Information content of snow hydrological signatures based on streamflow,precipitation and air temperature     

Ivan Horner  Flora Branger  Hilary McMillan  Olivier Vannier  Isabelle Braud 《水文研究》2020,34(12):2763-2779

Hydrological signatures that represent snow processes are valuable to gain insights into snow accumulation and snow melt dynamics. We investigated five snow signatures. Considering inter-annual average of each calendar day, two slopes derived from the relation between streamflow and air temperature for different periods and streamflow peak maxima are used as signatures. In addition, two different approaches are used to compute inter-annual average and yearly snow storage estimates. We evaluated the ability of these signatures to characterize average (a) snow melt dynamics and (b) snow storage. They were applied in 10 Critical Zone Observatory catchments of the Southern Sierra mountains (USA) characterized by a Mediterranean climate. The relevance and information content of the signatures are evaluated using snow depth and snow water equivalent measurements as well as inter-catchment differences in elevation. The slopes quantifying the relations between streamflow and air temperature and the date of streamflow peak were found to characterize snow melt dynamics in terms of snow melt rates and snow melt affected areas. Streamflow peak dates were linked to the period of highest snow melt rates. Snow storage could be estimated both on average, considering all years, and for each year. Snow accumulation dynamics could not be characterized due to the lack of streamflow response during the snow accumulation period. The signatures were found potentially valuable to gain insights into catchment scale snow processes. In particular, when comparing catchments or observed and simulated data, they could provide insights into differences in terms of (a) snow melt rate and/or snow melt affected area over the snow melt season and (b) average or yearly snow storage. Requiring only widely available data, these hydrological signatures can be valuable for snow processes characterization, catchment comparison/classification or model development, calibration or evaluation.  相似文献   

Linking hydrologic signatures to hydrologic processes: A review     

Hilary McMillan 《水文研究》2020,34(6):1393-1409

Hydrologic signatures are metrics that quantify aspects of streamflow response. Linking signatures to underlying processes enables multiple applications, such as selecting hydrologic model structure, analysing hydrologic change, making predictions in ungauged basins, and classifying watershed function. However, many lists of hydrologic signatures are not process-based, and knowledge about signature-process links has been scattered among studies from experimental watersheds and model selection experiments. This review brings together those studies to catalogue more than 50 signatures representing evapotranspiration, snow storage and melt, permafrost, infiltration excess, saturation excess, groundwater, baseflow, connectivity, channel processes, partitioning, and human alteration. The review shows substantial variability in the number, type, and timescale of signatures available to represent each process. Many signatures provide information about groundwater storage, partitioning, and connectivity, whereas snow processes and human alteration are underrepresented. More signatures are related to the seasonal scale than the event timescale, and land surface processes (ET, snow, and overland flow) have no signatures at the event scale. There are limitations in some signatures that test for occurrence but cannot quantify processes, or are related to multiple processes, making automated analysis more difficult. This review will be valuable as a reference for hydrologists seeking to use streamflow records to investigate a particular hydrologic process or to conduct large-sample analyses of patterns in hydrologic processes.  相似文献   

A first look at oxygen isotope records from modern and Holocene-aged gastropod (Stenomelania) shells from Lake Kutubu,Papua New Guinea     

Kelsie Long  Larissa Schneider  Ian S. Williams  Stewart J. Fallon  Hilary Stuart-Williams  Simon Haberle 《第四纪科学杂志》2020,35(3):457-464

The oxygen isotopic composition of Stenomelania gastropod shells was investigated to reconstruct Holocene palaeoclimate change at Lake Kutubu in the southern highlands of Papua New Guinea. Oxygen isotope (δ¹⁸O) values recorded in aquatic gastropod shells change according to ambient water δ¹⁸O values and temperature. The gastropod shells appear to form in oxygen isotopic equilibrium with the surrounding water and record a shift in average shell oxygen isotopic composition through time, probably as a result of warmer/wetter conditions at ca. 600–900 and 5900–6200 cal a bp. Shorter term fluctuations in oxygen isotope values were also identified and may relate to changes in the intensity or source of rainfall. Further δ¹⁸O analyses of gastropod shells or other carbonate proxies found in the Lake Kutubu sediments are warranted. © 2020 John Wiley & Sons, Ltd.  相似文献   

