To understand the carbon and energy exchange between the lake surface and the atmosphere, direct measurements of latent, sensible heat, and CO sub(2) fluxes were taken using the eddy covariance (EC) ...technique in Western Lake Erie during October 2011 to September 2013. We found that the latent heat flux (LE) had a marked one-peak seasonal change in both years that differed from the diurnal course and lacked a sinusoidal dynamic common in terrestrial ecosystems. Daily mean LE was 4.8 plus or minus 0.1 and 4.3 plus or minus 0.2MJm super(-2)d super( -1) in Year 1 and Year 2, respectively. The sensible heat flux (H) remained much lower than the LE, with a daily mean of 0.9 plus or minus 0.1 and 1.1 plus or minus 0.1MJm super(-2)d super( -1) in Year 1 and Year 2, respectively. As a result, the Bowen ratio was <1 during most of the 2year period, with the lowest summer value at 0.14. The vapor pressure deficit explained 35% of the variation in half hourly LE, while the temperature difference between the water surface and air explained 65% of the variation in half hourly H. Western Lake Erie acted as a small carbon sink holding -19.0 plus or minus 5.4 and -40.2 plus or minus 13.3gCm super(-2) in the first and second summers (May-September) but as an annual source of 77.7 plus or minus 18.6 and 49.5 plus or minus 17.9gCm super(-2)yr super(-1) in Year 1 and Year 2, respectively. The CO sub(2) flux rate varied from -0.45gCm super(-2)d super(-1) to 0.98gCm super(-2)d super(-1). Similar to LE had noticeable diurnal changes during the months that had high chlorophyll a months but not during other months. A significantly negative correlation (P<0.05) was found between and chlorophyll a on monthly fluxes. Three gap-filling methods, including marginal distribution sampling, mean diurnal variation, and monthly mean, were quantitatively assessed, yielding an uncertainty of 4%, 6%, and 10% in LE, H respectively. Key Points * Two-year eddy covariance measurements of large-lake latent, sensible heat, and CO sub(2) fluxes * Western Lake Erie acted as a yearly CO sub(2) source but a small CO sub(2) sink in summers * Western Lake Erie returns approximately 90% of annual rainfall via evaporation
Diverse, complex data are a significant component of Earth Science’s “big data” challenge. Some earth science data, like remote sensing observations, are well understood, are uniformly structured, ...and have well-developed standards that are adopted broadly within the scientific community. Unfortunately, for other types of Earth Science data, like ecological, geochemical and hydrological observations, few standards exist and their adoption is limited. The synthesis challenge is compounded in interdisciplinary projects in which many disciplines, each with their own cultures, must synthesize data to solve cutting edge research questions. Data synthesis for research analysis is a common, resource intensive bottleneck in data management workflows. We have faced this challenge in several U.S. Department of Energy research projects in which data synthesis is essential to addressing the science. These projects include AmeriFlux, Next Generation Ecosystem Experiment (NGEE) - Tropics, Watershed Function Science Focus Area, Environmental Systems Science Data Infrastructure for a Virtual Ecosystem (ESS-DIVE), and a DOE Early Career project using data-driven approaches to predict water quality. In these projects, we have taken a range of approaches to support (meta)data synthesis. At one end of the spectrum, data providers apply well-defined standards or reporting formats before sharing their data, and at the other, data users apply standards after data acquisition. As these projects continue to evolve, we have gained insights from these experiences, including advantages and disadvantages, how project history and resources led to choice of approach, and enabled data harmonization. In this talk, we discuss the pros and cons of the various approaches, and also present flexible applications of standards to support diverse needs when dealing with complex data.
Diverse, complex data are a significant component of Earth Science’s “big data” challenge. Some earth science data, like remote sensing observations, are well understood, are uniformly structured, ...and have well-developed standards that are adopted broadly within the scientific community. Unfortunately, for other types of Earth Science data, like ecological, geochemical and hydrological observations, few standards exist and their adoption is limited. The synthesis challenge is compounded in interdisciplinary projects in which many disciplines, each with their own cultures, must synthesize data to solve cutting edge research questions. Data synthesis for research analysis is a common, resource intensive bottleneck in data management workflows. We have faced this challenge in several U.S. Department of Energy research projects in which data synthesis is essential to addressing the science. These projects include AmeriFlux, Next Generation Ecosystem Experiment (NGEE) - Tropics, Watershed Function Science Focus Area, Environmental Systems Science Data Infrastructure for a Virtual Ecosystem (ESS-DIVE), and a DOE Early Career project using data-driven approaches to predict water quality. In these projects, we have taken a range of approaches to support (meta)data synthesis. At one end of the spectrum, data providers apply well-defined standards or reporting formats before sharing their data, and at the other, data users apply standards after data acquisition. As these projects continue to evolve, we have gained insights from these experiences, including advantages and disadvantages, how project history and resources led to choice of approach, and enabled data harmonization. In this talk, we discuss the pros and cons of the various approaches, and also present flexible applications of standards to support diverse needs when dealing with complex data.
碩士
國立東華大學
自然資源管理研究所
96
The Chi-Lan Mountain site (CLM site) located in north-eastern Taiwan (121°25’E, 24°35’N, 1650 m elevation) is a subtropical cloud motane forest site, which is characteristic by ...frequent fog events and diurnal mountain-valley wind circulation. The site is located at a relatively homogeneous south-eastern-faced slope with an angle of 15°, mainly occupied by natural regenerated 50-years-old yellow cypress (Chamaecyparis obtuse var. formosana) with canopy heights ranged from 11 m to 14 m.
With ideal meteorological and fetch conditions, the eddy covariance method could provide reliable ecosystem-scale flux measurements. However, as most studies indicated, challenges remain as applying the eddy covariance at sloping terrain such as the CLM site. In this thesis, seasonal and diurnal patterns of ecosystem CO2 and energy fluxes measured at the CLM site are presented. The storage in the forest canopy and advection effect on eddy flux measurement are also estimated and discussed.
With an open/clos
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