GeoEye has released the first, color half-meter ground resolution image taken from its GeoEye-1 satellite. The satellite has been undergoing calibration and check-out since it was launched on Sept. 6 from Vandenberg Air Force Base in Calif. The Company will begin selling GeoEye-1 imagery products later this fall.
Matthew O'Connell, GeoEye's chief executive officer, said, "We are pleased to release the first GeoEye-1 image, bringing us even closer to the start of the satellite's commercial operations and sales to our customers.
This is a remarkable achievement, and I want to thank all of our employees, customers, especially the National Geospatial-Intelligence Agency, strategic partners, vendors and investors for their support."
GeoEye-1 simultaneously collects 0.41-meter ground resolution black-and-white imagery in the panchromatic mode and 1.65-meter color (multispectral). This first image showing Kutztown University located midway between Reading and Allentown, Penn. was produced by fusing the satellite's panchromatic and multispectral data to produce a high-quality, true-color half-meter resolution image.
Though the satellite collects imagery at 0.41-meter ground resolution, due to U.S. licensing restrictions, commercial customers will only get access to imagery that has been processed to half-meter ground resolution.
Bill Schuster, GeoEye's chief operating officer, said, "We are bringing GeoEye-1 into service within four years of our contract award with no contract cost overruns. The entire program which includes the satellite, launch, insurance, financing and four ground stations was less than $502 million. That's the amount established and agreed to four years ago."
He further noted, "GeoEye-1 is an excellent fit to meet the U.S. Government's important requirements for mapping and broad area space-based imagery collection over the next decade."
Brad Peterson, GeoEye's vice president of operations, said, "This image captures what is in fact the very first location the satellite saw when we opened the camera door and started imaging. We expect the quality of the imagery to be even better as we continue the calibration activity."
The Kutztown University image shows the campus, which includes academic buildings, parking lots, roads, athletic fields and the track-and-field facility. The image was collected at 12:00 p.m. EDT on Oct. 7, 2008 while GeoEye-1 was moving north to south in a 423-mile-high (681 km) orbit over the eastern seaboard of the U.S. at a speed of four-and-one-half miles per second. GeoEye-1 was built by General Dynamics Advanced Information Systems in Gilbert, Ariz. The imaging system was built by ITT in Rochester, NY.
The thickness of sea ice in large parts of the Arctic declined by as much as 19% last winter compared to the previous five winters, according to data from ESA's Envisat satellite.
Using Envisat radar altimeter data, scientists from the Centre for Polar Observation and Modelling at University College London (UCL) measured sea ice thickness over the Arctic from 2002 to 2008 and found that it had been fairly constant until the record loss of ice in the summer of 2007.
Unusually warm weather conditions were present over the Arctic in 2007, which some scientists have said explain that summer ice loss. However, this summer reached the second-lowest extent ever recorded with cooler weather conditions present.
Dr Katharine Giles of UCL, who led the study, said: "This summer's low ice extent doesn't seem to have been driven by warm weather, so the question is, was last winter's thinning behind it?"
The research, reported in Geophysical Research Letters, showed that last winter the average thickness of sea ice over the whole Arctic fell by 26 cm (10%) compared with the average thickness of the previous five winters, but sea ice in the western Arctic lost around 49 cm of thickness.
Giles said the extent of sea ice in the Arctic is down to a number of factors, including warm temperatures, currents and wind, making it important to know how ice thickness is changing as well as the extent of the ice.
"As the Arctic ice pack is constantly moving, conventional methods can only provide sparse and intermittent measurements of ice thickness from which it is difficult to tell whether the changes are local or across the whole Arctic," Giles said.
"Satellites provide the only means to determine trends and a consistent and wide area basis. Envisat altimeter data have provided the critical third dimension to the satellite images which have already revealed a dramatic decrease in the area of ice covered in the Arctic."
The team, including Dr Seymour Laxon and Andy Ridout, was the first to measure ice thickness throughout the Arctic winter, from October to March, over more than half of the Arctic.
