Seminar

Abstract

Routine observations of methane (CH₄) concentrations over a range of spatial and temporal scales have been identified as necessary to constrain anthropogenic and biogenic contributions to CH₄ emissions. To-date, the focus of remote sensing observations has been directed towards strong CH₄ point source quantification, however, regional diffuse fluxes are a large contributor to the anthropogenic CH₄ budget and accurate remote sensing observations are needed for their constraint. To address the community's observational needs and those of the broader NASA weather, climate, carbon cycle, and atmospheric composition focus areas the NASA Langley Research Center has developed the multifunctional High-Altitude Lidar Observatory (HALO). HALO employs the Differential Absorption Lidar (DIAL) technique at 935 nm for high vertical resolution water vapor profiles, the Integrated Path DIAL (IPDA) technique at 1645 nm for high accuracy and precision column and multi-layer CH₄ measurements, and the high spectral resolution lidar (HSRL) and backscatter techniques at 532 nm and 1064 nm, respectively, for retrievals of aerosol extinction, backscatter, depolarization, and planetary boundary layer (PBL) heights. The novel combination of the DIAL/IPDA and HSRL techniques provide key context to CH₄ measurements, elucidating the atmosphere's layered structure by giving vertical mixing and PBL height estimation, and additionally provide a critical capability to validate aerosol and cloud induced biases from passive space-borne retrievals of column CH₄. This talk will focus on the CH₄/HSRL HALO configuration and using data collected by HALO during the NASA LISTOS, ACT-America, and STAQS field campaigns the CH₄ retrieval accuracy, precision and overall operational capabilities have been assessed in a multitude of measurement domains and atmospheric conditions, including diurnal city variations, within heavy biomass burning plumes, and through broken cloud fields. Examples of city-scale and regional measurements of CH₄, coincident aerosol properties, and PBL heights will be presented along with synergistic comparisons to NASA and NOAA in-situ observations. General methods for attributing the boundary layer enhancements and range resolving capabilities will be discussed and examples will be presented on the extraction of single point emission and diffuse emission estimates from high altitude column integrated observations.

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Rory Barton-Grimley currently serves as a Research Scientist within the Science Directorate at the NASA Langley Research Center. Dr. Barton-Grimley is an instrument scientist focused on advancing airborne and spaceborne lidar technologies and retrieval methods for measurements of methane, water vapor, and clouds/aerosols. As a co-investigator for NASA's High Altitude Lidar Observatory (HALO) he leads the development of HALO's methane measurement capability and supports national and international airborne field campaigns across a wide range of NASA science focus areas. As a part of the NASA Decadal Survey Planetary Boundary Layer (PBL) Incubation science team, Dr. Barton-Grimley leads the development and inclusion of space-based Differential Absorption Lidar (DIAL) instrument models and retrieval methods into NASA's PBL observing system simulation experiment. Additionally, Dr. Barton-Grimley is a co-investigator for NASA's Atmospheric Boundary Layer Lidar project, which is advancing the space-readiness of key lidar technologies to enable the first ever space-based DIAL measurements of water vapor, methane, and PBL heights. Beyond his research, Dr. Barton-Grimley is the chair of the American Meteorological Society's Committee on Laser Atmospheric Studies and provides graduate student mentorship in the field of lidar instrument science.