Incessant mountain rain, snow and melting glaciers in a comparatively small region of land that hugs the southern Alaska coast and empties fresh water into the Gulf of Alaska would create the sixth largest coastal river in the world if it emerged as a single stream, a recent study shows.
Since it's broken into literally thousands of small drainages pouring off mountains that rise quickly from sea level over a short distance, the totality of this runoff has received less attention, scientists say. But research that's more precise than ever before is making clear the magnitude and importance of the runoff, which can affect everything from marine life to global sea level.
The collective fresh water discharge of this region is more than four times greater than the mighty Yukon River of Alaska and Canada, and half again as much as the Mississippi River, which drains all or part of 31 states and a land mass more than six times as large.
"Freshwater runoff of this magnitude can influence marine biology, nearshore oceanographic studies of temperature and salinity, ocean currents, sea level and other issues," said David Hill, lead author of the research and an associate professor in the College of Engineering at Oregon State University.
"This is an area of considerable interest, with its many retreating glaciers," Hill added, "and with this data as a baseline we'll now be able to better monitor how it changes in the future."
The findings were reported in the Journal of Geophysical Research: Oceans, by Hill and Anthony Arendt at the University of Alaska-Fairbanks. It was supported by the North Pacific Research Board.
This is one of the first studies to accurately document the amount of water being contributed by melting glaciers, which add about 57 cubic kilometers of water a year to the estimated 792 cubic kilometers produced by annual precipitation in this region. The combination of glacial melt and precipitation produce an amount of water that's larger than many of the world's great rivers, such as the Ganges, Nile, Volga, Niger, Columbia, Danube or Yellow River.
"By combining satellite technology with on-the-ground hydraulic measurements and modeling, we're able to develop much more precise information over a wider area than ever before possible," Hill said.
The data were acquired as an average of precipitation, glacial melting and runoff over a six-year period, from 2003 to 2009. Knocked down in many places by steep mountains, the extraordinary precipitation that sets the stage for this runoff averages about 6 feet per year for the entire area, Hill said, and more than 30 feet in some areas.
The study does not predict future trends in runoff, Hill said. Global warming is expected in the future, but precipitation predictions are more variable. Glacial melt is also a variable. A warmer climate would at first be expected to speed the retreat of existing glaciers, but the amount of water produced at some point may decrease as the glaciers dwindle or disappear.
Additional precision in this study was provided by NASA's Gravity Recovery and Climate Experiment, or GRACE satellites, which can make detailed measurements of gravity and, as one result, estimate the mass of glaciers they are flying over. As the glacial mass decreases over time, the amount of melted water that was produced can be calculated.
The close agreement of land-based measurements also help confirm the accuracy of those made from space, a point that will be important for better global understanding of water stored in a high-altitude environment.
Some of the processes at work are vividly illustrated at Glacier Bay National Park, where some of the most rapidly retreating glaciers in the world are visited each year by hundreds of thousands of tourists, many on cruise ships.
David Hill | EurekAlert!
NASA sees the end of ex-Tropical Cyclone 02W
21.04.2017 | NASA/Goddard Space Flight Center
New research unlocks forests' potential in climate change mitigation
21.04.2017 | Clemson University
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...
Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.
A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
21.04.2017 | Physics and Astronomy
21.04.2017 | Health and Medicine
21.04.2017 | Physics and Astronomy