Putting the Blizzard of 2015 into Historical Context

                    January-25-28-2015-Snowfall-Totals-Map Credit: NOAA

The recent “Blizzard of 2015” shutdown several major metropolitan areas in the Northeast and left several locations across Connecticut, Maine, Massachusetts, New Hampshire, and New York covered in over two feet of snow. But, how did this snowstorm compare to the region’s most historic storms? To place this storm and its societal impacts into historical context, NCDC used the Regional Snowfall Index or RSI to rank it on a scale from 1 to 5—similar to the Fujita scale for tornadoes or the Saffir-Simpson scale for hurricanes. These ranks are based on the snowfall amount within the region’s borders, the spatial extent of the storm, and the relationship of these elements to the area’s population.

The RSI value for January 25­–28, 2015, snowstorm is 6.16, which makes it a Category 3 or major event for the Northeast. With that RSI value, the snowstorm ranks 26th out of the 423 northeastern snowstorms NCDC has analyzed since 1900. The area of snowfall and population affected by 20 inches of snow or more were the primary drivers for this storm’s raw RSI score. Almost 5 million people experienced over 20 inches of snow and 15 million experienced over 10 inches of new snow. While these are significant impacts, the footprint of the heavy snow was relatively small compared to RSI Category 5 storms. These rare events typically have over 45 million people experiencing over 10 inches of snow. Nonetheless, this storm is well within the top 10% of storms analyzed for the Northeast.

The late February snowstorm of 1969 remains the strongest storm to hit the Northeast, with an RSI value of 34.03 making it a Category 5 or extreme event. The March 1993 “Storm of the Century” remains the second strongest snowstorm to hit the Northeast, with an RSI value of 22.12 also making it a Category 5 event.

Learn more about the Regional Snowfall Index and use our interactive mapping tool to see RSI rankings for almost 600 snowstorms since 1900.

Source: NOAA

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The tsunami-early warning system for the indian ocean: Ten years after

Technical concept of GITEWS.

The day after Christmas this year will mark the 10 anniversary of the tsunami disaster in the Indian Ocean. On 26 December 2004, a quarter of a million people lost their lives, five million required immediate aid and 1.8 million citizens were rendered homeless. The natural disaster, which caused extreme devastation over huge areas and the accompanying grief and anxiety, especially in Indonesia, Thailand and Sri Lanka exceeded the imaginable and reached such drastic dimensions, mainly due to the lack of a warning facility and a disaster management plan for the entire Indian Ocean region at this time.

Germany and the international community of states reacted with immediate support. Within the framework of the German Flood Victim Aid the Federal Government commissioned the Helmholtz Association of German Research Centres under the direction of the GFZ German Research Centre for Geosciences with the development of an Early Warning System for the Indian Ocean. From 2005 to 2011, with the large-scale project GITEWS (German-Indonesian Tsunami Early Warning System), the core of an integrated, modern, and effective Tsunami Early Warning System in Indonesia was established. With the follow-up project PROTECTS (Project for Training, Education and Consulting for Tsunami Early Warning Systems, 2011-2014) the personnel of the participating Indonesian institutions were trained to proceed independently and to take over responsibility for the operation of the Early Warning System as well as for the diverse technical and organizational components. In this ways PROTECTS which started in June 2011 and comprised a total of 192 training courses, internships, and hands-on-practice courses, covering all aspects of operation and maintenance of the Tsunami-Early Warning System contributed significantly to the sustainability of InaTEWS.

Under the auspices of the IntergovernmentalOceanographicCommission of UNESCO and with the collaboration of international partner institutes from Germany, the USA, China and Japan, GITEWS was integrated into a Tsunami Early Warning System for Indonesia. GITEWS was positively reviewed by a commission of international experts in 2010 and handed over to Indonesia in March 2011. Since then it has been providing its services under the name InaTEWS -- Indonesian Tsunami Early Warning System and is operated by the Indonesian Service for Meteorology, Climatology and Geophysics BMKG.

On 12 October 2011 the exercise drill "IOWAVE11" was carried out in the Indian Ocean. With this drill, InaTEWS successfully demonstrated that it could, furthermore, take over the role of a Regional Tsunami Service Provider (RTSP). Since then Indonesia, in addition to Australia und India, performs the double function as a National Tsunami Warning Center (NTWC) and also as a RTSP and takes over the responsibility for the timely warning of 28 states around the Indian Ocean in the event of a threatening Tsunami. With the on-going step-by-step development, a comprehensive all-encompassing InaTEWS could be successfully realized.

Indonesia now avails of one of the most modern Tsunami Early Warning Systems. On the basis of data from approx. 300 measuring stations a warning can be issued at a maximum of five minutes after an earthquake. These measuring stations include e.g. seismometers, GPS stations und coastal tide gauges. With the data gained from the sensors and using the most modern evaluation systems such as SeisComP3 which was developed by GFZ scientists for the analyses of earthquake data and a Tsunami simulation system in the Warning Centre it is possible to compile a comprehensive picture of the situation. With the aid of a decision support system respectively classified warnings for the affected coastal areas can then be issued. A total of 70 people are involved the operation of the Warning Centre in Jakarta, with 30 employees working solely in a full shift system. According to information provided by the BMKG a total of 1700 earthquakes with a magnitude of more than M= 5 and 11 quakes with a magnitude of 7 and higher have been evaluated and six Tsunami Warnings have been issued to the public by the Earthquake Monitoring and Tsunami Early Warning Centre since the hand over in March 2011.

