HOT OR COLD - GLOBAL WARMING

While there is still some disagreement about global warming, many scientists believe it is the result of changes in the earth’s atmosphere. The atmosphere creates a blanket that surrounds the earth. Sunlight passes through the greenhouse gases in the atmosphere to reach the earth’s surface and is absorbed. Once this energy is absorbed it goes through various natural processes, such as photosynthesis, and is re-released back into the atmosphere.

Some of the energy escapes the atmosphere, but a considerable amount becomes trapped by the greenhouse gases and causes the earth to warm in temperature. This is known as the greenhouse effect. The greenhouse effect is naturally occurring and vital to our survival. Without it earth would not be warm enough to sustain life. However, many scientists believe the growth of industry and urbanization has had a direct impact on the earth’s atmosphere, resulting in an unhealthy build up greenhouse gases. The general consensus about global warming points in one direction and it seems that evidence of the serious challenge it presents can be directly attributed to human activity.

Carbon dioxide, the gas released during the burning of fossil fuels, such as coal, oil and natural gas heads the list of emissions that are damaging the atmosphere. This is followed by methane, which is released primarily from landfills, mining operations and gas pipelines, chlorofluorocarbons, which have also been found to contribute to ozone depletion, and nitrous oxide, that comes from fertilizers and other chemicals.

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China Olympics Traffic Measures Cut Carbon Emissions

A new NASA-funded study of the impacts of China's traffic restrictions for the 2008 Summer Olympics in Beijing shows how widespread changes in transportation patterns could greatly reduce the threat of climate change.

New research by an international team of scientists led by the National Center for Atmospheric Research (NCAR), Boulder, Colo., indicates that China's restrictions on motor vehicles designed to improve air quality during the games had the side benefit of dramatically cutting emissions of carbon dioxide by between 26,500 and 106,000 U.S. tons (24,000 and 96,000 metric tons) during the event.

To put this in perspective, the authors note that this reduction by a single city represents more than one-quarter of one percent of the emissions cut that would be necessary worldwide, on a sustained basis, to prevent the planet from heating up by more than about 3.6 degrees Fahrenheit (2 degrees Celsius) by the end of this century. That is the amount of heating generally considered to lead to major societal impacts.

While scientists have long known that reduced traffic would lead to lower carbon-dioxide emissions, precise estimates for an actual urban area are difficult to calculate. "The Beijing Olympics allowed us to actually measure what happens when people drive much less, and it turns out that it makes quite a substantial difference to our climate," says NCAR scientist Helen Worden, the lead author. "People may think their choice of how to commute to work doesn't make a difference, whether driving their cars or riding their bikes. But on a large scale, it really does."

Recent research has confirmed that China's traffic restrictions successfully reduced levels of air pollutants such as carbon monoxide and ozone. Worden and her colleagues, using new methods in satellite observations and computer simulations, were also able to estimate the impact on carbon dioxide, a powerful greenhouse gas. Data from the NCAR/University of Toronto Measurements of Pollution in the Troposphere (MOPITT) instrument aboard NASA's Terra satellite were used to obtain the carbon monoxide estimates utilized to infer the carbon dioxide emissions.

Worden adds that the same study could not be done for this summer's London Olympics, partly because the surface and cloud conditions in London aren't as favorable for the measurements of carbon monoxide near the surface from MOPITT. In addition, London is very different from Beijing in terms of pollution controls, and it has already restricted traffic in the central city for several years.

Funded primarily by NASA, the study was published in Geophysical Research Letters, a publication of the American Geophysical Union. It was co-authored by researchers at the University of Iowa, Iowa City; the University of Tsinghua in Beijing; Argonne National Laboratory, Lemont, Ill.; and NASA's Jet Propulsion Laboratory, Pasadena, Calif. NCAR is sponsored by the National Science Foundation.

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Storm sentinels

Beginning this summer and over the next several years, NASA will be sending unmanned aircraft dubbed "severe storm sentinels" above stormy skies to help researchers and forecasters uncover information about hurricane formation and intensity changes.

