Erratum to: Determination of a terrestrial reference frame via Kalman filtering of very long baseline interferometry data     

Benedikt Soja  Tobias Nilsson  Kyriakos Balidakis  Susanne Glaser  Robert Heinkelmann  Harald Schuh 《Journal of Geodesy》2016,90(12):1329-1329

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Estimation and evaluation of real-time precipitable water vapor from GLONASS and GPS   总被引：1，自引：0，他引：1  

Cuixian Lu  Xingxing Li  Maorong Ge  Robert Heinkelmann  Tobias Nilsson  Benedikt Soja  Galina Dick  Harald Schuh 《GPS Solutions》2016,20(4):703-713

The revitalized Russian GLONASS system provides new potential for real-time retrieval of zenith tropospheric delays (ZTD) and precipitable water vapor (PWV) in order to support time-critical meteorological applications such as nowcasting or severe weather event monitoring. In this study, we develop a method of real-time ZTD/PWV retrieval based on GLONASS and/or GPS observations. The performance of ZTD and PWV derived from GLONASS data using real-time precise point positioning (PPP) technique is carefully investigated and evaluated. The potential of combining GLONASS and GPS data for ZTD/PWV retrieving is assessed as well. The GLONASS and GPS observations of about half a year for 80 globally distributed stations from the IGS (International GNSS Service) network are processed. The results show that the real-time GLONASS ZTD series agree quite well with the GPS ZTD series in general: the RMS of ZTD differences is about 8 mm (about 1.2 mm in PWV). Furthermore, for an inter-technique validation, the real-time ZTD estimated from GLONASS-only, GPS-only, and the GPS/GLONASS combined solutions are compared with those derived from very long baseline interferometry (VLBI) at colocated GNSS/VLBI stations. The comparison shows that GLONASS can contribute to real-time meteorological applications, with almost the same accuracy as GPS. More accurate and reliable water vapor values, about 1.5–2.3 mm in PWV, can be achieved when GLONASS observations are combined with the GPS ones in the real-time PPP data processing. The comparison with radiosonde data further confirms the performance of GLONASS-derived real-time PWV and the benefit of adding GLONASS to stand-alone GPS processing.  相似文献   

A model for underpressure development in a glacial valley,an example from Adventdalen,Svalbard          下载免费PDF全文

Magnus Wangen  Alban Souche  Harald Johansen 《Basin Research》2016,28(6):752-769

The underpressure observed in the glacial valley Adventdalen at Svalbard is studied numerically with a basin model and analytically with a compartment model. The pressure equation used in the basin model, which accounts for underpressure generation, is derived from mass conservation of pore fluid and solid, in addition to constitutive equations. The compartment model is derived as a similar pressure equation, which is based on a simplified representation of the basin geometry. It is used to derive analytical expressions for the underpressure (overpressure) from a series of unloading (loading) intervals. The compartment model gives a characteristic time for underpressure generation of each interval, which tells when the pressure state is transient or stationary. The transient pressure is linear in time for short‐time spans compared to the characteristic time, and then it is proportional to the weight removed from the surface. We compare different contributions to the underpressure generation and find that porosity rebound from unloading is more important than the decompression of the pore fluid during unloading and the thermal contraction of the pore fluid during cooling of the subsurface. Our modelling shows that the unloading from the last deglaciation can explain the present day underpressure. The basin model simulates the subsurface pressure resulting from erosion and unloading in addition to the fluid flow driven by the topography. Basin modelling indicates that the mountains surrounding the valley are more important for the topographic‐driven flow in the aquifer than the recharging in the neighbour valley. The compartment model turns out to be useful to estimate the orders of magnitude for system properties like seal and aquifer permeabilities and decompaction coefficients, despite its geometric simplicity. We estimate that the DeGeerdalen aquifer cannot have a permeability that is higher than 1 · 10^?18 m², as otherwise, the fluid flow in the aquifer becomes dominated by topographic‐driven flow. The upper value for the seal permeability is estimated to be 1 · 10^?20 m², as higher values preclude the generation and preservation of underpressure. The porosity rebound is estimated to be <0.1% during the last deglaciation using a decompaction coefficient α_r = 1 · 10^?9 Pa^?1.  相似文献   

