非典型周期和气候突变的识别与判定          下载免费PDF全文

秦建国 《水文》2020,40(1):23-28

通过两种新方法分析了无锡站降水年际变化的突变性、周期性等特征,揭示了旱涝演化的自然规律。研究表明,1934、1978、2013年是我国近现代气候突变的临界点,这是旱涝演化的自然选择;无锡站年际降水的观测历史可分成四个特征不同的时段,每个时段节点对应的都是一次气候突变;气候突变会改变年际降水序列的一致性,分段法研究可以大幅度降低模拟难度、提高预测效率。发现并确认了3个气候突变点,实现了超长缺测中断期(13a)旱涝趋势的精确插补,完成了无锡站近百年降雨序列的周期性分析与旱涝趋势预测模拟,研究成果改变了近现代气候历史无法细分的现状。  相似文献   

Exploration prospects of oil and gas in the Northwestern part of the Offshore Indus Basin,Pakistan     

《China Geology》2020,3(4):633-642

Oil and gas resources are short in Pakistan and no commercially viable oil and gas sources have been yet discovered in its offshore areas up to now. In this study, the onshore-offshore stratigraphic correlation and seismic data interpretation were conducted to determine the oil and gas resource potential in the Offshore Indus Basin, Pakistan. Based on the comprehensive analysis of the results and previous data, it is considered that the Cretaceous may widely exist and three sets of source rocks may be developed in the Offshore Indus Basin. The presence of Miocene mudstones has been proven by drilling to be high-quality source rocks, while the Cretaceous and Paleocene–Eocene mudstones are potential source rocks. Tectonic-lithologic traps are developed in the northwestern part of the basin affected by the strike-slip faults along Murray Ridge. Furthermore, the Cretaceous and Paleocene–Eocene source rocks are thick and are slightly affected by volcanic activities. Therefore, it can be inferred that the northwestern part of Offshore Indus Basin enjoys good prospects of oil and gas resources.  相似文献   

Effect of Caliche Nodules on Soil Water Storage in the Northern Loess Plateau of China     

Tiexiong Gong  Yuanjun Zhu  Yunqiang Wang  Wei Hu  Ming'an Shao 《洁净——土壤、空气、水》2019,47(7)

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黄河干流头道拐河段凌汛期小流量过程变化及其影响因素研究     

全栋  李超  路新川  史小红  杨朝霞 《冰川冻土》2020,42(2):620-628

黄河干流内蒙古段河道冬季流凌封河期， 河道水量除一部分转化为冰量外， 很大一部分转化为槽蓄水量而贮存在河道中， 导致下游头道拐河段出现小流量过程， 上游河道流量转化为槽蓄水量和贮存的冰量越大， 小流量持续时间越长， 开河期发生凌汛洪水风险越高。通过对1998 - 2016年头道拐站凌讯期流量变化过程分析， 重新界定了小流量上限阈值为330 m³·s^-1， 并且以此值为标准进行小流量过程研究， 分别采用R/S极差分析法、 Fourier变换分析法对近年来小流量过程变化特征进行分析； 结合非线性概率Logit模型和Probit模型对小流量过程的影响因素进行讨论。结果表明： 小流量持续天数变化呈现缩短趋势； 同时， 小流量过程与上游相对来水之间变化关系显著且过程同步， 而滞后于河道槽蓄水量变化过程； 通过Logit模型和Probit模型分析各影响因素变化时相应小流量持续时间变化的响应概率大小， 明确河道冰流量是小流量过程第一影响因素， 气温条件是小流量过程的决定因素， 首封位置和相对来水量是小流量过程重要影响因素。  相似文献   

Obtaining the distribution of quiescent periods directly from the power spectral densities of Sea waves     

