Pollutants from Asia hover in stratosphere during monsoon

March 26, 2010 By Leave a Comment

Washington, March 26 (ANI): In a new study, scientists at the National Center for Atmospheric Research, US, pollutants from the Asian region are being wafted up to the stratosphere during monsoon season.

Using satellite observations and computer models, the research team determined that vigorous summertime circulation patterns associated with the Asian monsoon rapidly transport air upward from the Earth”s surface.

Those vertical movements provide a pathway for black carbon, sulfur dioxide, nitrogen oxides, and other pollutants to ascend into the stratosphere, about 20-25 miles above the Earth”s surface.

“The monsoon is one of the most powerful atmospheric circulation systems on the planet, and it happens to form right over a heavily polluted region,” said NCAR scientist William Randel, the lead author of the study.

“As a result, the monsoon provides a pathway for transporting pollutants up to the stratosphere,” he added.

Once in the stratosphere, the pollutants circulate around the globe for several years.

Some eventually descend back into the lower atmosphere, while others break apart.

The study suggests that the impact of Asian pollutants on the stratosphere may increase in coming decades because of the growing industrial activity in China and other rapidly developing nations.

In addition, climate change could alter the Asian monsoon.

Randel and his colleagues suspected that the monsoon might also transport air into the stratosphere during the Northern Hemisphere”s summer months.

This could explain satellite measurements showing anomalous levels of stratospheric ozone, water vapor, and other chemicals over Asia during summer.

To isolate the role of the monsoon on the stratosphere, the researchers focused on a chemical, hydrogen cyanide, that is produced largely as a result of the burning of trees and other vegetation.

The parcels of air over the tropical ocean that are lifted to the stratosphere by the Brewer-Dobson circulation contain low amounts of hydrogen cyanide, which breaks up over the ocean.

But air over land that gets lifted up by the monsoon contains high levels of the chemical, especially during times of year when Asia has widespread fires, many set to clear land for agriculture.

When they examined satellite measurements, the researchers detected significant amounts of hydrogen cyanide throughout the lower atmosphere and up into the stratosphere over the monsoon region.

Furthermore, satellite records from 2004 to 2009 showed a pattern of increases in the chemical”s presence in the stratosphere each summer, correlating with the timing of the monsoon.

The observations also showed hydrogen cyanide, which can last in the atmosphere for several years before breaking up, moving over the tropics with other pollutants and then circulating globally. (ANI)

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Scientists make interior weather map of Jupiter’s giant storm system

March 17, 2010 By Leave a Comment

Munich, March 17 (ANI): Using new ground-breaking thermal images obtained with ESO’s (European Southern Observatory’s) Very Large Telescope and other powerful ground-based telescopes, scientists have made the first detailed interior weather map of Jupiter’s giant storm system linking its temperature, winds, pressure and composition with its colour.

The images show swirls of warmer air and cooler regions never seen before within Jupiter’s Great Red Spot.

“This is our first detailed look inside the biggest storm of the Solar System,” said Glenn Orton, who led the team of astronomers that made the study.

“We once thought the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated,” he added.

The observations reveal that the reddest colour of the Great Red Spot corresponds to a warm core within the otherwise cold storm system, and images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet.

The observations, detailed in a paper appearing in the journal Icarus, give scientists a sense of the circulation patterns within the solar system’s best-known storm system.

Sky gazers have been observing the Great Red Spot in one form or another for hundreds of years, with continuous observations of its current shape dating back to the 19th century.

The spot, which is a cold region averaging about -160 degrees Celsius, is so wide that about three Earths could fit inside its boundaries.

The thermal images were mostly obtained with the VISIR instrument attached to ESO’s Very Large Telescope in Chile, with additional data coming from the Gemini South telescope in Chile and the National Astronomical Observatory of Japan’s Subaru Telescope in Hawaii.

“One of the most intriguing findings shows the most intense orange-red central part of the spot is about 3 to 4 degrees warmer than the environment around it,” said lead author Leigh Fletcher.

This temperature difference might not seem like a lot, but it is enough to allow the storm circulation, usually counter-clockwise, to shift to a weak clockwise circulation in the very middle of the storm.

Not only that, but on other parts of Jupiter, the temperature change is enough to alter wind velocities and affect cloud patterns in the belts and zones.

“This is the first time we can say that there’s an intimate link between environmental conditions – temperature, winds, pressure and composition – and the actual colour of the Great Red Spot,” said Fletcher. (ANI)

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Human impacts and environmental factors changing northwest Atlantic ecosystem

September 2, 2009 By Leave a Comment

Washington, Sept 2 (ANI): A new report by researchers at the National Oceanic and Atmospheric Administration (NOAA) has determined that human impacts and environmental factors are changing the northwest Atlantic ecosystem.

According to the report, fish in US waters from Cape Hatteras to the Canadian border have moved away from their traditional, long-time habitats over the past four decades because of fundamental changes in the regional ecosystem.

The 2009 Ecosystem Status Report also points out the need to manage the waters off the northeastern coast of the United States as a whole rather than as a series of separate and unrelated components.

Known as the Northeast US Continental Shelf Large Marine Ecosystem (NES LME), the ecosystem spans approximately 100,000 square miles and supports some of the highest revenue-generating fisheries in the nation.

