The dairy industry in the San Joaquin Valley (SJV) is one of California’s largest methane (CH 4 ) sources. Reducing dairy emissions is a priority for the state’s climate change plans. Observations of current dairy CH 4 emissions are key to monitoring actions taken toward this goal. To help support this, we present new ground‐based measurements of atmospheric column‐averaged CH 4 mixing ratio (XCH 4 ) gradients across a group of 600 dairies in the central SJV using EM27/SUN solar spectrometers. We used measurements from the 2019 summer and 2020 winter seasons for a top‐down emission inversion based on the WRF‐STILT model. Our top‐down estimates of the region’s dairy emissions range from 90% to 183% of the current CALGEM inventory’s emissions of 277 Gg/yr. In contrast to the strong temperature dependence found by earlier dairy CH 4 emission studies, we also find that our top‐down emissions during the winter measurement days are comparable to the summer measurement days, possibly due to seasonal changes in dairy management practices and meteorological conditions. Furthermore, we find significant interday variability in our measurements and find that our emission estimates overlap with earlier top‐down studies and bottom‐up inventories in this region. Our study demonstrates how analysis of ground‐based remotely sensed CH 4 gradient observations can help improve our understanding of CH 4 sources at scales relevant to mitigation policy. It also reflects the need for long‐term monitoring of CH 4 emissions in the region and at individual facilities to better understand their emissions.
Heerah, Sajjan, et al. "Dairy Methane Emissions in California's San Joaquin Valley Inferred With Ground‐Based Remote Sensing Observations in the Summer and Winter." Journal of Geophysical Research: Atmospheres, vol. 126, no. 24, Dec. 2021. https://doi.org/10.1029/2021JD034785
Heerah, Sajjan, Frausto‐Vicencio, Isis, Jeong, Seongeun, Marklein, Alison R., Ding, Yifan, Meyer, Aaron G., Parker, Harrison A., Fischer, Marc L., Franklin, Jonathan E., Hopkins, Francesca M., & Dubey, Manvendra (2021). Dairy Methane Emissions in California's San Joaquin Valley Inferred With Ground‐Based Remote Sensing Observations in the Summer and Winter. Journal of Geophysical Research: Atmospheres, 126(24). https://doi.org/10.1029/2021JD034785
Heerah, Sajjan, Frausto‐Vicencio, Isis, Jeong, Seongeun, et al., "Dairy Methane Emissions in California's San Joaquin Valley Inferred With Ground‐Based Remote Sensing Observations in the Summer and Winter," Journal of Geophysical Research: Atmospheres 126, no. 24 (2021), https://doi.org/10.1029/2021JD034785
@article{osti_1835324,
author = {Heerah, Sajjan and Frausto‐Vicencio, Isis and Jeong, Seongeun and Marklein, Alison R. and Ding, Yifan and Meyer, Aaron G. and Parker, Harrison A. and Fischer, Marc L. and Franklin, Jonathan E. and Hopkins, Francesca M. and others},
title = {Dairy Methane Emissions in California's San Joaquin Valley Inferred With Ground‐Based Remote Sensing Observations in the Summer and Winter},
annote = {Abstract The dairy industry in the San Joaquin Valley (SJV) is one of California’s largest methane (CH 4 ) sources. Reducing dairy emissions is a priority for the state’s climate change plans. Observations of current dairy CH 4 emissions are key to monitoring actions taken toward this goal. To help support this, we present new ground‐based measurements of atmospheric column‐averaged CH 4 mixing ratio (XCH 4 ) gradients across a group of 600 dairies in the central SJV using EM27/SUN solar spectrometers. We used measurements from the 2019 summer and 2020 winter seasons for a top‐down emission inversion based on the WRF‐STILT model. Our top‐down estimates of the region’s dairy emissions range from 90% to 183% of the current CALGEM inventory’s emissions of 277 Gg/yr. In contrast to the strong temperature dependence found by earlier dairy CH 4 emission studies, we also find that our top‐down emissions during the winter measurement days are comparable to the summer measurement days, possibly due to seasonal changes in dairy management practices and meteorological conditions. Furthermore, we find significant interday variability in our measurements and find that our emission estimates overlap with earlier top‐down studies and bottom‐up inventories in this region. Our study demonstrates how analysis of ground‐based remotely sensed CH 4 gradient observations can help improve our understanding of CH 4 sources at scales relevant to mitigation policy. It also reflects the need for long‐term monitoring of CH 4 emissions in the region and at individual facilities to better understand their emissions. },
doi = {10.1029/2021JD034785},
url = {https://www.osti.gov/biblio/1835324},
journal = {Journal of Geophysical Research: Atmospheres},
issn = {ISSN 2169-897X},
number = {24},
volume = {126},
place = {United States},
publisher = {American Geophysical Union (AGU)},
year = {2021},
month = {12}}
Dlugokencky, Edward J.; Nisbet, Euan G.; Fisher, Rebecca
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 369, Issue 1943https://doi.org/10.1098/rsta.2010.0341