Schooling, training and disaster precautions (capacity development) for the local community and Town and District councils have received special emphasis. This Capacity Development has been carried out since 2006 in three "typical" regions: Padang (Sumatra), Chilacap (South-Java) and Denpassar (Bali, tourist stronghold). Here particular emphasis was placed on understanding both the warnings issued and the planned evacuation measures.

Local disaster management structures are established with local decision-makers and Disaster Risk Reduction Strategies are developed. Specifically, the education of trainers who are, in turn, responsible for the further spreading of the developed concepts plays a significant role.

Another key element is the determination of hazard and risk maps as a basis for the local evacuation planning as well as for future town and land-use planning. In Bali communication with the hotel industry was an additional factor.

No Early Warning System will ever be able to prevent a strong earthquake and a resulting tsunami and also, in the future, there will be loss of life and material damage. However, through the existence of an Early Warning System and the integration of organizational measures together with comprehensive capacity building the adverse effects of such a natural disaster can certainly be reduced.

Source: Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

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Wild weather in the Arctic causes problems for people and wildlife

Svalbard's reindeer population can be severely affected by winter icing.
Credit: Brage Bremset Hansen

The residents of Longyearbyen, the largest town on the Norwegian Arctic island archipelago of Svalbard, remember it as the week that the weather gods caused trouble. Temperatures were ridiculously warm -- and reached a maximum of nearly +8 degrees C in one location at a time when mean temperatures are normally -15 degrees C. It rained in record amounts.

Snow packs became so saturated that slushy snow avalanches from the mountains surrounding Longyearbyen covered roads and took out a major pedestrian bridge. Snowy streets and the tundra were transformed into icy, rain-covered skating rinks that were difficult to navigate with snowmobiles. Flights were cancelled, the airport closed, and travel around town was tricky.

The situation was particularly problematic out on the Arctic tundra. Rain falling on snow can percolate to the base of a snowpack where it can pool at the soil surface and subsequently freeze. That makes it impossible for grazing reindeer to get at their food, for example, and extreme warm spells can even affect temperatures in the permanently frozen ground found throughout the archipelago.

But the extreme event also offered an interdisciplinary group of scientists, from climatologists to biologists to snow geophysicists and structural engineers, a chance to document the event and learn from it. Their cross-disciplinary report, "Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic," was published on 20 November in Environmental Research Letters.

"We had a unique opportunity to document what happened, and we did," said Brage Bremset Hansen, the first author on the paper, and co-author Øystein Varpe. "This was a case study from one event…but since it was an extreme event, and with all of our contacts in the different disciplines, we were able to compile this information into one story, which is quite rare."

Hansen is a biologist at the Norwegian University of Science and Technology's Centre for Biodiversity Dynamics, and Varpe is an associate professor at the University Centre in Svalbard.

Just a 0.2 percent chance of happening

Co-author Ketil Isaksen, a climatologist from the Norwegian Meteorological Institute, said that such an extreme event has a 500-year return period, which means that the probability of it happening in any one year is just 0.2 percent.

At the same time, climatologists say that Svalbard has seen the greatest increase in temperatures of any place in Europe over the last three decades.

And while no one can attribute the event directly to global warming, virtually all climate studies show that the High Arctic, including Svalbard, will become increasingly warmer and wetter over time.

"We expect this to be more likely to happen," Isaksen said.

Reindeer mortality up

As a biologist, Hansen was very interested in how the extreme weather would affect the archipelago's natural communities. Only four vertebrate species overwinter on Svalbard -- the wild Svalbard reindeer (Rangifer tarandus platyrhynchus), the Svalbard rock ptarmigan (Lagopus muta hyperborea), and the sibling vole (Microtus levis), and one animal that eats them all, the Arctic fox (Vulpes lagopus).

When Hansen and his colleagues compared summer population counts of reindeer after the January 2012 event to counts conducted for the previous summer, they found that the number of reindeer carcasses in many populations was among the highest ever recorded.
But it could have been worse, he said, in part because recent increases in summer temperatures have made for better foraging conditions for Svalbard reindeer overall.

"It wasn't like there were dead reindeer all over the tundra," he said. "If this had happened in the colder 1980s, it could have been much worse. …They had a nice winter up to this event, which occurred rather late."

Rain and permafrost

Hansen and colleagues have previously published research on the overwintering animal community on Svalbard, suggesting that such extreme events can affect all species. But what makes the new findings unique is the collaboration between different disciplines that enabled researchers to assemble a picture of what happened to Svalbard's physical environment, and to people living in the outposts of Longyearbyen and Ny-Ålesund, a tiny community with a winter population of about 30 people.

In Ny-Ålesund, for example, it rained nearly 100 mm in one day -- which would be more typical of the Norwegian coastal town of Bergen, renowned for its heavy rains. That one-day amount represented a quarter of the precipitation that Ny-Ålesund typically gets in a year.

