Uncertainty,entropy, scaling and hydrological stochastics. 1. Marginal distributional properties of hydrological processes and state scaling / Incertitude,entropie, effet d'échelle et propriétés stochastiques hydrologiques. 1. Propriétés distributionnelles marginales des processus hydrologiques et échelle d'état

Abstract

The well-established physical and mathematical principle of maximum entropy (ME), is used to explain the distributional and autocorrelation properties of hydrological processes, including the scaling behaviour both in state and in time. In this context, maximum entropy is interpreted as maximum uncertainty. The conditions used for the maximization of entropy are as simple as possible, i.e. that hydrological processes are non-negative with specified coefficients of variation (CV) and lag one autocorrelation. In this first part of the study, the marginal distributional properties of hydrological variables and the state scaling behaviour are investigated. Application of the ME principle under these very simple conditions results in the truncated normal distribution for small values of CV and in a nonexponential type (Pareto) distribution for high values of CV. In addition, the normal and the exponential distributions appear as limiting cases of these two distributions. Testing of these theoretical results with numerous hydrological data sets on several scales validates the applicability of the ME principle, thus emphasizing the dominance of uncertainty in hydrological processes. Both theoretical and empirical results show that the state scaling is only an approximation for the high return periods, which is merely valid when processes have high variation on small time scales. In other cases the normal distributional behaviour, which does not have state scaling properties, is a more appropriate approximation. Interestingly however, as discussed in the second part of the study, the normal distribution combined with positive autocorrelation of a process, results in time scaling behaviour due to the ME principle.     

Very quiet intervals of geomagnetic activity and the solar wind structure

Extended periods of very low geomagnetic activity as described by very quiet intervals (VQI's) occur only at those times when the solar wind velocityV has a generally decreasing trend, i.e., they mainly occur either after the velocity peak of a high speed solar stream has passed the Earth, or at times when the Earth is immersed in a low speed solar plasma provided that the daily mean value ofdV/dt is negative. The VQI's most frequently start whendV/dt<0 anddB _Z/dt>0 (B _Z is the geocentric solar magnetrospheric-GSMZ-component of the IMF) and end most likely whendV/dt>0 anddB _Z/dt<0. The temporal trends of the solar wind (SW) velocity affect the variation of thea _p index only when the level of geomagnetic activity is generally low.It is suggested that a gradual expansion or contraction of the magnetosphere, associated with a slow variation of the SW pressure, plays a role in the modification of the reconnection-driven magnetohydrodynamic (MHD) fluctuations in the magnetosphere.     

The influence of medium-range transport on O3 levels at a rural site in Israel

Simultaneous ozone measurements were made at a rural site, 25 km SSW of the city of Jerusalem, and in the center of the city during a period of 28 months. The ozone data were supplemented by SO₂, NO/NO _x ,and meteorological measurements at both sites. Elevated ozone concentrations were recorded at the rural site, mostly during the spring months (May and June) during which the monthly averages and the monthly averages of the daily 30 min maximum levels equalled those measured in the city. During the summer months, both average and peak levels were lower at the rural site by 20 and 35 ppb. The increased ozone levels at the rural site were accompanied by a parallel increase of SO₂ and NO _x ,suggesting hat the excess ozone at the rural site is a result of a transformation during transport of air pollutants from coastal sources.     

Global spectra of energy and enstrophy and their fluxes during July 1979

Transient and stationary spectra of kinetic energy (KE), available potential energy (APE) and enstrophy (EN), and their spectral fluxes as a function of the two-dimensional wavenumbern were computed for July 1979. Triangular truncation at zonal wavenumber 42 was used for computation. The slopes of various spectra in the wavenumber range 14≤n≤25 were obtained by fitting a straight line in log-log scale by the least square method. The transientKE, APE andEN spectra in the lower (upper) troposphere had slopes −2·21 (−2·30), −2·65 (−2·64) and −0·36 (−0·46), respectively. The effect of stationary and divergent motion on the slope values was investigated. The possible correlation between the slope and percentage of transient component in the combined energy and enstrophy was examined to identify the transient motion of the atmosphere with the two-dimensional homogeneous isotropic turbulence. The vertically averaged slope of kinetic energy and enstrophy in the lower (upper) troposphere was close to the value at 700 (200) hPa level. The spectral fluxes of kinetic energy and enstrophy in the wavenumber range 14≤n≤25 satisfied, to a very rough approximation, the criteria of inertial subrange. The stationary fluxes were small. The estimated stationary-transient component of flux was larger, comparable and less than the corresponding transient flux of APE, KE and EN. Representative levels for computation of energy and enstrophy spectra and their fluxes in the lower and upper troposphere were identified.     

