SAN FRANCISCO — Researchers seeking to measure global greenhouse gas emissions have discovered an innovative use for the Visible Infrared Imaging Radiometer Suite (VIIRS), a key weather and climate-monitoring sensor flying on the Suomi National Polar-orbiting Partnership (NPP) satellite. They are using VIIRS to pinpoint areas where fuel production is leading to gas flaring, the practice of burning off natural gas that comes to the surface with crude oil, and to estimate the amount of gas released at those sites.
Prior to NPP’s launch in October 2011, researchers relied on the U.S. Air Force’s Defense Meteorological Satellite Program (DMSP) to identify gas flares.
“We have done this for about 10 years with DMSP data,” said Chris Elvidge, head of the Earth Observation Group at the U.S. National Oceanic and Atmospheric Administration’s (NOAA) National Geophysical Data Center in Boulder, Colo. “It just doesn’t have the spectral band, spatial resolution or calibration to do it very well.”
In contrast, VIIRS, a scanning radiometer built by Raytheon Space and Airborne Systems of El Segundo, Calif., collects data in 22 spectral bands including a day-night band that combines hundreds of data samples to amplify faint light sources and reduce unwanted distortion. As a result, VIIRS is able to detect objects roughly 100 times dimmer than was possible with previous technology and provide six times better spatial resolution, Jeff Puschell, principal engineering fellow at Raytheon Space and Airborne Systems, said by email.
“The day-night band capability was designed into VIIRS to provide useful nighttime cloud imagery at very low light levels, down to quarter moon illumination,” Puschell said. “In nearly two years on orbit, the VIIRS day-night band has provided meteorologists and climate scientists unprecedented information about emerging weather patterns and ground fog conditions at night, ice characteristics during the polar winters and man-made light sources, including city lights, gas flares and wildfires.”
The nighttime observations made by VIIRS are helping NOAA officials estimate the temperature and size of individual gas flares. In early 2012, the National Geophysical Data Center obtained funding from the Joint Polar Satellite System Proving Ground program, an interagency effort to obtain maximum utility from Suomi NPP data, for a three-year campaign to develop tools to measure carbon dioxide released into the environment by gas flares.
“We are working on developing a calibration that will allow us to estimate how much gas is being flared at individual sites,” Elvidge said. “It is still a work in progress.”
Publication of data on 2012 gas flares has been delayed by sequestration, the across-the-board spending cuts imposed this year when Congress failed to reach agreement on a deficit reduction deal, and the Oct. 1 partial federal government shutdown. Satellite data published for 2011 show that flares sent about 140 billion cubic meters of natural gas into the atmosphere, an amount equivalent to approximately 20 percent of the annual natural gas consumption for the United States.
Prior to 2011, global gas flaring levels generally were declining from approximately 154 billion cubic meters in 2007 to 138 billion cubic meters in 2010. The increase between 2011 and 2012 stemmed largely from a significant increase in gas flaring in Russia and the United States, where shale oil production is expanding in the Bakken Formation that lies under North Dakota and Montana. Suomi NPP nighttime imagery of the United States released in December 2012 showed gas flares burning in North Dakota emitted as much light as the Boston metropolitan area.
Data on the size and intensity of gas flares are being sought by various governmental and nongovernmental organizations seeking to measure and reduce the impact of gas flares on the environment. The World Bank, for example, in 2002 established the Global Gas Flaring Reduction partnership program, which encourages government and private oil producers to refrain from burning gas associated with oil production. The World Bank is spearheading initiatives to use that gas to power on-site generators, transport it to markets where it can be sold or reinject it into wells.
“The [satellite-derived] estimates are far from perfect, but they are the only consistent and periodic source of global information that we have so far,” Mauricio O. Ríos Ibáñez, a communications specialist with the World Bank’s Oil, Gas and Mining Policy Unit, said by email. “New satellite technology will allow us to get better resolution and quality for the data.”
The California Air Resources Board also is eager to obtain VIIRS data on gas flares as part of the state’s campaign to reduce greenhouse gas emissions. In 2007, California Gov. Arnold Schwarzenegger signed an executive order directing government agencies to develop protocols to measure the life-cycle carbon intensity of transportation fuels. Those measurements are used to assist the state in complying with legislation signed into law in 2006 calling for a 10 percent reduction in the carbon intensity of California’s transportation fuels by 2020. Gas flares are an important component of carbon intensity calculations, said John Courtis, California Air Resources Board manager.
For some oil fields, including many in Canada, California officials are able to obtain local measurements of gas flares. When that information is not available for a particular site, officials rely on satellite data provided by NOAA.
The NOAA data are becoming increasingly accurate as officials use gas flare readings obtained locally for individual oil fields to assist in the calibration and validation of the VIIRS observations, Courtis added.