Rainfall interception by trees of Pinus radiata and Eucalyptus viminalis in a 1300 mm rainfall area of southeastern New South Wales: II. Influence of wind-borne precipitation

Analyses were made of the concurrent canopy precipitation balances of a seed orchard pine and a mature forest eucalypt during protracted rainfalls selected for their representativeness of the range of variation encountered in the two canopy types at Tallanganda State Forest (ca. 990 m a.s.l.) in the Upper Shoalhaven Valley of southeastern New South Wales. Although their canopy storage capacities were widely different there was consistent interception behaviour in the pine and the eucalypt in all events. Detailed weather data and the time courses of interception loss provided circumstantial evidence for a varying and, at times, substantial influence of cloud or mist deposition on the canopy precipitation balances during rainfall that made a significant contribution to the variation in rainfall interception data. Mean evaporation rates from the saturated canopies during rainfall varied from ?0·02 mm hr^?1 up to 0·68 mm hr^?1 in the pine; and from ?0·04 mm hr^?1 up to 0·13 mm hr^?1 in the eucalypt. The implications of cloud-capture during rainfall for studies of rainfall interception in forests of southeastern Australia are discussed.     

Discussion and reassessment of the method used for accepting or rejecting data observed by a Bowen ratio system

The Bowen ratio energy balance method often produces extremely inaccurate magnitudes of the flux due to resolution limits of the instruments. We analysed the criteria used for rejecting inaccurate data observed using a Bowen ratio system and the resolution limit of the sensors to analytically determine the reliable values of the Bowen ratio (β) and the latent and sensible heat fluxes. The formula used to calculate the error limit of the Bowen ratio (β) was corrected based on the theory of error analysis. An example was proposed for the common case with 0.2 °C resolution limit of temperature measurement and 0.08 kP_a resolution limit of water vapour pressure measurement, to show the steps of accepting or rejecting data observed by a Bowen ratio system. The acceptance or rejection of data observed by a Bowen ratio system is a dynamic process, which should be performed based on the excluded interval of the Bowen ratio and the qualitative relationships among the data observed by a Bowen ratio system. The excluded interval of the Bowen ratio can be structured based on the accuracy of the sensors used. Data are excluded first if they do not satisfy the qualitative relationships between the vapour pressure difference, the temperature difference, Bowen ratio, and the available energy, whereas the data in the rejection region range of the Bowen ratio are excluded second. It is necessary to improve the accuracy of the temperature and humidity probes to improve the acceptance rate for data collected using the Bowen ratio system, apart from improving the observed precision of available energy. Copyright © 2013 John Wiley & Sons, Ltd.     

Rainfall interception by trees of Pinus radiata,and Eucalyptus viminalis,in a 1300 mm rainfall area of southeastern New South Wales: I. Gross losses and their variability

Interception loss, I, was determined by continuous concurrent measurements of the canopy precipitation balances of a mature seed orchard tree of Pinus radiata, and a dominant tree of Eucalyptus viminalis at a mountainous high rainfall site (900 m a.s.l.) in Tallaganda State Forest of the Upper Shoalhaven Catchment. Approximate canopy storage capacity (Sc) of the pine was 54 l, and that of the eucalypt was 11·3 l. Gross pine I was 26·5 per cent and eucalypt I was 8·3 per cent of total incident rainfall over a period of 18 months, from June 1975 to December 1976. The exponential model that provided the best fit to overall data relating I to gross rainfall (P_g) was of good precision for the pine (r² = 0·73) but rather poor precision for the eucalypt (r² = 0·27). A consistent pattern in interception data of the two canopy types suggested that variation in I was related to change in pervasive conditions influencing rates of evaporation from wet canopies during rainfall. Multiple regression analyses confirmed that factors such as rainfall intensity and windspeed explained some of the variation in eucalypt I but little in pine I. Negative eucalypt I and corresponding low values of pine I over a wide range of P_g (up to 20 mm) suggest that capture of wind-borne precipitation (cloud, mist, or fog) had also complicated the canopy precipitation balances.     

