global warming
NASA, US, European Partner Satellite Returns First Sea Level Measurements
Sentinel-6 Michael Freilich, a joint U.S.-European satellite built to measure global sea surface height, has sent back its first measurements of sea level. The data provide information on sea surface height, wave height, and wind speed off the southern tip of Africa.
“We’re excited for Sentinel-6 Michael Freilich to begin its critical work studying sea level and helping us understand the many aspects of our planet’s global ocean,” said Thomas Zurbuchen, NASA’s associate administrator for science at the agency’s headquarters in Washington. “I know Mike would be thrilled that the satellite bearing his name has begun operating, but he’d also be looking forward to studying the data from this important mission, as we all are.”
Read the rest of this entry »Successful Ocean-Monitoring Satellite Mission Ends
Esprit Smith, Jet Propulsion Laboratory, Pasadena, Calif.
esprit.smith@jpl.nasa.gov
Pascale Bresson, CNES, Paris, France
pascale.bresson@cnes.fr
Raphaël Sart, CNES, Paris, France
raphael.sart@cnes.fr
John Leslie, NOAA National Environmental Satellite and Information Service, Silver Spring, Md.
john.leslie@noaa.gov
Neil Fletcher. EUMETSAT, Darmstadt, Germany
neil.fletcher@eumetsat.int
The Jason-2/Ocean Surface Topography Mission (OSTM), the third in a U.S.-European series of satellite missions designed to measure sea surface height, successfully ended its science mission on Oct. 1. NASA and its mission partners made the decision to end the mission after detecting deterioration in the spacecraft’s power system.
Jason-2/OSTM, a joint NASA mission with the French space agency Centre National d’Etudes Spatiales (CNES), the National Oceanic and Atmospheric Administration (NOAA), and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), launched in June 2008. The mission extended the long-term record of sea surface height measurements started by the NASA-CNES TOPEX/Poseidon and Jason-1 missions. Jason-2/OSTM’s 11-year lifetime well exceeded its three-year design life. These measurements are being continued by its successor, Jason-3, launched in 2016.
GRACE Mission: 15 Years of Watching Water on Earth
Written by Carol Rasmussen
NASA Earth Science News Team
Fast Facts
- In 15 years of operations, the GRACE satellite mission has revolutionized our view of how water moves and is stored on Earth.
- GRACE measures changes in the local pull of gravity as water shifts around Earth due to changing seasons, weather and climate processes.
- Among other innovations, GRACE gave us the first space-based view of water beneath Earth’s surface, giving insight into where aquifers may be shrinking or dry soils contributing to drought.
- The GRACE Follow-On mission, launching in early 2018, will extend GRACE’s innovative measurements
“Revolutionary” is a word you hear often when people talk about the GRACE mission. Since the twin satellites of the U.S./German Gravity Recovery and Climate Experiment launched on March 17, 2002, their data have transformed scientists’ view of how water moves and is stored around the planet.
“With GRACE, we effectively created a new field of spaceborne remote sensing: tracking the movement of water via its mass,” said Michael Watkins, the original GRACE project scientist and now director of NASA’s Jet Propulsion Laboratory, Pasadena, California.
NASA Satellite Finds Unreported Source of Toxic Air Pollution
 New research has detected smaller sulfur dioxide concentrations and sources around the world, including human-made sources such as medium-size power plants and oil-related activities.
Credit: EPA
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 Data from NASA’s Aura spacecraft, illustrated here, were analyzed by scientists to produce improved estimates of sulfur dioxide sources and concentrations worldwide between 2005 and 2014. Credit: NASA |
Using a new satellite-based method, scientists at NASA, Environment and Climate Change Canada, and two universities have located 39 unreported and major human-made sources of toxic sulfur dioxide emissions.
A known health hazard and contributor to acid rain, sulfur dioxide (SO2) is one of six air pollutants regulated by the U.S. Environmental Protection Agency. Current, sulfur dioxide monitoring activities include the use of emission inventories that are derived from ground-based measurements and factors, such as fuel usage. The inventories are used to evaluate regulatory policies for air quality improvements and to anticipate future emission scenarios that may occur with economic and population growth.
