Modelling the effect of changing precipitation inputs on deep soil water utilization          下载免费PDF全文

Ji Qi  Daniel Markewitz  David Radcliffe 《水文研究》2018,32(5):672-686

Forests in the Southeastern United States are predicted to experience future changes in seasonal patterns of precipitation inputs as well as more variable precipitation events. These climate change‐induced alterations could increase drought and lower soil water availability. Drought could alter rooting patterns and increase the importance of deep roots that access subsurface water resources. To address plant response to drought in both deep rooting and soil water utilization as well as soil drainage, we utilize a throughfall reduction experiment in a loblolly pine plantation of the Southeastern United States to calibrate and validate a hydrological model. The model was accurately calibrated against field measured soil moisture data under ambient rainfall and validated using 30% throughfall reduction data. Using this model, we then tested these scenarios: (a) evenly reduced precipitation; (b) less precipitation in summer, more in winter; (c) same total amount of precipitation with less frequent but heavier storms; and (d) shallower rooting depth under the above 3 scenarios. When less precipitation was received, drainage decreased proportionally much faster than evapotranspiration implying plants will acquire water first to the detriment of drainage. When precipitation was reduced by more than 30%, plants relied on stored soil water to satisfy evapotranspiration suggesting 30% may be a threshold that if sustained over the long term would deplete plant available soil water. Under the third scenario, evapotranspiration and drainage decreased, whereas surface run‐off increased. Changes in root biomass measured before and 4 years after the throughfall reduction experiment were not detected among treatments. Model simulations, however, indicated gains in evapotranspiration with deeper roots under evenly reduced precipitation and seasonal precipitation redistribution scenarios but not when precipitation frequency was adjusted. Deep soil and deep rooting can provide an important buffer capacity when precipitation alone cannot satisfy the evapotranspirational demand of forests. How this buffering capacity will persist in the face of changing precipitation inputs, however, will depend less on seasonal redistribution than on the magnitude of reductions and changes in rainfall frequency.  相似文献   

从太湖流域旱涝史料看历史气候信息处理   总被引：15，自引：1，他引：14  

陈家其 《地理学报》1987,(3)

历史气候信息处理建立在信息提取的基础上,目的在于建立一套方法,将定性的历史气候信息转化为气候变化参数,并消除各种不均—性,从而建立历史气候序列。本文着重介绍建立太湖流域历史旱涝等级序列的方法与步骤: 1)确立信息源,建立信息网络;2)站点等级的确定与订正;3)弱信息处理;4)信息的综合。  相似文献   

小波分析理论在GPS技术中的应用     

ZHENG Zuoya HUANG Cheng LU Xiushan 《中国科学院上海天文台年刊》2003,(1)

在GPS数据处理中 ,存在着误差影响、影响波的干扰、周跳和数据量大等问题。误差影响和影响波的干扰实质是在接收卫星信号时受到其它因素的影响 ;周跳是由于卫星信号的失锁而造成信号的不连续 ;数据量大是因为GPS观测需要采样间隔小又连续观测所致。由于小波理论具有时频分析、波形分解、特征提取和快速小波变换等特性 ,应用小波变换和波形分解可以解决误差影响和影响波的干扰的问题 ;应用特征提取可以解决周跳检测问题 ;应用快速小波变换可进行数据压缩  相似文献   

Precipitation patterns in flood season over China associated with the El Niño/Southern Osciliation     

Budong Qian 《中国地理科学(英文版)》1997,7(3):220-228

The precipitation patterns in flood season over China associated with the El Niño/Southern Oscillation (ENSO) are investigated, especially in the eastern China, using the rather long period rainfall data in this century. The results show that there were remarkable differences between the precipitation patterns in flood seasons of ENSO warm phase (El Niño year) and cold phase (La Niña year), as well as between the patterns in El Niño years and their following years. The most parts of China received below normal rainfall in flood season of the onset years of El Niño events, but the coastal area of Southeast China received above normal amounts. Comparatively, the most parts of China received above normal rainfall in flood season of the following years of El Niño events, but the eastern part of the reaches among the Huanghe (Yellow) River, the Huaihe River and the Haihe River, and the Northeast China received less. During ENSO cold phase, the reaches of the Changjiang (Yangtze) River and the North China received more amounts than normal rainfall in flood season of the onset years of La Niña events, and the other regions of China received less. In the following years of La Niña events, the coastal area of the Southeast China, the most part of the Northeast China and the regions between the Huanghe River and the Huaihe River received more precipitation during flood seasons, but the other parts received below normal precipitation.  相似文献   

