Thesis
Investigation of surface energy and BVOC fluxes in the western United States during ENSO phases using the community land model
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/100240
Abstract
Interactions between the biosphere and the atmosphere play a fundamental role in determining pollutant transport and fate. Surface energy fluxes directly affect boundary layer dynamics and pollutant mixing, while biogenic volatile organic (BVOC) emissions influence atmospheric chemistry. The important driving factors for exchange processes include: net radiation, cloud cover, landcover, surface albedo, soil moisture, precipitation, and ambient temperature. Changes in the atmosphere, such as the El Nino Southern Oscillation (ENSO), can directly affect these factors and the associated surface exchange processes. The Community Land Model (CLM) simulates biosphere/atmosphere interactions and provides a way to investigate the effects of ENSO on surface energy fluxes and BVOC emissions. In this research, the overall goal was to improve our understanding of biosphere/atmosphere interactions across the western US. The specific objectives were 1) to evaluate CLM against observed sensible heat fluxes (SHF) and latent heat fluxes (LHF) using eddy covariance flux data from 38 sites for the period 2010-2017, and 2) to assess the effects of ENSO on surface energy fluxes and BVOC emissions with particular focus on 2011 (a strong La Niña) and 2015 (a very strong El Niño). We ran CLM4.5 over the western US (12 km x 12 km grids) with atmospheric data from the North American Land Data Assimilation System. Overall, CLM performed well for SHF and LHF across all landuse types with fractional bias and error less than 15% and 25%, respectively. However, the CLM evaluation indicates a potential issue for simulating the complexities of forest canopies as well as correct cropland management activities (i.e., harvest). The simulated ENSO patterns were generally consistent with expected ENSO cycles. The overall departures of temperature and SHF due to ENSO are correlated. Similarly, the departures of precipitation and LHF are correlated. The Northwest and South climate regions had the largest contrasting behavior for SHF/LHF and BVOCs emissions during summer and spring and for SHF and BVOCs emissions during winter. The fluxes from specific land types are predominately affected by the climate zone.
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Details
- Title
- Investigation of surface energy and BVOC fluxes in the western United States during ENSO phases using the community land model
- Creators
- Mahmoudreza Momeni
- Contributors
- Brian Lamb (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525081201842
- Language
- English
- Resource Type
- Thesis