Several NASA centers are joining federal and university partners in the Hurricane and Severe Storm Sentinel (HS3) airborne mission targeted to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin.

NASA's unmanned sentinels are autonomously flown. The NASA Global Hawk is well-suited for hurricane investigations because it can over-fly hurricanes at altitudes greater than 60,000 feet with flight durations of up to 28 hours - something piloted aircraft would find nearly impossible to do. Global Hawks were used in the agency's 2010 Genesis and Rapid Intensification Processes (GRIP) hurricane mission and the Global Hawk Pacific (GloPac) environmental science mission.

"Hurricane intensity can be very hard to predict because of an insufficient understanding of how clouds and wind patterns within a storm interact with the storm’s environment. HS3 seeks to improve our understanding of these processes by taking advantage of the surveillance capabilities of the Global Hawk along with measurements from a suite of advanced instruments," said Scott Braun, HS3 mission principal investigator and research meteorologist at NASA's Goddard Space Flight Center in Greenbelt, Md.

HS3 will use two Global Hawk aircraft and six different instruments this summer, flying from a base of operations at Wallops Flight Facility in Virginia.

"One aircraft will sample the environment of storms while the other will measure eyewall and rainband winds and precipitation," Braun said. HS3 will examine the large-scale environment that tropical storms form in and move through and how that environment affects the inner workings of the storms.

HS3 will address the controversial role of the hot, dry, and dusty Saharan Air Layer in tropical storm formation and intensification. Past studies have suggested that the Saharan Air Layer can both favor or suppress intensification. In addition, HS3 will examine the extent to which deep convection in the inner-core region of storms is a key driver of intensity change or just a response to storms finding favorable sources of energy.

The HS3 mission will operate during portions of the Atlantic hurricane seasons, which run from June 1 to November 30. The 2012 mission will run from late August through early October.

The instruments to be mounted in the Global Hawk aircraft that will examine the environment of the storms include the scanning High-resolution Interferometer Sounder (S-HIS), the Advanced Vertical Atmospheric Profiling System (AVAPS) also known as dropsondes, and the Cloud Physics Lidar (CPL). The Tropospheric Wind Lidar Technology Experiment (TWiLiTE) Doppler wind lidar will likely fly in the 2013 mission.

Another set of instruments will fly on the Global Hawk focusing on the inner region of the storms. Those instruments include the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) conically scanning Doppler radar, the Hurricane Imaging Radiometer (HIRAD) multi-frequency interferometric radiometer, and the High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer (HAMSR) microwave sounder. Most of these instruments represent advanced technology developed by NASA, that in some cases are precursors to future satellite sensors.

NASA's Science Mission Directorate Global Hawk aircraft will deploy to Wallops Flight Facility from their home base at NASA's Dryden Flight Research Center on Edwards Air Force Base, Calif.


NASA's Global Hawk soars aloft from Edwards Air Force Base, Calif. The NASA Global Hawk is well-suited for hurricane investigations because it can over-fly hurricanes at altitudes greater than 60,000 feet with flight durations of up to 28 hours — something piloted aircraft would find nearly impossible to do. Credit: NASA/Tony Landis
"HS3 marks the first time that NASA's Global Hawks will deploy away from Dryden for a mission, potentially marking the beginning of an era in which they are operated regularly from Wallops," said Paul Newman, atmospheric scientist at NASA Goddard and deputy principal investigator on the HS3 mission.

NASA's Science Mission Directorate in Washington is establishing a Global Hawk operations center for science operations from Wallops. "With the Global Hawks at NASA Dryden in California, NASA Wallops will become the 'Global Hawk - Eastern' science center," Newman said.

From rockets studying the upper atmosphere to unmanned aircraft flying over hurricanes, NASA's Wallops Flight Facility is fast becoming a busy place for science. Wallops is one of several NASA centers involved with the HS3 mission. Others include Goddard, Dryden, Ames Research Center, Marshall Space Flight Center, and the Jet Propulsion Laboratory.

