Posts Tagged ‘atmospheric aerosols’

To Study Storms, NASA Flies a Plane Into Hurricane Earl

August 31st, 2010 08:35 admin View Comments

hurricane-earlAs Tropical Storm Earl grew into Hurricane Earl this past weekend, NASA had a plan: Fly a plane into it. A DC-8 aircraft, used for NASA’s new Genesis and Rapid Intensification Processes (GRIP) project, darted around the storm to trace the movement of atmospheric aerosols–particles suspended in the air–and to drop weather sensors, giving NASA researchers data on how such storms form and strengthen.

NASA’s DC-8 aircraft left Fort Lauderdale at 10:05 a.m. EDT on Saturday heading for St. Croix for a multi-day deployment that targeted (at that time) Tropical Storm Earl…. On Sunday, August 29, the DC-8 completed an 8.5-hour science flight over (then) Hurricane Earl west of St. Croix. The research aircraft flew at altitudes of 33,000 feet and 37,000 feet and descended to 7,000 feet northwest of the storm area to collect measurements of atmospheric aerosols. The flight originated in St. Croix but diverted to land in Fort Lauderdale, Fla., due to the degrading weather forecast for St. Croix associated with the approaching hurricane. [NASA]

Researchers in the plane successfully ejected parachuting weather sensors called dropsondes–which can measure such things as wind speed, temperature, and pressure–into the heart of the storm, explains NASA mission specialist, Scott Braun. The scientists hope the collected data will help them understand why some tropical storms become destructive monsters, while others lose power and fizzle out.

Braun, who was aboard the plane for Sunday’s 8.5-hour flight, said the aircraft managed to get into the storm reasonably quickly after takeoff, and flew multiple passes at an average altitude of around 35,000 feet (10,668 meters). Despite having to cut a few planned legs short because of lightning, Braun said the flight was a success. “We got good radar data, good dropsonde data, everything went well.” [OurAmazingPlanet]

An interactive GRIP map allows website visitors to track the path of both the plane and the storm, which will move north over the course of the week. For estimates of which East Coasters will get the worse weather for the next five days check out the Hurricane Warning Center’s projections.

Another wider (some 600 miles across) but weaker storm, Danielle, is further north over the Atlantic. Yesterday, Danielle was losing gusto, starting to degrade from hurricane to extra-tropical storm status. DISCOVER blogger Phil Plait describes (and depicts in full satellite image glory) both Earl and Danielle in a Bad Astronomy post.

A third storm, Fiona, is also on meteorologists’ radars. But Keith Blackwell of the University of South Alabama’s Coastal Weather Research Center says that Fiona isn’t expected to become a hurricane, and notes that Earl may not play nice with the newcomer.

The same factors pushing and powering Hurricane Earl are expected to remain in place for days, so tropical storm Fiona is likely to stay offshore of the U.S. But Fiona is unlikely to grow into Hurricane Fiona, Blackwell said, because winds from the more powerful Hurricane Earl will probably disrupt the new storm. If Fiona gets too close to Earl, he said, “Earl might eat it.” [National Geographic]

Image: NASA/MODIS Rapid Response Team

Source: To Study Storms, NASA Flies a Plane Into Hurricane Earl

Geoengineering Could Slow—But Not Stop—Sea Level Rise

August 24th, 2010 08:59 admin View Comments

Bay_of_bengalYou could plant huge new forests where none have been before. You could blast particles into the sky to block the sun’s radiation. You could put mirrors in space. These planetary hacks could slow global warming, but one thing that none of them could do, most likely, is to stop the rising sea levels that a warming planet will bring.

That’s the contention of John Moore, lead author of a study out in the Proceedings of the National Academy of Sciences. Moore’s team examined five different means that scientists have proposed to hack the planet and save ourselves from anthropogenic global warming. The geoengineering schemes—forestation, atmospheric aerosols, space mirrors, biochar, and the use of biofuels plus carbon sequestration—are focused either on reducing the amount of energy the Earth absorbs or pulling carbon out of the atmosphere. So Moore wanted to see what they could do about a side effect of the extra heat: melting ice raising the global average sea level.

The results weren’t terribly encouraging. Sea levels respond slowly to changes in the planet’s temperature, Moore told Nature News, so “you can’t just slam on the brakes.”

Injecting sulphate aerosols into the stratosphere – which reduces the amount of sunlight reaching the surface of the Earth – had little effect. If emissions are allowed to grow at current rates, the model showed sea levels rising by 1.1 metres by 2100. Aerosols could reduce that to 0.8 metres by 2100, but with the rate of rise showing no sign of slowing down at the end of the century, this would simply delay greater rises, not prevent them. [New Scientist].

Space mirrors began to reverse the rising sea level trend, but only at about the end of the 21st century. If people quickly developed biofuels and became adept at carbon sequestration, things were even a tad better—but in Moore’s model the sea level still rose by 30 centimeters, or about a foot, mostly because of effects that are already locked into the system. Says Moore:

“I think that sucking CO2 out of the atmosphere is the best way to stop sea-level rise before 2100.” That could be accomplished with the biomass power plants and new forests considered in the study, or by massively scaling up CO2 removal techniques currently deployed in spacecraft and submarines” [ScienceNOW].

Given the unintended consequences that could come with tinkering with the planet on such a massive scale, keeping intervention to a minimum would seem like the ideal choice. But Moore’s study reiterates that fear that it might be too late for little steps. It might be time to consider the “extreme geoengineering”—say, atmospheric aerosol injections every year and a half instead of every four years—that potentially could slow down rising temperatures and sea levels… at an unknown cost.

But once you start, you can’t stop.

Once started, geoengineering must be continued or temperatures will quickly rebound to what they would have been without intervention. An attendant surge in sea-level rise wouldn’t occur quite as quickly, but it would follow soon enough, at a rate of up to 1–2 centimetres per year, he says. “Those are speeds that were observed during the last deglaciation,” says Moore, “so we’re not forecasting anything that is out of the geological record” [Nature].

Image: Wikimedia Commons / Nafis Ahmed Kuntal

Source: Geoengineering Could Slow—But Not Stop—Sea Level Rise