RAPID: Fossil-Fuel Extraction Industry Methane Emission Ground Reference Measurements during the AVIRIS Response to the Gulf Oil Spill

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

Methane emissions from fossil fuel production are estimated as one of the major sources of the greenhouse gas CH4, estimated responsible for ~30% the radiative transfer impact of CO2, yet, virtually no peer-reviewed studies have field-evaluated these emissions, which EPA estimates are the largest non-anthropogenic US CH4 source. The current state of knowledge is in part because of the need for imaging spectrometric remote sensing, recently first demonstrated with AVIRIS (Airborne Visual Infrared Imaging Spectrometer) for a marine geologic source and sunglint. The approach is to use vicariously collected AVIRIS hyperspectral data during transit between Ellington AFB and the oil spill, during the current mission (Leifer is Airborne Mission Coordinating Scientist for the NASA spill response) of Gulf of Mexico platform flaring (>4300 active platforms). Typical uncombusted flaring CH4 is 5x106 m3 dy-1. These data will ground reference GOSAT data (Leifer/Roberts are on the GOSAT science team). Platform sources will be far easier to evaluate than the geologic source, and AVIRIS could collect order ~1000 platform-source observations over the current mission, but not critical ground reference measurements. Results also will aid future satellite platform development, like HyspIRI. This RAPID study uses SEBASS (hyperspectral thermal IR, allowing high cloud/nighttime observations) to map CH4 plumes from a Twin Otter with far higher spatial resolution than AVIRIS (during transit), which also allows in situ air sampling at a range of altitudes and down wind distances. Plume modeling allows radiative transfer-derived column-CH4 validation by in situ data. SEBASS is configured for tactical (near real time plume visualization) CH4 plume identification, allowing sample collection guidance. Hundreds of air samples will also be collected in evacuated cans and vials per flight-day from the Twin Otter as well as from surface vessels. This RAPID is thus part of a coordinated effort in response to the Gulf oil leak. The ultimate result will be an estimate of methane emissions from the Gulf oil leak.