“I’ve never seen an October like this.”
That’s been the refrain for much of the first month of the summer field season at McMurdo Station by most people who have spent some time in the U.S. Antarctic Program.
There have been few pauses between a string of relentless storms that brought strong winds and snow to the Ross Island region since the first planes of summer arrived on Sept. 30. Most of the deep-field research funded and supported by the National Science Foundation takes place between October and February, much of it based out of McMurdo Station.
Twice during the month, flights from Christchurch, New Zealand, were delayed by at least a week, forcing round-the-clock flight operations at the end of October to help the station catch up on receiving cargo and passengers stranded in the South Island’s largest city. The weather also postponed work by some research teams that required transportation by helicopter to the nearby McMurdo Dry Valleys.
By Oct. 26, there had been 22 days with some form of precipitation and 19 days of blowing snow in the region.
The result: As of Oct. 22, about 40 percent of October had been designated by what officials call instrument flight rules (IFR) or below, meaning that conditions required pilots to navigate primarily by instrumentation. IFR goes into effect when cloud ceilings drop to less than 1,500 feet and/or with less than three miles of visibility.
For comparison, 40 percent is almost twice as many IFR days as were recorded for “bad months” in McMurdo’s recent history. The station had experienced about 24 percent IFR in November 2000 and October 2003, according to Art Cayette, Meteorology manager.
“If the storms keep piling up – at least in the short-term history – we can be looking at the worst October that we’ve ever had, probably the worst collective month we’ve ever had in dealing with weather here.”
The culprit: A stubborn high pressure system sitting off the Weddell Sea has been redirecting the continent’s normal storm path, like throwing a switch and sending a train down a different track.
“McMurdo is right in line with the storm track,” Cayette said. “We’re getting hit by many more storms than we would normally get.”
Storm systems generally rotate clockwise around the continent, with a low-pressure system occasionally peeling off the merry-go-round and heading inland. But the high-pressure system has forced the storm track toward the Ross Sea region where McMurdo Station is located.
The change in weather may have a relationship with the phenomenon known as the El Niño and Southern Oscillation, or ENSO for short. El Niño refers to an anomalous change in the sea-surface temperature off the equatorial west coast of South America that accompanies large-scale air pressure changes of the overlying atmosphere, called the Southern Oscillation.
Source:: Antarctic Sun Featured Articles