"We will continue to use Envisat to monitor the evolution of ice thickness through this winter to see whether this downward trend will continue," Laxon said. "Next year we will have an even better tool to measure ice thickness in the shape of ESA's CryoSat-2 mission which will provide higher resolution data and with almost complete coverage to the pole."
A NASA/university team has published the first global satellite maps of the key greenhouse gas carbon dioxide in Earth's mid-troposphere, an area about 8 kilometers, or 5 miles, above Earth.
The team's study reveals new information on how carbon dioxide, which directly contributes to climate change, is distributed in Earth's atmosphere and moves around our world.
A research team led by Moustafa Chahine of NASA's Jet Propulsion Laboratory, Pasadena, Calif., found the distribution of carbon dioxide in the mid-troposphere is strongly influenced by major surface sources of carbon dioxide and by large-scale atmospheric circulation patterns, such as the jet streams and weather systems in Earth's mid-latitudes.
Patterns of carbon dioxide distribution were also found to differ significantly between the northern hemisphere, with its many land masses, and the southern hemisphere, which is largely covered by ocean.
The findings are based on data collected from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft between September 2002 and July 2008. Chahine, the instrument's science team leader, said the research products will be used by scientists to refine models of the processes that transport carbon dioxide within Earth's atmosphere.
"These data capture global variations in the distribution of carbon dioxide over time," Chahine said. "These variations are not represented in the four chemistry-transport models used to determine where carbon dioxide is created and stored."
Chahine said the AIRS data will complement existing and planned ground and aircraft measurements of carbon dioxide, as well as upcoming satellite missions to study Earth's carbon cycle and climate. Included in the new satellite missions is NASA's Orbiting Carbon Observatory, planned for launch in January 2009.
The combination of carbon dioxide data from AIRS and the Orbiting Carbon Observatory will allow scientists to determine the distribution of carbon dioxide in the lower atmosphere, above Earth's surface.
"Carbon dioxide is difficult to measure and track," he said. "No place on Earth is immune from its influence. It will take many independent measurements, including AIRS, to coax this culprit out of hiding and track its progress from creation to storage."
The new maps reveal enhanced concentrations of carbon dioxide south of the northern hemisphere jet stream, in a band between 30 and 40 degrees north latitude. These enhanced concentrations correspond to a well-documented belt of pollution in the northern hemisphere mid-latitudes.
The team attributed the increased levels of carbon dioxide detected over the western North Atlantic to emissions transported from the Southeast U.S. on warm atmospheric "conveyor belts." These belts lift carbon dioxide from Earth's surface into the middle and upper troposphere.
The AIRS maps also showed enhanced carbon dioxide over the Mediterranean, resulting from North American and European sources. Carbon dioxide from South Asia ended up over the Middle East, while carbon dioxide from East Asia flowed out over the Pacific Ocean.
In the southern hemisphere, a belt of mid-tropospheric air containing enhanced concentrations of carbon dioxide emerged between 30 and 40 degrees south latitude. This belt had not previously been seen in the four chemistry-transport models used in this study.
The researchers say the flow of air in this belt over South America's high Andes Mountains lifts carbon dioxide from major sources on Earth's surface, such as the respiration of plants, as well as forest fires and facilities used for synthetic fuel production and power generation.
A portion of this lifted carbon dioxide is then carried into the mid-troposphere, where it becomes trapped in the mid-latitude jet stream and transported rapidly around the world.
"The troposphere is like international waters," Chahine said. "What's produced in one place will travel elsewhere."
Study results were published recently in Geophysical Research Letters. Other participants included the California Institute of Technology, Pasadena, Calif.; and the University of California, Irvine.
Community
The 2008 ozone hole - a thinning in the ozone layer over Antarctica - is larger both in size and ozone loss than 2007 but is not as large as 2006.
Ozone is a protective atmospheric layer found in about 25 kilometres altitude that acts as a sunlight filter shielding life on Earth from harmful ultraviolet rays, which can increase the risk of skin cancer and cataracts and harm marine life.
This year the area of the thinned ozone layer over the South Pole reached about 27 million square kilometres, compared to 25 million square kilometres in 2007 and a record ozone hole extension of 29 million square kilometres in 2006, which is about the size of the North American continent.
