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Jessica D. Lundquist Susan Dickerson-Lange Ethan Gutmann Tobias Jonas Cassie Lumbrazo Dylan Reynolds 《水文研究》2021,35(7):e14274
When formulating a hydrologic model, scientists rely on parameterizations of multiple processes based on field data, but literature review suggests that more frequently people select parameterizations that were included in pre-existing models rather than re-evaluating the underlying field experiments. Problems arise when limited field data exist, when “trusted” approaches do not get reevaluated, and when sensitivities fundamentally change in different environments. The physics and dynamics of snow interception by conifers is just such a case, and it is critical to simulation of the water budget and surface albedo. The most commonly used interception parameterization is based on data from four trees from one site, but results from this field study are not directly transferable to locations with relatively warmer winters, where the dominant processes differ dramatically. Here, we combine a literature review with model experiments to demonstrate needed improvements. Our results show that the choice of model form and parameters can vary the fraction of snow lost through interception by as much as 30%. In most simulations, the warming of mean winter temperatures from −7 to 0°C reduces the modelled fraction of snow under the canopy compared to the open, but the magnitude of simulated decrease varies from about 10% to 40%. The range of results is even larger when considering models that neglect the melting of in-canopy snow in higher-humidity environments where canopy sublimation plays less of a role. Thus, we recommend that all models represent canopy snowmelt and include representation of increased loading due to increased adhesion and cohesion when temperatures rise from −3 to 0°C. In addition to model improvements, field experiments across climates and forest types are needed to investigate how to best model the combination of dynamically changing forest cover and snow cover to better understand and predict changes to albedo and water supplies. 相似文献
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Vivienne Cassie 《新西兰海洋与淡水研究杂志》2013,47(1):98-123
Between, May 1966 and May 1967, 110 preserved samples of the phytoplankton of Lake Rotorua, New Zealand, were examined. Species and cell counts have been compared with data from Lakes Rotoiti (21 samples) and Ohakuri (36 net samples). Brief comparisons have also been made with the flora of two of the Wellington City reservoirs and the oxidation ponds at Mangere, Auckland. In Lake Rotorua the autumn, maximum was more pronounced than the spring maximum. Cell numbers inshore at Kawaha Point were consistently lower than those further out in the open lake. The phytoplankton is classified as a eutrophic formation of the diatom type, with Chlorophyceae as main subordinates. Dominants include Melosira granulata Ralfs (winter, spring, and autumn), Melosira distans (Ehr.) Kütz. (spring, summer, and autumn), and Asterionella formosa Hass. (summer and autumn). 相似文献
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A key to common algae. Freshwater, estuarine and some coastal species. By E. G. Bellinger. The Institution of Water and Environmental Management, United Kingdom. Fourth edition. Published in 1992.138 p. ISBN 1–870752 163. Greater Cook Strait. By T. F. W. Harris, University of Auckland Marine Laboratory, Leigh. Published in 1990 by DSIR Marine & Freshwater, Wellington, New Zealand. ISBN 0–477–02580–3. Samples of New Zealand science on CD‐ROM (for IBM‐compatibles only). Edited by J. A. Jasperse, 1992. SIR Publishing, Wellington. ISBN 0–908654–34–0. Price: NZ/US$50.00. 相似文献
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Cassie Gurbisz W. Michael Kemp Lawrence P. Sanford Robert J. Orth 《Estuaries and Coasts》2016,39(4):951-966
There is a growing emphasis on preserving ecological resilience, or a system’s capacity to absorb or recover quickly from perturbations, particularly in vulnerable coastal regions. However, the factors that affect resilience to a given disturbance are not always clear and may be system-specific. We analyzed and synthesized time series datasets to explore how extreme events impacted a large system of submersed aquatic vegetation (SAV) in upper Chesapeake Bay and to identify and understand associated mechanisms of resilience. We found that physical removal of plants around the edge of the bed by high flows during a major flood event as well as subsequent wind-driven resuspension of newly deposited sediment and attendant light-limiting conditions were detrimental to the SAV bed. Conversely, it appears that the bed attenuated high flows sufficiently to prevent plant erosion at its inner core. The bed also attenuated wind-driven wave amplitude during seasonal peaks in plant biomass, thereby decreasing sediment resuspension and increasing water clarity. In addition, clear water appeared to “spill over” into adjacent regions during ebb tide, improving the bed’s capacity for renewal by creating more favorable growing conditions in areas where plant loss had occurred. These analyses demonstrate that positive feedback processes, whereby an SAV bed modifies its environment in ways that improve its own growth, likely serve as mechanisms of SAV resilience to flood events. Although this work focuses on a specific system, the synthetic approach used here can be applied to any system for which routine monitoring data are available. 相似文献
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Vivienne Cassie 《新西兰海洋与淡水研究杂志》2013,47(2):153-166
In a 1973–74 survey of preserved phytoplankton from Lakes Rotoiti, Rotoehu, Rotoma and Waikaremoana, 205 algal taxa (including 111 Chlorophyta, 56 Chrysophyta, 17 Cyanophyta, 16 Pyrrhophyta, and 5 Euglenophyta) were found. The greatest number of species was found in Lake Rotoehu, but monthly maxima based on cell counts were usually greater in Lake Rotoiti. A summer bloom of the toxic blue‐green alga Aphanizomenon flos‐aquae occurred in Lake Rotoehu. Each lake had its own pattern of dominance. Surface and subsurface samples showed marked differences in species composition and abundance. Diatoms were important winter and spring components, with desmids forming conspicuous subordinates. Cemtium hirundinella was prominent in subsurface layers of Lakes Rotoma and Waikaremoana. Compound indices (ratios of number of species of most other algae to that of desmids) point to Lake Rotoehu as extremely eutrophic, to Lake Rotoma as moderately eutrophic, and to Lakes Rotoiti and Waikaremoana as oligotrophic rather than meso‐ or eutrophic. 相似文献
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