Re-examination of Trends Related to Tropical Cyclone Activity over the Western North Pacific Basin

In order to re-examine some trends related to tropical cyclones（TCs） over the western North Pacific since 1949,the unreliable maximum sustained wind(V_max) recorded in the 1949-1978 TC best-track data from the Shanghai Typhoon Institute was modified based on the wind-pressure relationships（WPRs） in this study. Compared to the WPR scheme based on the cyclostrophic balance,the WPR scheme based on the gradient balance could give a better fit to TCs under higher wind speeds and could introduce smaller estimated errors for TCs locating at higher latitudes as well as TCs landing on the continent.After the V_max modification based on minimum sea-level pressure and TC center latitude,the revised annual number of category 4-5 typhoons shows no long-term trend,while the potential destructiveness measured by power-dissipation index decreases slightly,and this trend is not significant in the period 1949-2008.     

From rainfed agriculture to stress-avoidance irrigation: I. A generalized irrigation scheme with stochastic soil moisture

With vast regions already experiencing water shortages, it is becoming imperative to manage sustainably the available water resources. As agriculture is by far the most important user of freshwater and the role of irrigation is projected to increase in face of climate change and increased food requirements, it is particularly important to develop simple, widely applicable models of irrigation water needs for short- and long-term water resource management. Such models should synthetically provide the key irrigation quantities (volumes, frequencies, etc.) for different irrigation schemes as a function of the main soil, crop, and climatic features, including rainfall unpredictability. Here we consider often-employed irrigation methods (e.g., surface and sprinkler irrigation systems, as well as modern micro-irrigation techniques) and describe them under a unified conceptual and theoretical framework, which includes rainfed agriculture and stress-avoidance irrigation as extreme cases. We obtain mostly analytical solutions for the stochastic steady state of soil moisture probability density function with random rainfall timing and amount, and compute water requirements as a function of climate, crop, and soil parameters. These results provide the necessary starting point for a full assessment of irrigation strategies, with reference to sustainability, productivity, and profitability, developed in a companion paper [Vico G, Porporato A. From rainfed agriculture to stress-avoidance irrigation: II. Sustainability, crop yield, and net profit. Adv Water Resour 2011;34(2):272-81].     

应用FY-2地表蒸散产品监测西南特大干旱

基于能量平衡原理的卫星遥感地表蒸散产品具有清晰明确的物理含义,广泛地应用于遥感干旱监测领域。本研究以中国能量与水平衡监测系统（CEWBMS）和近11年的静止卫星遥感数据集为基础,利用FY-2/VISSR数据生成相对蒸散距平百分率（Percentage of Relative Evapotranspiration Anomaly,PRETA）产品,应用于全国范围的旱情连续监测。与极轨卫星同类产品相比,基于FY-2的PRETA产品在监测范围和频次上都具有明显的优势。由于距平百分率的引入,PRETA干旱指数等级划分不再与季节和地域气候类型等因素相关。针对2009年秋季至2010年春季西南大旱的监测结果进行了对比分析和统计,结果表明PRETA干旱指数真实客观地反映了旱情时空变化,面平均的PRETA和降水距平百分率时间序列变化趋势显示出良好的一致性,PRETA与10 cm土壤相对湿度有较高的相关性。本研究为实时、大范围、高分辨率、定量和动态卫星遥感监测干旱提供了切实可行的方法。     

Some challenges of an "upside down" nitrogen budget--science and management in Greenwich Bay, RI (USA)

When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Previous inventories of nitrogen (N) inputs to Greenwich Bay found that N inputs from Narragansett Bay exceeded those from the local watershed, suggesting that recent efforts to reduce local watershed N loads may have little effect on estuarine water quality. We used stable isotopes of N to characterize watershed and Narragansett Bay N sources as well as the composition of primary producers and consumers throughout Greenwich Bay. Results were consistent with previous assessments of the importance of N inputs to Greenwich Bay from Narragansett Bay. As multiple N sources contribute to estuarine water quality, effective management requires attention to individual sources commensurate with overall magnitude, regardless of the political complications that may entail.     