Isaksen documented a significant increase in ground temperatures in permafrost as deep as 5 metres below the surface as a result of the extreme warming. This temperature increase came on top of a decades-long larger trend of warming of the permafrost on Svalbard, the researchers said. Permafrost is permanently frozen ground that is found throughout the archipelago and the High Arctic. In regions in the Northern Hemisphere where permafrost is found, it occupies approximately 25% (23 million km²) of the land area.

Tourism and infrastructure

And for Svalbard residents, who are some of the most northerly inhabitants on the globe, there were significant socioeconomic effects. During and after the event, it was difficult for snowmobiles to travel out on the tundra on the thick layer of ice, Varpe said.

This thick layer, averaging 15.3 cm, persisted out on the tundra well after the event was over, said Jack Kohler, senior research scientist, glaciology, at the Norwegian Polar Institute.
"The winter rain event leads to the ground-ice formation, and the ice lasts the remainder of the melt season, until it melts, and that is what I would call the significant happening," Kohler said. "The rain is an event, for sure, but the ice is actually the (big) event."

The result was a strong decrease in tourism for the rest of the winter, specifically for activities such as guided snowmobile and dogsled tours. Tour numbers dropped by 28 percent compared to the previous winter, and were the lowest ever since 2001, which is when statistics were first continuously kept. The researchers also believe that had a ripple effect on hotel stays and other tourist activities.

Another potential problem exposed by the extreme event was the vulnerability of the town's infrastructure to avalanches. A major avalanche in June 1953 destroyed the town's hospital and other buildings, killing three people, but since then, many buildings have been constructed without regard to potential avalanche risks. If Svalbard's climate continues to warm as our downscaled climate scenarios predict, the likelihood of damaging avalanches will only increase, Hansen and colleagues say.

Hansen is continuing to investigate the consequences of a warmer Arctic on Svalbard's natural communities and human population with a research project called VINTERREGN (Winter rain). Of particular interest is whether or not plants, which usually do not grow taller than a couple of inches at this latitude, can withstand being completely covered in ice for several months.

Source:  The Norwegian University of Science and Technology (NTNU)

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Arctic conditions may become critical for polar bears by end of 21st century

This is a photo of an Arctic polar bear. Shifts in the timing and duration of ice cover, especially the possible lengthening of ice-free periods, may impact polar bears under projected warming before the end of the 21st century, according to a study published Nov. 26, 2014 in the open-access journal PLOS ONE by Stephen Hamilton from University of Alberta and colleagues. Credit: Andrew Derocher; CC-BY

Shifts in the timing and duration of ice cover, especially the possible lengthening of ice-free periods, may impact polar bears under projected warming before the end of the 21st century, according to a study published November 26, 2014 in the open-access journal PLOS ONE by Stephen Hamilton from University of Alberta and colleagues.

Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems, and polar bears are vulnerable to these changes in sea ice conditions. The authors of this study used sea ice projections for the Canadian Arctic Archipelago from 2006-2100 and metrics developed from polar bear energetics modeling to gain insight into the conservation challenges for polar bears facing habitat loss.

Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100. "We predict that nearly one-tenth of the world's polar bear habitat, as much as one-quarter of their global population, may undergo significant habitat loss under business-as-usual climate projections," said Stephen Hamilton.

Source: PLOS

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Improving forecasts for rain-on-snow flooding

Flooding in January 2009 closed a section of Interstate 5 south of Seattle.Washington State Dept. of Transportation Credit: Image courtesy of University of Washington

Many of the worst West Coast winter floods pack a double punch. Heavy rains and melting snow wash down the mountains together to breach riverbanks, wash out roads and flood buildings.

These events are unpredictable and difficult to forecast. Yet they will become more common as the planet warms and more winter precipitation falls as rain rather than snow.

University of Washington mountain hydrology experts are using the physics behind these events to better predict the risks.

"One of the main misconceptions is that either the rain falls and washes the snow away, or that heat from the rain is melting the snow," said Nicholas Wayand, a UW doctoral student in civil and environmental engineering. He will present his research Dec. 18 at the annual meeting of the American Geophysical Union.

Most of the largest floods on record in the western U.S. are associated with rain falling on snow. But it's not that the rain is melting or washing away the snow.

Instead, it's the warm, humid air surrounding the drops that is most to blame for the melting, Wayand said. Moisture in the air condenses on the cold snow just like water droplets form on a cold drink can. The energy released when the humid air condenses is absorbed by the snow. The other main reason is that rainstorms bring warmer air, and this air blows across the snow to melt its surface. His work support previous research showing that these processes provide 60 to 90 percent of the energy for melting.

Places that experience rain-on-snow flooding are cities on rivers that begin in the mountains, such as Sacramento, California, and Centralia, Washington. In the 1997 New Year's Day flood in Northern California, melting snow exacerbated flooding, which broke levees and caused millions of dollars in damage. The biggest recent rain-on-snow event in Washington was the 2009 flood in the Snoqualmie basin. And the Calgary flood in summer of 2013 included snow from the Canadian Rockies that caused rivers to overflow their banks.
The UW researchers developed a model by recreating the 10 worst rain-on-snow flooding events between 1980 and 2008 in three regions: the Snoqualmie basin in Washington state, the upper San Joaquin basin in central California and the East North Fork of the Feather River basin in southern California.

