New study finds atmospheric rivers increase snowfall in West Antarctica

A new study was published today in the journal Geophysical Research Letters they used NASA’s ice-measured laser satellite to identify atmospheric river storms as a key driver for more snow in West Antarctica during the harsh winter of 2019.

These findings from scientists at the Scripps Institute of Marine Science at the University of California San Diego and colleagues will help develop a holistic understanding of the processes that drive change in Antarctica, and lead to better predict sea level rise. The study was funded by NASA, with additional support from the Rhodium Group Climate Impact Lab, a consortium of major research centers studying the risks of climate change.

Rivers of air are wonders that carry many valves in long, narrow “rivers” in the sky. They are known to be the main shower driver on the west coast of the United States, making up 25-50 percent of annual rainfall in major parts of the West. Further research on atmospheric rivers finds that they are severely affecting the west coasts of most continents, due to the evacuation of oceans and storms raising high levels of humidity. in the atmosphere.

NASA’s Ice, Cloud, and Earth Elevation Satellite-2 (ICESat-2), launched into orbit in September 2018, takes a close look at the height of ice and snow on the continent. frozen land. The satellite works by sending 10,000 laser pulses per second to the Earth’s surface which measures the height of ice sheets, glaciers, and more by measuring the time it takes for a handful of impacts. that to return to the satellite. Each light photon has a time tag, and these tags come with GPS location to pinpoint the exact location and altitude of the earth. It measures a detailed set of routes across the Antarctic ice sheet every three months.

“ICESat-2 is the first satellite to have the ability to measure snow over the Antarctic continent in such a precise manner,” said Helen Amanda Fricker, a geologist at Scripps Oceanography and co-author of the study. “In the winter, the weather forbids a field crew there to look at the ground. ICESat-2 fills this lack of data over the big ice sheets, and makes sense better for us the gain and great loss of snow on a seasonal scale. ”

Looking at ICESat-2 data, scientists found an increase in altitude over the Antarctic ice sheet between April 2019 and June 2020 due to more snow. Using a computerized model of the atmosphere and snow, they found that 41 percent of altitude occurred over West Antarctica in the winter of 2019 due to very high rainfall events delivering large amounts of snow during short periods of time. . Of those incidents, 63 percent were identified as falling rivers to atmospheric. These systems were distinguished from other storms by the much higher humidity levels measured in the lower parts of the atmosphere.

The atmospheric rivers that land in Antarctica come from the subtropical, central hemisphere of the Southern Hemisphere. They travel long distances to continents to stop them, eventually landing in West Antarctica.

“We know that the frequency of atmospheric rivers is expected to increase, so it is important for scientists to be able to quantify their contribution to a large increase in snowfall or surface melting, “said Susheel Adusumilli, lead author and PhD candidate at Scripps Oceanography. “Knowing the amount of snow accumulated across the continent helps us to better understand how mass changes overall, and inform our understanding of the potential for increased sea ​​level from the Antarctic ice sheet. ”

Over one hundred gigatons of ice is lost to the ocean from Antarctica each year, contributing to a continuing rise in sea level. Much of this ice loss is driven by increased ice flow into the ocean from the melting of the ice shelves floating around Antarctica. Understanding the balance of significant benefit from avalanches in the interior of Antarctica and major losses from marine warming is crucial in developing predictions of sea level rise.

While this study monitored short-term ice masses, atmospheric rivers in Antarctica can move large amounts of snow. In fact, this study found that about 90 percent of summer atmosphere rivers and 10 percent of winter atmosphere rivers coincided with possible surface melting over the Antarctic ice sheet in the West. West. River-driven atmospheric melting is caused by the low clouds from these systems, which are able to absorb heat and redistribute it back to the surface. Scientists need further study to understand whether these events are caused by snow or melting makers, looking at factors such as seasonality, humidity level, cloud cover, or if each is responsible for a storm.

“In the U.S., scientists study atmospheric rivers and see if they could be beneficial for water supply in California or dangerous, causing flooding,” said study co-author Meredith Fish, a postdoctoral associate at Rutgers University and alumna of Scripps Oceanography, where she is studying at the Center for Western Weather and Aquatic Extremes. “The interesting question in Antarctica is, are atmospheric rivers going to contribute to snow accumulation or snow accumulation?”

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