🌍

• Improve climate and ocean models 📈

• Use the data to better understand the ocean's role in weather patterns, global climate variability, and El Niño prediction 🌦️

•  Get a better understanding of the exchange of freshwater between the ocean, atmosphere, and sea ice. 🌊❄️

Importance

Aquarius' salinity measurements are especially essential because salt concentration in the ocean, also known as salinity, is a key factor in understanding the water cycle and ocean circulation. As precipitation and evaporation patterns change, so do salinity levels, which can indicate how freshwater mixes with salty water. By monitoring changes in salinity, scientists can also understand what's happening in the water column below the surface. For example, if an area's freshwater becomes fresher or its salty water becomes saltier, that could show the water cycle is speeding up (going faster!) or slowing down.

Observing The Water Cycle

 NASA's Aquarius/SAC-D mission observed the water cycle by measuring ocean salinity from space. The mission's instruments detected small changes in the ocean's microwave emissions which is caused by salinity, which can be as small as 0.2 parts per thousand (PSS) each month. The Aquarius team (the people who are in charge of this mission) combined this data with other sensor measurements, such as sea level, ocean color, temperature, winds, and rainfall, to create monthly maps of sea surface salinity. These maps allowed scientists to identify global salinity changes over time, which can help improve predictions of future climate trends and short-term events like El Niño and La Niña. 

Observing Ocean Circulation

The Aquarius mission observed ocean circulation by measuring sea surface salinity. Salty water is denser than freshwater, so it sinks. This sinking water creates currents that move around the ocean. By measuring salinity, Aquarius could track these currents and learn more about how the ocean circulates. 

For example, Aquarius data showed how the Amazon River affects the ocean. The Amazon River is the largest in the world, and it dumps a lot of fresh water into the ocean. Aquarius data showed that this freshwater makes the ocean less salty. This less salty water then flows along the coast of South America and into the Atlantic Ocean. This flow of fresh water affects the ocean currents and the weather in South America and Africa. 

If You Didn't Understand, here's a real-life example!🙂:

Imagine a bathtub full of water. If you add a spoonful of salt to one side of the tub, the salty water will sink to the bottom. This will create a current that moves the fresh water from the other side of the tub to fill the space. Aquarius measured salinity in the same way but on a much larger scale.

Aquarius Instrument: Radiometers

The Aquarius instrument had three radiometers that measured changes in the ocean's brightness in three radio wave beams. These radiometers' changes in brightness were related to changes in the ocean's salt content. The radiometers could detect salinity changes as small as 0.2 parts per thousand (PSU), around 1/8 of a teaspoon of salt in a gallon of water (That's so little! 😲)

Aquarius' Orbit And Data

The Aquarius spacecraft flew in a "terminator" orbit, allowing it to collect solar energy while observing the dark side of the planet (night in EartH!) with little interference from sunlight reflecting off the water.

The mission, running from 2011 to 2015, provided new information into the exchange of freshwater between the ocean, atmosphere, and sea ice, and its impacts on ocean circulation, weather, and climate. For example, it showed how extreme floods and low-salinity river plumes can affect the seas and hurricane intensity.

Conclusion

In conclusion, the Aquarius mission has achieved the knowledge that could have been collected over 125 years! 🌍 Thanks to the team effort of various countries, we now have a better understanding about our Earth's systems.