But, to develop comprehensive and accurate inventories, industries, government agencies and scientists first must know the location of pollution sources.
“We now have an independent measurement of these emission sources that does not rely on what was known or thought known,” said Chris McLinden, an atmospheric scientist with Environment and Climate Change Canada in Toronto and lead author of the study published this week in Nature Geosciences.
“When you look at a satellite picture of sulfur dioxide, you end up with it appearing as hotspots – bull’s-eyes, in effect — which makes the estimates of emissions easier.”
The 39 unreported emission sources, found in the analysis of satellite data from 2005 to 2014, are clusters of coal-burning power plants, smelters, oil and gas operations found notably in the Middle East, but also in Mexico and parts of Russia. In addition, reported emissions from known sources in these regions were — in some cases — two to three times lower than satellite-based estimates.
Altogether, the unreported and underreported sources account for about 12 percent of all human-made emissions of sulfur dioxide – a discrepancy that can have a large impact on regional air quality, said McLinden.
The research team also located 75 natural sources of sulfur dioxide — non-erupting volcanoes slowly leaking the toxic gas throughout the year. While not necessarily unknown, many volcanoes are in remote locations and not monitored, so this satellite-based data set is the first to provide regular annual information on these passive volcanic emissions.
“Quantifying the sulfur dioxide bull’s-eyes is a two-step process that would not have been possible without two innovations in working with the satellite data,” said co-author Nickolay Krotkov, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
First was an improvement in the computer processing that transforms raw satellite observations from the Dutch-Finnish Ozone Monitoring Instrument aboard NASA’s Aura spacecraft into precise estimates of sulfur dioxide concentrations. Krotkov and his team now are able to more accurately detect smaller sulfur dioxide concentrations, including those emitted by human-made sources such as oil-related activities and medium-size power plants.
Being able to detect smaller concentrations led to the second innovation. McLinden and his colleagues used a new computer program to more precisely detect sulfur dioxide that had been dispersed and diluted by winds. They then used accurate estimates of wind strength and direction derived from a satellite data-driven model to trace the pollutant back to the location of the source, and also to estimate how much sulfur dioxide was emitted from the smoke stack.
“The unique advantage of satellite data is spatial coverage,” said Bryan Duncan, an atmospheric scientist at Goddard.
“This paper is the perfect demonstration of how new and improved satellite datasets, coupled with new and improved data analysis techniques, allow us to identify even smaller pollutant sources and to quantify these emissions over the globe.”
The University of Maryland, College Park, and Dalhousie University in Halifax, Nova Scotia, contributed to this study.
For more information about, and access to, NASA’s air quality data, visit: http://so2.gsfc.nasa.gov/
NASA uses the vantage point of space to increase our understanding of our home planet, improve lives, and safeguard our future. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.
For more information about NASA Earth science research, visit: http://www.nasa.gov/earth
New NASA Web Portal Shines Beacon on Rising Seas
Sea level rise is a critical global issue affecting millions across our planet. A new Web portal developed by NASA’s Jet Propulsion Laboratory, Pasadena, California, gives researchers, decision makers and the public alike a resource to stay up to date with the latest developments and scientific findings in this rapidly advancing field of study.
The portal, “Sea Level Change: Observations from Space,” is online at: https://sealevel.nasa.gov/
The portal’s key features include:
- “Understanding Sea Level,” a summary of decades of scientific research that has shaped our knowledge of sea level rise: its causes, including a warming, expanding ocean and melting ice on land; projections of future sea level rise; and ways in which humanity might adapt, largely drawn from NASA data.
- An interactive data analysis tool, launching in mid-2016, that will allow direct access to NASA datasets on sea level. Users will be able to manipulate these datasets to automatically generate charts, graphs and maps of sea surface height, temperature and other factors. The analysis tool will also allow users to make forecasts of future conditions, as well as “hindcasts” — retroactive calculations of past trends and conditions.
