Soil partitioning and surface store controls on spring runoff from a boreal forest peatland basin in north‐central Manitoba,Canada

The mid‐ to high‐boreal forest in Canada occupies the discontinuous permafrost zone, and is often underlain by glaciolacustrine sediments mantled by a highly porous organic mat. The result is a poorly drained landscape dominated by wetlands. Frost‐table dynamics and surface storage conditions help to control runoff contributions from various landscape elements, hydrological linkages between these elements, and basin streamflow during spring snowmelt. Runoff components and pathways in a forested peatland basin were assessed during two spring snowmelts with contrasting input and basin conditions. Runoff from relatively intense melt (up to 16 mm day^?1) on slopes with limited soil thawing combined with large pre‐melt storage in surface depressions to produce high flows composed primarily of meltwater (78% of the 0·29 m³ s^?1 peak discharge) routed over wetland surfaces and through permeable upper peat layers. Melt intensity was less in the subsequent year (maximum of 10 mm day^?1) and active layer development was relatively greater (0·2 m deeper at the end of spring melt), resulting in less slope runoff. Coupling of reduced slope contributions with lower storage levels in basin wetlands led to relatively subdued streamflows dominated by older water (73% of the 0·09 m³ s^?1 peak discharge) routed through less‐permeable deeper peat layers and mineral soil. Interannual differences in runoff conditions provide important insight for the development of distributed hydrological models for boreal forest basins and into potential influences on biogeochemical cycling in this landscape under a warming climate. Copyright © 2001 John Wiley & Sons, Ltd.     

Spatio-Temporal Characteristics of Spring Precipitation Days in Eastern Northwest China and Their Responses to the Intensity of Surface Heat-Field in the Qinghai-Tibetan Plateau

With spring precipitation-day data at 104 meteorological observation stations in eastern Northwest China from 1960 to 2000, and by EOF and REOF analysis, the spatio-temporal characteristics of precipitation-day anomalies in the eastern part of Northwest China in spring were studied. The results show that two centers of high-precipitation days lie in the southeast side of Qilian Mountains and northern Sichuan, respectively. And there are two kinds of spatial anomaly distributions, which are the consistent anomaly and east-west reverse anomaly, the former increases and the latter decreases gradually. In addition, this region can be divided into seven climate sections and in the Tibetan Plateau, precipitation days have a tendency of increasing,but in other places decreasing. When the intensity of surface heat-field changes more strongly during winter in the Qinghai-Tibetan Plateau, the rain days, in the next spring, along the Qilian Mountains, centre of Gansu Province, and the northeastern Longdong, are obviously more than that of normal years, and the rainy centre is mainly located at the mid-western of Qilian Mountains and the centre of Gansu Province.     

The role of local heat sources in synoptic activity within the polar basin

Abstract

A quasi‐geostrophic model of the atmosphere is used to determine the significance of the surface enthalpy flux in synoptic activity within the Polar Basin. Of primary interest is whether the enthalpy flux from open water in the seasonal sea‐ice zone is the predominant contributing mechanism or whether the advective fields of vorticity and thickness are controlling factors. This is of importance in discussions of the feedback processes between the atmosphere, cryosphere and ocean.

For a case selected in the Laptev Sea near the end of the fall period of ice growth, the surface enthalpy flux is as significant a contribution to synoptic activity as the vorticity advection is. The enthalpy flux is a relatively insignificant factor at this time in the Beaufort Sea, however, because of the smaller area of open water and the lower wind speeds associated with the weaker synoptic systems in this region. It is also relatively insignificant at both locations at the beginning of the fall freeze‐up interval and in June, during the melt period.     

Contribution of Global Warming and Atmospheric Circulation to the Hottest Spring in Eastern China in 2018

The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations, being 2.5°C higher than the 1961?90 mean and with more than 900 stations reaching the record spring mean temperature. This event exerted serious impacts in the region on agriculture, plant phenology, electricity transmission systems, and human health. In this paper, the contributions of human-induced climate change and anomalous anticyclonic circulation to this event are investigated using the newly homogenized observations and updated Met Office Hadley Centre system for attribution of extreme events, as well as CanESM2 (Second Generation Canadian Earth System Model) simulations. Results indicate that both anthropogenic influences and anomalous anticyclonic circulation played significant roles in increasing the probability of the 2018 hottest spring. Quantitative estimates of the probability ratio show that anthropogenic forcing may have increased the chance of this event by ten-fold, while the anomalous circulation increased it by approximately two-fold. The persistent anomalous anticyclonic circulation located on the north side of China blocked the air with lower temperature from high latitudes into eastern China. Without anthropogenic forcing or without the anomalous circulation in northern China, the occurrence probability of the extreme warm spring is significantly reduced.     

An Examination of the Predictability of Tropical Cyclone Genesis in High-Resolution Coupled Models with Dynamically Downscaled Coupled Data Assimilation Initialization

Predicting tropical cyclone(TC) genesis is of great societal importance but scientifically challenging. It requires fineresolution coupled models that properly represent air-sea interactions in the atmospheric responses to local warm sea surface temperatures and feedbacks, with aid from coherent coupled initialization. This study uses three sets of highresolution regional coupled models(RCMs) covering the Asia-Pacific(AP) region initialized with local observations and dynamically downscaled coupled data assimilation to evaluate the predictability of TC genesis in the West Pacific. The APRCMs consist of three sets of high-resolution configurations of the Weather Research and Forecasting-Regional Ocean Model System(WRF-ROMS): 27-km WRF with 9-km ROMS, and 9-km WRF with 3-km ROMS. In this study, a 9-km WRF with 9-km ROMS coupled model system is also used in a case test for the predictability of TC genesis. Since the local sea surface temperatures and wind shear conditions that favor TC formation are better resolved, the enhanced-resolution coupled model tends to improve the predictability of TC genesis, which could be further improved by improving planetary boundary layer physics, thus resolving better air-sea and air-land interactions.     