The HS3 mission is funded by NASA Headquarters and managed by NASA's Earth System Science Pathfinder Program at NASA's Langley Research Center, Hampton, Va. The HS3 mission also involves collaborations with various partners including the National Centers for Environmental Prediction, Naval Postgraduate School, Naval Research Laboratory, NOAA's Hurricane Research Division and Earth System Research Laboratory, Northrop Grumman Space Technology, National Center for Atmospheric Research, State University of New York at Albany, University of Maryland - Baltimore County, University of Wisconsin, and University of Utah.

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NASA's new carbon-counting instrument leaves the nest

Its construction now complete, the science instrument that is the heart of NASA's Orbiting Carbon Observatory-2 (OCO-2) spacecraft — NASA's first mission dedicated to studying atmospheric carbon dioxide — has left its nest at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and has arrived at its integration and test site in Gilbert, Ariz.

A truck carrying the OCO-2 instrument left JPL before dawn on Tuesday, May 9, to begin the trek to Orbital Science Corporation's Satellite Manufacturing Facility in Gilbert, southeast of Phoenix, where it arrived that afternoon. The instrument will be unpacked, inspected and tested. Later this month, it will be integrated with the Orbital-built OCO-2 spacecraft bus, which arrived in Gilbert on April 30.

Once technicians ensure the spacecraft is clean of any contaminants, the observatory's integration and test campaign will kick off. That campaign will be conducted in two parts, with the first part scheduled for completion in October. The observatory will then be stored in Gilbert for about nine months while the launch vehicle is prepared. The integration and test campaign will then resume, with completion scheduled for spring 2014. OCO-2 will then be shipped to Vandenberg Air Force Base, Calif., in preparation for a launch as early as the summer of 2014.

Technicians load the OCO-2 instrument and its ground support equipment aboard a moving van at JPL in preparation for its trek to Orbital Science Corporation's Satellite Manufacturing Facility in Gilbert, Ariz. Credit: NASA/JPL-Caltech.
"The OCO-2 instrument looks great, and its delivery to Orbital's Gilbert, Ariz., facility is a big step forward in successfully launching and operating the mission in space," said Ralph Basilio, OCO-2 project manager at JPL.

OCO-2 is the latest mission in NASA's study of the global carbon cycle. Carbon dioxide is the most significant human-produced greenhouse gas and the principal human-produced driver of climate change. The original OCO mission was lost shortly after launch on Feb. 24, 2009, when the Taurus XL launch vehicle carrying it malfunctioned and failed to reach orbit.

The experimental OCO-2 mission, which is part of NASA's Earth System Science Pathfinder Program, will uniformly sample the atmosphere above Earth's land and ocean, collecting more than half a million measurements of carbon dioxide concentration over Earth's sunlit hemisphere every day for at least two years. It will do so with the accuracy, resolution and coverage needed to provide the first complete picture of the regional-scale geographic distribution and seasonal variations of both human and natural sources of carbon dioxide emissions and their sinks-the places where carbon dioxide is removed from the atmosphere and stored.

Scientists will use OCO-2 mission data to improve global carbon cycle models, better characterize the processes responsible for adding and removing carbon dioxide from the atmosphere, and make more accurate predictions of global climate change.

The mission provides a key new measurement that can be combined with other ground and aircraft measurements and satellite data to answer important questions about the processes that regulate atmospheric carbon dioxide and its role in the carbon cycle and climate. This information could help policymakers and business leaders make better decisions to ensure climate stability and retain our quality of life. The mission will also serve as a pathfinder for future long-term satellite missions to monitor carbon dioxide.

Each of the OCO-2 instrument's three high-resolution spectrometers spreads reflected sunlight into its various colors like a prism, focusing on a different, narrow color range to detect light with the specific colors absorbed by carbon dioxide and molecular oxygen. The amount of light absorbed at these specific colors is proportional to the concentration of carbon dioxide in the atmosphere. Scientists will use these data in computer models to quantify global carbon dioxide sources and sinks.

