KESHAV P. KOIRALA

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KATHMANDU: NASA’s Sea Level Change team, which includes a Nepali-born scientist, has developed a new modeling method that links glaciers and global sea level.

The new method — developed by three-member team led by Surendra Adhikari — allows researchers to weave high-resolution models of changes in individual glaciers into global models of relative sea level and solid Earth deformation, with great numerical accuracy and computational efficiency, NASA said.

“And because changes in ice mass leave their marks on Earth’s gravitational and rotational fields—phenomena that generate so-called “sea level fingerprints”—the new model offers the possibility of precise, localized sea level forecasts,” NASA said.

Adhikari is the lead author of the paper announcing the discovery that was published in the journal Geoscientific Model Development last month.

Two other coauthors of the paper are senior research scientist Erik R. Ivins and Eric Larour, who is the leader of Ice Sheet System Model (ISSM) project. ISSM is a state of the art ice flow modeling software developed at JPL in collaboration with University of California Irvine.

One of the most fascinating and counter-intuitive features of these fingerprints is that sea level drops in the vicinity of a melting glacier, instead of rising as might be expected, according to a NASA release. The loss of ice mass reduces its gravitational attraction, and ocean water, no longer under its influence, migrates away, it adds, “But far from the glacier, the water it has added to the ocean causes sea level to rise at a much greater rate.”

NASA expects that the loss of mass from a particular Antarctic outlet glacier, for example, could be tied directly to a sea level record at any tide gauge station around the globe with the use of new method.

“At Miami, in principle, we can isolate what fraction of observed sea level is due to what specific source—Jakobshavn Isbrae in Greenland, Pine Island Glacier in the West Antarctica, tidewater glaciers in Alaska, maybe others,” Adhikari said. “(Another) application is that we can calculate sea level not only related to ice but also related to continental hydrology”—that is, the shifting of water mass on land through the action of storms, rivers, or even groundwater pumping.

The research team used an “unstructured mesh,” a way of dividing up Earth’s surface into manageable chunks that can be recombined by calculations to simulate changes—melting Antarctic glaciers, perhaps, or giant rainstorms that deposit large masses of water in South America, NASA informed.

Who is Surendra Adhikari

Adhikari is a NASA Postdoctoral Fellow at California Institute of Technology. He is affiliated with NASA’s Jet Propulsion Laboratory since 2014.

After doing BE in Agricultural Engineerin g from Tribhuvan University in Nepal in 2004, Adhikari went to Belgium where he did MSc in Engineering Geology from Free University of Brussels in 2007.

He did his PhD in Geography from University of Calgary in Canada in 2012.

He is involved in research related to ice, sea level, solid earth, and space geodesy.

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