The role of atmosphere feedbacks during ENSO in the CMIP3 models. Part II: using AMIP runs to understand the heat flux feedback mechanisms   总被引：2，自引：2，他引：0  

James Lloyd  Eric Guilyardi  Hilary Weller 《Climate Dynamics》2011,37(7-8):1271-1292

Several studies using ocean?Catmosphere general circulation models (GCMs) suggest that the atmospheric component plays a dominant role in the modelled El Ni?o-Southern Oscillation (ENSO). To help elucidate these findings, the two main atmosphere feedbacks relevant to ENSO, the Bjerknes positive feedback (??) and the heat flux negative feedback (??), are here analysed in nine AMIP runs of the CMIP3 multimodel dataset. We find that these models generally have improved feedbacks compared to the coupled runs which were analysed in part I of this study. The Bjerknes feedback,???, is increased in most AMIP runs compared to the coupled run counterparts, and exhibits both positive and negative biases with respect to ERA40. As in the coupled runs, the shortwave and latent heat flux feedbacks are the two dominant components of ?? in the AMIP runs. We investigate the mechanisms behind these two important feedbacks, in particular focusing on the strong 1997?C1998 El Ni?o. Biases in the shortwave flux feedback, ?? _SW, are the main source of model uncertainty in ??. Most models do not successfully represent the negative ??_SW in the East Pacific, primarily due to an overly strong low-cloud positive feedback in the far eastern Pacific. Biases in the cloud response to dynamical changes dominate the modelled ?? _SW biases, though errors in the large-scale circulation response to sea surface temperature (SST) forcing also play a role. Analysis of the cloud radiative forcing in the East Pacific reveals model biases in low cloud amount and optical thickness which may affect ?? _SW. We further show that the negative latent heat flux feedback, ?? _LH, exhibits less diversity than ?? _SW and is primarily driven by variations in the near-surface specific humidity difference. However, biases in both the near-surface wind speed and humidity response to SST forcing can explain the inter-model ??_LH differences.  相似文献   

Geochemistry and tectonic development of Cenozoic magmatism in the Carpathian–Pannonian region     

Ioan Seghedi  Hilary DownesAuthor vitae 《Gondwana Research》2011,20(4):655-672

This review considers the magmatic processes in the Carpathian–Pannonian Region (CPR) from Early Miocene to Recent times, as well as the contemporaneous magmatism at its southern boundary in the Dinaride and Balkans regions. This geodynamic system was controlled by the Cretaceous to Neogene subduction and collision of Africa with Eurasia, especially by Adria that generated the Alps to the north, the Dinaride–Hellenide belt to the east and caused extrusion, collision and inversion tectonics in the CPR. This long-lived subduction system supplied the mantle lithosphere with various subduction components. The CPR contains magmatic rocks of highly diverse compositions (calc-alkaline, K-alkalic, ultrapotassic and Na-alkalic), all generated in response to complex post-collisional tectonic processes. These processes formed extensional basins in response to an interplay of compression and extension within two microplates: ALCAPA and Tisza–Dacia. Competition between the different tectonic processes at both local and regional scales caused variations in the associated magmatism, mainly as a result of extension and differences in the rheological properties and composition of the lithosphere. Extension led to disintegration of the microplates that finally developed into two basin systems: the Pannonian and Transylvanian basins. The southern border of the CPR is edged by the Adria microplate via Sava and Vardar zones that acted as regional transcurrent tectonic areas during Miocene–Recent times.Major, trace element and isotopic data of post-Early Miocene magmatic rocks from the CPR suggest that subduction components were preserved in the lithospheric mantle after the Cretaceous–Miocene subduction and were reactivated especially by extensional tectonic processes that allowed uprise of the asthenosphere. Changes in the composition of the mantle through time support geodynamic scenarios of post-collision and extension processes linked to the evolution of the main blocks and their boundary relations. Weak lithospheric blocks (i.e. ALCAPA and western Tisza) generated the Pannonian basin and the adjacent Styrian, Transdanubian and Z?rand basins which show high rates of vertical movement accompanied by a range of magmatic compositions. Strong lithospheric blocks (i.e. Dacia) were only marginally deformed, where strike–slip faulting was associated with magmatism and extension. At the boundary of Adria and Tisza–Dacia strike–slip tectonics and core complex extension were associated with small volume Miocene magmatism in narrow extensional sedimentary basins or granitoids in core-complex detachment systems along older suture zones (Sava and Vardar) accommodating the extension in the Pannonian basin and afterward Pliocene–Quaternary inversion. Magmas of various compositions appear to have acted as lubricants in a range of tectonic processes.  相似文献   

