Precipitable water vapor (PWV) estimations from the site of the Eastern Anatolia Observatory<Superscript>∗</Superscript> (DAG), a new astronomical observatory in Turkey     

Sacit Özdemir  Cahit Yeşilyaprak  Bahadır Aktuğ  Derya Öztürk  Deniz Çoker  Recep Balbay 《Experimental Astronomy》2018,46(2):323-336

We present preliminary statistics on the precipitable water vapor (PWV) content over the Karakaya Hills in Erzurum city, where the largest optical and near-infrared astronomical telescope in Turkey will be operated. Since the observatory will observe in the near-infrared (NIR), it is intended to perform PWV measurements of the atmosphere above the site by using signal delays in Global Positioning System (GPS) communication. The analysis of the GPS data recorded on the summit for almost one year shows that the atmosphere over the site of the observatory, which has an altitude of 3170 m, has favorable conditions for NIR observations. From GPS measurements, we report that the site had an average PWV of 3.2 mm and a median PWV of 2.7 mm between October 6, 2016, and June 15, 2017. We also present the time dependency of the PWV content and the correlations between the amount of PWV and the other meteorological records gathered from radiosonde flights and ground-based measurements.  相似文献   

一种基于熵权法的小波去噪复合评价指标   总被引：2，自引：0，他引：2  

容静  刘立龙  康昊华  李松青  周吕 《大地测量与地球动力学》2018,38(7):689-694

传统的评价指标在真值未知的情况下不能满足小波去噪质量评价的要求。为此，借助变化率特征重新构建均方根误差变化量和平滑度变化量两个指标，利用熵权法定权将归一化后的两个指标线性组合，所得到的新指标即为复合评价指标。该方法借助指标的变化率随分解层数的增加表现出明显的收敛特性来确定去噪最优分解层数。实验表明，该方法能够在真值未知的情况下准确地指导小波分解，确定去噪最优分解层数，从而达到最优去噪效果。  相似文献   

Terahertz band simulations using two different radiative transfer models     

Linjun PAN  Daren Lü 《中国科学:地球科学(英文版)》2018,61(10):1482-1490

A high-resolution dual-band terahertz (THz) radiometer was designed to measure vertical distributions of chemical elements in the middle atmosphere of the Tibetan Plateau. A forward simulation, which always should be conducted firstly for the development of a matching retrieval algorithm, has not been done before. We use two radiative transfer models, ARTS and AM, to simulate the water vapor, ozone and carbon monoxide spectra on the plateau based on the spectral design of the THz radiometer. The emission line characteristics of the three gases in this spectral band are identified. Reasons for the differences in the spectral simulations between the two models are analyzed for individual gases. The impact of several different spectral parameter settings on the simulations are evaluated through a series of sensitivity experiments. This study suggests that the ARTS is more suitable for the development of the THz radiometer retrieval algorithm. An optimal parameter setting of the ARTS for the three elements are given.  相似文献   

Coupled groundwater flow and heat transport simulation for estimating transient aquifer–stream exchange at the lowland River Spree (Germany)          下载免费PDF全文

Gunnar Nützmann  Christian Levers  Jörg Lewandowski 《水文研究》2014,28(13):4078-4090

Subsurface flow and heat transport near Freienbrink, NE Germany, was simulated in order to study groundwater–surface water exchange between a floodplains aquifer and a section of the lowland River Spree and an adjacent oxbow. Groundwater exfiltration was the dominant process, and only fast surface water level rises resulted in temporary infiltration into the aquifer. The main groundwater flow paths are identified based on a 3D groundwater flow model. To estimate mass fluxes across the aquifer–surface water interfaces, a 2D flow and heat transport modelling approach along a transect of 12 piezometers was performed. Results of steady‐state and transient water level simulations show an overall high accuracy with a Spearman coefficient ρ = 0.9996 and root mean square error (RMSE) = 0.008 m. Based on small groundwater flow velocities of about 10^?7 to 10^?6 ms^?1, mean groundwater exfiltration rates of 233 l m^?2 d^?1 are calculated. Short periods of surface water infiltration into the aquifer do not exceed 10 days, and the infiltration rates are in the same range. The heat transport was modelled with slightly less accuracy (ρ = 0.8359 and RMSE = 0.34 °C). In contrast to the predominant groundwater exfiltration, surface water temperatures determine the calculated temperatures in the upper aquifer below both surface water bodies down to 10 m during the whole simulation period. These findings emphasize prevailing of heat conduction over advection in the upper aquifer zones, which seems to be typical for lowland streams with sandy aquifer materials and low hydraulic gradients. Moreover, this study shows the potential of coupled numerical flow and heat transport modelling to understand groundwater–surface water exchange processes in detail. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Hydrodynamics of Canal Istanbul and its impact in the northern Sea of Marmara under extreme conditions     

Saçu  Şehriban  Erdik  Tarkan  Stanev  Emil V.  Şen  Olgay  Erdik  Jasna Duricic  Öztürk  İzzet 《Ocean Dynamics》2020,70(6):745-758

Ocean Dynamics - The Bosphorus, located at the junction of Asia and Europe, controls the transports of water, material, and energy between the Black Sea (BS) and the Mediterranean Sea. The Canal...  相似文献   

Subaquatic slope instabilities: The aftermath of river correction and artificial dumps in Lake Biel (Switzerland)     