- News highlights and feature stories with strong visual elements that explore the findings of sea level researchers in detail.
- An extensive library of published papers on sea level-related topics, hyperlinked to individual citations throughout “Understanding Sea Level.”
- A multimedia section with dynamic still and video imagery, and a glossary of sea level terms.
- A “frequently asked questions” section maintained by sea level scientists. Users can submit questions to scientists and data managers.
The website is optimized for most mobile devices, including smartphones and tablets.
“Sea Level Change: Observations from Space” is managed by a team led by JPL scientist Carmen Boening. The team is part of the NASA Sea Level Change Team research group.
“With sea levels rising globally, as observed by satellites over the past decades, sea level change is a hot topic in climate research,” Boening said. “This new tool provides a NASA resource for researchers and a wealth of information for members of the public seeking a deeper understanding of sea level change.”
For more information on NASA’s Earth science activities, visit: http://www.nasa.gov/earth and http://climate.nasa.gov
JPL is a division of the California Institute of Technology in Pasadena.
A Still-Growing El Niño Set to Bear Down on US
The current strong El Niño brewing in the Pacific Ocean shows no signs of waning, as seen in the latest satellite image from the U.S./European Ocean Surface Topography Mission (OSTM)/Jason-2 mission.
El Niño 2015 has already created weather chaos around the world. Over the next few months, forecasters expect the United States to feel its impacts as well.
The latest Jason-2 image bears a striking resemblance to one from December 1997, by Jason-2’s predecessor, the NASA/Centre National d’Etudes Spatiales (CNES) Topex/Poseidon mission, during the last large El Niño event. Both reflect the classic pattern of a fully developed El Niño. The images can be viewed at:
http://sealevel.jpl.nasa.gov/elnino2015/index.html
The images show nearly identical, unusually high sea surface heights along the equator in the central and eastern Pacific: the signature of a big and powerful El Niño. Higher-than-normal sea surface heights are an indication that a thick layer of warm water is present.
El Niños are triggered when the steady, westward-blowing trade winds in the Pacific weaken or even reverse direction, triggering a dramatic warming of the upper ocean in the central and eastern tropical Pacific. Clouds and storms follow the warm water, pumping heat and moisture high into the overlying atmosphere. These changes alter jet stream paths and affect storm tracks all over the world.
This year’s El Niño has caused the warm water layer that is normally piled up around Australia and Indonesia to thin dramatically, while in the eastern tropical Pacific, the normally cool surface waters are blanketed with a thick layer of warm water. This massive redistribution of heat causes ocean temperatures to rise from the central Pacific to the Americas. It has sapped Southeast Asia’s rain in the process, reducing rainfall over Indonesia and contributing to the growth of massive wildfires that have blanketed the region in choking smoke.
El Niño is also implicated in Indian heat waves caused by delayed monsoon rains, as well as Pacific island sea level drops, widespread coral bleaching that is damaging coral reefs, droughts in South Africa, flooding in South America and a record-breaking hurricane season in the eastern tropical Pacific. Around the world, production of rice, wheat, coffee and other crops has been hit hard by droughts and floods, leading to higher prices.
In the United States, many of El Niño’s biggest impacts are expected in early 2016. Forecasters at the National Oceanic and Atmospheric Administration favor an El Niño-induced shift in weather patterns to begin in the near future, ushering in several months of relatively cool and wet conditions across the southern United States, and relatively warm and dry conditions over the northern United States. The latest El Niño forecast from NOAA’s Climate Prediction Center is at: http://www.cpc.ncep.noaa.gov/
While scientists still do not know precisely how the current El Niño will affect the United States, the last large El Niño in 1997-98 was a wild ride for most of the nation. The “Great Ice Storm” of January 1998 crippled northern New England and southeastern Canada, but overall, the northern tier of the United States experienced long periods of mild weather and meager snowfall. Meanwhile, across the southern United States, a steady convoy of storms slammed most of California, moved east into the Southwest, drenched Texas and — pumped up by the warm waters of the Gulf of Mexico — wreaked havoc along the Gulf Coast, particularly in Florida.
