ESRL Quarterly Newsletter - Summer 2010

Target: Gulf Spill

Instrumented aircraft heads to Gulf, to help assess air quality

On April 20, a now all-too-well known deepwater oil rig exploded in the Gulf of Mexico, killing 11 people on board and igniting a fireball visible for miles.

ESRL’s Tom Ryerson (Chemical Sciences Division) was among several NOAA scientists scheduled to fly a research airplane from Florida to Colorado three days later, and he and his colleagues figured they might shift the flight slightly to sample the plume from the burning rig on the way. The airplane was already extensively outfitted for a major air quality and climate mission over California, with instruments that would be ideal for understanding some of the air quality implications of the disaster.

“We would have done it, but the rig sank the day before we flew,” Ryerson said, “we thought the sinking, which extinguished the rig fire, would be the end of it.” He and his colleagues left the Gulf tragedy behind and concentrated on CalNex (a study focused on the nexus of air quality and climate in California). It would be a week before the first eye-opening estimates of 5,000 barrels of spilled oil daily were available—now up to 35,000-60,000 barrels daily, of which about 24,000 barrels are being recovered.

The ESRL-led team got its chance in early June. NOAA redirected the WP-3D airplane from California back to the Gulf of Mexico, to help in a multi-agency effort to understand the environmental effects of the now disastrous BP Deepwater Horizon Oil Spill. The spill itself and controlled burns of spilled oil and natural gas could affect air quality, with implications for the health and safety of response workers and others.

The WP-3D—filled with customized, real-time chemistry instruments and air sample flasks—flew for a total of about 14 hours directly over the spill site, downwind, and in “clean air” parts of the Gulf, currently unaffected by the spill, Ryerson said. During two flights June 8 and 10, the aircraft flew mostly between altitudes of 600 to 2,000 feet, to sample the marine boundary layer, which was expected to trap most pollutants. At its lowest, the airplane was just 200 feet above the water.

“The only way we could have responded so quickly is that CalNex was happening, so we already had everything tested, installed, and ready to go,” Ryerson said. “We were lucky to already have had the aircraft instrumented for an air quality study. Even if we had plenty of time to figure out a specific payload for this sort of incident, we probably wouldn’t have changed much.”

In California, the airplane was one of several platforms involved in CalNex, which has been in planning for more than four years and included researchers from all ESRL divisions, several other NOAA laboratories and centers, the state of California, and academic and international collaborators.

ESRL’s custom instruments onboard included those to assess the concentrations of volatile organic compounds (some of which are damaging to human health), aerosols, ozone (a lung-damaging pollutant at Earth’s surface), and particulate matter including soot, as well as the transport and evolution of plumes of polluted air.

In the Gulf, the U.S. Environmental Protection Agency, EPA, has been conducting extensive air quality monitoring throughout the oil spill response effort. EPA, NOAA, and the Occupational Safety and Health Administration, OSHA, worked collaboratively to take advantage of NOAA’s specialized instruments.

“Ensuring the health and safety of Gulf Coast families is a priority for NOAA,” Jane Lubchenco, under secretary of commerce for oceans and atmosphere and NOAA administrator, said in a statement. “We want to make certain that the air is safe for coastal residents as well as workers on the water. We are pleased to partner with EPA in this effort and to provide state-of-the-science air quality instruments in our flying laboratory aboard the P-3 aircraft.”

“We have a lot of data to get through and we’re still trying to understand everything we saw,” Ryerson said. An initial assessment suggested that most pollutants were trapped within a well-mixed boundary layer, and data from the WP-3D were consistent with measurements taken by EPA and OSHA, and independent measurements from a ship in the region. More detailed information will be available in coming weeks.

Top: A burning oil plume in the Gulf in early June, courtesy of U.S. Coast Guard.

Middle: NOAA's WP-3D research airplane at the Rocky Mountain Regional Airport, during instrument installation. Courtesy of Morgan Heim, CIRES.

Bottom: Oil slick, courtesy of Dan Lack, NOAA/CIRES.