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Title: Ammonia and methane dairy emissions in the San Joaquin Valley of California from individual feedlot to regional scale

Agricultural ammonia (NH 3) emissions are highly uncertain, with high spatiotemporal variability and a lack of widespread in situ measurements. Regional NH 3 emission estimates using mass balance or emission ratio approaches are uncertain due to variable NH 3 sources and sinks as well as unknown plume correlations with other dairy source tracers. We characterize the spatial distributions of NH 3 and methane (CH 4) dairy plumes using in situ surface and airborne measurements in the Tulare dairy feedlot region of the San Joaquin Valley, California, during the NASA Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality 2013 field campaign. Surface NH 3 and CH 4 mixing ratios exhibit large variability with maxima localized downwind of individual dairy feedlots. The geometric mean NH 3:CH 4 enhancement ratio derived from surface measurements is 0.15 ± 0.03 ppmv ppmv –1. Individual dairy feedlots with spatially distinct NH 3 and CH 4 source pathways led to statistically significant correlations between NH 3 and CH 4 in 68% of the 69 downwind plumes sampled. At longer sampling distances, the NH 3:CH 4 enhancement ratio decreases 20–30%, suggesting the potential for NH 3 deposition as a loss termmore » for plumes within a few kilometers downwind of feedlots. Aircraft boundary layer transect measurements directly above surface mobile measurements in the dairy region show comparable gradients and geometric mean enhancement ratios within measurement uncertainties, even when including NH 3 partitioning to submicron particles. Individual NH 3 and CH 4 plumes sampled at close proximity where losses are minimal are not necessarily correlated due to lack of mixing and distinct source pathways. As a result, our analyses have important implications for constraining NH 3 sink and plume variability influences on regional NH 3 emission estimates and for improving NH 3 emission inventory spatial allocations.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [6] ;  [6] ;  [8] ;  [3] ;  [3]
  1. Princeton Univ., Princeton, NJ (United States); Brown Univ., Providence, RI (United States)
  2. Princeton Univ., Princeton, NJ (United States); Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  3. Princeton Univ., Princeton, NJ (United States)
  4. Univ. of Colorado, Boulder, CO (United States); Aerodyne Research, Inc., Billerica, MA (United States)
  5. Sandia National Lab. (SNL-CA), Livermore, CA (United States); Ramboll Environ US Corp., Novato, CA (United States)
  6. NASA Langley Research Center, Hampton, VA (United States)
  7. National Institute of Aerospace, Hampton, VA (United States)
  8. NASA Langley Research Center, Hampton, VA (United States); Science Systems and Applications, Inc., Hampton, VA (United States)
Publication Date:
OSTI Identifier:
1235313
Report Number(s):
SAND-2015-5504J
Journal ID: ISSN 2169-897X; 594840
Grant/Contract Number:
AC04-94AL85000; AC04-94-AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 120; Journal Issue: 18; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES