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Naval Research Laboratory scientist Dr. Michael Stevens is leading an international consortium of scientists in tracking the rapid transport of the exhaust plume from the final launch of the space shuttle in July 2011. The team has found that the plume moved quickly to the Arctic, forming unusually bright polar mesospheric clouds (PMCs) there a day after launch.

Understanding the rapid transport of high altitude exhaust plumes near 105 km is providing new insight into the effects of winds at the bottom edge of the space weather regime towards improved forecasts of the co-located E-region of the ionosphere. This knowledge is critical for improving models of communication signal propagation and over-the-horizon-radar, explains Dr. Stevens, a Research Physicist in NRL's Space Science Division. Current theories suggest that the plumes are rapidly transported because of narrow, high-speed wind shears. These wind shears are also linked to the occurrence of so-called Sporadic E events, thus establishing a possible link between plume transport and the lower ionosphere.

During every launch, the space shuttle injects about 350 tons of water vapor from its three main engines off the east coast of the United States between 100 and 115 km altitude. Many studies have now shown that the poleward transport of this water vapor is much faster than global-scale models predict, and a few have furthermore shown that bursts of PMCs near 83 km altitude can result. These observations are forcing researchers to reexamine their understanding of global wind patterns in the lower thermosphere.

The long-term PMC record is also likely to be modified by increased space traffic, which is important because PMCs have been implicated as indicators of upper atmospheric climate change, explains Dr. Stevens. By assembling a suite of satellite and ground-based observations following the space shuttle's final launch, the NRL-led research team has revealed the nature of these shuttle clouds for the first time. The observations from both European and American collaborators show not only the rapid poleward transport of the plume and ensuing PMC formation, but that shuttle clouds are brighter than over 99% of all other PMCs and that the ice particles are larger at higher altitudes, which is the opposite of conventional models.

By allowing researchers to distinguish the shuttle PMCs from more typical clouds, these results will ultimately enable a search of the historical record to separate the anthropogenic PMCs from the natural PMCs.

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Journal Reference:

1. Michael H. Stevens, Lance E. Deaver, Mark E. Hervig, James M. Russell, David E. Siskind, Patrick E. Sheese, Edward J. Llewellyn, Richard L. Gattinger, Josef Höffner, B. T. Marshall. Validation of upper mesospheric and lower thermospheric temperatures measured by the Solar Occultation for Ice Experiment. Journal of Geophysical Research, 2012; 117 (D16) DOI: 10.1029/2012JD017689

This year scientists working on NASA's Operation IceBridge, a multi-year airborne science mission to study changing ice conditions at both poles, debuted a new data product with the potential to improve Arctic sea ice forecasts.

Using new data processing techniques, IceBridge scientists were able to release an experimental quick look product before the end of the 2012 Arctic campaign. The main challenge faced when producing data for seasonal forecasts is the time needed to crunch the numbers, something that has in the past taken IceBridge scientists more than six months to do after the data was collected in the spring. This is too late to use for Arctic sea ice forecasts of the annual seasonal minimum, which takes place in September.

The new product could potentially be used in seasonal sea ice forecasts in the future. "The community is excited about it," said IceBridge science team co-lead Jackie Richter-Menge of the U.S. Army Corps of Engineers Cold Regions Research Laboratory, Hanover, N.H. "We're hoping to build on this season's momentum and interest."

Scientists have been keeping an eye on Arctic sea ice in recent years because it is changing and they want to understand what those changes might mean. Arctic sea ice grows and recedes in a seasonal pattern, with a maximum coverage in March and a minimum in September. These high and low points vary from year to year, but there is a clear trend toward smaller minimums that mean more open water in the Arctic each summer and fall. This decrease in ice is already affecting ocean and terrestrial life in the Arctic, accelerating warming in the region and leading to economic and social changes.

"Sea ice is a sensitive indicator of a changing climate," said NASA researcher Nathan Kurtz at NASA's Goddard Space Flight Center, Greenbelt, Md. It can also act as a feedback to warming in the Arctic. Because ice is much lighter in color than ocean water it has a higher albedo, meaning it reflects more sunlight than water. "A loss of sea ice can cause the Earth as a whole to warm," Kurtz said. The loss of sea ice has also been linked to shifts in weather patterns and distribution of nutrients in the ocean.

