Observations of The Effects of Aerosol Loading on Carbon and Water Cycles Over Various Landscapes

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dc.contributor.advisor Dr.Fredrick Semazzi, Committee Member en_US
dc.contributor.advisor Dr.Vin Saxena, Committee Co-Chair en_US
dc.contributor.advisor Dr.Dev Niyogi, Committee Chair en_US
dc.contributor.author Chang, Hsin-I en_US
dc.date.accessioned 2010-04-02T18:18:48Z
dc.date.available 2010-04-02T18:18:48Z
dc.date.issued 2005-02-13 en_US
dc.identifier.other etd-11122004-134251 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/2923
dc.description.abstract I present multi-site observational evidence that atmosphere aerosols affect regional terrestrial carbon and water cycle. Past studies have indicated that increase in diffuse irradiance due to cloudiness and aerosols could increase net ecosystem exchanges. Though the effect of clouds on terrestrial CO2 and LHF exchanges have been reported, there have been no field scale, direct observations relating aerosol loading and CO2 /LHF fluxes. We present first direct observations in support of the hypothesis that atmospheric aerosols affect the regional terrestrial carbon cycle. Observations from six CO2 flux and latent heat flux monitoring sites (forest, grasslands, and croplands) with collocated aerosol and surface radiation measurements were analyzed. The daytime (10AM to 4PM) growing season (summer, June to August) CO2 flux observations were subject to three clustering: (1) high and low diffuse radiation fraction (DRF) of the global radiation; (2) DRF changes with and without cloud cover; and (3) high DRF, no-cloud cover regimes for high and low aerosol optical depths (AOD). Results suggest that, aerosols exert a significant impact on potentially increasing the CO2 fluxes, and their effect may be even more advantageous than that due to clouds (which reduced the total radiation). For the data analyzed, the response of increasing aerosol loading on landscape CO2 fluxes, appears to be a general feature irrespective of the landscape (forest, crops, or grasslands) and photosynthesis pathway (C3 or C4). The CO2 sink increased with aerosol loading for forest and crop lands, and decreased for grassland. The slope of the AOD - CO2 flux correlation however, was wavelength dependent and appeared to affect the woody trees more than the crops or grasslands. The analysis of the direct field measurements indicate; aerosol loading could play a significant role in the variability of the regional terrestrial carbon exchange by altering the amount of diffuse solar radiation. As for water cycle, we examined latent heat flux (LHF) using the same time periods and locations. But instead of analyzing DRF and CO2 correlation, we were more focus on (1) heat fluxes and aerosol-loading correlation; (2) whether leaf area would affect the heat fluxes during aerosol loading; (3) soil moisture effect and (4) air temperature effect on the heat fluxes. Results indicate: (1) for corn, soybean croplands and forest sites, aerosol loadings had little impact on latent heat fluxes, but it had more impact in winter wheat and grassland sites; (2) after accounting for the leaf area index (LAI), our analysis results showed that aerosol loading had more significant impact in the heat fluxes for agriculture sites, where there were still no obvious trend for forest sites; (3) for agricultural site, latent heating tend to be affected more under low LAI condition; (4) grassland sites are more sensitive to soil moisture changes than agricultural sites; (5) agricultural sites have more obvious heat flux changes when air temperature changes than grassland site. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject carbon en_US
dc.subject water en_US
dc.subject Aerosols en_US
dc.title Observations of The Effects of Aerosol Loading on Carbon and Water Cycles Over Various Landscapes en_US
dc.degree.name MS en_US
dc.degree.level thesis en_US
dc.degree.discipline Marine, Earth and Atmospheric Sciences en_US

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