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121.
Brenton A. Wilder Jeremy T. Lancaster Peter H. Cafferata Drew B. R. Coe Brian J. Swanson Donald N. Lindsay William R. Short Alicia M. Kinoshita 《水文研究》2021,35(1):e13976
Following wildfires, the probability of flooding and debris flows increase, posing risks to human lives, downstream communities, infrastructure, and ecosystems. In southern California (USA), the Rowe, Countryman, and Storey (RCS) 1949 methodology is an empirical method that is used to rapidly estimate post-fire peak streamflow. We re-evaluated the accuracy of RCS for 33 watersheds under current conditions. Pre-fire peak streamflow prediction performance was low, where the average R2 was 0.29 and average RMSE was 1.10 cms/km2 for the 2- and 10-year recurrence interval events, respectively. Post-fire, RCS performance was also low, with an average R2 of 0.26 and RMSE of 15.77 cms/km2 for the 2- and 10-year events. We demonstrated that RCS overgeneralizes watershed processes and does not adequately represent the spatial and temporal variability in systems affected by wildfire and extreme weather events and often underpredicted peak streamflow without sediment bulking factors. A novel application of machine learning was used to identify critical watershed characteristics including local physiography, land cover, geology, slope, aspect, rainfall intensity, and soil burn severity, resulting in two random forest models with 45 and five parameters (RF-45 and RF-5, respectively) to predict post-fire peak streamflow. RF-45 and RF-5 performed better than the RCS method; however, they demonstrated the importance and reliance on data availability. The important parameters identified by the machine learning techniques were used to create a three-dimensional polynomial function to calculate post-fire peak streamflow in small catchments in southern California during the first year after fire (R2 = 0.82; RMSE = 6.59 cms/km2) which can be used as an interim tool by post-fire risk assessment teams. We conclude that a significant increase in data collection of high temporal and spatial resolution rainfall intensity, streamflow, and sediment loading in channels will help to guide future model development to quantify post-fire flood risk. 相似文献
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123.
David J. Wilton Grant R. Bigg James D. Scourse Jeremy C. Ely Chris D. Clark 《第四纪科学杂志》2021,36(5):934-945
The British and Irish Ice Sheet (BIIS) was highly dynamic during the Late Quaternary, with considerable regional differences in the timing and extent of its change. This was reflected in equally variable offshore ice-rafted debris (IRD) records. Here we reconcile these two records using the FRUGAL intermediate complexity iceberg–climate model, with varying BIIS catchment-level iceberg fluxes, to simulate change in IRD origin and magnitude along the western European margin at 1000-year time steps during the height of the last BIIS glaciation (31–6 ka bp ). This modelled IRD variability is compared with existing IRD records from the deep ocean at five cores along this margin. There is general agreement of the temporal and spatial IRD variability between observations and model through this period. The Porcupine Bank off northwestern Ireland was confirmed by the modelling as a major dividing line between sites possessing exclusively northern or southern source regions for offshore IRD. During Heinrich events 1 and 2, the cores show evidence of a proportion of North American IRD, more particularly to the south of the British Isles. Modelling supports this southern bias for likely Heinrich impact, but also suggests North American IRD will only reach the British margin in unusual circumstances. 相似文献
124.
Jisun Park Brent D. Turrin Gregory F. Herzog Fara N. Lindsay Jeremy S. Delaney Carl C. Swisher III Masayuki Uesugi Yuzuru Karouji Toru Yada Masanao Abe Tatsuaki Okada Yukihiro Ishibashi 《Meteoritics & planetary science》2015,50(12):2087-2098
The Hayabusa mission to asteroid 25143, Itokawa, brought back 2000 small particles, which most closely resemble material found in LL4‐6 chondrites. We report an 40Ar/39Ar age of 1.3 ± 0.3 Ga for a sample of Itokawa consisting of three grains with a total mass of ~2 μg. This age is lower than the >4.0 Ga ages measured for 75% of LL chondrites but close to one for Y‐790964 and its pairs. The flat 40Ar/39Ar release spectrum of the sample suggests complete degassing 1.3 Ga ago. Recent solar heating in Itokawa's current orbit does not appear likely to have reset that age. Solar or impact heating 1.3 Ga ago could have done so. If impact heating was responsible, then the 1.3 Ga age sets an upper bound on the time at which the Itokawa rubble pile was assembled and suggests that rubble pile creation was an ongoing process in the inner solar system for at least the first 3 billion years of solar system history. 相似文献
125.
Pichel WG Churnside JH Veenstra TS Foley DG Friedman KS Brainard RE Nicoll JB Zheng Q Clemente-Colón P 《Marine pollution bulletin》2007,54(8):1207-1211
Floating marine debris, particularly derelict fishing gear, is a hazard to fish, marine mammals, turtles, sea birds, coral reefs, and even human activities. To ameliorate the economic and environmental impact of marine debris, we need to efficiently locate and retrieve dangerous debris at sea. Guided by satellite-derived information, we made four flights north of Hawaii in March and April 2005. During these aerial surveys, we observed over 1800 individual pieces of debris, including 122 derelict fishing nets. The largest debris concentrations were found just north of the North Pacific Transition Zone Chlorophyll Front (TZCF) within the North Pacific Subtropical Convergence Zone (STCZ). Debris densities were significantly correlated with sea-surface temperature (SST), chlorophyll-a concentration (Chla), and the gradient of Chla. A Debris Estimated Likelihood Index (DELI) was developed to predict where high concentrations of debris would be most likely in the North Pacific during spring and early summer. 相似文献
126.
