Annmarie Eldering - NIST-coordinated intercomparison exercise: Methane plumes from EMIT measurements

Abstract

I will present an overview and results of our intercomparison experiment focused on methane plume detection and quantification based on EMIT remote sensing measurements. The experiment consisted of eight teams analyzing four measurement scenes from EMIT and reporting back results such as plume origins, plume outlines, estimated emission rates, and uncertainties. Comparisons of results across the team are reported, as well as the aggregate statistics, such as box and whisker plots of the emission rates, scatter of the plume origins, and coefficient of variance (COV) for the results. The small size of the datasets limits the generalizability of the results. One key outcome of this work was the development of methods for comparison of results, including application of rotation to plume origins to evaluate in the context of the wind field. We also tested the impact of holding variables constants, such as the wind speed. In this report, we show that the emission rate estimates have COVs of 30% to 50% in the majority of cases, and using the same wind speed across all teams did not drastically change this. The plume origin analysis showed that the cross wind spread of plume origin results was 50 m to 110 m in all but one case, and across wind was 60 m to 120 m in 13 of the 15 cases. The EMIT footprint is 60m, so the variations were roughly 1 to 2 pixels. In future work, we will build on the methods developed here and include measurements over controlled releases where the bias of the emission estimates can be assessed.

Bio

Annmarie Eldering, Ph.D., is a member of the Greenhouse Gas Measurement Program at the National Institute of Standards and Technology. She joined NIST in 2022 after over 20 years at the NASA Jet Propulsion Laboratory. Her expertise is in satellite remote sensing of greenhouse gases and air pollutants. Her work at NIST in the Greenhouse Gas Measurement Program focuses on facilitating efforts to better connect satellite remote sensing measurements of CO2 and CH4 to international standards.