Multi-functional heat pulse probe measurements of coupled vadose zone flow and transport

Simultaneous measurement of coupled water, heat, and solute transport in unsaturated porous media is made possible with the multi-functional heat pulse probe (MFHPP). The probe combines a heat pulse technique for estimating soil heat properties, water flux, and water content with a Wenner array measurement of bulk soil electrical conductivity (EC_bulk). To evaluate the MFHPP, we conducted controlled steady-state flow experiments in a sand column for a wide range of water saturations, flow velocities, and solute concentrations. Flow and transport processes were monitored continuously using the MFHPP. Experimental data were analyzed by inverse modeling of simultaneous water, heat, and solute transport using an adapted HYDRUS-2D model. Various optimization scenarios yielded simultaneous estimation of thermal, solute, and hydraulic parameters and variables, including thermal conductivity, volumetric water content, water flux, and thermal and solute dispersivities. We conclude that the MFHPP holds great promise as an excellent instrument for the continuous monitoring and characterization of the vadose zone.     

Partitioning of rainfall in a eucalypt forest and pine plantation in southeastern australia: II stemflow and factors affecting stemflow in a dry sclerophyll eucalypt forest and a pinus radiata plantation

Stemflow of a dry sclerophyll eucalypt forest and a nearby Pinus radiata plantation was studied on a rainfall event basis. The stemflow yields of the forests are quantified, compared, and presented on an annual basis for four years. Yields of the individual eucalypt species are compared and the tree characteristics responsible for the yield differences are discussed. The influence of event size, type, and season on stemflow are also shown. Rainfall angle is shown to have a significant effect on stemflow yield.     

响应比法的地磁异常分析

将加卸载响应比的理论应用于地磁方法中，取太阳日照为加载，地磁垂直分量Ｚ为响应，应用马陵山地震台１９９３年１月～１９９５年１１月对相观测资料计算其响应比值。得出结果：响应比的变化在１９９５年９月２０日苍山５．２级地震前明显异常显示，分析认为，这一异常变化是苍山地震的前兆异常。     

The solute budget of a forest catchment and solute fluxes within a Pinus radiata and a secondary native forest site,southern Chile

Solute concentrations and fluxes in rainfall, throughfall and stemflow in two forest types, and stream flow in a 90 ha catchment in southern Chile (39°44′S, 73°10′W) were measured. Bulk precipitation pH was 6·1 and conductivity was low. Cation concentrations in rainfall were low (0·58 mg Ca²⁺ l^?1, 0·13 mg K⁺ l^?1, 0·11 mg Mg²⁺ l^?1 and <0·08 mg NH₄–N l^?1), except for sodium (1·10 mg l^?1). Unexpected high levels of nitrate deposition in rainfall (mean concentration 0·38 mg NO₃–N l^?1, total flux 6·3 kg NO₃–N ha^?1) were measured. Concentrations of soluble phosphorous in bulk precipitation and stream flow were below detection limits (<0·09 mg l^?1) for all events. Stream‐flow pH was 6·3 and conductivity was 28·3 μs. Stream‐water chemistry was also dominated by sodium (2·70 mg l^?1) followed by Ca, Mg and K (1·31, 0·70 and 0·36 mg l^?1). The solute budget indicated a net loss of 3·8 kg Na⁺ ha^?1 year^?1, 5·4 kg Mg²⁺ ha^?1 year^?1, 1·5 kg Ca²⁺ ha^?1 year^?1 and 0·9 kg K⁺ ha^?1 year^?1, while 4·9 kg NO₃–N ha^?1 year^?1 was retained by the ecosystem. Stream water is not suitable for domestic use owing to high manganese and, especially, iron concentrations. Throughfall and stemflow chemistry at a pine stand (Pinus radiata D. Don) and a native forest site (Siempreverde type), both located within the catchment, were compared. Nitrate fluxes within both forest sites were similar (1·3 kg NO₃–N ha^?1 year^?1 as throughfall). Cation fluxes in net rainfall (throughfall plus stemflow) at the pine stand generally were higher (34·8 kg Na⁺ ha^?1 year^?1, 21·5 kg K⁺ ha^?1 year^?1, 5·1 kg Mg²⁺ ha^?1 year^?1) compared with the secondary native forest site (24·7 kg Na⁺ ha^?1 year^?1, 18·9 kg K⁺ ha^?1 year^?1 and 4·4 kg Mg²⁺ ha^?1 year^?1). However, calcium deposition beneath the native forest stand was higher (15·9 kg Ca²⁺ ha^?1 year^?1) compared with the pine stand (12·6 kg Ca²⁺ ha^?1 year^?1). Copyright © 2002 John Wiley & Sons, Ltd.     

