Education & Certifications

  • B.S., UC Berkeley, Environmental Sciences (2017)

Stanford Advisors

Lab Affiliations

Work Experience

  • Research Assistant, NASA Jet Propulsion Laboratory (6/2017 - 7/2019)


    Pasadena, CA

All Publications

  • Attribution of methane point source emissions using airborne imaging spectroscopy and the Vista-California methane infrastructure dataset ENVIRONMENTAL RESEARCH LETTERS Rafiq, T., Duren, R. M., Thorpe, A. K., Foster, K., Patarsuk, R., Miller, C. E., Hopkins, F. M. 2020; 15 (12)
  • Assessment of Regional Methane Emission Inventories through Airborne Quantification in the San Francisco Bay Area ENVIRONMENTAL SCIENCE & TECHNOLOGY Guha, A., Newman, S., Fairley, D., Dinh, T. M., Duca, L., Conley, S. C., Smith, M. L., Thorpe, A. K., Duren, R. M., Cusworth, D. H., Foster, K. T., Fischer, M. L., Jeong, S., Yesiller, N., Hanson, J. L., Martien, P. T. 2020; 54 (15): 9254–64


    This study derives methane emission rates from 92 airborne observations collected over 23 facilities including 5 refineries, 10 landfills, 4 wastewater treatment plants (POTWs), 2 composting operations, and 2 dairies in the San Francisco Bay Area. Emission rates are measured using an airborne mass-balance technique from a low-flying aircraft. Annual measurement-based sectorwide methane emissions are 19,000 ± 2300 Mg for refineries, 136,700 ± 25,900 Mg for landfills, 11,900 ± 1,500 Mg for POTWs, and 11,100 ± 3,400 Mg for composting. The average of measured emissions for each refinery ranges from 4 to 23 times larger than the corresponding emissions reported to regulatory agencies, while measurement-derived landfill and POTW estimates are approximately twice the current inventory estimates. Significant methane emissions at composting facilities indicate that a California mandate to divert organics from landfills to composting may not be an effective measure for mitigating methane emissions unless best management practices are instituted at composting facilities. Complementary evidence from airborne remote sensing imagery indicates atmospheric venting from refinery hydrogen plants, landfill working surfaces, composting stockpiles, etc., to be among the specific source types responsible for the observed discrepancies. This work highlights the value of multiple measurement approaches to accurately estimate facility-scale methane emissions and perform source attribution at subfacility scales to guide and verify effective mitigation policy and action.

    View details for DOI 10.1021/acs.est.0c01212

    View details for Web of Science ID 000558753900011

    View details for PubMedID 32633497

  • Using remote sensing to detect, validate, and quantify methane emissions from California solid waste operations ENVIRONMENTAL RESEARCH LETTERS Cusworth, D. H., Duren, R. M., Thorpe, A. K., Tseng, E., Thompson, D., Guha, A., Newman, S., Foster, K. T., Miller, C. E. 2020; 15 (5)
  • Methane emissions from underground gas storage in California ENVIRONMENTAL RESEARCH LETTERS Thorpe, A. K., Duren, R. M., Conley, S., Prasad, K. R., Bue, B. D., Yadav, V., Foster, K. T., Rafiq, T., Hopkins, F. M., Smith, M. L., Fischer, M. L., Thompson, D. R., Frankenberg, C., McCubbin, I. B., Eastwood, M. L., Green, R. O., Miller, C. E. 2020; 15 (4)
  • California's methane super-emitters NATURE Duren, R. M., Thorpe, A. K., Foster, K. T., Rafiq, T., Hopkins, F. M., Yadav, V., Bue, B. D., Thompson, D. R., Conley, S., Colombi, N. K., Frankenberg, C., McCubbin, I. B., Eastwood, M. L., Falk, M., Herner, J. D., Croes, B. E., Green, R. O., Miller, C. E. 2019; 575 (7781): 180-+


    Methane is a powerful greenhouse gas and is targeted for emissions mitigation by the US state of California and other jurisdictions worldwide1,2. Unique opportunities for mitigation are presented by point-source emitters-surface features or infrastructure components that are typically less than 10 metres in diameter and emit plumes of highly concentrated methane3. However, data on point-source emissions are sparse and typically lack sufficient spatial and temporal resolution to guide their mitigation and to accurately assess their magnitude4. Here we survey more than 272,000 infrastructure elements in California using an airborne imaging spectrometer that can rapidly map methane plumes5-7. We conduct five campaigns over several months from 2016 to 2018, spanning the oil and gas, manure-management and waste-management sectors, resulting in the detection, geolocation and quantification of emissions from 564 strong methane point sources. Our remote sensing approach enables the rapid and repeated assessment of large areas at high spatial resolution for a poorly characterized population of methane emitters that often appear intermittently and stochastically. We estimate net methane point-source emissions in California to be 0.618 teragrams per year (95 per cent confidence interval 0.523-0.725), equivalent to 34-46 per cent of the state's methane inventory8 for 2016. Methane 'super-emitter' activity occurs in every sector surveyed, with 10 per cent of point sources contributing roughly 60 per cent of point-source emissions-consistent with a study of the US Four Corners region that had a different sectoral mix9. The largest methane emitters in California are a subset of landfills, which exhibit persistent anomalous activity. Methane point-source emissions in California are dominated by landfills (41 per cent), followed by dairies (26 per cent) and the oil and gas sector (26 per cent). Our data have enabled the identification of the 0.2 per cent of California's infrastructure that is responsible for these emissions. Sharing these data with collaborating infrastructure operators has led to the mitigation of anomalous methane-emission activity10.

    View details for DOI 10.1038/s41586-019-1720-3

    View details for Web of Science ID 000496159900058

    View details for PubMedID 31695210