P and S tomography using normal-mode and surface waves data with a neighbourhood algorithm   总被引：1，自引：0，他引：1  

Caroline Beghein  Joseph S. Resovsky  Jeannot Trampert 《Geophysical Journal International》2002,149(3):646-658

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Meteorological inventory of rain-on-snow events in the Canadian Arctic Archipelago and satellite detection assessment using passive microwave data     

Caroline Dolant  A. Langlois  L. Brucker  A. Royer  A. Roy  B. Montpetit 《自然地理学》2018,39(5):428-444

The spatial and temporal distributions of rain-on-snow (ROS) events across the Canadian Arctic Archipelago (CAA) remain poorly understood owing to their sporadic nature in time and space. This situation motivated the development of remote sensing detection algorithms. This paper uses a large meteorological dataset across the CAA to adapt an existing ROS-detection algorithm developed in a previous study by our group. Results highlight the spatial distribution and evolution of ROS occurrences reported since 1985 at 14 weather stations across the CAA. Results show that >600 ROS events were inventoried since 1985, for which >70% were classified as pure rain (liquid form) and 30% as mixed precipitation (solid/liquid). Of the pure rain events, 75% occurred during spring, 14% during fall, 8% during summer and <1% during winter. Such events can have significant impacts on ungulate grazing conditions through the creation of ice layers, causing serious problems for caribou calf survival, especially during the migration period. This paper introduces an adaptation for larger scale Arctic application of a detection algorithm (sensitivity analysis on the detection threshold) with an error of ~5%. The validation, however, remains limited due to a short study period and limited number of sites.  相似文献   

From Shiny Shoes to Muddy Reality: Understanding How Meso-State Actors Negotiate the Implementation Gap in Participatory Forest Management     

Anne Kairu  Caroline Upton  Mark Huxham  Kiplagat Kotut  Robert Mbeche  James Kairo 《社会与自然资源》2018,31(1):74-88

Recent research on participatory forest management (PFM) in the global south has highlighted the existence of a widespread “implementation gap” between the ambitious intent enshrined in legislation and the often partial, disappointing rollout of devolved forest governance on the ground. Here, through an ethnographic case study of forest officers (FOs) in Kenya, we draw on a framework of critical institutionalism to examine how key meso-level actors, or “interface bureaucrats,” negotiate and challenge this implementation gap in everyday forest governance. We go beyond consideration of institutional bricolage in isolation or as an aggregate category, to analyze how bricolage as aggregation, alteration, and/or articulation is variously driven, shaped, and constrained by FOs’ multiple accountabilities and agency. Our analysis highlights the locally specific, contingent, and mutually reinforcing nature of accountability, agency and bricolage, and their explanatory power in relation to the performance and nature of “actually existing” PFM.  相似文献   

On the use of long-term observation of water level and temperature along the shore for a better understanding of the dynamics: example of Toulon area,France     

Rey  Vincent  Dufresne  Christiane  Fuda  Jean-Luc  Mallarino  Didier  Missamou  Tathy  Paugam  Caroline  Rougier  Gilles  Taupier-Letage  Isabelle 《Ocean Dynamics》2020,70(7):913-933

Ocean Dynamics - A dense network of instruments has been deployed within harbors along the Mediterranean coast, in the Toulon Metropole area, between the Hyères islands and the Sanary Bay in...  相似文献   

Importance of Spatial Resolution in Global Groundwater Modeling     

Robert Reinecke  Alexander Wachholz  Steffen Mehl  Laura Foglia  Christoph Niemann  Petra Döll 《Ground water》2020,58(3):363-376

Global-scale gradient-based groundwater models are a new endeavor for hydrologists who wish to improve global hydrological models (GHMs). In particular, the integration of such groundwater models into GHMs improves the simulation of water flows between surface water and groundwater and of capillary rise and thus evapotranspiration. Currently, these models are not able to simulate water table depth adequately over the entire globe. Unsatisfactory model performance compared to well observations suggests that a higher spatial resolution is required to better represent the high spatial variability of land surface and groundwater elevations. In this study, we use New Zealand as a testbed and analyze the impacts of spatial resolution on the results of global groundwater models. Steady-state hydraulic heads simulated by two versions of the global groundwater model G³M, at spatial resolutions of 5 arc-minutes (9 km) and 30 arc-seconds (900 m), are compared with observations from the Canterbury region. The output of three other groundwater models with different spatial resolutions is analyzed as well. Considering the spatial distribution of residuals, general patterns of unsatisfactory model performance remain at the higher resolutions, suggesting that an increase in model resolution alone does not fix problems such as the systematic overestimation of hydraulic head. We conclude that (1) a new understanding of how low-resolution global groundwater models can be evaluated is required, and (2) merely increasing the spatial resolution of global-scale groundwater models will not improve the simulation of the global freshwater system.  相似文献   

River Seepage Conductance in Large‐Scale Regional Studies          下载免费PDF全文

Hubert J. Morel‐Seytoux  Calvin D. Miller  Cinzia Miracapillo  Steffen Mehl 《Ground water》2017,55(3):399-407

