News Excerpt:

The Southern Ocean is renowned for having the cleanest air on Earth. But the precise reasons why have remained a mystery, until now.

About Southern Ocean:

• The Southern Ocean (also known as the Antarctic Ocean) is one of the five great ocean basins on Earth.
•  It was formed around 34 million years ago when Antarctica and South America drifted apart, creating the Drake Passage.
•  This makes it the youngest ocean basin on Earth. 

• Today, it is the only ocean that flows around the globe uninterrupted by land, encircling Antarctica like a moat.
• Around the northern limit of the Southern Ocean there is a natural, biological boundary called the Antarctic Convergence, or Polar Front. 
• North of the convergence, the water temperature near the surface sits at around 42.1°F (5.6 °C), ideal for marine species adapted to the subantarctic climate.
• South of the convergence, the water temperature drops dramatically to below 36 °F (2 °C), creating the perfect conditions for uniquely Antarctic wildlife to flourish.

• As the primary mixing zone between the world’s major oceans, the Southern Ocean plays an important role in the circulation of water around the globe. 
• It also plays a key role in regulating the earth’s climate through its currents, seasonal sea ice and by absorbing heat and carbon dioxide from the atmosphere.

• The Southern Ocean is known for its strong winds, intense storms, dramatic seasonal changes and cold temperatures. 
• Each of these factors plays a role in the many important processes that occur in this part of the ocean, and help regulate the global climate.

• The Southern Ocean is dominated by the Antarctic Circumpolar Current (ACC): the longest, strongest, deepest-reaching current on earth. 
• The ACC circulates clockwise around the continent, carrying more water around the globe than any other current.

• Powerful currents, cold temperatures and nutrient and oxygen-rich waters make the Southern Ocean one of the most productive marine ecosystems on Earth. 
• In summer billions of microscopic algae (phytoplankton) proliferate, spreading into blooms large enough to be seen from space.

What are the factors contributing to the clean air over the Southern Ocean?

• The region experiences minimal human activity compared to other parts of the world, resulting in fewer industrial emissions and less burning of fossil fuels.
• Aerosol levels are influenced by seasonal variations, such as the amount of salt spray and the growth of phytoplankton, which are a source of airborne sulfate particles. 
• The Southern Ocean experiences fewer sulfates during winter, contributing to pristine air conditions.

• Distinctive honeycomb-shaped cloud patterns(Open and closed Honeycomb cells) in the region influence the amount and distribution of rainfall. 
• Clouds and rain play a crucial role in scrubbing the atmosphere clean. 
• Research indicates that open honeycomb-shaped clouds, which are prevalent in the Southern Ocean, 
• It generates intense rain showers that effectively wash aerosol particles out of the air. 
• Rain scrubs the aerosols out of the sky in much the same way as a washing machine acts to clean clothes.
• Moreover, the study revealed that these open honeycomb clouds are more prevalent during the winter months, coinciding with the period when the Southern Ocean's air is at its cleanest.
• Large-scale weather systems, including storms, control the pattern of the cloud field over the Southern Ocean. 
• These weather systems produce open and closed honeycomb cells, which further affect rainfall and aerosol levels.