Evaporation from boreal reservoirs: A comparison between eddy covariance observations and estimates relying on limited data     

Judith Fournier  Antoine Thiboult  Daniel F. Nadeau  Nikki Vercauteren  François Anctil  Annie-Claude Parent  Ian B. Strachan  Alain Tremblay 《水文研究》2021,35(8):e14335

Hydrological models used for reservoir management typically lack an accurate representation of open-water evaporation and must be run in a scarce data context. This study aims to identify an accurate means to estimate reservoir evaporation with simple meteorological inputs during the open-water season, using long-term eddy covariance observations from two boreal hydropower reservoirs with contrasting morphometry as reference. Unlike the temperate water bodies on which the majority of other studies have focused, northern reservoirs are governed by three distinct periods: ice cover in the cold season, warming in the summer and energy release in the fall. The reservoirs of interest are Eastmain-1 (52°N, mean depth of 11 m) and Romaine-2 (51°N, mean depth of 42 m), both located in eastern Canada. Four approaches are analysed herein: a combination approach, a radiation-based approach, a mass-transfer approach, and empirical methods. Of all the approaches, the bulk transfer equation with a constant Dalton number of 1.2 x 10⁻³ gave the most accurate estimation of evaporation at hourly time steps, compared with the eddy covariance observations (RMSE of 0.06 mm h⁻¹ at Eastmain-1 and RMSE of 0.04 mm h⁻¹ at Romaine-2). The daily series also showed good accuracy (RMSE of 1.38 mm day⁻¹ at Eastmain-1 and RMSE of 0.62 mm day⁻¹ at Romaine-2) both in the warming and energy release phases of the open-water season. The bulk transfer equation, on the other hand, was incapable of reproducing condensation episodes that occurred soon after ice breakup. Basic and variance-based sensitivity analyses were conducted, in particular to measure the variation in performance when the bulk transfer equation was applied with meteorological observations collected at a certain distance (~10–30 km) from the reservoir. This exercise illustrated that accurate estimates of open water evaporation require representative measurements of wind speed and water surface temperature.  相似文献   

Vertical mixing of gravel over a long flood series     

Judith K. Haschenburger 《地球表面变化过程与地形》2011,36(8):1044-1058

Vertical sediment exchange is a fundamental component of bedload transport in gravel‐bed channels. This paper describes the characteristic depth of exchange achieved over a long flood series. Analysis is based on 11 recoveries of magnetically tagged gravels deployed in Carnation Creek, Canada, completed between 1990 and 2008. Vertical grain exchange mixes gravels throughout the streambed relatively rapidly. Within one to eight floods the mean burial depth approaches two times the surface layer thickness, quantified by the 90th percentile of the size distribution. Finer gravels are mixed more rapidly into the bed than coarser gravels. Both active and passive grain exchanges throughout most of the bed produce the overall vertical distribution of marked grains. Gravel exchanges exhibit fairly consistent patterns once tracers are well mixed by large floods. Results highlight the role of flood sequence in determining exchange depths, support the notion of an upper limit to exchange, and underscore the importance of passive grain exchange. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Curating NASA's extraterrestrial samples—Past, present, and future     

Carlton Allen  Astromaterials Curator  Judith Allton  Genesis Sample Curator  Gary Lofgren  Lunar Sample Curator  Kevin Righter  Antarctic Meteorite Curator  Michael Zolensky  Cosmic Dust  Stardust Sample Curator 《Chemie der Erde / Geochemistry》2011,(1):1-20

The NASA Johnson Space Center Astromaterials Acquisition and Curation Office has the unique responsibility to curate NASA's extraterrestrial samples – from past and forthcoming missions – into the indefinite future. Presently curation includes documentation, preservation, preparation, and distribution of samples from the Moon, asteroids, comets, the solar wind, and the planet Mars. Each of these sample sets has a unique history and comes from a unique environment. The curation laboratories and procedures developed over forty years have proven both necessary and sufficient to serve the evolving needs of a worldwide research community. A new generation of sample return missions is being planned and proposed to destinations across the solar system. Curation must evolve to meet the increased challenges of these new samples.  相似文献   

Numerical investigation of wave propagation in the Liverpool Bay, NW England     

LI Ming  RAYMOND Ip  WOLF Judith  CHEN Xueen  BURROWS Richard 《海洋学报(英文版)》2011,30(5):1-13

