NASA orbiters discover ‘seasons’ of dust storms

When it comes to putting people on Mars, timing can’t be taken for granted. Now, thanks to nearly two decades of work, NASA’s Red Planet orbiters have determined three distinct annual patterns for dust storms that bring about great weather shifts.

At about the same time each Martian year, or approximately every two Earthling years, dust storms cover large areas of Mars. After observing the temperature records of six recent Martian years, it has become easier to predict the formation of those dust storms than when they were merely observed in images.

"When we look at the temperature structure instead of the visible dust, we finally see some regularity in the large dust storms," said David Kass of NASA’s Jet Propulsion Laboratory in the US. "Recognizing a pattern in the occurrence of regional dust storms is a step toward understanding the fundamental atmospheric properties controlling them."

Temperature records from six recent Martian years show pattern of three types of large regional dust storms occurring in sequence at about the same times each year during the southern hemisphere spring and summer.

A dustier atmosphere means warmer weather, sometimes a lot warmer. As the sun heats up the dust, it can raise temperatures by up to 95 degrees Fahrenheit (35 degrees Celsius). Wind also plays a role, heating regions outside the dust storms as well, meaning that the planet’s temperature records reveal both the direct and indirect impacts of the weather cycles.

The information collected was based on temperatures registered 15 ½ miles (25 kilometers) above ground and noted regional, and not just local, changes. The dust storms can last just a few days, covering about 1,242 miles (2,000 kilometers), or last three weeks and cover much greater swaths of Martian land.

Three regional storms, A, B and C, all took place in each of the six Martian years studied.

Just as the Earth’s Arctic storms pick up in cold seasons, so do storms at Mars’ North Pole ahead of that region’s fall season, researchers found in the study published in the Geophysical Research Letters journal.