基于准地转垂直运动方程对Q矢量的进一步探讨

Q矢量是诊断大气大尺度垂直运动的重要物理量.在f平面近似下,从原始运动方程组出发可以推导出Q矢量以及相关的半地转Q矢量、非地转Q矢量和湿Q矢量等表达式,但这种传统的推导方法没有考虑大气准地转运动的属性.本文利用数学物理变换,直接从准地转ω方程出发推导出Q矢量及其相关表达式,从而克服了传统方法在大气准地转运动属性表达方面...     

河南省两次春季暴雨过程的对比

利用常规观测资料和NCEP1°×1°再分析资料对2008和2009年春季河南出现的两次区域暴雨过程进行了诊断对比分析。结果表明：500 hPa低槽、中低空切变、地面气旋是这两次过程共同的影响系统。Q矢量辐合和上升运动为两次春季暴雨的发生提供了有利的动力条件。两次过程的水汽均集中在800 hPa以下,主要是低层和边界层的水汽辐合,强的水汽输送和水汽辐合对暴雨的产生有非常重要的贡献。两次过程的大气层结均表现为对流稳定,这点与夏季暴雨有明显的区别。     

植被气孔阻抗对区域气候影响的数值试验

应用区域气候模式RegCM3,单向嵌套NASA/NCAR全球环流模式CAM30的输出结果,模拟1992—1997年不同气候背景下,植被气孔阻抗变化对鄱阳湖流域地表水循环过程和地面热量平衡的影响。结果表明,在现代气候条件下,气孔阻抗加倍导致年平均温度增加了033 ℃（193%）,降水减少了023 mm/d（24%）;在CO2加倍的未来情景下（1）气孔阻抗不变时,平均温度增加了169 ℃（996%）,降水增加了083 mm/d（86%）,（2）气孔阻抗加倍时,年平均温度增加了202 ℃（119%）,降水增加了068 mm/d（71%）。总的看来,气孔阻抗加倍的放大了CO2浓度增加（即温室效应）带来的影响。     

冰川均衡调整对南极冰质量平衡监测的影响及其不确定性

本文研究了新的全球冰川均衡调整(GIA)模型对南极冰盖质量平衡监测的影响,考虑现有冰川负荷模型和地幔黏滞度模型的差异,完整评估了结果的不确定性,最后结合GRACE和卫星测高的结果进行了对比分析.结果表明,GIA对GRACE监测的等效水柱变化有重大影响,较大的GIA影响出现在西南极,沿罗斯冰架-卡姆布冰流-罗尼冰架-南极...     

Assessment of temporal variation and sources of PCBs in the sediments of Mediterranean Sea, Mersin Bay, Turkey

Information on temporal distribution of polychlorinated biphenyls (PCBs) in the coastal sediments of Mediterranean Sea, Mersin was compiled using data published between 1980 and 2009, and the present study. The first congener specific PCB results from the region yield concentration levels of Σ₄₁PCBs in sediments ranging from 0.61 to 1.04 ng g⁻¹. Sediment profiles show penta-, hexa- and hepta-chlorobiphenyls, specifically, #149 and 153 as the most abundant congeners in all samples. Comparison of total PCB concentrations over time suggests no recent PCB input to the region. Using congener specific PCB data for the region, identity and contribution of PCB sources were also predicted using a chemical mass balance -based (CMB) receptor model. The CMB model identified Aroclor 1260 to be the major PCB source in coastal sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.     

A model of boiling for fluid inclusion studies: Application to the Bolaños Ag–Au–Pb–Zn epithermal deposit,Western Mexico

Boiling can be inferred from fluid inclusion microthermometry studies when a progressive increase in apparent salinity is observed along with a decrease of homogenization temperature (T_H) and depth, thus reflecting the partitioning of non-volatile solutes into the liquid phase during steam loss. We propose a model for fluid evolution during boiling based on mass and heat balance equations, which establishes paths in the T_H-salinity space that can be compared with fluid inclusion data to confirm or discard boiling. Additionally, the model allows calculating paleo-depths, for which the effect of steam bubbles lowering the hydrostatic pressure is taken into account.