Getting the Whole Picture

Sea ice modulates a complex interaction between two systems — the ocean and the atmosphere — and is affected by a number of factors. Surface temperature is the one that most readily comes to mind. Warming air and ocean temperatures melt the ice over time. But ice thickness and the amount of snow that accumulates on it are important in controlling the amount of growth and melt. As anyone who has been to a summer barbecue knows, larger masses of ice melt slower than smaller ones. Thicker sea ice will stay around longer than thin ice.

The largest portion of sea ice is hidden under the water's surface, which makes measuring its thickness trickier than getting its extent. To find thickness, researchers rely on a variety of advanced instruments and a law of physics that goes back to ancient Greece — the Archimedes Principle. "If you know how much ice is above the water and know its density, you can calculate the thickness," said Kurtz. "On average 80 to 90 percent of the ice is below the surface." With this knowledge, it's possible to take the ice freeboard, the amount above the water's surface, and calculate its thickness. IceBridge's Airborne Topographic Mapper, or ATM, instrument uses a laser to measure how high the ice surface is above sea level. But snow accumulation means that what ATM measures is not just ice. To address this complication, IceBridge uses one of its radar instruments to measure snow thickness, and then with simple subtraction, researchers can figure out the true ice freeboard.

It's important to factor for snow thickness because while it adds height to sea ice, it adds less mass than an equivalent thickness of ice. But snow thickness is a valuable measurement in its own right. "There's growing interest in our snow depth measurements as a stand-alone product," Richter-Menge said.

Snow affects how sea ice grows and melts by insulating it, slowing growth, and further increasing albedo as snow is even lighter colored than ice. But snow can also speed up melting. Snow melts, forming ponds of water that — due to increased albedo — absorb more heat than either snow or ice would. Snow also plays a role in the Arctic ecosystem. "For instance, snow needs to be a certain depth for the survival of seal pups," said Richter-Menge.

Putting It All Together

Creating a new data product calls for new processing methods and a good understanding of how data are collected. To facilitate this, Kurtz traveled to Greenland during the 2012 Arctic campaign. For about two weeks in March, Kurtz participated in survey flights on the NASA P-3B aircraft to see how instrument operators gathered sea ice data. "I asked a lot of questions," Kurtz said. "And I got a good impression for a short stay." Although it is tempting to use this data in this year's seasonal forecasts, both Kurtz and Richter-Menge caution that while they are optimistic about the new product, it still needs testing. After the upcoming sea ice minimum, researchers can compare the quick look and traditional products and test models using the quick look data against observations. "As the season goes on, we'll see how useful the quick look product is," Richter-Menge said.

Next year's Arctic campaign will see further refinement of the methods used to create the quick look product. "The key is knowing how to deal with the data," Kurtz said. He plans to return to Greenland in 2013 to work on ways to speed up processing. "I learned a lot this year," Kurtz said. "It should be easier now that I've done it once."

For more information on the Airborne Topographic Mapper and snow radar instruments, visit:

• http://www.nasa.gov/mission_pages/icebridge/instruments/atm.html
• http://www.nasa.gov/mission_pages/icebridge/instruments/snow.html

As Tropical Storm Isaac heads toward Louisiana on the verge of hurricane strength a lot can be at stake, including your health. According to the American College of Allergy, Asthma and Immunology (ACAAI), the drastic climate changes brought on by the storm can cause mild to life-threating allergy and asthma symptoms.

As heavy rain hits several areas of the south, ragweed pollens that are in bloom can be washed away. However, once the rain clears, pollen counts can soar. Cold and warm fronts, along with winds created by the storm, can also affect pollen and increase mold levels.

"Hurricanes and other severe storms can create drastic climate changes," said allergist Stanley Fineman, MD, president of the American College of Allergy, Asthma and Immunology. "This erratic weather can influence the severity of allergy and asthma symptoms for the more than 40 million Americans that suffer from these conditions."