Biological and physical events involved in the origin,effects, and control of organic matter in solar saltworks

Aspects of communities and events in the concentrating ponds (S.G. 1.130 to 1.214) and salt crystallizing ponds (S.G. 1.215 to 1.264) of solar saltworks pertinent to salt manufacture are described. Communities that aid salt manufacture enable continuous and efficient production of high quality salt at a saltworks' design capacity, and they provide important controls on levels of organic matter in the brine. Fluctuating salinities, high concentrations of nutrients, and petroleum products are disturbances that causeAphanothece halophytica andDunaliella salina to release excessive quantities of organic matter, and that suppress or cause death to nutrient stripping organisms. Disturbances result in decreased quality and quantity of salt and increased costs for salt harvest, washing, and pond upkeep. Organic matter can be controlled by management techniques that keep nutrient stripping communities at proper levels and maintain a narrow and unchanging range of salinities in each pond, by constructing pond dikes able to withstand wind and water erosion, and by preventing spills of petroleum products in the ponds.     

西北地区太阳辐射量变化的研究

根据西北地区１５个日射甲种站观测的近３０年来到达地面的太阳辐射量观测资料，经方差分析表明：太阳散射辐射量有２／５的地区在增加，２／５的地区在减少，还有１／５的地区太阳散射、直接辐射量在时间变化上差异都不明显；太阳直接辐射量有４／５的地区在显著减减少；太阳总辐射量几乎各地都在减少，这种减少趋势大致从１９７８年开始，并且用太阳辐射倾向率的形式概括出３种太阳辐射量季节变化类型。     

中国西部干旱地区太阳直接辐射通量密度与大气质量的关系

本文根据中国西部干旱地区大气物理状态(大气可降水量和大气浑浊度)的变化范围,利用太阳直接辐射通量密度的理论计算公式,计算了各种大气透明系数状况下的太阳直接辐射通量密度。计算结果表明,大气质量m=2时的透明系数P_2和m相同时,由于水汽和气溶胶的含量配置不同而引起太阳直接辐射通量密度的差异,在辐射日变程的主要时段(m=1-3)内并不大。于是得到各种透明系数P_2状况下太阳直接辐射通量密度随大气质量变化的平均关系。不同海拔高度比较,当透明系数P_2相同时,各自的大气物理状态虽然不同,但m相同时的太阳直接辐射通量密度基本相同。现有的表征太阳直接辐射通量密度值和大气质量联系的关系式都不能很好地描述计算结果。根据太阳直接辐射通量密度随大气质量变化的特性,我们提出了新的关系式。最后,整理了不同拔海高度和不同地理景观的四个日射站(西藏那曲、青海格尔木、甘肃敦煌和民勤)的多年观测资料。经验计算结果与观测值比较,一致性良好。     

Flood dynamics of a concrete-lined,urban stream in Kansas City,Missouri

Brush Creek drains a 76·1 km² watershed within urban Kansas City, Missouri and eastern Kansas. A concrete-lined reach trending 6·1 km through the Plaza District of Kansas City, Missouri has been the focus for several major floods over the past ten years. Channel geometry, slope, and floodwater elevations were determined in the field for segments of the concrete-lined section of Brush Creek for a flood event that occurred on September 18, 1986. Discharge was computed by indirect methods and compared to a value determined from a rating curve established by the Water Resources Division of the U.S.G.S. Boundary shear stress, unit stream power, and average velocity were also computed in order to establish a quantitative relationship between sediment distribution, volume, and size fractions; and flow dynamics operating throughout the channel during this event. Boundary shear stress ranged from 91-96 Nm^?2, stream power was 528-557 Wm^?2, while average velocity was 5-8 ms^?1. These values were sufficient to displace concrete slabs as large as 5 m long by 4·6 m wide by 0·23 m thick weighing an estimated 12 245 kg. As the channel was sediment free and unsecured prior to the flood, the distribution of deposits and subsequent channel scour provide valuable evidence for potentially hazardous sections of this urban stream.     

辽南核电站厂址区断层的评价问题

作者通过对核安全法规的学习和前人对辽南核电站厂址区断层的调查，并结合对断层实际踏勘，认为厂址区附近的东岗断层属于现行法规（ＨＡＦ０１０１）中规定的能动断层。但是，仅此一点并不能构成对推荐厂址的威胁，因为断层距厂址直线距离约４ｋｍ，断层的地表或近地表错动不会直接影响到核反应堆的安全。