Nav: Home

New study explains Antarctica's coldest temperatures

June 25, 2018

Tiny valleys near the top of Antarctica's ice sheet reach temperatures of nearly -100 degrees Celsius, according to a new study published this week in the AGU journal Geophysical Research Letters. The finding could change scientists' understanding of just how low temperatures can get at Earth's surface, and how it happens, according to the researchers.

After sifting through data from several Earth-observing satellites, scientists announced in 2013 that they found surface temperatures of -93 degrees Celsius (-135 degrees Fahrenheit) in several spots on the East Antarctic Plateau, a high snowy plateau in central Antarctica that encompasses the South Pole. That preliminary study has been revised with new data showing that the coldest sites actually reach -98 degrees Celsius (-144 degrees Fahrenheit). The temperatures are observed during the southern polar night, mostly during July and August.

When the researchers first announced they had found the coldest temperatures on Earth five years ago, they determined that persistent clear skies and light winds are required for temperatures to dip this low. But the new study adds a twist to the story: Not only are clear skies necessary, but the air must also be extremely dry, because water vapor blocks the loss of heat from the snow surface.

The researchers observed the ultra-low temperatures in small dips or shallow hollows in the Antarctic Ice Sheet where cold, dense, descending air pools above the surface and can remain for several days. This allows the surface, and the air above it, to cool still further, until the clear, calm, and dry conditions break down and the air mixes with warmer air higher in the atmosphere.

"In this area, we see periods of incredibly dry air, and this allows the heat from the snow surface to radiate into space more easily," said Ted Scambos, a senior research scientist at the National Snow and Ice Data Center at the University of Colorado Boulder and the study's lead author.

The record of -98 degrees Celsius is about as cold as it is possible to get at Earth's surface, according to the researchers. For the temperature to drop that low, clear skies and dry air need to persist for several days. Temperatures could drop a little lower if the conditions lasted for several weeks, but that's extremely unlikely to happen, Scambos said.

Finding the coldest place

The high elevation of the East Antarctic Plateau and its proximity to the South Pole give it the coldest climate of any region on Earth. The lowest air temperature ever measured by a weather station, -89 degrees Celsius (-128 degrees Fahrenheit), was recorded there at Russia's Vostok Station in July 1983.

But weather stations can't measure temperatures everywhere. So in 2013, Scambos and his colleagues decided to analyze data from several Earth-observing satellites to see if they could find temperatures on the plateau even lower than those recorded at Vostok.

In the new study, they analyzed satellite data collected during the Southern Hemisphere's winter between 2004 and 2016. They used data from the MODIS instrument aboard NASA's Terra and Aqua satellites as well as data from instruments on NOAA's Polar Operational Environmental Satellites.

The researchers observed snow surface temperatures regularly dropping below -90 degrees Celsius (-130 degrees Fahrenheit) almost every winter in a broad region of the plateau, more than 3,500 meters (11,000 feet) above sea level. Within this broad region, they found dozens of sites had much colder temperatures. Nearly 100 locations reached surface temperatures of -98 degrees Celsius.

The atmosphere in this region can sometimes have less than 0.2 mm total precipitable water above the surface. But even when it is that dry and cold, the air traps some of the heat and sends it back to the surface. This means that the cooling rates are very slow as the surface temperatures approach the record values. Conditions do not persist long enough--it could take weeks--for the temperatures to dip below the observed records. However, the temperature measured from satellites is the temperature of the snow surface, not the air above it. So the study also estimated the air temperatures by using nearby automatic weather stations and the satellite data.

Interestingly, even though the coldest sites were spread out over hundreds of kilometers, the lowest temperatures were all nearly the same. That got them wondering: Is there a limit to how cold it can get on the plateau?

How cold is it really?

Using the difference between the satellite measurements of the lowest surface snow temperatures at Vostok and three automated stations, and the air temperatures at the same place and time, the researchers inferred that the air temperatures at the very coldest sites (where no stations exist) are probably around -94 degrees Celsius, or about -137 degrees Fahrenheit.

The research team has also developed a set of instruments designed to survive and operate at the very coldest places through the winter and measure both snow and air temperatures. They are planning to deploy the instruments in the next year or two, during the Antarctic summer when the temperatures are a comparatively mild -30 degrees Celsius (-22 degrees Fahrenheit).
-end-


University of Colorado at Boulder

Related Satellites Articles:

Spotting air pollution with satellites, better than ever before
Researchers from Duke University have devised a method for estimating the air quality over a small patch of land using nothing but satellite imagery and weather conditions.
New patented invention stabilizes, rotates satellites
Many satellites are in space to take photos. But a vibrating satellite, like a camera in shaky hands, can't get a sharp image.
Satellite broken? Smart satellites to the rescue
The University of Cincinnati is developing robotic networks that can work independently but collaboratively on a common task.
Combining satellites, radar provides path for better forecasts
Every minute counts when it comes to predicting severe weather.
Satellites are key to monitoring ocean carbon
Satellites now play a key role in monitoring carbon levels in the oceans, but we are only just beginning to understand their full potential.
New safer, inexpensive way to propel small satellites
A team at Purdue University has developed a new safer and inexpensive way to propel small satellites.
New developments with Chinese satellites over the past decade
To date, 17 Chinese self-developed FengYun (FY) meteorological satellites have been launched, which are widely applied in weather analysis, numerical weather forecasting and climate prediction, as well as environment and disaster monitoring.
First detection of rain over the ocean by navigation satellites
In order to analyse climate change or provide information about natural hazards, it is important to gather knowledge about the rain.
Earth's dust cloud satellites confirmed
A team of Hungarian astronomers and physicists may have confirmed two elusive clouds of dust, in semi-stable points just 400,000 kilometres from Earth.
Virtual contact lenses for radar satellites
Radar satellites supply the data used to map sea level and ocean currents.
More Satellites News and Satellites Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.