In previous years, allergists have seen an increase in patients presenting heightened allergy and asthma symptoms during severe storms. These climate changes may also mean more misery this fall allergy season. Moisture and humidity can cause pollen and mold to linger. An Indian Summer can also lead to extended allergen counts.

"Although symptoms may not always be severe, allergies and asthma are serious and, in some cases, deadly," said Dr. Fineman. "The conditions, however, can be effectively controlled with proper diagnosis and treatment by a board certified allergist."

ACAAI allergists recommend treating allergies and asthma before symptoms begin. Knowing the weather changes that affect your allergy and asthma symptoms can help you predict flare-ups. These climate changes include:

• Heavy rainfall -Pollen and mold counts increase, and attract West Nile carrying mosquitos

• Cool nights and warm days — Tree, grass and ragweed pollens thrive in this environment

• Heat and humidity — Mold spores can multiply

• Wind — Pollen and mold can be stirred into the air, and when it's warm, pollen counts surge

• Calm days — Absent winds cause allergens to be grounded, but they can be stirred into the air when mowing the lawn or raking leaves

In the event of flooding, ACAAI recommends removing the water as soon as possible and cleaning any visible mold before it spreads.

— Seven years after the powerful Category 3 Hurricane Katrina caused widespread devastation along the Gulf Coast, a Category 1 Hurricane Isaac, with maximum sustained winds of 80 miles per hour (70 knots), made landfall Aug. 28 in southeast Louisiana. And one of the reasons why Isaac is not Katrina is the path it took across the Gulf of Mexico and the temperature of the ocean below, which helps to fuel hurricanes.

In 2005, Hurricane Katrina's maximum wind speeds increased dramatically as the storm passed over a warm ocean circulation feature called the Loop Current that is part of the Gulf Stream. The storm evolved quickly from a Category 3 to a Category 5 event on the Saffir-Simpson Hurricane Wind Scale in a matter of nine hours as it drew heat from the Loop Current. It subsequently dropped in intensity to a Category 3 storm at landfall.

Because the Loop Current and its eddies are warmer, and thus higher in surface elevation, than the surrounding waters, they are easily spotted by satellite altimeter instruments, such as those aboard the NASA/French Space Agency Jason 1 and Ocean Surface Topography Mission/Jason 2 satellites. Scientists use the latest satellite measurements of sea-surface height from these and other satellite altimeters to create maps showing the location, direction and speed of currents in the Gulf of Mexico.

This color-enhanced image of sea surface heights in the northeastern Gulf, produced using data from available satellite altimeters, including NASA's Jason-1 and Jason-2 satellites, shows Isaac's path through the Gulf. The storm skirted around the Loop Current, then caught the outer edge of a warm eddy before passing directly over a cold eddy. The storm's track away from the Gulf's warmest waters has helped to keep Isaac from intensifying rapidly, as Hurricanes Katrina and Rita did in 2005.

Warm eddies have high heat content and great potential to intensify hurricanes, whereas cold eddies have low heat content and may even cause hurricanes to weaken, as was the case with Hurricane Ivan in 2004.

For more on NASA's satellite altimetry missions, visit: http://sealevel.jpl.nasa.gov/ .

Strong winds and storm surge from Hurricane Isaac's landfall forced the Mississippi River to flow backwards for nearly 24 hours on Tuesday, August 28. The USGS streamgage at Belle Chasse, Louisiana, showed the Mississippi River flowing upstream at 182,000 cubic feet per second, surging to 10 feet above than its previous height. Average flow for the Mississippi River at Belle Chase is about 125,000 cfs towards the Gulf of Mexico.

Although it doesn't happen often, hurricanes can cause coastal rivers to reverse flow. Between the extremely strong winds and the massive waves of water pushed by those winds, rivers at regular or low flow are forced backwards until either the normal river-flow or the elevation of the land stop the inflow.

As Hurricane Isaac pushes further inland, it is causing storm surge in the Mississippi River as far north as Baton Rouge, where the river has crested at 8 feet above its prior height.

"This reversal of flow of the mighty Mississippi is but one measure of the extreme force of Isaac," said USGS Director Marcia McNutt. "While such events are ephemeral, they are yet another reminder of why we need to respect hurricane warnings."