“In 2014, the current El Niño teased us — wavering off and on,” said Josh Willis, project scientist for the Jason missions at JPL. “But in early 2015, atmospheric conditions changed, and El Niño steadily expanded in the central and eastern Pacific. Although the sea surface height signal in 1997 was more intense and peaked in November of that year, in 2015, the area of high sea levels is larger. This could mean we have not yet seen the peak of this El Niño.”
During normal, non-El Niño conditions, the amount of warm water in the western equatorial Pacific is so large that sea levels are about 20 inches (50 centimeters) higher in the western Pacific than in the eastern Pacific. “You can see it in the latest Jason-2 image of the Pacific,” said Willis. “The 8-inch [20-centimeter] drop in the west, coupled with the 10-inch [25-centimeter] rise in the east, has completely wiped out the tilt in sea level we usually have along the equator.”
The new Jason-2 image shows that the amount of extra-warm surface water from the current El Niño (depicted in red and white shades) has continuously increased, especially in the eastern Pacific within 10 degrees latitude north and south of the equator. In the western Pacific, the area of low sea level (blue and purple) has decreased somewhat from late October. The white and red areas indicate unusual patterns of heat storage. In the white areas, the sea surface is between 6 and 10 inches (15 to 25 centimeters) above normal, while in the red areas, it is about 4 inches (10 centimeters) above normal. The green areas indicate normal conditions. The height of the ocean water relates, in part, to its temperature, and is an indicator of the amount of heat stored in the ocean below.
Within this area, surface temperatures are greater than 86 degrees Fahrenheit (30 degrees Celsius) in the central equatorial Pacific and near 70 degrees Fahrenheit (21 degrees Celsius) off the coast of the Americas. This El Niño signal encompasses a surface area of 6 million square miles (16 million square kilometers) — more than twice as big as the continental United States.
While no one can predict the exact timing or intensity of U.S. El Niño impacts, for drought-stricken California and the U.S. West, it’s expected to bring some relief.
“The water story for much of the American West over most of the past decade has been dominated by punishing drought,” said JPL climatologist Bill Patzert. “Reservoir levels have fallen to record or near-record lows, while groundwater tables have dropped dangerously in many areas. Now we’re preparing to see the flip side of nature’s water cycle — the arrival of steady, heavy rains and snowfall.”
In 1982-83 and 1997-98, large El Niños delivered about twice the average amount of rainfall to Southern California, along with mudslides, floods, high winds, lightning strikes and high surf. But Patzert cautioned that El Niño events are not drought busters. “Over the long haul, big El Niños are infrequent and supply only seven percent of California’s water,” he said.
“Looking ahead to summer, we might not be celebrating the demise of this El Niño,” cautioned Patzert. “It could be followed by a La Niña, which could bring roughly opposite effects to the world’s weather.”
La Niñas are essentially the opposite of El Niño conditions. During a La Niña episode, trade winds are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. La Niña episodes change global weather patterns and are associated with less moisture in the air over cooler ocean waters. This results in less rain along the coasts of North and South America and along the central and eastern equatorial Pacific, and more rain in the far Western Pacific.
El Niño events are part of the long-term, evolving state of global climate, for which measurements of sea surface height are a key indicator.
For an animation of the evolution of the 2015 and 1997 El Niños, visit: https://sealevel.jpl.nasa.gov/elnino2015/2015-animated.gif
For more information on how NASA studies El Niño, visit: http://climatesciences.jpl.nasa.gov/enso
To learn more about NASA’s satellite altimetry programs, visit: http://sealevel.jpl.nasa.gov
For more information about NASA’s Earth science activities, visit: http://www.nasa.gov/earth
NASA Finds New Way to Track Ocean Currents from Space
A team of NASA and university scientists has developed a new way to use satellite measurements to track changes in Atlantic Ocean currents, which are a driving force in global climate. The finding opens a path to better monitoring and understanding of how ocean circulation is changing and what the changes may mean for future climate.