The possible response of life zones in China under global climate change   总被引：5，自引：0，他引：5  

Xiongwen Chen  Xin-Shi Zhang  Bai-Lian Li 《Global and Planetary Change》2003,38(3-4):327-337

The response of natural vegetation to climate change is of global concern. In this research, an aggregated Holdridge Life Zone System was used to study the possible response of life zones in China under doubled atmospheric CO₂ concentration with the input climatic parameters at 0.5×0.5° resolution of longitude and latitude from NCAR regional climate model 2 (RegCM2) coupled with the CSIRO global climate model. The results indicate that the latitudinal distribution of life zones would become irregular because of the complicated climate change. In particular, new life zones, such as subtropical desert (SD), tropical desert (TDE) and tropical thorn woodland (TTW), would appear. Subtropical evergreen broadleaved forest (SEBF), tropical rainforest and monsoon forest (TRF), SD, TDE and TTW zones would appear in the northeastern China. Cool-temperate mixed coniferous and broadleaved forest (CMC) and warm-temperate deciduous broadleaved forest (WDBF) zones would appear at latitudes 25–35°N. The temperate desert (TD) in the western China would become Tibetan high-cold plateau (THP), SEBF, WDBF and temperate steppe (TS), and a large part of THP would be replaced by TRF, TDE, SEBF, TS and TTW. The relative area (distribution area/total terrestrial area) of CMC, TRF, TDE and TTW zone would increase about 3%, 21%, 3% and 6%, respectively. However, the relative area of SEBF, TS, TD and THP would decrease about 5%, 3%, 19% and 4%, respectively. In all, the relative area of forests (CCF, CMC, WDBF, SEBF, TRF) would increase about 15%, but the relative area of desert (TD, SD, TDE, and TTW) and THP would decrease about 9% and 4%, respectively. Therefore, responses of different life zones in China to climate change would be dramatic, and nationwide corridors should be considered for the conservation of migrating species under climate change.  相似文献   

Stability of the periodic solutions of the restricted three-body problem representing analytic continuations of Keplerian rectilinear periodic motions     

Abdul Ahmad 《Celestial Mechanics and Dynamical Astronomy》1995,61(2):181-196

The periodic solutions of the restricted three-body problem representing analytic continuations of Keplerian rectilinear periodic motions are well known (Kurcheeva, 1973). Here the stability of these solutions are examined by applying Poncaré's characteristic equation for periodic solutions. It is found that the isoperiodic solutions are stable and all other solutions are unstable.  相似文献   

雅砻江流域主汛期降水长期预报的一种方法     

赵守尧 《成都信息工程学院学报》1994,(1)

本文使用天气学方法，从影响雅砻江区域主汛期降水量的长期预报有关因子出发，再运用数理统计方法反复筛选，仅取３个主要因子：西部青藏高原８个站冬春积温，北部冬季极涡面积指数，南部冬季印缅槽平均强度，建立逐步回归预报方程。结果显示：对主汛期６～９月降水量预报拟合准确率为１６／１７即约９４％。回归分析中发现：尽管西太平洋副热带高压对盆地西部降水有很大影响，盛夏且与高原积温有较密切相关，但由放大范围长时段的青藏高原积温，对于雅砻江区域主汛期降水量的影响超过西太平洋副热高压，因而在逐步回归过程中，副高因子仍被剔除．  相似文献   