When Hurricane Katrina came ashore in 2005, the Mississippi River also reversed flow, cresting at 13 feet above its previous level, with Baton Rouge reaching 9 feet above its previous stage as well.

Another phenomenon that USGS streamgages have recorded as Hurricane Isaac moves inland is that periodically, coastal rivers in Louisiana have lost height, only to gain it back again soon after. This rising and falling of the rivers is a common occurrence during hurricanes and is caused by the spiral nature of these storms.

As the winds sweep to the southwest, they force water out of the rivers, lowering their height. However, once the winds complete their turn to the southwest, they begin back to the northeast, allowing the storm surge to raise the river levels.

These oddities in river behavior are recorded in real-time by USGS' extensive network of streamgages, located through Louisiana and the rest of the country. These streamgages, which are installed along rivers and streams, record data like streamflow, river height, and, in some cases, even water chemistry.

Many transmit their data in real-time to satellites, updating with new information every 15 minutes. This wealth of data allows USGS scientists, emergency managers and responders, and even the general public to have accurate and up-to-date knowledge of what the rivers and streams in their areas are doing. This data is particularly critical during massive flooding events like Hurricane Isaac.

In fact, anyone can sign up to receive notices from USGS streamgages when waters are rising in nearby rivers and streams through a program called WaterAlert (http://water.usgs.gov/wateralert/). It is a free service that allows members of the public to receive notifications about water levels at any of over 7,000 USGS real-time streamgages around the country. Learn more about how to sign up at: http://www.usgs.gov/newsroom/article.asp?from=rss&ID=2919#.UD5HrVI6W7w .

All USGS streamgage information is housed online (http://waterdata.usgs.gov/nwis/rt). For Hurricane Isaac, USGS has compiled a list of all streamgages in affected areas (http://water.usgs.gov/floods/events/2012/isaac/StormTideAndRDG.html).

For the latest forecasts on the storm, listen to NOAA radio. For information on preparing for the storm, visit Ready.gov or Listo.gov

— Hurricane Isaac is continuing to drop heavy rainfall over Louisiana and Mississippi, and NASA's TRMM satellite identified that rainfall as the storm was making landfall.

On Aug. 29, 2012 at 1 p.m. EDT, Isaac was still a hurricane with maximum sustained winds near 75 mph (120 kmh). Isaac was located about 10 miles northwest (15 km) of Houma, Louisiana and moving slowly. It is moving to the northwest near 6 mph (9 km). Isaac continued bringing heavy rainfall to southeastern Louisiana and southern Mississippi. The threat for dangerous coastal storm surge and inland flooding are expected to continue overnight.

The Tropical Rainfall Measuring Mission (TRMM) satellite flew over Hurricane Isaac twice on the night that Isaac made landfall in Louisiana and headed for New Orleans. TRMM is a joint mission managed by both NASA and JAXA, the Japanese Space Agency.

In the first of the two overflights, the TRMM radar saw two hot towers in the eyewall of Hurricane Isaac just hours before landfall. While hot towers were shooting up in the eyewall over the ocean, Isaac's inner rainband was already lashing Louisiana with heavy rain. Hot towers are common in intensifying tropical cyclones are are a sign that energy is being pumped into the hurricane from the ocean's surface. A "hot tower" is a tall cumulonimbus cloud that reaches at least to the top of the troposphere, the lowest layer of the atmosphere. It extends approximately nine miles (14.5 km) high in the tropics.

Two images were created by Owen Kelley, of NASA's Goddard Space Flight Center, Greenbelt, Md. The background of the first image showed TRMM infrared observations that give a sense of the height of the cloud cover the hides the heavy precipitation inside of of the hurricane. The blue-gray 3D volume contains the light precipitation inside the hurricane, using a 20 dBZ radar-reflectivity threshold.

In the image, an insert reveals details at the center of the hurricane. Two hot towers are indicated by the yellow and orange colors. They are locations where strong updrafts are lifting frozen precipitation above a 14.5 km (9.1 mile) threshold. Water that condenses in updrafts will soon freeze if updrafts lift it above the zero-degree isotherm near 5 kilometers (3.1 miles) altitude. The freezing releases another boost of latent heat, the fuel of hurricanes, following the initial release of latent heat when the water vapor condenses into liquid.