The computer model for near shore wave propagation,SWAN,was used to study wave climates in Liverpool Bay,northwest England with various input parameters,including bottom friction factor,white capping,wind drag formulation and effects of tidal modulations.Results were compared with in-situ measurements and reveal the impacts from these inputs on the predictions of wave height and propagation distributions.In particular,the model results were found very sensitive to different input formulations,and tend to underestimate the wave parameters under storm conditions in comparison with the observations.It is therefore important to further validate the model against detailed field measurements,particularly under large storms that are often of the primary concern.  相似文献   

Role for Eurasian Arctic shelf sea ice in a secularly varying hemispheric climate signal during the 20th century     

Marcia Glaze Wyatt  Judith A. Curry 《Climate Dynamics》2014,42(9-10):2763-2782

A hypothesized low-frequency climate signal propagating across the Northern Hemisphere through a network of synchronized climate indices was identified in previous analyses of instrumental and proxy data. The tempo of signal propagation is rationalized in terms of the multidecadal component of Atlantic Ocean variability—the Atlantic Multidecadal Oscillation. Through multivariate statistical analysis of an expanded database, we further investigate this hypothesized signal to elucidate propagation dynamics. The Eurasian Arctic Shelf-Sea Region, where sea ice is uniquely exposed to open ocean in the Northern Hemisphere, emerges as a strong contender for generating and sustaining propagation of the hemispheric signal. Ocean-ice-atmosphere coupling spawns a sequence of positive and negative feedbacks that convey persistence and quasi-oscillatory features to the signal. Further stabilizing the system are anomalies of co-varying Pacific-centered atmospheric circulations. Indirectly related to dynamics in the Eurasian Arctic, these anomalies appear to negatively feed back onto the Atlantic‘s freshwater balance. Earth’s rotational rate and other proxies encode traces of this signal as it makes its way across the Northern Hemisphere.  相似文献   

Large-scale stochastic linear inversion using hierarchical matrices     

Sivaram Ambikasaran  Judith Yue Li  Peter K. Kitanidis  Eric Darve 《Computational Geosciences》2013,17(6):913-927

Stochastic inverse modeling deals with the estimation of functions from sparse data, which is a problem with a nonunique solution, with the objective to evaluate best estimates, measures of uncertainty, and sets of solutions that are consistent with the data. As finer resolutions become desirable, the computational requirements increase dramatically when using conventional solvers. A method is developed in this paper to solve large-scale stochastic linear inverse problems, based on the hierarchical matrix (or ? ² matrix) approach. The proposed approach can also exploit the sparsity of the underlying measurement operator, which relates observations to unknowns. Conventional direct algorithms for solving large-scale linear inverse problems, using stochastic linear inversion techniques, typically scale as ??(n ² m+nm ²), where n is the number of measurements and m is the number of unknowns. We typically have n ? m. In contrast, the algorithm presented here scales as ??(n ² m), i.e., it scales linearly with the larger problem dimension m. The algorithm also allows quantification of uncertainty in the solution at a computational cost that also grows only linearly in the number of unknowns. The speedup gained is significant since the number of unknowns m is often large. The effectiveness of the algorithm is demonstrated by solving a realistic crosswell tomography problem by formulating it as a stochastic linear inverse problem. In the case of the crosswell tomography problem, the sparsity of the measurement operator allows us to further reduce the cost of our proposed algorithm from ??(n ² m) to $\mathcal {O}(n^{2} \sqrt {m} + nm)$ . The computational speedup gained by using the new algorithm makes it easier, among other things, to optimize the location of sources and receivers, by minimizing the mean square error of the estimation. Without this fast algorithm, this optimization would be computationally impractical using conventional methods.  相似文献   

The deep geothermal potential of the Berlin area     

Oliver Kastner  Judith Sippel  Magdalena Scheck-Wenderoth  Ernst Huenges 《Environmental Earth Sciences》2013,70(8):3567-3584

In this study, we model the geothermal potential of deep geological formations located in the Berlin region in Germany. Berlin is situated in a sedimentary geological setting (northeastern German basin), comprising low-enthalpic aquifers at horizons down to 4–5 km depth. In the Berlin region, the temperature increases almost linearly with depth by about 30 K per kilometer, thus allowing for direct heating from deep aquifer reservoirs in principle. Our model incorporates eight major sedimentary units (Jurassic, Keuper, Muschelkalk, Upper/Middle/Lower Buntsandstein, Zechstein Salt and Sedimentary Rotliegend). Owing to lack of available petro-physical rock data for the Berlin region, we have evaluated literature data for the larger northeastern German basin to develop a thermodynamic field model which regards depth-corrected equations of state within statistical intervals of confidence. Integration over the thicknesses of the respective structural units yields their “heat in place”—energy densities associated with the pore fluid and the rock matrix under local conditions in Joule per unit area at the surface. The model predicts that aquifers in the Middle Buntsandstein and in the Sedimentary Rotliegend may well exhibit energy densities about 10 GJ m^?2 for the pore fluids and 20 GJ m^?2 to 40 GJ m^?2 for the rock matrices on average. Referring these figures to the city area of Berlin (about 892 km²), a significant hydrothermal potential results, which however remained undeveloped until today for the reason of present development risks. The model accounts for these risks through statistical intervals of confidence which are in the order of ±60 to ±80 % of the trend figures. To minimize these uncertainties, scientific field explorations were required in order to assess the petro-physical aquifer properties locally.  相似文献   