For more information on the mission, visit: the JPL and NASA OCO-2 websites.

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Mild fire forecast

Forests in the Amazon Basin are expected to be less vulnerable to wildfires this year, according to the first forecast from a new fire severity model developed by university and NASA researchers.

Fire season across most of the Amazon rain forest typically begins in May, peaks in September and ends in January. The new model, which forecasts the fire season’s severity from three to nine months in advance, calls for an average or below-average fire season this year within 10 regions spanning three countries: Bolivia, Brazil and Peru.

“Tests of the model suggested that predictions should be possible before fire activity begins in earnest,” said Doug Morton, a co-investigator on the project at NASA’s Goddard Space Flight Center in Greenbelt, Md. “This is the first year to stand behind the model and make an experimental forecast, taking a step from the scientific arena to share this information with forest managers, policy makers, and the public alike.”


Gauges convey the fire severity forecast for 10 regions in the Amazon Basin where fire activity varies greatly from year to year, and where climate conditions have a significant impact on fire activity. Credit: Yang Chen/UC Irvine
The model was first described last year in the journal Science. Comparing nine years of fire data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite, with a record of sea surface temperatures from NOAA, scientists established a connection between sea surface temperatures in the Pacific and Atlantic oceans and fire activity in South America.

“There will be fires in the Amazon Basin, but our model predictions suggest that they won’t be as likely in 2012 as in some previous years,” said Jim Randerson of the University of California, Irvine, and principal investigator on the research project.

Specifically, sea surface temperatures in the Central Pacific and North Atlantic are currently cooler than normal. Cool sea surface temperatures change patterns of atmospheric circulation and increase rainfall across the southern Amazon in the months leading up to the fire season.

“We believe the precipitation pattern during the end of the wet season is very important because this is when soils are replenished with water,” said Yang Chen of UC Irvine. “If sea surface temperatures are higher, there is reduced precipitation across most of the region, leaving soils with less water to start the dry season.”

Without sufficient water to be transported from the soil to the atmosphere by trees, humidity decreases and vegetation is more likely to burn. Such was the case in 2010, when above-average sea surface temperatures and drought led to a severe fire season. In 2011, conditions shifted and cooler sea surface temperatures and sufficient rainfall resulted in fewer fires, similar to the forecast for 2012.


Improvements to the model are possible by incorporating data from the MODIS instrument on NASA's Aqua satellite, accounting for fires that occur in the afternoon when conditions are hotter and drier. Credit: Doug Morton.
Building on previous research, the researchers said there is potential to adapt and apply the model to other locations where large-scale climate conditions are a good indicator of the impending fire season, such as Indonesia and the United States.

Amazon forests, however, are particularly relevant because of their high biodiversity and vulnerability to fires. Amazon forests also store large amounts of carbon, and deforestation and wildfires release that carbon back to the atmosphere. Predictions of fire season severity may aid initiatives – such as the United Nation’s Reducing Emissions from Deforestation and forest Degradation program – to reduce the emissions of greenhouse gases from fires in tropical forests.

“The hope is that our experimental fire forecasting information will be useful to a broad range of communities to better understand the science, how these forests burn, and what predisposes forests to burning in some years and not others,” Morton said. “We now have the capability to make predictions, and the interest to share this information with groups who can factor it into their preparation for high fire seasons and management of the associated risks to forests and human health.”

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Muddled outlook

The 2012 hurricane season in North and Central America arrives with a muddled outlook. Sea surface temperatures are not particularly warm or cool, and the El Niño–Southern Oscillation (ENSO) is drifting in a neutral state that NASA climate scientist Bill Patzert playfully calls “La Nada.”

The map above shows sea surface temperatures (SSTs) in the tropical Atlantic Ocean and tropical eastern Pacific on May 30, 2012. The map was built with data from the Microwave Optimally Interpolated SST product, a NASA-supported effort at Remote Sensing Systems. Researchers combine observations and analyses from NASA’s Tropical Rainfall Measurement Mission and Aqua and Terra satellites, as well as the U.S. Navy’s WindSAT instrument on the Coriolis satellite (operated jointly with the Air Force).