Their results allow them to gauge the risks for any basin and any incoming storm. The three factors that matter most, they found, are the shape of the basin, the elevation of the rain-to-snow transition before and during the storm, and the amount of tree cover. Basins most vulnerable to snowmelt are treeless basins with a lot of area within the rain-snow transition zone, where the precipitation can fall as snow and then rain.

Trees reduce the risk of flooding because they slow the storm's winds.

"If you've ever been in a forest on a windy day, it's a lot calmer," Wayand said. That slows the energy transferred from condensation and from contact with warm air to the snowpack.
Simulations also show that meltwater accounted for up to about a quarter of the total flooding. That supports earlier research showing that snow is not the main contributor to rain-on-snow floods, but cannot be neglected since it adds water to an already heavy winter rainstorm.

The complexity of mountain weather also plays a role.

"The increase in precipitation with elevation is much greater than usual for some of these storms," said Jessica Lundquist, a UW associate professor of civil and environmental engineering. "Higher flows can result from heavier rainfall rates at higher elevations, rather than from snowmelt."

In related work, Lundquist's group has developed a tennis-ball snow sensor and is measuring growth and melt of the snowpack in the foothills east of Seattle. The scientists aim to better understand how changes in climate and forestry practices might affect municipal water supplies and flood risks.

Wayand and another student in the group have developed a high school curriculum for Seattle teachers to explain rain-on-snow events and the physics behind why they occur. They hope to begin teaching the curriculum sometime next year.

The other collaborator on the work being presented in San Francisco is Martyn Clark at the National Center for Atmospheric Research in Colorado.

Source: University of Washington

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Massive study provides first detailed look at how Greenland's ice is vanishing

This NASA visualization shows the change in the surface elevation of the southeast region of the Greenland ice sheet between 2003 and 2012. Thinning ... [show more]
 Credit: NASA's Goddard Space Flight Center Scientific Visualization Studio

The Greenland Ice Sheet is the second-largest body of ice on Earth. It covers an area about five times the size of New York State and Kansas combined, and if it melts completely, oceans could rise by 20 feet. Coastal communities from Florida to Bangladesh would suffer extensive damage.

Now, a new study is revealing just how little we understand this northern behemoth.

Led by geophysicist Beata Csatho, PhD, an associate professor of geology at the University at Buffalo, the research provides what the authors think is the first comprehensive picture of how Greenland's ice is vanishing. It suggests that current ice sheet modeling studies are too simplistic to accurately predict the future contributions of the entire Greenland Ice Sheet to sea level rise, and that Greenland may lose ice more rapidly in the near future than previously thought.

"The great importance of our data is that for the first time, we have a comprehensive picture of how all of Greenland's glaciers have changed over the past decade," Csatho says.

"This information is crucial for developing and validating numerical models that predict how the ice sheet may change and contribute to global sea level over the next few hundred years," says Cornelis J. van der Veen, PhD, professor in the Department of Geography at the University of Kansas, who played a key role in interpreting glaciological changes.

The project was a massive undertaking, using satellite and aerial data from NASA's ICESat spacecraft and Operation IceBridge field campaign to reconstruct how the height of the Greenland Ice Sheet changed at nearly 100,000 locations from 1993 to 2012.

Ice loss takes place in a complex manner, with the ice sheet both melting and calving ice into the ocean.

The study had two major findings:

• First, the scientists were able to provide new estimates of annual ice loss at high spatial resolution.

• Second, the research revealed that current models fail to accurately capture how the entire Greenland Ice Sheet is changing and contributing to rising oceans.

The second point is crucial to climate change modelers.

Today's simulations use the activity of four well-studied glaciers -- Jakobshavn, Helheim, Kangerlussuaq and Petermann -- to forecast how the entire ice sheet will dump ice into the oceans.

But the new research shows that activity at these four locations may not be representative of what is happening with glaciers across the ice sheet. In fact, glaciers undergo patterns of thinning and thickening that current climate change simulations fail to address, Csatho says.

"There are 242 outlet glaciers wider than 1.5 km on the Greenland Ice Sheet, and what we see is that their behavior is complex in space and time," Csatho says. "The local climate and geological conditions, the local hydrology -- all of these factors have an effect. The current models do not address this complexity."

The team identified areas of rapid shrinkage in southeast Greenland that today's models don't acknowledge. This leads Csatho to believe that the ice sheet could lose ice faster in the future than today's simulations would suggest.

The results will be published on Dec. 15 in the Proceedings of the National Academy of Sciences.

How much ice is the Greenland Ice Sheet losing?

To analyze how the height of the ice sheet was changing, Csatho and UB research professor and photogrammetrist Anton Schenk, PhD, developed a computational technique called Surface Elevation Reconstruction And Change detection to fuse together data from NASA satellite and aerial missions.

The analysis found that the Greenland Ice Sheet lost about 243 metric gigatons of ice annually -- equivalent to about 277 cubic kilometers of ice per year -- from 2003-09, the period for which the team had the most comprehensive data. This loss is estimated to have added about 0.68 millimeters of water to the oceans annually.

The figures are averages, and ice loss varied from year to year, and from region to region.

Why are today's projections of sea level rise flawed, and how can we fix them?

Glaciers don't just gradually lose mass when the temperature rises. That's one reason it's difficult to predict their response to global warming.