The TRMM radar happened to overfly Hurricane Isaac again just five hours later, shortly after the eyewall made landfall. Robbed of its oceanic source of energy, the eyewall hot towers are gone in this later overflight. Instead of reaching 14.5 km (9.1 mile) altitude, the eyewall merely reaches a 10 km (6.2 mile) altitude, which is indicated by the light green shading at the top of the blue-green volume of light precipitation.

Unfortunately for New Orleans and surrounding areas, TRMM sees that Hurricane Isaac's eyewall was remarkably well organized at that time, despite having made landfall. The insert shows a ring of very intense radar echos in red, echos that exceed 40 dBZ radar reflectivity. The northwest quadrant of his ring of heavy precipitation is almost on top of New Orleans at the time of observation.

— Reservoirs near the mouth of the Susquehanna River just above Chesapeake Bay are nearly at capacity in their ability to trap sediment. As a result, large storms are already delivering increasingly more suspended sediment and nutrients to the Bay, which may negatively impact restoration efforts.

Too many nutrients rob the Bay of oxygen needed for fish and, along with sediment, cloud the waters, disturbing the habitat of underwater plants crucial for aquatic life and waterfowl.

"The upstream reservoirs have served previously to help reduce nutrient pollutant loads to the Chesapeake Bay by trapping sediment and the pollutants attached to them behind dams," explained USGS Director Marcia McNutt. "Now that these reservoirs are filling to capacity with sediment, they have become much less effective at preventing nutrient-rich sediments from reaching the Bay. Further progress in meeting the goals for improving water quality in the Chesapeake will be more difficult to achieve as a result."

"It has been understood for many years that as the reservoirs on the Lower Susquehanna River fill with sediment, there will be a substantial decrease in their ability to limit the influx of sediment and nutrients, especially phosphorus, to the Chesapeake Bay," said Bob Hirsch, research hydrologist and author of the report. "Analysis of USGS water quality data from the Susquehanna River, particularly the data from Tropical Storm Lee in September 2011, provides evidence that the increases in nutrient and sediment delivery are not just a theoretical issue for future consideration, but are already underway."

According to a new USGS report, the Susquehanna River delivered more phosphorus and sediment to the Bay during 2011 than from than any other year since monitoring began in 1978. Flooding from Tropical Storm Lee made up a large fraction of the Susquehanna River's inputs to the Bay for both 2011 and over the last decade. During the flooding the Susquehanna River delivered about 2 percent of total water to the Bay for the last decade; however, it delivered 5 percent of the nitrogen, 22 percent of the phosphorus, and 39 percent of the suspended sediment.

According to the report, from 1996-2011 total phosphorus moving into the Bay has increased by 55 percent, and suspended sediment has increased by 97 percent. Over this time period, total nitrogen decreased by about 3 percent overall, but showed increases during large events.

These results represent the combined effects of the changes in sediment within the reservoirs, as well as changes in the sources of these constituents upstream. Another recent USGS study reported about a 25 percent reduction in nutrients and sediment concentrations just upstream of the reservoirs, reflecting the benefit of actions to improve water quality in the upper portion of the Susquehanna River watershed.

"Progress on reducing loadings of these pollutants from the Susquehanna River Basin depends on efforts made to limit the loadings in the watershed, as well as the effects of the downstream reservoirs," said Hirsch. "In general, the changes we have observed in the reservoirs and the resulting greater impact of storms are already overshadowing the ongoing progress being made in the watershed to reduce the amount of nutrients and sediments entering the Bay."

Sediment and nutrient loadings from the Susquehanna River are crucial to understanding the status and progress of water quality in the Chesapeake Bay. On average, the Susquehanna River contributes nearly 41 percent of the nitrogen, 25 percent of the phosphorus, and 27 percent of the sediment load to the Bay.

"The findings of this USGS study increase the urgency of identifying and implementing effective management options for addressing the filling reservoirs," said Bruce Michael, director, Resource Assessment Service for the Maryland Department of Natural Resources. "The Lower Susquehanna River Watershed Assessment study, a 3-year partnership of federal, state, private sector, and non-governmental organizations, is developing potential management options for extending the sediment-holding capacity of the reservoirs. The USGS information is critical for guiding the strategies undertaken by the Chesapeake Bay Program to assure that the actions taken in the watershed will serve to meet restoration goals."

