On the applicability of KirchofPs law and the principle of heat balance in thermal infrared remote sensing:A non-isothermal system

This paper proposes a basic equation of thermal radiation interaction between surface objects on the basis of the principle of heat balance in the interface. The solution of this equation takes account of the contribution of sensible heat flux and latent heat flux more completely, compared with traditional solution for surface cooling and heating processes. By the aid of the experimental data conducted in the Xiaotangshan experimental site, Beijing, both the non-applicability of Kirchoff's law and the measurability of surface emissivity in a non-isothermal system have been highlighted. Two methods called ventilation and time-delay compensations have been proposed to reduce the error induced by change of surface temperatures of non-isothermal objects during the measurement of emissivity. Based on the solution of the basic equation, this paper has analyzed and pointed out the misunderstanding in comprehension and application of Kirchoff's law published in literature.     

基于GRACE RL06数据监测和分析南极冰盖27个流域质量变化

本文基于CSR最新公布的GRACE RL06版本数据,采用Slepian空域反演法估算了南极冰盖27个流域的质量变化.Slepian空域反演法结合了Slepian空间谱集中法和空域反演法的技术优势,能够有效降低GRACE在小区域反演时信号出现的严重泄漏和衰减,进而精确获得南极冰盖在每个流域的质量变化.相对于GRACE RL05版本数据,RL06在条带误差的控制上要更加优化,获得的南极冰盖质量变化时间序列也更加平滑,但在趋势估算上差别并不明显（小于10 Gt/a）.本文的估算结果显示：在2002年4月至2016年8月期间,整个南极冰盖质量变化速率为-118.6±16.3 Gt/a,其中西南极为-142.4±10.5 Gt/a,南极半岛为-29.2±2.1 Gt/a,东南极则为52.9±8.6 Gt/a.南极冰盖损失最大的区域集中在西南极Amundsen Sea Embayment（流域20-23）,该地区质量变化速率为-203.5±4.1 Gt/a,其次为南极半岛（流域24-27）以及东南极Victoria-Wilkes Land（流域13-15）,质量变化速率分别为-29.2±2.1 Gt/a和-19.0±4.7 Gt/a,其中Amundsen Sea Embayment和南极半岛南部两个地区的冰排放呈现加速状态.南极冰盖质量显著增加的区域主要有西南极的Ellsworth Land（流域1）和Siple Coast（流域18和19）以及东南极的Coats-Queen Maud-Enderby Land（流域3-8）,三个地区质量变化速率分别为17.2±2.4 Gt/a、43.9±1.9 Gt/a和62.7±3.8 Gt/a,质量增加大多来自降雪累积,比如：Coats-Queen Maud-Enderby Land在2009年和2011年发生的大规模降雪事件,但也有来自冰川的增厚,如：Siple Coast地区Kamb冰流的持续加厚.此外,对GRACE估算的南极冰盖质量变化年际信号进行初步分析发现,GRACE年际信号与气候模型估算的冰盖表面质量平衡年际信号存在显著的线性相关关系,但与主要影响南极气候年际变化的气候事件之间却不存在线性相关关系,这说明南极冰盖质量变化的年际信号主要受冰盖表面质量平衡的支配,而气候事件对冰盖表面质量平衡的影响可能是复杂的非线性耦合过程.

     

福建沿海地区水资源紧缺问题及其解决途径

本文针对福建沿海地区存在的水资源紧问题,通过对福沿海地区水资源数量,供需平衡的分析探讨了水资源紧缺问题存在的主要原因,并结合水资源利用的现状特征,进一步深入评述了现状利用中存在的问题,最后从可持续利用水资源的角度出发,重点讨论解决途径。     

全球温度变化的热力学平衡和最新发现

本文提出了一种新的研究全球气候温度变化的思路。为发现全球气候变化的宏观规律,把生物圈系统作为一个整体的物质进行研究,从而把纷繁复杂的全球气候温度变化问题归纳成经典物理学的热量与温度变化问题。给出了广义生物圈的热平衡测量Q值和温度变化的热力学公式,并在实际数据的基础上通过计算发现人类使用矿物燃料和核能所排放的热量理论上可使全球海平面每年升高35 mm或者可使大气对流层温度每年升高011 ℃。该发现表明:能源热量因素已成为影响全球温度变化的重要因素。     

A mass‐balance approach to estimate in‐stream processes in a large river

A mass‐balance approach was used to estimate in‐stream processes related to inorganic nitrogen species (NH₄⁺, NO₂^? and NO₃^?) in a large river characterized by highly variable hydrological conditions, the Garonne River (south‐west France). Studies were conducted in two consecutive reaches of 30 km located downstream of the Toulouse agglomeration (population 760 000, seventh order), impacted by modification of discharge regime and high nitrogen concentrations. The mass‐balance was calculated by two methods: the first is based on a variable residence time (VRT) simulated by a one‐dimensional (1‐D) hydraulic model; the second is a based on a calculation using constant residence time (CRT) evaluated according to hydrographic peaks. In the context of the study, removal of dissolved inorganic nitrogen (DIN) for a reach of 30 km is underestimated by 11% with the CRT method. In sub‐reaches, the discrepancy between the two methods led to a 50% overestimation of DIN removal in the upper reach (13 km) and a 43% underestimation in the lower reach (17 km) using the CRT method. The study highlights the importance of residence time determination when using modelling approaches in the assessment of whole stream processes in short‐duration mass‐balance for a large river under variable hydrological conditions. Copyright © 2007 John Wiley & Sons, Ltd.     