In the study, scientists found that some of Greenland's glaciers thickened even when the temperature rose. Others exhibited accelerated thinning. Some displayed both thinning and thickening, with sudden reversals.

As a step toward building better models of sea level rise, the research team divided Greenland's 242 glaciers into 7 major groups based on their behavior from 2003-09.

"Understanding the groupings will help us pick out examples of glaciers that are representative of the whole," Csatho says. "We can then use data from these representative glaciers in models to provide a more complete picture of what is happening."

In a new project, she and colleagues are investigating why different glaciers respond differently to warming. Factors could include the temperature of the surrounding ocean; the level of friction between a glacier and the bedrock below; the amount of water under a glacier; and the geometry of the fjord.

"The physics of these processes are not well understood," Csatho says.

The NASA missions: A colossal undertaking

The study combined data from various NASA missions, including:

• NASA's Ice, Cloud and Land Elevation Satellite (ICESat), which measured the ice sheet's elevation multiple times a year at each of the nearly 100,000 locations from 2003-09.

• NASA's, massive aerial survey that employs highly specialized research aircrafts to collect data at less frequent intervals than ICESat. These missions began measuring the Greenland Ice Sheet's elevation in 1993. Operation IceBridge was started in 2009 to bridge the time between ICESat-1 and ICESat-2, and will continue until at least 2017, when NASA's next generation ICESat-2 satellite is expected to come online.

Csatho says the new study shows why careful monitoring is critical: Given the complex nature of glacier behavior, good data is crucial to building better models.

Collaborators

Besides Csatho, Schenk and van der Veen, the project included additional researchers from the University at Buffalo, Utrecht University in The Netherlands, the Technical University of Denmark and Florida Atlantic University.

Source:  University at Buffalo

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Satellites measure increase of Sun's energy absorbed in the Arctic

The Arctic Ocean is absorbing more of the sun's energy in recent years as white, reflective sea ice melts and darker ocean waters are exposed. The increased darker surface area during the Arctic summer is responsible for a 5 percent increase in absorbed solar radiation since 2000.
Credit: NASA Goddard's Scientific Visualization Studio/Lori Perkins

NASA satellite instruments have observed a marked increase in solar radiation absorbed in the Arctic since the year 2000 -- a trend that aligns with the steady decrease in Arctic sea ice during the same period.

While sea ice is mostly white and reflects the sun's rays, ocean water is dark and absorbs the sun's energy at a higher rate. A decline in the region's albedo -- its reflectivity, in effect -- has been a key concern among scientists since the summer Arctic sea ice cover began shrinking in recent decades. As more of the sun's energy is absorbed by the climate system, it enhances ongoing warming in the region, which is more pronounced than anywhere else on the planet.

Since the year 2000, the rate of absorbed solar radiation in the Arctic in June, July and August has increased by five percent, said Norman Loeb, of NASA's Langley Research Center, Hampton, Virginia. The measurement is made by NASA's Clouds and the Earth's Radiant Energy System (CERES) instruments, which fly on multiple satellites.

While a five percent increase may not seem like much, consider that the rate globally has remained essentially flat during that same time. No other region on Earth shows a trend of potential long-term change.

When averaged over the entire Arctic Ocean, the increase in the rate of absorbed solar radiation is about 10 Watts per square meter. This is equivalent to an extra 10-watt light bulb shining continuously over every 10.76 square feet of Arctic Ocean for the entire summer.

Regionally, the increase is even greater, Loeb said. Areas such as the Beaufort Sea, which has experienced the some of the most pronounced decreases in sea-ice coverage, show a 50 watts per square meter increase in the rate of absorbed solar radiation.

"Advances in our understanding of Arctic climate change and the underlying processes that influence it will depend critically upon high quality observations like these from CERES," Loeb said.

As a region, the Arctic is showing more dramatic signs of climate change than any other spot on the planet. These include a warming of air temperatures at a rate two to three times greater than the rest of the planet and the loss of September sea ice extent at a rate of 13 percent per decade.

While these CERES measurements could ultimately become another of those signs of dramatic climate change, right now scientists say they have obtained the bare minimum of a data record needed to discern what's happening over the long term.

Getting data beyond 15 years will allow scientists to better assess if recent trend falls outside the realm of natural variability, said Jennifer Kay, an atmospheric scientist at the Cooperative Institute for Research and Environmental Science at the University of Colorado.

"We need long time series to detect climate change signals over the internal variability. For example, observed sea ice loss over the last 30 years cannot be explained by natural variability alone." Kay said. "Fifteen years is long, but climate is often defined as the average over 30 years -- so we are only half-way there with the CERES observations."

Kay and colleagues have also analyzed satellite observations of Arctic clouds during this same 15-year period. Kay's research shows summer cloud amounts and vertical structure are not being affected by summer sea ice loss. While surprising, the observations show that the bright sea ice surface is not automatically replaced by bright clouds. Indeed, sea ice loss, not clouds, explain the increases in absorbed solar radiation measured by CERES.

Increasing absorbed solar radiation is causing multiple changes in the sea ice cover, said Walt Meier, a sea ice scientist from NASA's Goddard Space Flight Center, Greenbelt, Maryland. Two of those changes include the timing of the beginning of the melt season each year and the loss of older, thicker sea ice.