The lower reaches of the Susquehanna River, just upstream from Chesapeake Bay, include three reservoirs: Safe Harbor Dam and Holtwood Dam in Pennsylvania and Conowingo Dam in Maryland. Over the past several decades these reservoirs have been gradually filling with sediment.

While the reservoirs are filling, they are a trap for sediment and the nutrients attached to that sediment. As a reservoir approaches its sediment storage capacity, it can't hold as much sediment. When reservoirs are near capacity, significant flow events, such as flooding from Tropical Storm Lee, have greater potential to cause scour, or the sudden removal of large amounts of sediment, allowing that sediment and attached nutrients to flow out of the reservoirs and into the Bay.

Additionally, as the reservoir becomes filled, the channel that water flows through gets smaller. As a result, for any given amount of flow, the water moves through the channel faster, further increasing the likelihood of scour. Higher velocities also result in lower rates of settling, decreasing the amount of sediment that will be deposited.

This new report is based on 34 years of monitoring streamflow and water quality for the Susquehanna River by the USGS and its state and local partners. The report compares nutrients and sediment behavior during high flow events, such as the flood after Tropical Storm Lee in September of 2011, the high flows of March 2011, and Hurricane Ivan in 2004, with high flow conditions of the past.

This research was conducted as part of The USGS National Research Program in Water Resources and the USGS Chesapeake Bay Ecosystems Program. The report, titled Flux of nitrogen, phosphorus, and suspended sediment from the Susquehanna River Basin to the Chesapeake Bay during Tropical Storm Lee, September 2011, as an indicator of the effects of reservoir sedimentation on water quality, can be found online (http://pubs.usgs.gov/sir/2012/5185).

NASA's Radiation Belt Storm Probes (RBSP), the first twin-spacecraft mission designed to explore our planet's radiation belts, launched into the predawn skies at 4:05 a.m. EDT Thursday from Cape Canaveral Air Force Station, Fla.

"Scientists will learn in unprecedented detail how the radiation belts are populated with charged particles, what causes them to change and how these processes affect the upper reaches of the atmosphere around Earth," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate at Headquarters in Washington. "The information collected from these probes will benefit the public by allowing us to better protect our satellites and understand how space weather affects communications and technology on Earth."

The two satellites, each weighing just less than 1,500 pounds, comprise the first dual-spacecraft mission specifically created to investigate this hazardous regions of near-Earth space, known as the radiation belts. These two belts, named for their discoverer, James Van Allen, encircle the planet and are filled with highly charged particles. The belts are affected by solar storms and coronal mass ejections and sometimes swell dramatically. When this occurs, they can pose dangers to communications, GPS satellites and human spaceflight.

"We have never before sent such comprehensive and high-quality instruments to study high radiation regions of space," said Barry Mauk, RBSP project scientist at the Johns Hopkins University's Applied Physics Laboratory (APL) in Laurel, Md. "RBSP was crafted to help us learn more about, and ultimately predict, the response of the radiation belts to solar inputs."

The hardy RBSP satellites will spend the next 2 years looping through every part of both Van Allen belts. By having two spacecraft in different regions of the belts at the same time, scientists finally will be able to gather data from within the belts themselves, learning how they change over space and time. Designers fortified RBSP with special protective plating and rugged electronics to operate and survive within this punishing region of space that other spacecraft avoid. In addition, a space weather broadcast will transmit selected data from those instruments around the clock, giving researchers a check on current conditions near Earth.

"The excitement of seeing the spacecraft in orbit and beginning to perform science measurements is like no other thrill," said Richard Fitzgerald, RBSP project manager at APL. "The entire RBSP team, from across every organization, worked together to produce an amazing pair of spacecraft."

