“We found there’s an increase in water vapor in the middle atmosphere in connection with dust storms. Water vapor is carried up with the same air mass rising with the dust,” said Dr. Nicholas Heavens, a researcher at Hampton University and the lead author of the study, published in the journal Nature Astronomy.

A link between the presence of water vapor in Mars’ middle atmosphere (30-60 miles, or 50-100 km, high) and escape of hydrogen from the top of the atmosphere has been detected by the NASA/ESA Hubble Space Telescope and ESA’s Mars Express orbiter, but mainly in years without the dramatic changes produced in a global dust storm.

NASA’s MAVEN mission arrived at Mars in 2014 to study the process of atmosphere escape.

“It would be great to have a global dust storm we could observe with all the assets now at Mars, and that could happen this year,” said co-author Dr. David Kass, a researcher at NASA’s Jet Propulsion Laboratory and deputy principal investigator for MRO’s Mars Climate Sounder instrument.

Rising air during a 2007 global dust storm on Mars lofted water vapor into the planet’s middle atmosphere, researchers learned from data derived from observations by the Mars Climate Sounder instrument on NASA’s Mars Reconnaissance Orbiter. Image credit: NASA / JPL-Caltech / Hampton University.

Rising air during a 2007 global dust storm on Mars lofted water vapor into the planet’s middle atmosphere, researchers learned from data derived from observations by the Mars Climate Sounder instrument on NASA’s Mars Reconnaissance Orbiter. Image credit: NASA / JPL-Caltech / Hampton University.

Decades of Mars observations document a pattern of multiple regional dust storms arising during the northern spring and summer.

In most Martian years, which are nearly twice as long as Earth years, all the regional storms dissipate and none swells into a global dust storm.

But such expansion happened in 1977, 1982, 1994, 2001 and 2007. The next Martian dust storm season is expected to begin this summer and last into early 2019.

MRO’s Mars Climate Sounder can scan the planet’s atmosphere to directly detect dust and ice particles and can indirectly sense water vapor concentrations from effects on temperature.

“The Mars Climate Sounder data show slight increases in middle-atmosphere water vapor during regional dust storms and reveal a sharp jump in the altitude reached by water vapor during the 2007 global dust storm,” the scientists said.

Using recently refined analysis methods for the 2007 data, they found an increase in water vapor by more than a hundred-fold in the middle atmosphere during that global storm.

Before MAVEN reached Mars, many researchers expected to see loss of hydrogen from the top of the atmosphere occurring at a rather steady rate, with variation tied to changes in the solar wind’s flow of charged particles from the Sun.

Data from MAVEN and Mars Express haven’t fit that pattern, instead showing a pattern that appears more related to Martian seasons than to solar activity.

“The dust storms’ hoisting of water vapor to higher altitudes is a likely key to the seasonal pattern in hydrogen escape from the top of the atmosphere,” the authors said.

“MAVEN observations during the stronger effects of a global dust storm could boost understanding of their possible link to the escape of gas from the atmosphere.”

Source: Sci-News