Shades of blue depict water temperatures below 27.8 degrees Celsius (about 82 degrees Fahrenheit), while yellows, oranges, and reds depict waters above that threshold. Scientists generally agree that waters above that temperature are needed to build and sustain hurricanes, though there are exceptions. Of course, measurements of sea surface temperature account for only the top few millimeters of the ocean, and the amount of heat stored at greater depths (which is harder to measure) can also be a factor in hurricane development. So SSTs do not tell the whole story, but they are a fair predictor of the readiness of the ocean to sustain tropical storms.

“The waters look on the slightly cool side across some of the ‘main development region (MDR)’—the tropical band extending over the east and central Atlantic off Africa,” noted Jeff Halverson, a hurricane researcher at the University of Maryland–Baltimore County. “Whether this will persist for several months as we get into the high season, I don't know.”

The official start of hurricane season is June 1, though four named tropical storms in May—Alberto and Beryl in the Atlantic, Aletta and Bud in the Pacific—didn't wait for the calendar. The Hurricane Research Division of the National Oceanic and Atmospheric Administration (NOAA) announced on May 24, 2012, that it is expecting a near-normal season, with nine to fifteen named storms and four to eight hurricanes. According to NOAA, an average season between 1980 to 2010 produced 12 named storms with six hurricanes, including three major hurricanes.
“We shouldn't be fooled by the storms that have already developed off the southeast U.S. in May,” Halverson said. “Development can and does happen this early—albeit infrequently—and these developments are almost always not far off the U.S. mainland. They have little to do with what is coming off Africa and streaming across the MDR. So these early home-grown storms are not necessarily a predictor of the August to October season, which is dominated by Cape Verde storms.”

Meteorologists often look to ENSO for a sense of whether atmospheric weather patterns will promote or tamp down hurricane formation. In general, researchers believe that El Niño reduces hurricane activity and La Niña promotes it. But the science on the matter is not really settled, and it may be that ENSO affects the number but not necessarily the intensity of storms.

La Niña just ended earlier this spring, and the next El Niño may be some months off. “The equatorial Pacific is neutral, with no El Niño developing...not even a hint,” said Patzert, who is based at the Jet Propulsion Laboratory. “If El Niño builds, I think it will be late and whimpy.”
In the eastern Pacific, NOAA is calling for a near-normal or below-normal season. “Forecasters estimate a 70 percent chance of 12 to 18 named storms, which includes 5 to 9 hurricanes.”

Regardless of the predictions, the key to hurricane season is vigilance. “The important issue is hurricane preparedness along the coasts,” said Patzert. “All it takes is one in your neighborhood to wreak havoc. Listen to the National Hurricane Center, know your evacuation routes, and be super prepared.”

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NASA study: Earth's energy budget 'out of balance'

02.01.12
By Adam Voiland,
NASA's Earth Science News Team
A new NASA study underscores the fact that greenhouse gases generated by human activity—not changes in solar activity—are the primary force driving global warming.

The study offers an updated calculation of the Earth's energy imbalance, the difference between the amount of solar energy absorbed by Earth's surface and the amount returned to space as heat. The researchers' calculations show that, despite unusually low solar activity between 2005 and 2010, the planet continued to absorb more energy than it returned to space.


A prolonged solar minimum left the sun's surface nearly free of sunspots and accompanying bright areas called faculae between 2005 and 2010. Total solar irradiance declined slightly as a result, but the Earth continued to absorb more energy than it emit throughout the minimum. An animation of a full solar cycle is available here. Credit: NASA Goddard's Scientific Visualization Studio
James Hansen, director of NASA's Goddard Institute for Space Studies (GISS) in New York City, led the research. Atmospheric Chemistry and Physics published the study last December.