Roel Plant Jeremy Walker Scott Rayburg Jacqueline Gothe Teresa Leung 《The Australian geographer》2012,43(1):75-91
Agricultural chemicals are a notoriously intractable source of environmental pollution. Offering enhanced agricultural productivity, they simultaneously risk degrading the ecological basis upon which agriculture depends. This paper considers chemicalisation as a cause of the erosion of aquatic biodiversity and ecosystem resilience, focusing on the Hawkesbury-Nepean River and the small-scale horticulturalists who supply the city's fresh vegetable markets, working under the pressure of urbanisation, retail monopolies, indifferent land-use planning, and often without access to information about pesticide use in the languages they understand. Arguing that standard practices of ‘risk management’ are unable to adequately control chemical contamination, the paper presents findings from interviews with actors within the ‘assemblage’ of institutions with responsibility for agriculture, water quality, and environmental protection, in order to assess the effectiveness of pesticide governance in the Greater Sydney Basin. It appears that pesticide pollution is far from being tamed: it is rarely measured nor monitored, neither is it a priority of any particular agency. Arguing that public health, the long-term viability of local farming and the ecological well-being of the Hawkesbury-Nepean River are mutually consistent goals, we conclude that these vital elements of the common-weal are currently subject to a system of ‘organised irresponsibility’. The paper concludes by proposing several ways forward. 相似文献
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128.
Robert J. Kieber Jeremy Smith Katherine M. Mullaugh Melissa W. Southwell G. Brooks Avery Jr. Joan D. Willey 《Journal of Atmospheric Chemistry》2009,64(2-3):149-158
The influence of sunlight and dissolved organic carbon (DOC) on the photochemically mediated cycling of hydrogen peroxide (H2O2) was investigated in rainwater samples collected in Wilmington, North Carolina USA. Upon exposure to simulated sunlight 14 of 19 authentic rainwater samples exhibited significant decreases in H2O2. The concentration of hydrogen peroxide did not change significantly in organic-free synthetic rainwater spiked with H2O2 in the light or in dark controls suggesting that the loss was not due to direct photolysis or dark mediated reactions. There was a significant correlation between pseudo-first order rate constants of H2O2 decay and initial H2O2 concentrations. There was also a significant correlation between the rate constant and the abundance of DOC suggesting that rainwater organic carbon plays an important role during photolytic decay either via direct reaction or indirectly through production of peroxide reactive species or scavenging of peroxide generating radicals. Several rain samples exhibited an initial increase in H2O2 during the first 2 h of irradiation. These increases were generally small and most likely do not represent a significant input of peroxide in precipitation. The photo-induced destruction of H2O2 is important because it may partly explain the late afternoon decrease of peroxide concentrations observed in earlier field studies and the substantial under saturation (<10%) of this oxidant in rainwater compared with gas phase concentrations. 相似文献
129.
Jeremy J. Davis Daniele Mortari Christian Bruccoleri 《Celestial Mechanics and Dynamical Astronomy》2010,108(1):59-72
Seven sequential starter values for solving Kepler’s equation are proposed for fast orbit propagation. The proposed methods
have constant complexity (not iterative), do not require pre-computed data, and can be implemented in just a few lines of
code. The resulting sequential orbit propagation techniques can be done at different levels of accuracy and speed, depending
essentially on the value of orbit eccentricity. Accuracy and algorithmic complexity are evaluated for all the proposed approaches
and compared with several existing single-point techniques to solve Kepler’s equation. The new methods obtain improved accuracy
at lower computational cost as compared to the best existing methods. 相似文献
130.
Robert S. Weigel Doug M. Lindholm Anne Wilson Jeremy Faden 《Earth Science Informatics》2010,3(1-2):29-40
Time Series Data Server (TSDS) is a software package for implementing a server that provides fast super-setting, sub-setting, filtering, and uniform gridding of time series-like data. TSDS was developed to respond quickly to requests for long time spans of data. Data may be served from a fast database, typically created by aggregating granules (e.g., data files) from a remote data source and storing them in a local cache that is optimized for serving time series. The system was designed specifically for time series data, and is optimized for requests where the longest dimension of the requested data structure is time. Scalar, vector, and spectrogram time series types are supported. The user can interact with the server by requesting a time series, a date range, and an optional filter to apply to the data. Available filters include strides, block average/minimum/maximum, exclude, and inequality. Constraint expressions are supported, which allow such operations as a request for data from one time series when a different time series satisfied a specified relationship. TSDS builds upon DAP (Data Access Protocol), NcML (netCDF Mark-up language) and related software libraries. In this work, we describe the current design of this server, as well as planned features and potential implementation strategies. 相似文献