Estimating evapotranspiration from small watersheds using a water and energy balance approach

Meteorological and environmental data measured in semiarid watersheds during the summer monsoon and winter periods were used to study the interrelationships among flux, meteorological and soil water variables, and to evaluate the effects of these variables on the daily estimation of actual evapotranspiration (AET). The relationship between AET and potential evapotranspiration (PET) as a function of soil water content, as suggested by Thornthwaite–Mather and by Morton, was studied to determine its applicability to the study area. Furthermore, multiple linear regression (MLR) analysis was employed to evaluate the order of importance of the meteorological and soil water factors involved. The results of MLR analysis showed that the combined effects of available energy, soil water content and wind speed were responsible for more than 70% of the observed variations in AET during the summer monsoon period. The analyses also indicate that the combined effects of available energy, vapour pressure deficit and wind speed were responsible for more than 70% of the observed variations in AET during the winter period. However, the test results of two different approaches, using the relationships between AET and PET as a function of soil water content, indicated some inadequacy. Copyright © 2007 John Wiley & Sons, Ltd.     

Climatic control on river discharge simulations,Zackenberg River drainage basin,northeast Greenland

A spatially distributed, physically based, hydrologic modeling system (MIKE SHE) was applied to quantify intra‐ and inter‐annual discharge from the snow and glacierized Zackenberg River drainage basin (512 km²; 20% glacier cover) in northeast Greenland. Evolution of snow accumulation, distribution by wind‐blown snow, blowing‐snow sublimation, and snow and ice surface melt were simulated by a spatially distributed, physically based, snow‐evolution modelling system (SnowModel) and used as input to MIKE SHE. Discharge simulations were performed for three periods 1997–2001 (calibration period), 2001–2005 (validation period), and 2071–2100 (scenario period). The combination of SnowModel and MIKE SHE shows promising results; the timing and magnitude of simulated discharge were generally in accordance with observations (R² = 0·58); however, discrepancies between simulated and observed discharge hydrographs do occur (maximum daily difference up to 44·6 m³ s^?1 and up to 9% difference between observed and simulated cumulative discharge). The model does not perform well when a sudden outburst of glacial dammed water occurs, like the 2005 extreme flood event. The modelling study showed that soil processes related to yearly change in active layer depth and glacial processes (such as changes in yearly glacier area, seasonal changes in the internal glacier drainage system, and the sudden release of glacial bulk water storage) need to be determined, for example, from field studies and incorporated in the models before basin runoff can be quantified more precisely. The SnowModel and MIKE SHE model only include first‐order effects of climate change. For the period 2071–2100, future IPCC A2 and B2 climate scenarios based on the HIRHAM regional climate model and HadCM3 atmosphere–ocean general circulation model simulations indicated a mean annual Zackenberg runoff about 1·5 orders of magnitude greater (around 650 mmWE year^?1) than from today 1997–2005 (around 430 mmWE year^?1), mainly based on changes in negative glacier net mass balance. Copyright © 2007 John Wiley & Sons, Ltd.     

Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns

Abstract

This study examined the end-of-winter snow storage, its distribution and the spatial and temporal melt patterns of a large, low gradient wetland at Polar Bear Pass, Bathurst Island, Nunavut, Canada. The project utilized a combination of field observations and a physically-based snowmelt model. Topography and wind were the major controls on snow distribution in the region, and snow was routinely scoured from the hilltop regions and deposited into hillslopes and valleys. Timing and duration of snowmelt at Polar Bear Pass were similar in 2008 and 2009. The snowmelt was initiated by an increase in air temperature and net radiation receipt. Inter-annual variability in spatial snowmelt patterns was evident at Polar Bear Pass and was attributed to a non-uniform snow cover distribution and local microclimate conditions. In situ field studies and modelling remain important in High Arctic regions for assessing wetland water budgets and runoff, in addition to model parameterization and validation of satellite imagery.

Editor Z.W. Kundzewicz

Citation Assini, J. and Young, K.L., 2012. Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns. Hydrological Sciences Journal, 57 (4), 738–755.     

Mass movements in cave sediments: investigation of a ∼40,000-year-old guano mudflow inside the entrance of the Great Cave of Niah, Sarawak, Borneo

The West Mouth of the Great Cave at Niah in Sarawak, northwest Borneo and the North Passage that leads to the West Mouth contain large deposits of guano. The main deposit, several metres thick in places, forms the sloping floor of the entire North Passage. A mass movement deposit identified in the West Mouth, having a volume of 600 m³, originated as a guano mudflow up the North Passage in the order of 40,000 years ago. This failure of the guano slope was investigated to determine whether particular conditions or events could be identified as the most likely causes. The physical, hydrological and geotechnical properties of samples of the material were determined so that the stability of the slope could be assessed. Stability analyses showed that shearing failure of the slope would require inputs of water to the slope in quantities for which no feasible explanation can be suggested. However, the properties of the guano are similar to those of loess, indicating a high susceptibility to ‘hydrocollapse’. Very shallow failure of the slope, possibly as several smaller mudflows, could therefore have occurred due to additional water in quantities that could realistically be supplied as rainwater spray, possibly with a seismic trigger. The climate must therefore have been wetter than it is at present. These findings have implications for the interpretation of sediment deposits in other relict caves.     

Compositional Geometry and Mass Conservation

A geometrical structure is imposed on compositional data by physical and chemical laws, principally mass conservation. Therefore, statistical or mathematical investigation of possible relations between data values and such laws must be consistent with this structure. This demands that geometrical concepts, such as points that specify both mass and composition in linear space, and lines in projective space that specify composition only, be clearly defined and consistent with mass conservation. Mass thus becomes the norm in composition space in place of the Euclidean norm of ordinary space. Coordinate transformations inconsistent with this geometry are accordingly unnatural and misleading. They are also unnecessary because correlation arising from the constant mass presents no unusual difficulty in the analysis of the underlying quadratic form.