《Applied Ocean Research》2019

There is a growing practical interest in the ability to increase the sea states at which marine operations can be safely undertaken by exploiting the quiescent periods that are well known to exist under a wide range of sea conditions. While the actual prediction of quiescent periods at sea for the control of operations is a deterministic process, the long term planning of future maritime tasks that rely on these quiescent periods is a statistical process involving the anticipated quiescence properties of the forecasted sea conditions in the geographical region of interest. It is in principle possible to obtain such data in tabular form either large scale simulation or from field data. However, such simulations are computationally intensive and libraries of appropriate field data are not common. Thus, it is clearly attractive to develop techniques that exploit standard wave spectral models for describing the quiescence statistics directly from such spectra. The present study focuses upon such techniques and is a first step towards the production of a computationally low-cost quiescence prediction tool and compares its efficacy against simulations. Two significant properties emerge for a large class of wave spectral models that encompasses the ubiquitous Neumann and Pierson Moskowitz or Bretschneider forms. Firstly, the auto-correlation function of the wave profile that are required to produce the quiescence property can be obtained analytically in terms of standard special functions. This considerably reduces the computational cost making desktop computer-based planning tools a reality. Secondly, for each class of these parametric spectra, the probability of a given number of consecutive wave heights (normalised to the significant wave heights) less than some critical value is in fact independent of absolute wave height. Thus, for a broad class of practically interesting wave spectra all that is required to obtain the statistical distribution of the quiescent periods is simple rescaling.  相似文献   

Evaluation of the temporal variations of groundwater storage and its interactions with climatic variables using GRACE data and hydrological models: A study from Turkey     

Behnam Khorrami  Orhan Gunduz 《水文研究》2021,35(3):e14076

Monitoring of the fluctuations of groundwater storage is particularly important in arid and semi-arid regions where water scarcity brings about various challenges. Remote sensing data and techniques play a preponderant role in developing solutions to environmental problems. The launch of Gravity Recovery and Climate Experiment (GRACE) satellites has eased the remote monitoring and evaluation of groundwater resources with an unprecedented precision over large scales. Within the scope of the current study, the latest release (RL06) of GRACE mass concentrations (Mascons) from Jet Propulsion Laboratory (JPL) dataset as well as Global Land Data Assimilation System (GLDAS) models of Noah and Catchment Land Surface Model (CLSM) were used to provide Groundwater Storage Anomalies (GWSA) over Turkey. The temporal interactions of the estimated GWSA with the climatic variables of precipitation and temperature (derived from the reanalysis datasets of CHELSA [Climatologies at High resolution for the Earth's Land Surface Areas] and FLDAS [the Famine Early Warning Systems Network Land Data Assimilation System], respectively) were investigated statistically. The results suggest that there is a descending trend (from 2003 to 2016) for Terrestrial Water Storage Anomalies (TWSA) and GWSA over Turkey with a total loss of 11 and 6 cm of water, respectively. The statistical analysis results also indicate that the monthly variations of GWSA over Turkey are highly correlated with precipitation and temperature at 2-month lag. The analysis of the climatology (long-term) values of monthly GWSA, precipitation and temperature also revealed high agreement between the variables.  相似文献   

Consistency of precipitation products over the Arabian Peninsula and interactions with soil moisture and water storage     

Youssef Wehbe  Marouane Temimi  Dawit T. Ghebreyesus  Adam Milewski  Hamid Norouzi  Elsy Ibrahim 《水文科学杂志》2018,63(3):408-425

The regional-scale consistency between four precipitation products from the GPCC, TRMM, WM, and CMORPH datasets over the Arabian Peninsula was assessed. Their macroscale relationships were inter-compared with soil moisture and total water storage (TWS) estimates from AMSR-E and GRACE. The consistency analysis was studied with multivariate statistical hypothesis testing and Pearson correlation metrics for the period from January 2000 to December 2010. The products and GRACE estimates were assessed over a representative sub-domain (United Arab Emirates) with available in situ well observations. Next, geographically temporally weighted regression (GTWR) was employed to examine the interdependencies among the peninsula’s hydrological components. The results showed GPCC-TRMM recording the highest correlation (0.85) with insignificant mean differences over more than 90% of the peninsula. The highest GTWR predictive performance of TWS (R² = 0.84) was achieved with TRMM forcing, which indicates its potential to monitor changes in TWS over the arid peninsular region.  相似文献   