Nathalie Dubois  Love Råman Vinnå  Marvin Rabold  Michael Hilbe  Flavio S. Anselmetti  Alfred Wüest  Laetitia Meuriot  Alice Jeannet  Stéphanie Girardclos 《Sedimentology》2020,67(2):971-990

River engineering projects are developing rapidly across the globe, drastically modifying water courses and sediment transfer. Investigation of the impact of engineering works focuses usually on short-term impacts, thus a longer-term perspective is still missing on the effects that such projects have. The ‘Jura Water Corrections’ – the largest river engineering project ever undertaken in Switzerland – radically modified the hydrological system of Lake Biel in the 19th and 20th Century. The deviation of the Aare River into Lake Biel more than 140 years ago, in 1878, thus represents an ideal case study to investigate the long-term sedimentological impacts of such large-scale river rerouting. Sediment cores, along with new high-resolution bathymetric and seismic reflection datasets were acquired in Lake Biel to document the consequences of the Jura Water Corrections on the sedimentation history of Lake Biel. Numerous subaquatic mass transport structures were detected on all of the slopes of the lake. Notably, a relatively large mass transport complex (0·86 km²) was observed on the eastern shore, along the path of the Aare River intrusion. The large amount of sediment delivered by the Aare River since its deviation into the lake likely caused sediment overloading resulting in subaquatic mass transport. Alternatively, the dumping since 1963 in a subaquatic landfill of material excavated during the second phase of river engineering, when the channels flowing into and out of Lake Biel were widened and deepened, might have triggered the largest mass transport, dated to 1964 or 1965. Additional potential triggers include two nearby small earthquakes in 1964 and 1965 (M_W 3·9 and 3·2, respectively). The data for this study indicate that relatively large mass transports have become recurrent in Lake Biel following the deviation of the Aare River, thus modifying hazard frequency for the neighbouring communities and infrastructure.  相似文献   

An improved input energy spectrum verified by the shake table tests     

Ahmet Güllü  Ercan Yüksel  Cem Yalçın  A. Anıl Dindar  Hasan Özkaynak  Oral Büyüköztürk 《地震工程与结构动力学》2019,48(1):27-45

Input energy is the principal component of the energy balance equation. It is beneficial to determine, through its components, how the recoverable and irrecoverable energies are distributed within the structural elements. Several equations and attenuation relations to define mass-normalized input energy spectra exist in the literature. They are mainly proposed for elastic systems subjected to far-fault EQs. There is a lack of experimental verification of these proposed spectra. In this paper, experimental assessment was performed to the existing spectra, and further improvements were accomplished. For this purpose, steel cantilever columns were tested on the shake table for two specific historical EQs coincidently having similar spectral acceleration values. Based on the experimental results, a three-part mass-normalized relative input energy spectrum was formulated including soil type, EQ (corner period, intensity, duration, spectral acceleration, and velocity), and structural behavioral characteristics (period and structural damping). The proposed input energy spectrum was experimentally calibrated and numerically validated for various EQs featuring near- and far-field types. Analytical and experimental comparisons were made between the previously developed spectrum and the newly proposed one. The validation studies and the statistical evaluations exposed that the proposed spectrum yielded better agreement with the experimental and numerical results.  相似文献   

Hydrogeophysical modelling of Hisarcik (Kütahya) geothermal field,western Turkey     

Serkan Üner  Gülçin Özürlan Ağaçgözgü  Doğa Düşünür Doğan 《Geophysical Prospecting》2019,67(8):2176-2195

Western Anatolia hosts many low-to-moderate and high-temperature geothermal sources in which active faults play a dominant role to control the recharge and the discharge of geothermal fluid. In this study, we used the two-dimensional geoelectric structure of Kütahya Hisarcık geothermal field, and created a conceptual hydrogeophysical model that includes faults, real topographical variations and geological units. The temperature distribution and fluid flow pattern are also investigated. The depth extension of Hisarcık Fault, electrical basement and low resistivity anomalies related to the presence of geothermal fluid are determined by using resistivity studies in the area. Numerical simulations suggest that Hisarcık fault functioning as a fluid conduit primarily enables hot fluid to be transported from depth to the surface. It is shown that the locations of predicted outflow vents coincide with those of hot springs in the area.  相似文献   

Dynamical system analysis of a five-dimensional cosmological model     

A. Savaş Arapoğlu  Ezgi Yalçınkaya  A. Emrah Yükselci 《Astrophysics and Space Science》2018,363(10):215

A five-dimensional cosmological model including a single perfect fluid is studied in the framework of dynamical system analysis. All the critical points of the system are listed with their stability properties and some representative phase diagrams are explicitly shown. It is found that the stabilization of extra dimension is possible and the observed flatness of the three-dimensional space is provided for certain ranges of the equation of state parameter of the fluid. The model suggested here can be considered as a simplified model for examining the possible effects of the extra dimensions in the early universe.  相似文献   

灰色稳健总体最小二乘估计及高铁路基变形预测     

陈洋  文鸿雁  覃辉  王清涛  周吕 《大地测量与地球动力学》2018,38(2):140-146

最小二乘估计和部分变量误差模型的总体最小二乘估计不具备抵御粗差的能力。鉴于粗差可能同时出现在灰色白化微分方程的观测值和系数矩阵中，本文提出基于IGGⅢ抗差方案的部分变量总体最小二乘稳健估计。结合仿真数据和高铁路基观测数据，系统地比较稳健最小二乘、部分变量总体最小二乘、本文算法参数估计结果和算法稳定性。结果表明，本文算法预测精度高，可以应用到高铁路基沉降预测中。  相似文献