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Title: Methane emissions from dairies in the Los Angeles Basin

We estimate the amount of methane (CH 4) emitted by the largest dairies in the southern California region by combining measurements from four mobile solar-viewing ground-based spectrometers (EM27/SUN), in situ isotopic 13/12CH 4 measurements from a CRDS analyzer (Picarro), and a high-resolution atmospheric transport simulation with a Weather Research and Forecasting model in large-eddy simulation mode (WRF-LES). The remote sensing spectrometers measure the total column-averaged dry-air mole fractions of CH 4 and CO 2 (X CH4 and X CO2) in the near infrared region, providing information on total emissions of the dairies at Chino. Differences measured between the four EM27/SUN ranged from 0.2 to 22ppb (part per billion) and from 0.7 to 3ppm (part per million) for X CH4 and X CO2, respectively. To assess the fluxes of the dairies, these differential measurements are used in conjunction with the local atmospheric dynamics from wind measurements at two local airports and from the WRF-LES simulations at 111m resolution. Our top-down CH 4 emissions derived using the Fourier transform spectrometers (FTS) observations of 1.4 to 4.8ppts -1 are in the low end of previous top-down estimates, consistent with reductions of the dairy farms and urbanization in the domain. However, the wide rangemore » of inferred fluxes points to the challenges posed by the heterogeneity of the sources and meteorology. Inverse modeling from WRF-LES is utilized to resolve the spatial distribution of CH 4 emissions in the domain. Both the model and the measurements indicate heterogeneous emissions, with contributions from anthropogenic and biogenic sources at Chino. A Bayesian inversion and a Monte Carlo approach are used to provide the CH 4 emissions of 2.2 to 3.5ppts -1 at Chino.« less
Authors:
 [1] ;  [2] ; ORCiD logo [1] ;  [3] ;  [4] ;  [4] ;  [4] ;  [2] ;  [2] ; ORCiD logo [5] ;  [5] ; ORCiD logo [1] ;  [1] ;  [3] ;  [4] ;  [1]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Geological and Planetary Sciences
  2. Pennsylvania State Univ., University Park, PA (United States). Dept. of Meteorology
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences
  5. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
Publication Date:
Report Number(s):
LA-UR-18-21241
Journal ID: ISSN 1680-7324
Grant/Contract Number:
AC52-06NA25396; 1337512
Type:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 17; Journal Issue: 12; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); California Inst. of Technology (CalTech), Pasadena, CA (United States); Harvard Univ., Cambridge, MA (United States)
Sponsoring Org:
USDOE; LANL Laboratory Directed Research and Development (LDRD) Program; National Aeronautic and Space Administration (NASA); W. M. Keck Foundation (United States); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1463494