生物土壤结皮铁代谢微生物组成及其功能基因对演替的响应     

王岩松  刘玉冰  王增如  赵丽娜  漆婧华  张雯莉 《中国沙漠》2020,40(3):193-200

采用微生物宏基因组学微阵列GeoChip 5.0技术，选择腾格里沙漠东南缘沙坡头地区不同年代人工固沙植被区的生物土壤结皮（BSC）为对象，分析BSC演替过程中参与铁代谢的功能微生物组成及其功能基因变化特征，研究微生物铁代谢对BSC演替的响应及调控。结果表明：真菌参与铁吸收和转运过程，古菌参与铁转运和贮存过程，细菌则在铁代谢吸收、转运和贮存过程中均起主要调控作用。门水平上，BSC铁代谢功能微生物组成变化对演替的响应不敏感，BSC铁代谢微生物主要为变形菌门（Proteobacteria）。BSC铁代谢功能基因多样性的显著提高和三类铁代谢过程基因信号强度达到最高水平需要经过61 a的演替。调控BSC铁吸收过程的主要功能基因为亚铁氧化酶编码基因iro；调控原核生物铁转运过程的主要功能基因，为羟基苯甲酰丝氨酸铁外膜转运体编码基因cirA和Fe（Ⅱ）转运蛋白编码基因feoB，真菌铁转运过程主要依靠含铁细胞转运体和铁氧化酶高亲和力的作用；调控铁贮存过程的主要功能基因为固定相类核蛋白编码基因dps。在BSC演替阶段末期，上述铁代谢功能基因强度的显著增加促进了微生物的铁代谢潜能。干旱、半干旱荒漠生态系统植被恢复过程中微生物铁代谢潜能的恢复需要较长时间。  相似文献   

南海北部海域油气资源调查技术及其应用研究——震源子波检测及模拟分析          下载免费PDF全文

曾宪军  翟继锋  韦成龙 《海洋技术学报》2019,38(2)

在野外采集中考察气枪的稳定性以及室内进行确定性子波反褶积处理,都要求能够获得气枪阵列的实时远场子波。从震源子波检测方法出发,阐述了近场子波采集、幅值转换及记录流程,并列举出实测近场子波时需要考虑解决的问题;接着介绍了震源远场子波的获取方法和主要途径;震源近场子波及远场子波的实测方案,检测震源子波所需的仪器设备和采集技术方法。文中分析了气枪子波的气泡干扰问题,虚反射与后续气泡震荡间的关系以及吸收衰减对子波的影响,并根据实测远场子波,对齐氏和范氏两种气体模型进行了模拟效果对比,结果表明:采用范氏气体模型所模拟的子波与实际子波更为吻合,模拟出的气枪的子波波形、振幅大小、气泡周期上,与业界通用的Nucleus软件的模拟结果吻合较好,在后续的使用中将继续优化。  相似文献   

Stochastic and analytical approaches for sediment accumulation in river reservoirs     

Tanju Akar 《水文科学杂志》2020,65(6):984-994

ABSTRACT

Sediment accumulation in a river reservoir is studied by stochastic time series models and analytical approach. The first-order moving average process is found the best for the suspended sediment discharge time series of the Juniata River at Newport, Pennsylvania, USA. Synthetic suspended sediment discharges are first generated with the chosen model after which analytical expressions are derived for the expected value and variance of sediment accumulation in the reservoir. The expected value and variance of the volume of sediment accumulation in the reservoir are calculated from a thousand synthetic time series each 38 years long and compared to the analytical approach. Stochastic and analytical approaches perfectly trace the observation in terms of the expected value and variability. Therefore, it is concluded that the expected value and variance of sediment accumulation in a reservoir could be estimated by analytical expressions without the cost of synthetic data generation mechanisms.  相似文献