In the Atlantic, currents at the ocean surface, such as the Gulf Stream, carry sun-warmed water from the tropics northeastward. As the water moves through colder regions, it sheds its heat. By the time it gets to Greenland, it’s so cold and dense that it sinks a couple of miles down into the ocean depths. There it turns and flows back south. This open loop of shallow and deep currents is known to oceanographers as the Atlantic Meridional Overturning Circulation (AMOC) — part of the “conveyor belt” of ocean currents circulating water, heat and nutrients around the globe and affecting climate.
Because the AMOC moves so much heat, any change in it is likely to be an important indicator of how our planet is responding to warming caused by increasing greenhouse gases. In the last decade, a few isolated measurements have suggested that the AMOC is slowing down and moving less water. Many researchers are expecting the current to weaken as a consequence of global warming, but natural variations may also be involved. To better understand what is going on, scientists would like to have consistent observations over time that cover the entire Atlantic
“This [new] satellite approach allows us to improve projections of future changes and — quite literally — get to the bottom of what drives ocean current changes,” said Felix Landerer of NASA’s Jet Propulsion Laboratory, Pasadena, California, who led the research team.
Landerer and his colleagues used data from the twin satellites of NASA’s Gravity Recovery and Climate Experiment (GRACE) mission. Launched in 2002, GRACE provides a monthly record of tiny changes in Earth’s gravitational field, caused by changes in the amount of mass below the satellites. The mass of Earth’s land surfaces doesn’t change much over the course of a month; but the mass of water on or near Earth’s surface does, for example, as ice sheets melt and water is pumped from underground aquifers. GRACE has proven invaluable in tracking these changes.
At the bottom of the atmosphere — on Earth’s surface — changes in air pressure (a measure of the mass of the air) tell us about flowing air, or wind. At the bottom of the ocean, changes in pressure tell us about flowing water, or currents. Landerer and his team developed a way to isolate in the GRACE gravity data the signal of tiny pressure differences at the ocean bottom that are caused by changes in the deep ocean currents.
“We’ve wanted to observe this phenomenon with GRACE since we launched 13 years ago, but it took us this long to figure out how to squeeze the information out of the data stream,” said Michael Watkins, director of the Center for Space Research at the University of Texas at Austin, former GRACE project scientist and a co-author of the study.
The squeezing process required some very advanced data processing, but not as many data points as one might think. “In principle, you’d think you’d have to measure every 10 yards or so across the ocean to know the whole flow,” Landerer explained. “But in fact, if you can measure the farthest eastern and western points very accurately, that’s all you need to know how much water is flowing north and south in the entire Atlantic at that section. That theory has long been known and is exploited in buoy networks, but this is the first time we’ve been able to do it successfully from space.”
The new measurements agreed well with estimates from a network of ocean buoys that span the Atlantic Ocean near 26 degrees north latitude, operated by the Rapid Climate Change (RAPID) group at the U.K.’s National Oceanography Centre, Southampton. The agreement gives the researchers confidence that the technique can be expanded to provide estimates throughout the Atlantic. In fact, the GRACE measurements showed that a significant weakening in the overturning circulation, which the buoys recorded in the winter of 2009-10, extended several thousand miles north and south of the buoys’ latitude.
Gerard McCarthy, a research scientist in the RAPID group who was not involved with the study, said, “The results highlight synergies between [direct measurements] like [those from] RAPID and remote sensing — all the more important given the rapid and surprising changes occurring in the North Atlantic at the present time.” Eric Lindstrom, NASA’s Physical Oceanography Program manager at the agency’s headquarters in Washington, pointed out, “It’s awesome that GRACE can see variations of deep water transport, [but] this signal might never have been detected or verified without the RAPID array. We will continue to need both in situ and space-based systems to monitor the subtle but significant variations of the ocean circulation.”
A paper in the journal Geophysical Research Letters describing the new technique and first results is available online in prepublication form: http://onlinelibrary.wiley.com/doi/10.1002/2015GL065730/abstract?campaign=wolacceptedarticle
Cosmology & Space Research Institute 
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