超声实验中谱比法衰减的散射与本征吸收特性

实际地球介质的弹性波衰减,无论是对于地球内部结构反演、含油气储层描述,还是对于地震岩石物理本身的基础研究而言,都十分重要.通过岩石物理实验测量岩石的弹性波衰减是相关研究的基本手段,而谱比法是一种最常用的测量方法.利用谱比法测量的弹性波衰减,简称谱比法衰减,由介质的本征吸收特性和非均质散射特性共同决定.然而,在谱比法理论中,没有将这两种衰减特性的作用区分对待.因此,实验室测量的谱比法衰减中是否含有散射特性,其散射特性是否可以忽略,常不明确.本文基于对岩石物理实验中样品波形特征的基本认识,通过能流理论描述了弹性波的本征吸收和非均质散射过程,以及对应的尾波形成机理.文章还应用能流理论测量岩石的弹性波衰减,即能流法衰减.无论是通过理论推导,还是通过实验验证,谱比法衰减与能流法衰减都显示出良好的一致性.这两种直达波衰减的一致性暗示了谱比法衰减中存在着两种衰减特性.文中还对比分析了谱比法衰减与喷射流本征衰减的实验结果,该结果同样展示了谱比法衰减中可能存在着散射特性.因此,通过能流理论,可以利用样品波形的尾波特征定性判断谱比法衰减中可能存在的散射特性.即异常明显的尾波振幅可能意味着强烈的直达波非均质散射,谱比法衰减中的散射特性因而不可忽略.

     

Near-fault acceleration pulses and non-acceleration pulses: Effects on the inelastic displacement ratio

Near-fault ground motions can impose particularly high seismic demands on the structures due to the pulses that are typically observed in the velocity time-histories. The velocity pulses can be further categorized into either a distinct acceleration pulse (acc-pulse) or a succession of high-frequency, one-sided acceleration spikes (non-acc-pulse). The different characteristics of velocity pulses imply different frequency content of the ground motions, potentially causing different seismic effects on the structures. This study aims to investigate the characteristics of the two types of velocity pulses and their impacts on the inelastic displacement ratio (C_R) of single-degree-of-freedom systems. First, a new method that enables an automated classification of velocity pulses is used to compile a ground motion dataset which consists of 74 acc-pulses and 45 non-acc-pulses. Several intensity measures characterizing different seismological features are then compared using the two groups of records. Finally, the influences of acc-pulses and non-acc-pulses on the C_R spectra are studied; the effects of pulse period and hysteretic behavior are also considered. Results indicate that the characteristics of the two types of velocity pulses differ significantly, resulting in clearly distinct C_R spectral properties between acc-pulses and non-acc-pulses. Interestingly, mixing acc-pulses and non-acc-pulses can lead to local “bumps” that were found in the C_R spectral shape by previous studies. The findings of this study highlight the importance of distinguishing velocity pulses of different types when selecting near-fault ground motions for assessing the nonlinear dynamic response of structures.     

多通道瞬变电磁法频率域比值算法及视电阻率计算研究

视电阻率在电磁法勘探中起重要作用,可以作为初步解释结果,多通道瞬变电磁法通过大地脉冲响应的峰值时刻定义视电阻率.鉴于传统方法计算峰值时刻视电阻率需要恢复完整大地脉冲响应,本文通过研究大地脉冲响应及其频谱特征,提出一种新的频率域比值法.利用参考谱及其与一般谱的伸缩因子计算一般谱的峰值时刻,进而得到视电阻率.该方法只需大地脉冲响应单个频点幅度谱,从而不用估计整个大地脉冲响应.实际计算时,可以用大地脉冲响应多个频点幅度谱得到平均视电阻率.模拟数据与实测数据结果表明,在一维介质中,频率域比值法可以得到合理的视电阻率.