Three-dimensional P and S wave velocity structures of the Sichuan basin and Longmen Shan: Implications for Seismic Hazard     

WANG Maomao  Judith HUBBARD  Andreas PLESCH  John H. SHAW  JIA Dong  LI Yiquan 《《地质学报》英文版》2013,87(Z1):399-400

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Enigmatic clastic pipe swarms and implications for fluidization dynamics in aeolian deposits     

Marjorie A. Chan  Stephen T. Hasiotis  Judith T. Parrish 《Sedimentology》2019,66(2):513-535

Soft‐sediment deformation of contorted and massive sandstone is common throughout much of the siliciclastic record, but clastic pipes represent a distinctive class of pressurized synsedimentary features. Remarkable centimetre to metre‐scale clastic pipe exposures in the Jurassic Navajo Sandstone of Utah (USA) establish a range of pipe sizes, expressions and relationships to the host rock in an erg margin setting, traditionally thought to be just a dry desert system. In particular, the field and laboratory characterizations of cylindrical pipes show internal concentric, annular rings that imply water fluidization, with alignment of long grain axes due to shear flow along pipe margins. Central interior parts of decimetre‐scale pipes appear massive in plan view, but display weakly developed pseudobedding from post‐pressure release, gravitational settling in the cross‐sectional view. Deformation features of conjugate fractures, ring faults, hypotrochoid patterns (geometric arcs and circles) and breccia in the host material reflect both brittle and ductile behaviour in response to the fluidization and injection of the clastic pipes. The stratigraphic context of individual pipes and the stratabound intervals of pipe features imply dynamic deformation nearly coincident with deposition in this Early Jurassic aeolian system related to multiple factors of groundwater expulsion, timing and local host sediment properties that influenced pipe development. Although the pipe features might be easily overlooked as a smaller scale feature of soft‐sediment deformation in dune deposits, these are valuable environmental indications of disrupted fluid pathways within porous, reservoir quality sands, associated with possible combinations of periodic springs, high water‐table conditions and strong ground‐motion events. These pipe examples may be important analogues where exposures are not so clear, with applications to diverse modern and ancient clastic settings internationally on Earth as well as in planetary explorations such as on Mars.  相似文献   

Stable and clumped isotopes in desert carbonate spring and lake deposits reveal palaeohydrology: A case study of the Lower Jurassic Navajo Sandstone,south‐western USA     

Judith Totman Parrish  Ethan G. Hyland  Marjorie A. Chan  Stephen T. Hasiotis 《Sedimentology》2019,66(1):32-52

Carbon, oxygen and clumped isotope (Δ₄₇) values were measured from lacustrine and tufa (spring)‐mound carbonate deposits in the Lower Jurassic Navajo Sandstone of southern Utah and northern Arizona in order to understand the palaeohydrology. These carbonate deposits are enriched in both ¹⁸O and ¹³C across the basin from east to west; neither isotope is strongly sensitive to the carbonate facies. However, ¹⁸O is enriched in lake carbonate deposits compared to the associated spring mounds. This is consistent with evaporation of the spring waters as they exited the mounds and were retained in interdune lakes. Clumped isotopes (Δ₄₇) exhibit minor systematic differences between lake and tufa‐mound temperatures, suggesting that the rate of carbonate formation under ambient conditions was moderate. These clumped isotope values imply palaeotemperature elevated beyond reasonable surface temperatures (54 to 86°C), which indicates limited bond reordering at estimated burial depths of ca 4 to 5 km, consistent with independent estimates of sediment thickness and burial depth gradients across the basin. Although clumped isotopes do not provide surface temperature information in this case, they still provide useful burial information and support interpretations of the evolution of groundwater locally. The findings of this study significantly extend the utility of combining stable isotope and clumped isotope methods into aeolian environments.  相似文献