Image of the Week — Greenland ice sheet and clouds

The effects of clouds on the Surface Mass Balance (SMB) of the Greenland ice sheet during the period September 2007–September 2010. (Credit: Van Tricht et al, 2016)

A new study combining satellite observations and model simulations shows that clouds increase meltwater runoff in Greenland by one-third compared to a cloud-free scenario.

Precipitation effects not considered, clouds above the Greenland ice sheet reduce its Surface Mass Balance (SMB) [red in figure] compared to clear-sky conditions [blue in figure]. Because clouds trap the outgoing radiation from the ice-sheet surface, they locally warm the atmosphere below, which reduces Greenland’s meltwater refreezing at night. Hence, clouds increase runoff from the ice sheet by 56 billion tons of water each year.

Reference/further reading:

• Van Tricht, K., S. Lhermitte, J. T. M. Lenaerts, I. V. Gorodetskaya, T. S. L’Ecuyer, B. Noël, M. R. van den Broeke, D. D. Turner, and N. P. M. van Lipzig. 2016. “Clouds Enhance Greenland Ice Sheet Meltwater Runoff.” Nature Communications 7 (January). Nature Publishing Group: 10266. doi:10.1038/ncomms10266.
• Article in the Washington Post about the paper.
• You can follow Kristof Van Tricht the study’s lead author on twitter @kristofvt.