孟加拉湾春季小型暖池对热带气旋的影响研究

本文研究了2017年春季孟加拉湾小型暖池对热带气旋Maarutha（4月14-17日）以及热带气旋Mora（5月27-30日）的影响.利用卫星遥感和现场观测数据分析发现,尽管春季孟加拉湾热带气旋确实能引起海洋上层冷却效应,但是其冷却强度受到暖池强度的影响.本文进一步对比孟加拉湾小型暖池对两个热带气旋的响应情况,发现当春季小型暖池的温度大于31℃（热带气旋Mora期间）,暖池效应能有效抑制海洋上层混合层的加深,降低热带气旋引起的潜热通量损失带来的冷却效应,并在一定程度上加强了热带气旋.     

利用废旧轮胎防治滚石的数值模拟分析

为克服传统刚性拦石结构体系,刚性过大,受落石冲击易破坏,场地适应性差等缺点,设想将汽车废旧轮胎堆栈于刚性拦石结构前,形成一种刚柔并重的结构体系。利用废旧轮胎的弹性和韧性缓解落石的冲击力,从而提高传统刚性拦石结构体系防护落石的能力。并通过利用LS-DYNA有限元软件对废旧轮胎在落石冲击作用下的耗能性能进行了分析,计算结果表明废旧轮胎具有较好的吸能效果,对提高刚性拦石结构体系的防护能力有很大的帮助。     

地下水埋深对作物产量与水分利用效率的影响及作物系数变化

采用排水式蒸渗仪试验,研究不同地下水埋深对冬小麦和春玉米产量和水分利用效率的影响及其作物系数的变化,表明冬小麦和春玉米生育期的地下水位分别控制在1.5 m和1.0 m以下时产量和水分利用效率最为适宜,作物系数随地下水埋深的变化而变化,幅度可达到0.5～0.6,作物系数最大值处于1.2 m埋深处。研究结果可为地下水埋深较...     

腾冲火山区壳内岩浆囊现今温度:来自温泉逸出气体 CO2、CH4间碳同位素分馏的估计

温度是岩浆囊的重要物理参数,获取温度参数并监测其变化对更好地理解岩浆囊的物理化学性质和行为、评价火山的活动性和喷发危险性具有重要的理论和现实意义.本文通过对温泉逸出气体CO2和CH4碳同位素样品的采集、分析测试,利用Horita通过实验矫正的Richet的平衡分馏系数的理论计算数据,通过拟合得到的CO2-CH4碳同位素平衡分馏方程T(K)=3880.3(10001nα(CO2-CH4))-0.5984,计算了腾冲火山区现存3个岩浆囊的温度.结果表明:在整个腾冲火山区,由CO2和CH4的碳同位素分馏值计算的气体源区平衡温度最低397℃,最高1163℃,平均615℃.腾冲火山区的3个岩浆囊中,南部五合-龙江-浦川岩浆囊的现今温度在464～1163℃,平均773℃,温度最高;中部腾冲-和顺-热海岩浆囊的现今温度在438 ～773℃间,平均达566℃,温度次之;北部马站-曲石-永安岩浆囊的现今温度在397～651℃间,平均达524℃,温度最低.我们认为,腾冲火山区地下岩浆囊顶部气体富集区目前的温度变化范围为400～ 1200℃,岩浆囊的实际温度应高于平均值615℃.3个岩浆囊的边缘温度可能在400 ～600℃间,中心温度可能在700～1200℃间.3个岩浆囊中心的现今温度已达到流纹岩浆(600～900℃)、安山岩(800 ～ 1100℃)和玄武岩浆(1000～1250℃)的形成温度,进一步说明腾冲火山区目前3个岩浆囊是客观存在的.另外,我们发现在用δ-△图解法判断CO2-CH4间碳同位素分馏平衡的过程中,在保持2条拟合直线的斜率符号相反的条件下,无论如何剔除数据点,都不能使δ13CCO2-ΔCO2-CH4拟合直线的截距bCO2和δ13 CCH4-ΔCO2-CH14拟合直线的截距bCH4之差bΔ小于0.1245,说明2条拟合直线的交点不能落于δ轴上,而这一数值与Horita方程的常数项接近,这说明CO2-CH4间碳同位素分馏方程中确实存在常数项,CO2和CH4间在再高的温度下都存在碳同位素的分馏.δ-△图解法判断CO2-CH4间碳同位素分馏平衡准则应修正为:在保持2条拟合直线的斜率符号相反的条件下,δ13 CCO2-ΔCO2-CH4拟合直线和δ13CCH4-ΔCO2-CH4拟合直线应相交于δ轴附近截距差0.1245处.     

基于三次B样条函数的非线性PLSR分析及其在泉流量预测中的应用

地下水系统内部及其外界环境中的各种要素之间往往存在复杂的多重共线性和非线性,这是在建立统计模型时遇到的2个主要难点。介绍了基于三次B样条函数的非线性偏最小二乘建模方法和进行非线性结构分析的原理,分析了存在变量相关性的条件下该原理的适用性,并将其应用于黑龙洞泉流量的预测分析中。应用结果表明:模型拟合阶段平均误差7.6%,检验阶段平均误差11.2%,该方法能有效地处理建模过程中的多重共线性和非线性问题,并可进行非线性结构分析。