During the past 40 years, the ecosystem has experienced extensive fishing by domestic and foreign fleets, changes in ocean water temperatures due to climate change, and pressures from increasing human populations along the coast.

According to Michael Fogarty, who heads the Ecosystem Assessment Program at the Northeast Fisheries Science Center (NEFSC) of NOAA’s Fisheries Service in Woods Hole, Massachusetts, his team’s report highlights the need to understand natural and human-related changes in this region and to develop effective management and mitigation strategies.

“There are many pressures on the ecosystem including fishing, pollution, habitat loss from coastal development, and impacts on marine life from shipping and other uses of the ocean,” Fogarty said.

“In addition, changing climate conditions are warming ocean waters, changing ocean chemistry and circulation patterns, and altering atmospheric systems. These changes have, in turn, been linked to changes in the distribution and abundance of fish species in the region and their major sources of food,” he added.

The report is the first in a planned series of ecosystem status reports by Fogarty and his colleagues in the NEFSC’s Ecosystem Assessment Program to document changes in the NES LME, one of 64 regions in the world’s ocean designated as a large marine ecosystem.

Fogarty said that sustained long-term monitoring by many agencies and institutions in the Northeast region has enabled scientists and others to trace changes in the ecosystem.

“In the future, we need to continue to monitor the oceanographic, ecological, and human indicators analyzed in this report to detect any additional changes in the system. These indicators also provide important inputs to models that can be used to help guide management decisions and to forecast future changes,” he said. (ANI)

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New form of El Nino may increase chances of hurricanes making landfall

July 3, 2009 By Leave a Comment

Washington, July 3 (ANI): A study by climatologists at the Georgia Institute of Technology suggests that a new form of El Nino may be changing potentially causing not only a greater number of hurricanes than in average years, but also a greater chance of hurricanes making landfall.

“Normally, El Nino results in diminished hurricanes in the Atlantic, but this new type is resulting in a greater number of hurricanes with greater frequency and more potential to make landfall,” said Peter Webster, professor at Georgia Tech’s School of Earth and Atmospheric Sciences.

That’s because this new type of El Nino, known as El Nino Modoki (from the Japanese meaning “similar, but different”), forms in the Central Pacific, rather than the Eastern Pacific as the typical El Nino event does.

Warming in the Central Pacific is associated with a higher storm frequency and a greater potential for making landfall along the Gulf coast and the coast of Central America.

Even though the oceanic circulation pattern of warm water known as El Nino forms in the Pacific, it affects the circulation patterns across the globe, changing the number of hurricanes in the Atlantic.

This regular type of El Nino is more difficult to forecast, with predictions of the December circulation pattern not coming until May.

At first glance, that may seem like plenty of time.

However, the summer before El Nino occurs, the storm patterns change, meaning that predictions of El Nino come only one month before the start of hurricane season in June. But El Nino Modoki follows a different prediction pattern.

“This new type of El Nino is more predictable,” said Webster. “We’re not sure why, but this could mean that we get greater warning of hurricanes, probably by a number of months,” he added.

As to why the form of El Nino is changing to El Nino Modoki, that’s not entirely clear yet, said Webster.

“This could be part of a natural oscillation of El Nino,” he said. “Or it could be El Nino’s response to a warming atmosphere. There are hints that the trade winds of the Pacific have become weaker with time and this may lead to the warming occurring further to the west. We need more data before we know for sure,” he added. (ANI)

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Global warming may go on hold for decades

March 4, 2009 By Leave a Comment

Washington, March 3 (ANI): A new study has determined that global warming may have hit a speed bump and could go into hiding for decades.

Earth’s climate continues to confound scientists. Following a 30-year trend of warming, global temperatures have flatlined since 2001 despite rising greenhouse gas concentrations, and a heat surplus that should have cranked up the planetary thermostat.

“This is nothing like anything we’ve seen since 1950,” Kyle Swanson of the University of Wisconsin-Milwaukee told Disocvery News.

“Cooling events since then had firm causes, like eruptions or large-magnitude La Ninas. This current cooling doesn’t have one,” Swanson added.

Instead, Swanson and colleague Anastasios Tsonis think a series of climate processes have aligned, conspiring to chill the climate. In 1997 and 1998, the tropical Pacific Ocean warmed rapidly in what Swanson called a “super El Nino event.”

It sent a shock wave through the oceans and atmosphere, jarring their circulation patterns into unison.

When added up with the other four years since 2001, Swanson said the overall trend is flat, even though temperatures should have gone up by 0.2 degrees Centigrade (0.36 degrees Fahrenheit) during that time.

The discrepancy gets to the heart of one of the toughest problems in climate science – identifying the difference between natural variability from human-induced change.

But just what’s causing the cooling is a mystery.

Sinking water currents in the north Atlantic Ocean could be sucking heat down into the depths. Or an overabundance of tropical clouds may be reflecting more of the sun’s energy than usual back out into space.

“It is possible that a fraction of the most recent rapid warming since the 1970′s was due to a free variation in climate,” Isaac Held of the National Oceanic and Atmospheric Administration in Princeton, New Jersey told Discovery News. “Suggesting that the warming might possibly slow down or even stagnate for a few years before rapid warming commences again,” he added.

“When the climate kicks back out of this state, we’ll have explosive warming. Thirty years of greenhouse gas radiative forcing will still be there and then bang, the warming will return and be very aggressive,” Swanson said. (ANI)

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