The onset of the melt season in the high Arctic is now on average seven days earlier than it was in 1982, Meier said. Earlier melting can lead to increased solar radiation absorption. This is one step in a potential feedback cycle of warming leading to melting, melting leading to increased solar radiation absorption, and increased absorption leading to enhanced warming.

Since 2000, the Arctic has lost 1.4 million square kilometers (541,000 square miles) of older ice that is more than 3 meters thick, which during winter has essentially been replaced by ice that is less than 2 meters thick, according to data provided by Mark Tschudi at the University of Colorado. Once again, Meier said, this trend is a step in a feedback cycle.

"Having younger and thus thinner ice during winter makes the system more vulnerable to ice loss during the summer melt season," Meier said.

CERES instruments are currently flying on the Terra, Aqua and Suomi-NPP satellites. The Terra satellite launched Dec. 18, 1999, and CERES first started collecting Arctic data in 2000 so 2015 will mark 15 continuous years of CERES measurements over the Arctic.

The instruments include three radiometers -- one measuring solar radiation reflected by Earth (shortwave), one measuring thermal infrared radiation emitted by Earth (longwave), and one measuring all outgoing radiation, whether emitted or reflected.

Source:  NASA/Goddard Space Flight Center

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NASA data underscore severity of California drought

Trends in total water storage in California, Nevada and bordering states from NASA's Gravity Recovery and Climate Experiment (GRACE) satellite mission, September 2011 to September 2014. NASA scientists use these images to better quantify drought and its impact on water availability. Two-thirds of the measured losses were a result of groundwater depletion in California's Central Valley. Credit: NASA JPL/Caltech

It will take about 11 trillion gallons of water (42 cubic kilometers) -- around 1.5 times the maximum volume of the largest U.S. reservoir -- to recover from California's continuing drought, according to a new analysis of NASA satellite data.

The finding was part of a sobering update on the state's drought made possible by space and airborne measurements and presented by NASA scientists Dec. 16 at the American Geophysical Union meeting in San Francisco. Such data are giving scientists an unprecedented ability to identify key features of droughts, and can be used to inform water management decisions.

A team of scientists led by Jay Famiglietti of NASA's Jet Propulsion Laboratory in Pasadena, California, used data from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites to develop the first-ever calculation of this kind -- the volume of water required to end an episode of drought.

Earlier this year, at the peak of California's current three-year drought, the team found that water storage in the state's Sacramento and San Joaquin river basins was 11 trillion gallons below normal seasonal levels. Data collected since the launch of GRACE in 2002 show this deficit has increased steadily.

"Spaceborne and airborne measurements of Earth's changing shape, surface height and gravity field now allow us to measure and analyze key features of droughts better than ever before, including determining precisely when they begin and end and what their magnitude is at any moment in time," Famiglietti said. "That's an incredible advance and something that would be impossible using only ground-based observations."

GRACE data reveal that, since 2011, the Sacramento and San Joaquin river basins decreased in volume by four trillion gallons of water each year (15 cubic kilometers). That's more water than California's 38 million residents use each year for domestic and municipal purposes. About two-thirds of the loss is due to depletion of groundwater beneath California's Central Valley.

In related results, early 2014 data from NASA's Airborne Snow Observatory indicate that snowpack in California's Sierra Nevada range was only half of previous estimates. The observatory is providing the first-ever high-resolution observations of the water volume of snow in the Tuolumne River, Merced, Kings and Lakes basins of the Sierra Nevada and the Uncompahgre watershed in the Upper Colorado River Basin.

To develop these calculations, the observatory measures how much water is in the snowpack and how much sunlight the snow absorbs, which influences how fast the snow melts. These data enable accurate estimates of how much water will flow out of a basin when the snow melts, which helps guide decisions about reservoir filling and water allocation.

"The 2014 snowpack was one of the three lowest on record and the worst since 1977, when California's population was half what it is now," said Airborne Snow Observatory Principal Investigator Tom Painter of JPL. "Besides resulting in less snow water, the dramatic reduction in snow extent contributes to warming our climate by allowing the ground to absorb more sunlight. This reduces soil moisture, which makes it harder to get water from the snow into reservoirs once it does start snowing again."

New drought maps show groundwater levels across the U.S. Southwest are in the lowest 2 to 10 percent since 1949. The maps, developed at NASA's Goddard Space Flight Center in Greenbelt, Maryland, combine GRACE data with other satellite observations.

"Integrating GRACE data with other satellite measurements provides a more holistic view of the impact of drought on water availability, including on groundwater resources, which are typically ignored in standard drought indices," said Matt Rodell, chief of the Hydrological Sciences Laboratory at Goddard.

The scientists cautioned that while the recent California storms have been helpful in replenishing water resources, they aren't nearly enough to end the multi-year drought.

"It takes years to get into a drought of this severity, and it will likely take many more big storms, and years, to crawl out of it," said Famiglietti.

NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. The agency develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information on GRACE, visit: http://www.nasa.gov/grace and http://www.csr.utexas.edu/grace

For more on the Airborne Snow Observatory, visit: http://aso.jpl.nasa.gov/

For more information about NASA's Earth science activities, visit: http://www.nasa.gov/earthrightnow

Source: NASA/Jet Propulsion Laboratory

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Lead pollution beat explorers to South Pole, persists today

Composite ice core records of lead in Antarctica from 1600 to 2010. The areas shaded in blue and red indicate when lead values were below or above the 410-year average, respectively, highlighting the dramatic change before and after industrialization in the Southern Hemisphere. Credit: Desert Research Institute

Norwegian explorer Roald Amundsen became the first man to reach the South Pole in December 1911. More than 100 years later, an international team of scientists that includes a NASA researcher has proven that air pollution from industrial activities arrived to the planet's southern pole long before any human.

Using data from 16 ice cores collected from widely spaced locations around the Antarctic continent, including the South Pole, a group led by Joe McConnell of the Desert Research Institute (DRI) in Reno, Nevada, created the most accurate and precise reconstruction to date of lead pollution over Earth's southernmost continent. The new record, described in an article published today in the online edition of the Nature Publishing Group's journal Scientific Reports, spans a 410-year period from 1600 to 2010.

"Our new record shows the dramatic impact of industrial activities such as smelting, mining and fossil fuel burning on even the most remote parts of the world," McConnell said.

"It is very clear that industrial lead contamination was pervasive throughout Antarctica by the late 19th century, more than two decades before the first explorers made it to the South Pole," he added. "The idea that Amundsen and Scott were traveling over snow that clearly was contaminated by lead from smelting and mining in Australia, and that lead pollution at that time was nearly as high as any time ever since, is surprising to say the least."

This study included ice cores collected as part of projects funded by the National Science Foundation. Additional ice cores were contributed to the study by international collaborators including the British Antarctic Survey, the Australian Antarctic Division and the Alfred Wegener Institute in Germany.
"The ice cores obtained through international collaborations were critical to the success of this study in that they allowed us to develop records from parts of Antarctica not often visited by U.S.-based scientists," said co-author Tom Neumann of NASA's Goddard Space Flight Center in Greenbelt, Maryland, who participated in a Norway-U.S. traverse that collected several of the cores used in this study. "This included the Law Dome region of East Antarctica and a big section of East Antarctica visited by the Norwegian-United States Scientific Traverse of East Antarctica."

Composite ice core records of lead in Antarctica from 1600 to 2010. The areas shaded in blue and red indicate when lead values were below or above the 410-year average, respectively, highlighting the dramatic change before and after industrialization in the Southern Hemisphere.

All measurements of lead and other chemicals used in this study were made using DRI's continuous ice core analytical system. Low background atmospheric concentrations, together with well-known and often distinct isotopic characteristics (variants of lead with different atomic weights) of industrial sources make lead an ideal tracer of industrial pollution.

"Lead is a toxic heavy metal with strong potential to harm ecosystems," said co-author Paul Vallelonga of the University of Copenhagen. "While concentrations measured in Antarctic ice cores are very low, the records show that atmospheric concentrations and deposition rates increased approximately six-fold in the late 1880s, coincident with the start of mining at Broken Hill in southern Australia and smelting at nearby Port Pirie."

The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today, the authors report.

Data from the new ice core array illustrates that Antarctic lead concentrations reached a peak in 1900 and remained high until the late 1920s, with brief declines during the Great Depression and the end of World War II. Concentrations then increased rapidly until 1975 and remained elevated until the 1990s.

Concentrations across the Antarctic continent have since declined, but still are about four-fold higher than before industrialization, despite the phase out of leaded gasoline and other mitigation efforts in many countries in the Southern Hemisphere, the report states.

"Our measurements indicate that approximately 660 tonnes [1.5 million pounds] of industrial lead have been deposited on the snow-covered surface of Antarctic during the past 130 years," McConnell said. "While recent contamination levels are lower, clearly detectable industrial contamination of the Antarctic continent persists today, so we still have a ways to go."

Source: NASA/Goddard Space Flight Center

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2010 Chilean earthquake causes icequakes in Antarctica

The HOWD Polenet seismic station is located near the northwest corner of the Antarctica's Ellsworth Mountains. It was the station that showed the clearest indication of high-frequency signals following the 2010 Chilean earthquake.
Credit: Eric Kendrick/Ohio State University

Seismic events aren't rare occurrences on Antarctica, where sections of the frozen desert can experience hundreds of micro-earthquakes an hour due to ice deformation. Some scientists call them icequakes. But in March of 2010, the ice sheets in Antarctica vibrated a bit more than usual because of something more than 3,000 miles away: the 8.8-magnitude Chilean earthquake. A new Georgia Institute of Technology study published in Nature Geoscience is the first to indicate that Antarctica's frozen ground is sensitive to seismic waves from distant earthquakes.

To study the quake's impact on Antarctica, the Georgia Tech team looked at seismic data from 42 stations in the six hours before and after the 3:34 a.m. event. The researchers used the same technology that allowed them to "hear" the seismic response at large distances for the devastating 2011 magnitude 9 Japan earthquake as it rumbled through Earth. In other words, they simply removed the longer-period signals as the seismic waves spread from the distant epicenter to identify high-frequency signals from nearby sources. Nearly 30 percent (12 of the 42 stations) showed clear evidence of high-frequency seismic signals as the surface-wave arrived on Antarctica.

