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The Influence of Land Surface Changes on Regional Climate in Northwest China 被引量:1
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作者 徐兴奎 张凤 jason k.levy 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2007年第3期527-537,共11页
Land surface changes effect the regional climate due to the complex coupling of land-atmosphere interactions. From 1995 to 2000, a decrease in the vegetation density and an increase in ground-level thermodynamic activ... Land surface changes effect the regional climate due to the complex coupling of land-atmosphere interactions. From 1995 to 2000, a decrease in the vegetation density and an increase in ground-level thermodynamic activity has been documented by multiple data sources in Northwest China, including meteorological, reanalysis from European Centre for Medium-Range Weather Forecasts (ECMWF), National Oceanic and Atmospheric Administration's (NOAA) Advanced Very High Resolution Radiometer (AVHRR) and TIROS Operational Vertical Sounder (TOVS) satellite remote sensing data. As the ground-level thermodynamic activity increases, humid air from the surrounding regions converge toward desert (and semi-desert) regions, causing areas with high vegetation cover to become gradually more arid. Furthermore, land surface changes in Northwest China are responsible for a decrease in total cloud cover, a decline in the fraction of low and middle clouds, an increase in high cloud cover (due to thermodynamic activity) and other regional climatic adaptations. It is proposed that, beginning in 1995, these cloud cover changes contributed to a "green- house" effect, leading to the rapid air temperature increases and other regional climate impacts that have been observed over Northwest China. 展开更多
关键词 land surface features climatic effect Northwest China TOVS NOAA-AVHRR
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The Impact of Agricultural Practices in China on Land-Atmosphere Interactions
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作者 徐兴奎 jason k.levy 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2011年第4期821-831,共11页
Human-induced land use changes and the resulting alterations in vegetation features are major but poorly recognized drivers of regional climatic patterns.In order to investigate the impacts of anthropogenically-induce... Human-induced land use changes and the resulting alterations in vegetation features are major but poorly recognized drivers of regional climatic patterns.In order to investigate the impacts of anthropogenically-induced seasonal vegetation cover changes on regional climate in China,harmonic analysis is applied to 1982-2000 National Oceanic and Atmospheric Administration(NOAA) Advanced Very High Resolution Radiometer(AVVHRR)-derived normalized difference vegetation index(NDVI) time series(ten day interval data).For two climatic divisions of South China,it is shown that the first harmonic term is in phase with air temperature,while the second and third harmonics are in phase with agricultural cultivation.The Penman-Monteith Equation and the Complementary Relationship Areal Evapotranspiration(CRAE) model suggest that monthly mean evapotranspiration is out of phase with temperature and precipitation in regions with signiffcant second or third harmonics.Finally,seasonal vegetation cover changes associated with agricultural cultivation are identiffed:for cropped areas,the temperature and precipitation time series have a single maximum value,while the monthly evapotranspiration time series has a bimodal distribution.It is hypothesized that multi-cropping causes the land surface albedo to sharply increase during harvesting,thereby altering the energy distribution ratio and contributing to observed seasonal vegetation cover changes. 展开更多
关键词 NDVI land surface cover phenologies multi-crop latent heat discrete Fourier transform
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中国区域陆表热力作用时空分布及异常变化区域的成因 被引量:2
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作者 徐兴奎 金晓青 jason k.levy 《中国科学(D辑)》 CSCD 北大核心 2009年第11期1530-1541,共12页
基于互补相关理论,通过20cm蒸发皿气象观测数据分析了中国区域1980~2000年地表热力时空变化和分布.结果显示:四川盆地为中心的长江中上游流域和黑龙江北部地区热力作用显著异常增强;新疆和云南部分区域热力作用显著减少.上述区域内低... 基于互补相关理论,通过20cm蒸发皿气象观测数据分析了中国区域1980~2000年地表热力时空变化和分布.结果显示:四川盆地为中心的长江中上游流域和黑龙江北部地区热力作用显著异常增强;新疆和云南部分区域热力作用显著减少.上述区域内低云覆盖率也同步发生显著的异常变化.通过西太平洋副热带高压波动数据和热带风暴频率资料证实,天气系统是造成地表热力异常分布的主要原因,并合理地解释了中国大部分区域年降水周期性和准周期性波动的成因.同时利用NOAA-AVHRR卫星遥感数据,分析了下垫面性质变化对地表热力异常分布的影响.在地表植被增加区域,地表热力作用下降;在地表植被减少强度最大的城市化周边地区,热力作用显著增强,而更大范围的热力增强却与天气系统引发的低云异常减少有关. 展开更多
关键词 地表热力作用 西太平洋副热 带高压 低云覆盖 遥感数据
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ADVANCES IN DECISION ANALYSIS AND SYSTEMS ENGINEERING FOR MANAGING LARGE-SCALE ENTERPRISES IN A VOLATILE WORLD: INTEGRATING BENEFITS, OPPORTUNITIES, COSTS AND RISKS (BOCR) WITH THE BUSINESS MOTIVATION MODEL (BMM) 被引量:1
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作者 Tom FEGLAR jason k.levy +1 位作者 Tatiana FEGLAR Tomas FEGLAR 《Journal of Systems Science and Systems Engineering》 SCIE EI CSCD 2006年第2期141-153,共13页
Over the past few decades, innovations in Information and Communication Technologies (ICT) have led to a significant increase in the complexity of enterprise information systems. This has led to new challenges for e... Over the past few decades, innovations in Information and Communication Technologies (ICT) have led to a significant increase in the complexity of enterprise information systems. This has led to new challenges for enterprise architects, systems engineers, business managers and other decision makers who must cope with the complexity of business plans and processes (particularly automated engineering processes). In order to better manage this complexity, the Business Rule Group (BRG) has put forth the Business Motivation Model (BMM). The original BMM uses a SWOT (Strength, Weakness, Opportunity, and Threat) decision analysis approach. However, the SWOT framework contains significant limitations with respect to decision making and ICT risks, hampering the decision making ability of enterprise architects, business managers, engineers, and other decision makers. The AHP (Analytic Hierarchy Process) and ANP (Analytic Network Process) are among the most widely used decision making tools: they commonly implement a Benefit - Opportunity - Cost - Risk (BOCR) analysis to improve the effectiveness of business decision making. A new approach is put forth that replaces the original SWOT assessment with an ANP-based BOCR analysis. As well, the original BMM is modified and applied in a Component Architecture Framework (CAF). 展开更多
关键词 Analytic Network Process (ANP) Business Motivation Model (BMM) architecture framework Benefits-Opportunities-Costs-Risks (BOCR)
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