Total solar irradiance, the amount of energy produced by the sun that reaches the top of each square meter of the Earth's atmosphere, typically declines by about a tenth of a percent during cyclical lulls in solar activity caused by shifts in the sun's magnetic field. Usually solar minimums occur about every eleven years and last a year or so, but the most recent minimum persisted more than two years longer than normal, making it the longest minimum recorded during the satellite era.

Pinpointing the magnitude of Earth's energy imbalance is fundamental to climate science because it offers a direct measure of the state of the climate. Energy imbalance calculations also serve as the foundation for projections of future climate change. If the imbalance is positive and more energy enters the system than exits, Earth grows warmer. If the imbalance is negative, the planet grows cooler.

Hansen's team concluded that Earth has absorbed more than half a watt more solar energy per square meter than it let off throughout the six year study period. The calculated value of the imbalance (0.58 watts of excess energy per square meter) is more than twice as much as the reduction in the amount of solar energy supplied to the planet between maximum and minimum solar activity (0.25 watts per square meter).

"The fact that we still see a positive imbalance despite the prolonged solar minimum isn't a surprise given what we've learned about the climate system, but it's worth noting because this provides unequivocal evidence that the sun is not the dominant driver of global warming," Hansen said.

According to calculations conducted by Hansen and his colleagues, the 0.58 watts per square meter imbalance implies that carbon dioxide levels need to be reduced to about 350 parts per million to restore the energy budget to equilibrium. The most recent measurements show that carbon dioxide levels are currently 392 parts per million and scientists expect that concentration to continue to rise in the future.


Data collected by Argo floats, such as this one, helped Hansen's team improve the calculation of Earth's energy imbalance. Credit: Argo Project Office
Climate scientists have been refining calculations of the Earth's energy imbalance for many years, but this newest estimate is an improvement over previous attempts because the scientists had access to better measurements of ocean temperature than researchers have had in the past.

The improved measurements came from free-floating instruments that directly monitor the temperature, pressure and salinity of the upper ocean to a depth of 2,000 meters (6,560 feet). The network of instruments, known collectively as Argo, has grown dramatically in recent years since researchers first began deploying the floats a decade ago. Today, more than 3,400 Argo floats actively take measurements and provide data to the public, mostly within 24 hours.

Hansen's analysis of the information collected by Argo, along with other ground-based and satellite data, show the upper ocean has absorbed 71 percent of the excess energy and the Southern Ocean, where there are few Argo floats, has absorbed 12 percent. The abyssal zone of the ocean, between about 3,000 and 6,000 meters (9,800 and 20,000 feet) below the surface, absorbed five percent, while ice absorbed eight percent and land four percent.

The updated energy imbalance calculation has important implications for climate modeling. Its value, which is slightly lower than previous estimates, suggests that most climate models overestimate how readily heat mixes deeply into the ocean and significantly underestimates the cooling effect of small airborne particles called aerosols, which along with greenhouse gases and solar irradiance are critical factors in energy imbalance calculations.

"Climate models simulate observed changes in global temperatures quite accurately, so if the models mix heat into the deep ocean too aggressively, it follows that they underestimate the magnitude of the aerosol cooling effect," Hansen said.

Aerosols, which can either warm or cool the atmosphere depending on their composition and how they interact with clouds, are thought to have a net cooling effect. But estimates of their overall impact on climate are quite uncertain given how difficult it is to measure the distribution of the particles on a broad scale. The new study suggests that the overall cooling effect from aerosols could be about twice as strong as current climate models suggest, largely because few models account for how the particles affect clouds.


A chart shows the global reach of the network of Argo floats. (Credit: Argo Project Office)
"Unfortunately, aerosols remain poorly measured from space," said Michael Mishchenko, a scientist also based at GISS and the project scientist for Glory, a satellite mission designed to measure aerosols in unprecedented detail that was lost after a launch failure in early 2011. "We must have a much better understanding of the global distribution of detailed aerosol properties in order to perfect calculations of Earth's energy imbalance," said Mishchenko.

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