Evaluation of remote sensing‐based seismic site characterization using earthquake damage data     

Muhammad Shafique  Mark van der Meijde  Harald M. A. van der Werff 《地学学报》2012,24(2):123-129

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Cumulative probability functions and their role in evaluating the chronology of geomorphological events during the Holocene     

Richard C. Chiverrell  Varyl R. Thorndycraft  Thomas O. Hoffmann 《第四纪科学杂志》2011,26(1):76-85

Cumulative probability functions (CPFs) for large numbers of radiocarbon age determinations are increasingly being used by scientists as a methodology to discern environmental histories. While the recent compilation of regional databases of the radiocarbon dating control for fluvial sediment sequences has been beneficial for identifying gaps in knowledge and stimulating new research, there are a number of problems that critically undermine the use of these CPFs as sensitive hydroclimatic proxies. (i) The CPF method is underpinned by the assumption that each radiocarbon measurement is a true age estimate for a point in time, whereas each measured age in fact forms a scatter around the true age of the sample; (ii) calibration of radiocarbon ages is responsible for much of the structure in CPFs and compounds the problem of scatter and smears the chronological control; (iii) the databases incorporate multiple types of environmental changes differing chronological relationships between the ¹⁴C measurements and the dated events, with pre‐dating, dating or post‐dating chronological control each displaying variable length temporal lags all mixed together in the same analysis; and (iv) the radiocarbon ages from individual case studies need to be more robustly tested before being incorporated into regional databases. All these factors negate the value of CPFs as sensitive proxies of environmental change, because peaks in probability for individual radiocarbon measurements are likely to be an incorrect estimate for the age of a geomorphological event and this problem is compounded by combining probabilities for multiple unrelated events. In this paper we present a critical analysis of CPFs and their interpretation before suggesting alternative approaches to analysing radiocarbon geochronologies of geomorphic events, which include: (i) Bayesian age modelling of river terrace development; (ii) developing regional databases that test specific geomorphic hypotheses; (iii) Bayesian age modelling of palaeoflood records; and (iv) analysis of sedimentation rates. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

The feeding habits of Austrolethops wardi, a gobiid fish inhabiting burrows of the thalassinidean shrimp Neaxius acanthus     

Ha Trieu Hung Liu  Dominik Kneer  Harald Asmus  Harald Ahnelt 《Estuarine, Coastal and Shelf Science》2008,79(4):620-767

The feeding habit of Austrolethops wardi (Gobiidae) in the seagrass beds of Barrang Lompo and Bone Batang Island in the Spermonde Archipelago, South West Sulawesi, Indonesia, was investigated through gut content analysis. The feeding preferences of this species are very similar on both islands: A. wardi, a burrow associate of Neaxius acanthus, was found to feed almost exclusively on seagrass (which was found in 100% of the investigated stomachs and made up >94% of food items). However, seagrass epiphytes (<5% of food items) and animal food (<1% of food items) occurred in the guts as well, the latter predominantly in terms of copepods and to a lesser degree in other small invertebrates. These results indicate that animal food is of little importance for A. wardi. Some specimens even contained no parts of animal food.  相似文献   

晚震旦世至早寒武世扬子地台北缘碳同位素研究   总被引：6，自引：0，他引：6  

郭庆军  刘丛强  Harald Strauss  Tatiana Goldberg 《地球学报》2004,25(2):151-156

震旦-寒武交变期是地史上一个重大转折期,亦是一个具有特殊意义的过渡时期。运用碳同位素地球化学方法,探讨扬子地台北缘四川南江地区晚震旦世-早寒武世交变期,碳同位素地球化学异常与环境变化和生物演化的相互联系。南江剖面沉积岩有机碳同位素组成在-35．8‰～-30．1‰间变化;碳酸盐碳同位素组成从-3．5‰～ 0．5‰。在灯影组顶部、牛蹄塘组下部和上部,变化的碳、硫同位素组成和不同的黄铁矿与有机碳含量反映了有机碳埋藏量和环境的变化。下寒武统富有机碳和黄铁矿的黑色页岩沉积,暗示了早寒武世早期缺氧环境的存在。  相似文献   