"We interpret these events as small icequakes, most of which were triggered during or immediately after the passing of long-period Rayleigh waves generated from the Chilean mainshock," said Zhigang Peng, an associate professor in the School of Earth and Atmospheric Sciences who led the study. "This is somewhat different from the micro-earthquakes and tremor caused by both Love and Rayleigh-type surface waves that traditionally occur in other tectonically active regions thousands of miles from large earthquakes.

Peng says the subtle difference is that micro-earthquakes respond to both shearing and volumetric deformation from distant events. The newly found icequakes respond only to volumetric deformation.

"Such differences may be subtle, but they tell us that the mechanism of these triggered icequakes and small earthquakes are different," Peng added. "One is more like cracking, while the other is like a shear slip event. It's similar to two hands passing each other."

Some of the icequakes were quick bursts and over in less than one second. Others were long duration, tremor-like signals up to 10 seconds. They occurred in various parts of the continent, including seismic stations along the coast and near the South Pole.

The researchers found the clearest indication of induced high-frequency signals at station HOWD near the northwest corner of the Ellsworth Mountains. Short bursts occurred when the P wave hit the station, then continued again when the Rayleigh wave arrived. The triggered icequakes had very similar high waveform patterns, which indicates repeated failure at a single location, possibly by the opening of cracks.

Peng says the source locations of the icequakes are difficult to determine because there isn't an extensive seismic network coverage in Antarctica.

"But at least some of the icequakes themselves create surface waves, so they are probably formed very close to the ice surface," he added. "While we cannot be certain, we suspect they simply reflect fracturing of ice in the near surface due to alternating volumetric compressions and expansions as the Rayleigh waves passed through Antarctica's frozen ice."

Antarctica was originally not on the research team's target list. While examining seismic stations in the Southern Hemisphere, Peng "accidently" found the triggered icequakes at a few openly available stations. He and former Georgia Tech postdoctoral student Jake Walter (now a research scientist at the Institute for Geophysics at UT Austin) then reached out to other seismologists (the paper's four co-authors) who were in charge of deploying more broadband seismometers in Antarctica.

Source: Georgia Institute of Technology

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The Network for tracking earthquakes exposes glacier activity: Accidental find offers big potential for research on Alaska's glaciers

Alaska’s seismic network records thousands of quakes produced by glaciers, capturing valuable data that scientis ts could use to better understand their behavior, but instead their seismic signals are set aside as oddities. The current earthquake monitoring system could be “tweaked” to target the dynamic movement of the state’s glaciers.
Credit: Chris Larson

Alaska's seismic network records thousands of quakes produced by glaciers, capturing valuable data that scientists could use to better understand their behavior, but instead their seismic signals are set aside as oddities. The current earthquake monitoring system could be "tweaked" to target the dynamic movement of the state's glaciers, suggests State Seismologist Michael West, who will present his research today at the annual meeting of the Seismological Society of America (SSA).

"In Alaska, these glacial events have been largely treated as a curiosity, a by-product of earthquake monitoring," said West, director of the Alaska Earthquake Center, which is responsible for detecting and reporting seismic activity across Alaska.

The Alaska seismic network was upgraded in 2007-08, improving its ability to record and track glacial events. "As we look across Alaska's glacial landscape and comb through the seismic record, there are thousands of these glacial events. We see patterns in the recorded data that raise some interesting questions about the glaciers," said West.

As a glacier loses large pieces of ice on its leading edge, a process called calving, the Alaska Earthquake Center's monitoring system automatically records the event as an earthquake. Analysts filter out these signals in order to have a clear record of earthquake activity for the region. In the discarded data, West sees opportunity.

"We have amassed a large record of glacial events by accident," said West. "The seismic network can act as an objective tool for monitoring glaciers, operating 24/7 and creating a data flow that can alert us to dynamic changes in the glaciers as they are happening." It's when a glacier is perturbed or changing in some way, says West, that the scientific community can learn the most.

Since 2007, the Alaska Earthquake Center has recorded more than 2800 glacial events along 600 km of Alaska's coastal mountains. The equivalent earthquake sizes for these events range from about 1 to 3 on the local magnitude scale. While calving accounts for a significant number of the recorded quakes, each glacier's terminus -- the end of any glacier where the ice meets the ocean -- behaves differently. Seasonal variations in weather cause glaciers to move faster or slower, creating an expected seasonal cycle in seismic activity. But West and his colleagues have found surprises, too.

In mid-August 2010, the Columbia Glacier's seismic activity changed radically from being relatively quiet to noisy, producing some 400 quakes to date. These types of signals from the Columbia Glacier have been documented every single month since August 2010, about the time when the Columbia terminus became grounded on sill, stalling its multi-year retreat.

That experience highlighted for West the value of the accidental data trove collected by the Alaska Earthquake Center. "The seismic network is blind to the cause of the seismic events, cataloguing observations that can then be validated," said West, who suggests the data may add value to ongoing field studies in Alaska.

Many studies of Alaska's glaciers have focused on single glacier analyses with dedicated field campaigns over short periods of time and have not tracked the entire glacier complex over the course of years. West suggests leveraging the data stream may help the scientific community observe the entire glacier complex in action or highlight in real time where scientists could look to catch changes in a glacier.

"This is low-hanging fruit," said West of the scientific advances waiting to be gleaned from the data.

Source: Seismological Society of America

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