Would you like to know more? The effect of personalized wildfire risk information and social comparisons on information-seeking behavior in the wildland–urban interface     

Meldrum  James R.  Brenkert-Smith  Hannah  Champ  Patricia A.  Gomez  Jamie  Byerly  Hilary  Falk  Lilia  Barth  Christopher M. 《Natural Hazards》2021,106(3):2139-2161

Natural Hazards - Private landowners are important actors in landscape-level wildfire risk management. Accordingly, wildfire programs and policy encourage wildland–urban interface homeowners...  相似文献   

Hydrological field data from a modeller's perspective: Part 2: process‐based evaluation of model hypotheses     

Martyn P. Clark  Hilary K. McMillan  Daniel B. G. Collins  Dmitri Kavetski  Ross A. Woods 《水文研究》2011,25(4):523-543

The current generation of hydrological models has been widely criticized for their inability to adequately simulate hydrological processes. In this study, we evaluate competing model representations of hydrological processes with respect to their capability to simulate observed processes in the Mahurangi River basin in Northland, New Zealand. In the first part of this two‐part series, the precipitation, soil moisture, and flow data in the Mahurangi were used to estimate the dominant hydrological processes and explore several options for their suitable mathematical representation. In this paper, diagnostic tests are applied to gain several insights for model selection. The analysis highlights dominant hydrological processes (e.g. the importance of vertical drainage and baseflow compared to sub‐surface stormflow), provides guidance for the choice of modelling approaches (e.g. implicitly representing sub‐grid heterogeneity in soils), and helps infer appropriate values for model parameters. The approach used in this paper demonstrates the benefits of flexible model structures in the context of hypothesis testing, in particular, supporting a more systematic exploration of current ambiguities in hydrological process representation. The challenge for the hydrological community is to make better use of the available data, not only to estimate parameter values but also to diagnostically identify more scientifically defensible model structures. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Seasonal and areal temperature variation in lake Wakatipu (note)     

J. Irwin  V. Hilary Jolly 《新西兰海洋与淡水研究杂志》2013,47(2):210-216

Summer isotherms in Lake Wakatipu (maximum depth 380 m) show clear stratification and develop a downslope to the south or downwind end. The thermocline reaches a maximum depth of 150 m and the major part of seasonal temperature variation occurs above 130 m.  相似文献   

Cloning and analysis of the CYP1A promoter from the atlantic killifish (Fundulus heteroclitus)     

Powell WH  Morrison HG  Weil EJ  Karchner SI  Sogin ML  Stegeman JJ  Hahn ME 《Marine environmental research》2004,58(2-5):119-124

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Winifred Tutin (1915–2007)     

H. J. B. Birks  Hilary H. Birks 《Journal of Paleolimnology》2007,38(4):601-605

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