Validation of official erosion modelling based on high‐resolution radar rain data by aerial photo erosion classification          下载免费PDF全文

Franziska Katharina Fischer  Michael Kistler  Robert Brandhuber  Harald Maier  Melanie Treisch  Karl Auerswald 《地球表面变化过程与地形》2018,43(1):187-194

The universal soil loss equation (USLE) is the most frequently applied erosion prediction model and it is also implemented as an official decision‐making instrument for agricultural regulations. The USLE itself has been already validated using different approaches. Additional errors, however, arise from input data and interpolation procedures that become necessary for field‐specific predictions on a national scale for administrative purposes. In this study, predicted event soil loss using the official prediction system in Bavaria (Germany) was validated by comparison with aerial photo erosion classifications of 8100 fields. Values for the USLE factors were mainly taken from the official Bavarian high‐resolution (5 × 5 m²) erosion cadastre. As series of erosion events were examined, the cover and management factor was replaced by the soil loss ratio. The event erosivity factor was calculated from high‐resolution (1 × 1 km², 5 min), rain gauge‐adjusted radar rain data (RADOLAN). Aerial photo erosion interpretation worked sufficiently well and average erosion predictions and visual classifications correlated closely. This was also true for data broken down to individual factors and different crops. There was no reason to assume a general invalidity of the USLE and the official parametrization procedures. Event predictions mainly suffered from errors in the assumed crop stage period and tillage practices, which do not reflect interannual and farm‐specific variation. In addition, the resolution of radar data (1 km²) did not seem to be sufficient to predict short‐term erosion on individual fields given the strong spatial gradients within individual rains. The quality of the input data clearly determined prediction quality. Differences between USLE predictions and observations are most likely caused by parametrization weaknesses but not by a failure of the model itself. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Future high- and low-flow estimations for Central Vietnam: a hydro-meteorological modelling chain approach     

Quang Thinh Dang  Harald Kunstmann 《水文科学杂志》2017,62(11):1867-1889

We apply a complex hydro-meteorological modelling chain for investigating the impact of climate change on future hydrological extremes in Central Vietnam, a region characterized by limited data availability. The modelling chain consists of six General Circulation Models (GCMs), six Regional Climate Models (RCMs), six bias correction (BC) approaches, the fully distributed Water Flow and Balance Simulation Model (WaSiM), and extreme values analysis. Bias corrected and raw climate data are used as input for WaSiM. To derive hydrological extremes, the generalized extreme value distribution is fitted to the annual maxima/minima discharge. We identify limitations according to the fitting procedure and the BC methods, and suggest the usage of the delta change approach for hydrological decision support. Tendencies towards increased high- and decreased low flows are concluded. Our study stresses the challenges in using current GCMs/RCMs in combination with state-of-the-art BC methods and extreme value statistics for local impact studies.  相似文献   

贵州瓮安陡山沱组剖面碳同位素生物地球化学研究   总被引：4，自引：0，他引：4  

郭庆军  刘丛强  Harald Strauss  杨卫东 《矿物岩石》2005,25(2):75-80

在对扬子地台贵州瓮安陡山沱组剖面干酪根碳同住素组成进行分析后发现其变化显示了一定的规律性。碳同住素规律变化反映了最初的沉积信息,特别是有机质埋藏量的变化。获得的陡山沱期沉积岩中碳同位素组成研究结果初步反映了震旦一寒武交变期沉积环境的面貌;碳同位素组成变化规律可以用于反映扬子地台沉积层序和世界同期地层全球碳循环的对比和参考。为扬子区陡山沱期环境变化和生物演化提供了证据。δ^13Cker值在-32．3‰和-24．5‰(PDB)间漂移与δ^13Ccarb值在-4．9‰和3．6‰(PDB)间的变化,反映了当时海水的碳同位素组成。无机和有机碳同位素组成之差的△δorg-carb值沿剖面不断变化,是由于沉积有机质中有促进发酵功能的细菌数量比例变化所致。  相似文献