海量多波段星表数据的交叉证认的实现   总被引：2，自引：1，他引：1  

高丹  张彦霞  赵永恒 《天文研究与技术》2005,2(3):186-193

许多天文学家需要星表来选源、证认和研究。目前国外有一些大的数据中心提供了星表查询、多源查询(即小样本交叉证认)、可视化等功能。但是随着大数据量及全波段天文时代的到来,这些服务已经越来越不能满足天文学家的需求。在详细分析了国外数据中心的服务后,提出了新的问题,并给出一套解决方案。着重讨论了任意两个星表的交叉证认和大数据量星表的交叉证认的实现,以及交叉证认结果的分类和参数的自由选择等方面的课题。  相似文献   

INVERSE DDA OF A SYSTEM OF BLOCKS IN SPHERE COORDINATES     

Wu Yun  Wang Hui  Zhou Shuoyu  Shi Shunying 《大地测量与地球动力学》2003,23(Z1)

1　IntroductionDiscontinuousDeformationAnalysis(DDA)developedbyShiin 1 980’s[1 ,2 ] maybeusedtocalculatethedeformationanddisplacementsinamulti blocksystemandtoanalyzetherelationbe tweenforcesanddisplacementsinthesystem .Ifthesurveydisplacementofeverypointordirectionisknown,alldisplacementsanddeformationsofblocks,eventheglide ,theclosureandthestretchoftheboundary planeofblocks ,canbecalculated .TheresultisoptimallyfittedaccordingtotheLeastSquarePrinciple.DDAismainlyusedinrockblockssystems…  相似文献   

Restricted Three-Body Problem: An Approximation of its General Solution – Part One – the Manifold of Symmetric Periodic Solutions     

Kostantinos Papadakis  Constantine Goudas 《Astrophysics and Space Science》2006,305(2):99-124

This paper gives the results of a programme attempting to exploit ‘la seule bréche’ (Poincaré, 1892, p. 82) of non-integrable systems, namely to develop an approximate general solution for the three out of its four component-solutions of the planar restricted three-body problem. This is accomplished by computing a large number of families of ‘solutions précieuses’ (periodic solutions) covering densely the space of initial conditions of this problem. More specifically, we calculated numerically and only for μ = 0.4, all families of symmetric periodic solutions (1st component of the general solution) existing in the domain D:(x ₀ ∊ [−2,2],C ∊ [−2,5]) of the (x ₀, C) space and consisting of symmetric solutions re-entering after 1 up to 50 revolutions (see graph in Fig. 4). Then we tested the parts of the domain D that is void of such families and established that they belong to the category of escape motions (2nd component of the general solution). The approximation of the 3rd component (asymmetric solutions) we shall present in a future publication. The 4th component of the general solution of the problem, namely the one consisting of the bounded non-periodic solutions, is considered as approximated by those of the 1st or the 2nd component on account of the `Last Geometric Theorem of Poincaré' (Birkhoff, 1913). The results obtained provoked interest to repeat the same work inside the larger closed domain D:(x ₀ ∊ [−6,2], C ∊ [−5,5]) and the results are presented in Fig. 15. A test run of the programme developed led to reproduction of the results presented by Hénon (1965) with better accuracy and many additional families not included in the sited paper. Pointer directions construed from the main body of results led to the definition of useful concepts of the basic family of order n, n = 1, 2,… and the completeness criterion of the solution inside a compact sub-domain of the (x ₀, C) space. The same results inspired the ‘partition theorem’, which conjectures the possibility of partitioning an initial conditions domain D into a finite set of sub-domains D i that fulfill the completeness criterion and allow complete approximation of the general solution of this problem by computing a relatively small number of family curves. The numerical results of this project include a large number of families that were computed in detail covering their natural termination, the morphology, and stability of their member solutions. Zooming into sub-domains of D permitted clear presentation of the families of symmetric solutions contained in them. Such zooming was made for various values of the parameter N, which defines the re-entrance revolutions number, which was selected to be from 50 to 500. The areas generating escape solutions have being investigated. In Appendix A we present families of symmetric solutions terminating at asymptotic solutions, and in Appendix B the morphology of large period symmetric solutions though examples of orbits that re-enter after from 8 to 500 revolutions. The paper concludes that approximations of the general solution of the planar restricted problem is possible and presents such approximations, only for some sub-domains that fulfill the completeness criterion, on the basis of sufficiently large number of families.  相似文献