Flow exchange between surface and groundwater is of great importance be it for beneficial allocation and use of water resources or for the proper exercise of water rights. In large‐scale regional studies, most numerical models use coarse grid sizes, which make it difficult to provide an accurate depiction of the phenomenon. In particular, a somewhat arbitrary leakance coefficient in a third type (i.e., Cauchy, General Head) boundary condition is used to calculate the seepage discharge as a function of the difference of head in the river and in the aquifer, whose value is often found by calibration. A different approach is presented to analytically estimate that leakance coefficient. It is shown that a simple equivalence can be deduced from the analytical solution for the empirical coefficient, so that it provides the accuracy of the analytical solution while the model maintains a very coarse grid, treating the water‐table aquifer as a single calculation layer. Relating the empirical leakance coefficient to the exact conductance, derived from physical principles, provides a physical basis for the leakance coefficient. Factors such as normalized wetted perimeter, degree of penetration of the river, presence of a clogging layer, and anisotropy can be included with little computational demand. In addition the river coefficient in models such as MODFLOW, for example, can be easily modified when grid size is changed without need for recalibration.  相似文献   

First interactions with the hydrologic cycle determine pyrogenic carbon's fate in the Earth system     

Caroline Ann Masiello  Asmeret Asefaw Berhe 《地球表面变化过程与地形》2020,45(10):2394-2398

Fires produce an aromatic particulate residue commonly referred to as pyrogenic carbon (PyC). Particulate PyC is low density, high porosity, and is predominantly deposited on the soil surface in post-fire landscapes. These characteristics create a material that is prone to mobility, both vertically down the soil profile and laterally across the landscape even in low-relief landforms. Because of its tendency for lateral mobilization, we argue here that PyC's first interaction with water determines its environmental fate and persistence, not its interactions with soil minerals or microbes. PyC's first interactions with water determine: the amount of PyC that will enter the soil profile and experience microbial and geochemical alterations, whether it will be buried in depositional environments and stored on the landscape, or if it will be transported to streams and eventually to the ocean. Here we posit that this crucial first interaction with the hydrologic cycle occurs on the timescale of days to weeks, and therefore supersedes microbial decomposition as the primary control on PyC's environmental persistence. © 2020 John Wiley & Sons, Ltd.  相似文献   

Buildings in GI: How to deal with building models in the GIS domain     

Laura Knoth  Manfred Mittlbck  Bernhard Vockner  Michael Andorfer  Caroline Atzl 《Transactions in GIS》2019,23(3):435-449

Digital building information is important during a building's lifecycle, it is needed from first design until demolition. The two domains that mainly contribute are AEC (architecture, engineering, and construction) during design, construction, and operation, and GIS as a supporting discipline for analysis and further integration of the building's environment. However, there is a challenge in information exchange between the two domains, resulting in the remodeling of digital building information in GIS. In this article, we identify three major data sources from the AEC domain and show transformation processes to enable the integration of such models into the geographical environment in the form of one transition model. Furthermore, we show that this model can either be used directly or exported in the form of de facto standards that allow for further analysis.  相似文献   

Timing,magnitude and geochemistry of major Southeast Asian volcanic eruptions: identifying tephrochronologic markers     

Caroline Bouvet De Maisonneuve  Olga Bergal-Kuvikas 《第四纪科学杂志》2020,35(1-2):272-287

We review the current knowledge about Southeast Asian volcanoes and their eruption histories, and focus on identifying tephrochronologic markers representing major explosive eruptions in order to further future palaeoclimate and volcanological studies. Forty-one volcanic edifices in Southeast Asia have been classified as large calderas by Whelley et al. (2015) and thus have, or are likely to have, produced large explosive eruptions with a Volcanic Explosivity Index (VEI) of 6–8. Unfortunately, only 20 such eruptions have known ages, spanning from 1.2 Ma to 1991 ad , and fewer have geochemical data that can be used for tephrostratigraphic correlations. Volcanic products from different geodynamic regions and different sources can generally be distinguished on major element plots (e.g. K₂O versus CaO) of matrix glass composition. However, the distinction of multiple eruptions from the same source often requires additional data such as trace element compositions of matrix glass and/or mineral compositions. Biotite, but also magnetite compositions (MgO and TiO₂ content in particular) appear to be very discriminating. Up to nine tuffs in addition to the three to four Toba tuffs can be utilised as widespread tephrochronologic markers and span a range from 1.2 to 1.6 Ma to recent. As only a few Holocene major eruptions have been well characterised and dated, many large calderas are still unstudied, and many distal tephra layers are still lacking a source, more tephrochronologic markers can certainly be defined in the future.  相似文献   

Abundance and size distribution of transparent exopolymer particles (TEP) in a coccolithophorid bloom in the northern Bay of Biscay     

Jérôme Harlay  Caroline De Bodt  Anja Engel  Sandra Jansen  Quentin d’Hoop  Judith Piontek  Nicolas Van Oostende  Steve Groom  Koen Sabbe  Lei Chou 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(8):1251-1265

The distribution of transparent exopolymer particles (TEP) was investigated during a coccolithophorid bloom in the northern Bay of Biscay (North Atlantic Ocean) in early June 2006. MODIS chlorophyll-a (Chl-a) and reflectance images before and during the cruise were used to localize areas of important biological activity and high reflectance (HR). TEP profiles along the continental margin, determined using microscopic (TEP_micro) and colorimetric (TEP_color) methods, showed abundant (6.1×10⁶–4.4×10⁷ L^?1) and relatively small (0.5–20 μm) particles, leading to a low total volume fraction (0.05–2.2 ppm) of TEP_micro and similar vertical profiles of TEP_color. Estimates of carbon content in TEP (TEP-C) derived from the microscopic approach yielded surface concentration of 1.50 μmol C L^?1. The contribution of TEP-C to particulate organic carbon (POC) was estimated to be 12% (molar C ratio) during this survey. Our results suggest that TEP formation is a probable first step to rapid and efficient export of C during declining coccolithophorid blooms.  相似文献