     

基于卫星高度计资料分析南海热含量的年际变化特征

本文从海面高度异常与海洋热含量变化的线性关系出发,利用1992～2004年多颗卫星融合海面高度资料,对南海海域的热含量异常进行了计算.这一计算结果与基于气候态温盐资料计算的热含量季节变化具有很好的一致性.本文得到的结果还显示南海热含量异常具有明显的长周期变化,表现为:1992～1998年基本保持比较稳定的年际变化特征,1998年之后,热含量出现明显的跃变,这一跃变一直维持到2001年,在2002年开始出现热含量的递减趋势.对此时间序列进行谐波分析可以看出,南海热含量异常除了具有显著的年变化周期外,还存在明显的0.5、1.5、2.4、4年和6年的变化周期.进一步分析还发现,南海12月份热含量异常可以作为南海夏季风爆发的一种预报指标.     

Comparison of three remote sensing based models for the estimation of latent heat flux over India

The aim of this work is to compare three remote sensing based models: two contextual and one physically-based single-pixel model for the estimation of daytime integrated latent heat flux without the use of any ground measurements over Indian ecosystems. Satellite datasets from the MODIS sensors aboard the Terra and the Aqua satellites were used. The latent heat flux estimated from the remote sensing models was compared with that estimated from Bowen ratio energy balance towers at five sites in India. The root mean square error (RMSE) of the latent heat flux estimated from the contextual and the physically-based models was found to be in the order of 40 and 70 W m^?2, respectively. The relatively inferior performance of the more complex physically-based model in comparison with the contextual models was found to be largely due to inaccurate parameterizations estimated only from remote sensing datasets without any ground data.     

3D finite volume groundwater and heat transport modeling with non-orthogonal grids,using a coordinate transformation method

Many popular groundwater modeling codes are based on the finite differences or finite volume method for orthogonal grids. In cases of complex subsurface geometries this type of grid either leads to coarse geometric representations or to extremely fine meshes. We use a coordinate transformation method (CTM) to circumvent this shortcoming. In computational fluid dynamics (CFD), this method has been applied successfully to the general Navier–Stokes equation. The method is based on tensor analysis and performs a transformation of a curvilinear into a rectangular unit grid, on which a modified formulation of the differential equations is applied. Therefore, it is not necessary to reformulate the code in total. We applied the CTM to an existing three-dimensional code (SHEMAT), a simulator for heat conduction and advection in porous media. The finite volume discretization scheme for the non-orthogonal, structured, hexahedral grid leads to a 19-point stencil and a correspondingly banded system matrix. The implementation is straightforward and it is possible to use some existing routines without modification. The accuracy of the modified code is demonstrated for single phase flow on a two-dimensional analytical solution for flow and heat transport. Additionally, a simple case of potential flow is shown for a two-dimensional grid which is increasingly deformed. The result reveals that the corresponding error increases only slightly. Finally, a thermal free-convection benchmark is discussed. The result shows, that the solution obtained with the new code is in good agreement with the ones obtained by other codes.     

利用H-K叠加方法和CCP叠加方法研究中国东北地区地壳结构与泊松比

利用中国东北布设的流动地震台阵（116个）以及国家和区域台网（121个）的宽频带台站记录的824个远震事件,采用P波接收函数CCP叠加和H-K叠加两种方法获得了研究区详尽的地壳厚度图像.研究结果显示,两种方法获得的地壳厚度分布特征具有很好的一致性,中国东北下方地壳厚度存在明显的东西横向差异.重力梯度带西侧和佳木斯地块的台站下方地壳较厚,介于36~41 km之间,而在兴蒙槽地褶带中重力梯度带往东从36 km减薄至34 km左右.松辽盆地北侧、东侧和南侧地壳厚度较薄,为29~34 km,反映了该区复杂的地壳变形过程.CCP剖面显示郯庐断裂深切地壳,敦化—密山断裂下方莫霍面出现错断.H-K叠加得到的地壳平均泊松比显示,东北地区绝大部分台站下方的泊松比值较大,0.24~0.29.长白山、松辽盆地东部、燕山台隆东部和大兴安岭北部,泊松比值达到0.27~0.30,可能有幔源物质上涌,下地壳铁镁组分含量增加.     