The depletion of ozone is caused by extreme cold temperatures at high altitude and the presence of ozone-destructing gases in the atmosphere such as chlorine and bromine, originating from man-made products like chlorofluorocarbons (CFCs), which were phased out under the 1987 Montreal Protocol but continue to linger in the atmosphere.
Depending on the weather conditions, the size the Antarctic ozone hole varies every year. During the southern hemisphere winter, the atmosphere above the Antarctic continent is kept cut off from exchanges with mid-latitude air by prevailing winds known as the polar vortex - the area in which the main chemical ozone destruction occurs.
The polar vortex is characterized by very low temperatures leading to the presence of so-called stratospheric clouds (PSCs).
As the polar spring arrives in September or October, the combination of returning sunlight and the presence of PSCs leads to a release of highly ozone-reactive chlorine radicals that break ozone down into individual oxygen molecules. A single molecule of chlorine has the potential to break down thousands of molecules of ozone.
Julian Meyer-Arnek of the German Aerospace Centre (DLR), which monitors the hole annually, explained the impact of regional meteorological conditions on the time and range of the ozone hole by comparing 2007 with 2008.
"In 2007 a weaker meridional heat transport was responsible for colder temperatures in the stratosphere over the Antarctic, leading to an intensified formation of PSCs in the stratosphere," Meyer-Arnek said.
"Therefore, we saw a fast ozone hole formation in the beginning of September 2007."
"In 2008 a stronger-than-usual meridional heat transport caused warmer temperatures in the Antarctic stratosphere than usual, reducing the formation of PSCs. Consequently, the conversion of chemically inactive halogens into ozone-destroying substances was reduced. As a result in the beginning of September 2008, the ozone hole area was slightly smaller than average," he continued.
"Since the polar vortex remained undisturbed for a long period, the 2008 ozone hole became one of the largest ever observed." Minimum values of the ozone layer of about 120 Dobson Units are observed this year compared to around 100 Dobson Units in 2006. A Dobson Unit is a unit of measurement that describes the thickness of the ozone layer in a column directly above the location of measurement.
DLR's analysis is based upon the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) atmospheric sensor onboard ESA's Envisat, the Global Ozone Monitoring Experiment (GOME) aboard ESA's ERS-2 and its follow-on instrument GOME-2 aboard EUMETSAT's MetOp.
Scientists say that since the size and precise time of the ozone hole is dependent on the year-to-year variability in temperature and atmospheric dynamics, the detection of signs of ozone recovery is difficult.
"In order to detect these signs of recovery, a continuous monitoring of the global ozone layer and in particular of the Antarctic ozone hole is crucial," Meyer-Arnek said.
In order to train the next generation of atmospheric scientists to continue the monitoring, students at ESA's Advanced Atmospheric Training Course, held 15-20 September at University of Oxford, UK, were given the task of analysing this year's ozone hole with Envisat sensors.
Studying the Envisat data, the students' findings were in line with atmospheric scientists that the south polar vortex was more concentric in 2008 than in 2007, leading to a relatively late onset of ozone depletion, and that the size of this year's hole is similar to previous years.
"This exercise led us to realise that although many questions have been answered and much has been learned about the stratospheric chemistry and atmospheric dynamics driving ozone hole behaviour, many new questions must be raised especially concerning ozone hole recovery," said Deborah C Stein Zweers, a post-doc satellite researcher from the Royal Netherlands Meteorological Institute (KNMI) who attended the course.
"We want to know when the ozone hole will recover, how its recovery will be complicated by an environment with increasing greenhouse gases and how atmospheric dynamics will shape future ozone holes. These and many other questions will attract the attention of our generation of scientists for the next several decades." Community
GeoEye has released the first, color half-meter ground resolution image taken from its GeoEye-1 satellite. The satellite has been undergoing calibration and check-out since it was launched on Sept. 6 from Vandenberg Air Force Base in Calif. The Company will begin selling GeoEye-1 imagery products later this fall.