RBSP was lifted into orbit aboard an Atlas V 401 rocket from Space Launch Complex-41, as the rocket's plume lit the dark skies over the Florida coast. The first RBSP spacecraft is scheduled to separate from the Atlas rocket's Centaur booster 1 hour, 18 minutes, 52 seconds after launch. The second RBSP spacecraft is set to follow 12 minutes, 14 seconds later. Mission controllers using APL's 60-foot satellite dish will establish radio contact with each probe immediately after separation.

During the next 60 days, operators will power up all flight systems and science instruments and deploy long antenna booms, two of which are more than 54 yards long. Data about the particles that swirl through the belts, and the fields and waves that transport them, will be gathered by five instrument suites designed and operated by teams at the New Jersey Institute of Technology in Newark; the University of Iowa in Iowa City; University of Minnesota in Minneapolis; and the University of New Hampshire in Durham; and the National Reconnaissance Office in Chantilly, Va. The data will be analyzed by scientists across the nation almost immediately.

RBSP is the second mission in NASA's Living With a Star (LWS) program to explore aspects of the connected sun-Earth system that directly affect life and society. LWS is managed by the agency's Goddard Space Flight Center in Greenbelt, Md. APL built the RBSP spacecraft and will manage the mission for NASA. NASA's Launch Services Program at Kennedy is responsible for launch management. United Launch Alliance provided the Atlas V launch service.

 Isaac — once a Category 1 hurricane and now a strong tropical storm with maximum sustained winds of 70 miles per hour (60 knots) — continues to create havoc across the Gulf Coast, from eastern Texas to Florida. While "only" reaching Category 1 on the Saffir-Simpson hurricane wind scale upon landfall on Aug. 28, Isaac is a slow mover, crawling along at only about six miles (10 kilometers) per hour. This slow movement is forecast to continue over the next 24 to 36 hours, bringing a prolonged threat of flooding to the northern Gulf Coast and south-central United States.

As seen in this infrared image from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft, acquired at 2:41 p.m. CDT on Aug. 29, 2012, the large storm is still relatively well organized and is producing strong bands of thunderstorms. The broad area of purple in the image represents cloud-top temperatures colder than minus 63 degrees Fahrenheit (minus 52 degrees Celsius) around the center of the storm's circulation. It is here that Isaac's strongest storms and heaviest rainfall are now occurring.

According to the National Oceanic and Atmospheric Administration's National Hurricane Center, strong bands of thunderstorms continue to develop over water in the storm's eastern semicircle and southwest of the center. These strong rain bands are forecast to spread gradually to the west tonight across coastal southeastern Louisiana and southern Mississippi, including the New Orleans metropolitan area. The storm is expected to weaken to a tropical depression by Thursday night and a post-tropical remnant low-pressure system by Friday.

For more on NASA's Atmospheric Infrared Sounder, visit: http://airs.jpl.nasa.gov/.

The stress of drought is acutely felt by aquatic animals such as salamanders. The extreme drought in the southeastern United States in 2007-2008 provided an opportunity to study how salamanders react and survive during such dry conditions. It also gave us clues as to how salamanders and other aquatic organisms may react to global warming.

The journal Herpetologica reports on a 5-year study of the Northern Dusky Salamander, common to eastern North America. From 2005 to 2009, including two severe drought years, the presence of salamanders was recorded at 17 first-order streams in the Piedmont region of North Carolina. Data on the amphibians' presence were established by capturing, marking, and recapturing salamanders over the course of the study.

Researchers found that the adult salamanders had a high rate of survival over the course of the study, even during the drought years. The abundance of larval salamanders, however, decreased by an average of 30 percent during the drought. This differential mortality suggests a between-generation survival strategy, with the high survival rate of adults mitigating the effect of drought on the numbers of larvae.

During the extreme drought, water levels reached a 110-year low. Many streams were dry for periods of 2 to 3 months at a time, reduced to pools rather than flowing water. These conditions brought about another survival strategy, temporary migration of adult salamanders — at twice the rate of non-drought years. They moved from stream beds to underground or high-humidity refuges. Crayfish burrows and rocks provided shelter from the hot and dry conditions.

Because climate change is expected to bring warming trends and more drought, this study offers implications for the survival of stream-dwelling salamanders. An increase in the mortality of larvae, or early metamorphosis, could mean declines in salamander fitness and size.