On September 20, after six months of darkness, the return of the sun at the South Pole signaled the arrival of spring in the Southern Hemisphere. For scientists at NOAA's South Pole Atmospheric Baseline Observatory (SPO), located at the Amundsen-Scott South Pole Research Station, that's a welcome sight.

Station Chief Krystian Kopka from NOAA's Global Monitoring Laboratory wintered over at the South Pole.

"It's hard to believe that after six months of darkness, the sun is finally back at the South Pole," said Kopka. "The horizon is starting to glow again and it feels like we are slowly waking up from a frozen dream. Not only has it been both a challenging and rewarding experience wintering at the Pole, but knowing that I will be back home soon adds a layer of bittersweet reflection."

Kopka's replacements will arrive at SPO in early November, and he'll head home shortly after. Until then, Kopka will have a critical role monitoring the seasonal Antarctic ozone hole, which starts forming in September when sunlight triggers chemical reactions in the atmosphere that deplete Earth's protective ozone layer.

NOAA's South Pole Observatory is located at the geographic South Pole on the Antarctic plateau at an elevation of 2,837 meters above sea level. The National Science Foundation provides the infrastructure for the Global Monitoring Laboratory's scientific operations, including the Atmospheric Research Observatory and the Balloon Inflation Facility.

The South Pole has some of the cleanest air in the world, which makes it an ideal location for NOAA scientists to take long-term climate measurements including greenhouse gases like carbon dioxide, monitor air quality and track the seasonal Antarctic ozone hole every September and October.