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81.
新疆棉花"矮密早"栽培技术的气候条件 总被引:2,自引:0,他引:2
李星华 《沙漠与绿洲气象(新疆气象)》2002,25(6):19-21
简要论述了新疆棉花“矮密早”栽培技术形成的气候条件和依据。 相似文献
82.
Study on the processing method of nighttime CO_2 eddy covariance flux data in ChinaFLUX 总被引:1,自引:0,他引:1
《中国科学D辑(英文版)》2006,(Z2)
At present, using Eddy Covariance (EC) method to estimate the "true value" of carbon sequestration in terrestrial ecosystem arrests more attention. However, one issue is how to solve the uncertainty of observations (especially the nighttime CO2 flux data) appearing in post-processing CO2 flux data. The ratio of effective and reliable nighttime EC CO2 flux data to all nighttime data is relatively low (commonly, less than 50%) for all the long-term and continuous observation stations in the world. Thus, the processing method of nighttime CO2 flux data and its effect analysis on estimating CO2 flux annual sums are very important. In this paper, the authors analyze and discuss the reasons for underestimating nighttime CO2 flux using EC method, and introduce the general theory and method for processing nighttime CO2 flux data. By analyzing the relationship between nighttime CO2 flux and air fraction velocity u., we present an alternate method, Average Values Test (AVT), to determine the thresholds of fraction velocity (u.c) for screening the effective nighttime CO2 flux data. Meanwhile, taking the data observed in Yucheng and Changbai Mountains stations for an example, we analyze and discuss the effects of different methods or parameters on nighttime CO2 flux estimations. Finally, based on the data of part ChinaFLUX stations and related literatures, empirical models of nighttime respiration at different sites in ChinaFLUX are summarized. 相似文献
83.
Liu WenHui Chen MengJin Guan Ping Zheng JianJing Jin Qiang Li Jian Wang WanChun Hu GuoYi Xia YanQing Zhang DianWei 《中国科学D辑(英文版)》2007,50(10):1494-1503
The establishment of geochemical-tracing system of gas generation and accumulation is helpful to re-elucidating the gas migration and accumulation in time and space. To deduce the complex process of gas accumulation, a ternary geochemical-tracing system is set up, according to stable isotope inheritance of source rocks, kinetic fractionation of stable isotopes, time-accumulating effect of noble gas isotopes, mantle-derived volatile inheritance, and organic molecule inheritance of light hydrocarbons and thermally kinetic fractionation in their generation, in combination with the previous achievements of gas geochemistry and geochemical parameters of gas-source correlation. There are tight interactions for the geochemical parameters with much information about parent inheritance and special biomarkers, in which they are confirmed each other, reciprocally associated and preferentially used for the requirement so that we can use these geochemical parameters to effectively demonstrate the sources of natural gas, sedimentary environments and thermal evolution of source rocks, migration and accumulation of natural gas, and rearrangement of natural gas reservoirs. It is necessary for the ternary geochemical-tracing system to predict the formation of high efficient gas reservoir and their distribution in time and space. 相似文献
84.
采用决策树方法和非线性回归方法建立湖泊水华预警模型。决策树方法预测水华爆发时机,非线性回归方法预测水华爆发强度,并运用信号灯显示方法,划分出水华爆发的预警区间。以北京六海为例,模型结果表明来水水量Q,温度T和总磷浓度是影响“六海”湖泊水华爆发的主要影响因子,选择叶绿素a(Chl-a)<30 μg/L的预警信号为绿色,30 μg/L60 μg/L为红色。当每月来水量Q>79.0万m3或来水量Q<79.0万m3,水温<13.4℃,预警指标为绿色;Q<79.0万m3,水温T>13.4℃,水华预警为黄色;Q<38.7万m3时,T>23.25℃,TP>0.13 mg/L,水华预警为红色。对模型结果分类进行了验证。结果表明:模型对于限制因素发生变化时的水华预测结果更为准确,并且结构简单,输入输出关系明显,结果易于解释。 相似文献
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86.
基于三旋转自由度激光经纬仪的结构光工程测量原理与应用 总被引:4,自引:0,他引:4
围绕具有三旋转自由度的激光经纬仪,阐述它在封闭构筑物测量中应用的优越性,提出结构光工程测量中各种扫描关系式的解算式,并用实例证明所述理论的正确性与高效率。 相似文献
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Stream temperature will be subject to changes because of atmospheric warming in the future. We investigated the effects of the diurnal timing of air temperature changes – daytime warming versus nighttime warming – on stream temperature. Using the physically based model, Heat Source, we performed a sensitivity analysis of summer stream temperatures to three diurnal air temperature distributions of +4 °C mean air temperature: i) uniform increase over the whole day, ii) warmer daytime and iii) warmer nighttime. The stream temperature model was applied to a 37‐km section of the Middle Fork John Day River in northeastern Oregon, USA. The three diurnal air temperature distributions generated 7‐day average daily maximum stream temperatures increases of approximately +1.8 °C ± 0.1 °C at the downstream end of the study section. The three air temperature distributions, with the same daily mean, generated different ranges of stream temperatures, different 7‐day average daily maximum temperatures, different durations of stream temperature changes and different average daily temperatures in most parts of the reach. The stream temperature changes were out of phase with air temperature changes, and therefore in many places, the greatest daytime increase in stream temperature was caused by nighttime warming of air temperatures. Stream temperature changes tended to be more extreme and of longer duration when driven by air temperatures concentrated in either daytime or nighttime instead of uniformly distributed across the diurnal cycle. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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