框架-阻尼框筒结构附加阻尼比简化计算方法

针对框架-阻尼框筒新型减震结构体系,考虑钢板阻尼墙屈服后强化和框架弹塑性,推导了结构附加阻尼比简化计算公式。以某框架-阻尼框筒结构为例,采用试验和有限元分析方法确定公式的参数取值,以此得到结构附加阻尼比的公式计算值,通过与结构动力弹塑性分析值进行对比,论证了简化计算公式的可用性。进一步基于参数分析给出了不同因素对公式计算值的影响。该简化计算方法为框架-阻尼框筒结构方案的快速设计提供了有效途径。     

CEC比值法在凝灰质砂岩储层测井评价中的应用——以海-塔盆地X凹陷凝灰质砂岩储层为例

凝灰质砂岩储层一直是测井评价中的难点.凝灰质的存在使储层的孔隙结构和物性变化都很大,其含量直接影响储层参数的求取,对储层饱和度的影响不容忽视.本文以海-塔盆地X凹陷的凝灰质砂岩储层为例进行测井评价研究.基于泥质和凝灰质的测井响应差异利用粒子群和细菌觅食的混合优化算法计算储层中两者的含量,然后通过阳离子交换量(CEC)的实验数据验证了凝灰质具有导电性,进而利用CEC与电阻率之间的关系得到凝灰质电阻率的计算方法,并且应用到饱和度的计算,最终得到了一种新的计算凝灰质砂岩储层饱和度的方法——CEC比值法,并取得了良好的应用效果.     

一种基于频率域偏振分析提高三分量地震资料信噪比的方法

三分量地震资料包含着丰富的运动学和动力学信息,各种随机噪声的存在严重降低了资料的信噪比,给有效信息的提取带来了一定的困难.本文在引入多窗谱分析方法的基础上,通过对谱密度矩阵特征问题的求解提取三分量地震记录的偏振参数,实现频率域偏振分析;根据所求得的偏振参数以及随机噪声和有效信号的偏振特性差异,设计相应的自适应滤波器,通过该滤波器的滤波作用,最终实现压制随机噪声的目的.     

Electromagnetic response function for the semi-annual variations estimated by the single-station method using the night-time values of the geomagnetic fields

The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep geomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper.     

一种基于地表能量平衡的遥感干旱监测新方法及其在甘肃河东地区干旱监测中的应用初探

目前遥感干旱监测方法的精度普遍不高,探求新的遥感干旱监测方法有助于干旱监测预警技术的提升与发展.波文比是感热通量与潜热通量之比,能综合反映地表水热特征,可尝试将其引入到遥感干旱监测领域加以利用.应用甘肃河东地区的EOS-MODIS卫星资料和同步地面气象资料,基于地表能量平衡原理构建了波文比干旱监测模型,对比分析了波文比（β）指数、温度植被指数（TVX）与土壤水分的相关性,并以典型晴空影像（2014年10月5日）为例初步建立了β的干旱分级标准,对研究区进行了旱情评估.结果表明：β与土壤相对湿度呈现出高度负相关,相比于当下广泛应用的TVX,β与0～20 cm平均土壤相对湿度具有更好的相关性,监测精度得到了显著提高.用β干旱分级标准评估的研究区干湿状况与前期降水空间分布吻合得相当好,评估表明2014年10月5日研究区基本为适宜（无旱）,与2014年9月的降水距平百分率特征一致.基于地表能量平衡的波文比（β）指数在干旱监测中效果突出,具有很好的应用前景.     

地球磁场对太阳风的加载响应与地震

地磁预报地震的方法越来越多,本文应用加卸载响应比方法,分析山西地区2009—2016年观测的加卸载响应比与山西地区4.0级地震之间的对应关系,初步给出适用于山西地区震例特征的磁异常判别指标。