4,365 research outputs found
SNOWMIP2: An evaluation of forest snow process simulation
No full textThe Northern Hemisphere has large areas that are forested and seasonally snow covered. Compared with open areas, forest canopies strongly influence interactions between the atmosphere and snow on the ground by sheltering the snow from wind and solar radiation and by intercepting falling snow, and these influences have important consequences for the meteorology, hydrology and ecology of forests. Many of the land surface models used in meteorological and hydrological forecasting now include representations of canopy snow processes, but these have not been widely tested in comparison with observations. Phase 2 of the Snow Model Intercomparison Project (SnowMIP2) was therefore designed as an intercomparison of surface mass and energy balance simulations for snow in forested areas. Model forcing and calibration data for sites with paired forested and open plots were supplied to modelling groups. Participants in 11 countries contributed outputs from 33 models, and results are published here for sites in Canada, the USA and Switzerland. On average, the models perform fairly well in simulating snow accumulation and ablation, although there is a wide inter-model spread and a tendency to underestimate differences in snow mass between open and forested areas. Most models capture the large differences in surface albedos and temperatures between forest canopies and open snow well. There is, however, a strong tendency for models to underestimate soil temperatures under snow, particularly for forest sites, and this would have large consequences for simulations of runoff and biological processes in the soil
Alice Rowe Snow Correspondence
No full textEntries include brief biographical information, a typed biography, a handwritten letter of presentation to the collection, a handwritten biographical letter detailing the lives of her parents and husband as well as herself, a print publisher advertisement with a book description and illustrations including the Bark Russell in a school of whales with a book order form, and a typed letter of correspondence from the Maine State Library concerning the diary of Snow\u27s father as it appeared in American Neptune magazine and in receipt of Snow\u27s book gift to the Maine Author Collection
Morphological and behavioral adaptations of moose to climate, snow, and forage
No full textThis thesis focuses on the behavioural and morphological adaptations of moose to snow and climate: specifically, seasonal migration, habitat choice, and following behaviour, plus the relationships among morphology, climate, snow, and seasonality. I examine intake and availability of winter forage, and perform one of the first large-scale tests of a widely used optimal foraging model by videotaping free-ranging moose making their own choices. The study of seasonal migration and habitat choice showed that the effect of snow differs with variation in snow severity: in locations with large differences in snow depths in a short distance, snow depth is important, but in locations where snow depth is less variable, snow quality emerges as more important. The thesis is one of the first to use a new method to evaluate the importance of snow quality. Testing between competing hypotheses to explain morphology, the importance of snow was further emphasized relative to temperature and latitude. In snowier areas, moose had larger hooves and longer legs than expected from their size and age. Morphology both conformed to, and was in opposition to some of the most well-known ecogeographical rules: in areas with cold winters, moose were heavier (Bergmann’s rule) and had shorter ears (Allen’s rule). There was also some evidence that moose morphology was related to heat stress during summer. The quality of the two main winter forages (birch and willows) differed within and between species. Willows had more available browse, and lower levels of secondary defence compounds than birch, but also less nitrogen and more fibre. These differences in forage quality also emerged in the test of the Spalinger-Hobbs model, as moose preferentially fed on willow, which was also the faster food to ingest. Most importantly, the analysis revealed that the foraging parameters varied within a foraging bout, and thus parameterizing the model from only the first few minutes of a bout would greatly mis-estimate intake. In the face of climate change, my results emphasize the need for research relating behaviour and morphology to environmental conditions. As moose are well adapted to snow and winter conditions, climate change may have negative consequences on southern populations as temperatures will rise, and some ranges may become unsuitable
Polynesia [cartographic material] /
No full textMap of Polynesia, with eastern Australia as Terra Australis, showing the Pacific islands, population, religions, number of missionaries and native assistants.; Imprint on map: London: Published by John Snow, 35 Paternsoter Row.; Prime meridian: Greenwich.; Plate from: A narrative of missionary enterprises in the South Sea Islands / John Williams. London : Published for the author, by J. Snow, 1837.; Also available in an electronic version via the internet at: http://nla.gov.au/nla.map-rm3970
UV written evanescent devices fabricated in micro-structured substrates for optofluidics
No full textWe report our recent developments in micro-structured evanescent devices. Micromachining prior to direct UV writing of channel waveguides provides additional flexibility to fabricate evanescent interacting devices such as modulators and sensors, which allow adiabatic operation
Edgar Snow in China
No full textIn 1928, Edgar Snow (1905-1972) set out to see the world, hoping to make his mark as a travel-adventure writer. Shanghai was to be a mere stopover, but Snow stayed on in China for thirteen more years. The idealistic young Midwesterner became a journalist and ultimately developed close friendships with China's emerging revolutionary leaders. His 1938 classic, Red Star over China , strongly influenced American views of the Chinese Communists and is still in print nearly sixty years later.This biography breaks fresh ground with its unique and extensive use of Snow's diaries of over forty years. These writings convey Snow's private hopes and fears, his moods and motivations. Thomas skillfully links them with Snow's public writings and deeds. By recreating the milieu in which Snow worked in China, Thomas provides a clearer understanding of both the man and his times.Snow came to China devoid of any political agenda or sinological background. He returned home a politically astute China hand and famed journalist-author. His writing had taken on the nature of political action, which resulted in troubled soul-searching that Snow usually confined to his diary. Thomas's portrait of Ed Snow reveals a man caught up in an important historical moment, a man who profoundly influenced, and was influenced by, the events that swirled around him
The author tells the legend of her grandfather, Cyrus Rackliff, who ignored a pr
No full textThe author tells the legend of her grandfather, Cyrus Rackliff, who ignored a premonition and went duck hunting on Green Island, where he shot himself below the knee. Illustrated with Andrew Wyeth painting and the poem Cyrus by Wilbert Snow
UV written planar Bragg grating sensors: geometries and applications
No full textBragg gratings in optical fibres are a well developed technology that finds many applications in photonics, including wavelength stabilization, dispersion compensation, and use as temperature and strain sensors. In recent years we have developed planar Bragg grating devices as integrated counterparts to fibre based devices[1]. The implementation of Bragg gratings in planar opens many new degrees of freedom because it is possible to make more intricate circuits incorporating splitters, interferometers, couplers, etc
Photonic microcantilevers with interferometric Bragg grating interrogation
No full textGermanosilicate glass microcantilevers are fabricated featuring an integrated Fabry-Pérot interferometer. Direct UV writing of single-mode planar waveguides and Bragg gratings is combined with physical micromachining, using a precision dicing saw, to realize glass microcantilevers on a silicon platform. The device presented here has a wavelength shift force sensitivity of 330 nm/N, which is calibrated using a surface profilometer measurement and is an order of magnitude better than current state-of-the-art Bragg-grating-based sensors. The device also shows an approximately tenfold increase in amplitude modulation compared with a similar device architecture utilizing a single Gaussian-apodized Bragg grating. By forming the Fabry-Pérot cavity around the point of greatest strain, we reduce the unwanted effects of grating chirp as the cantilever is deflected and relate the performance to a mechanical model that relates cavity phase shift to deflection
Improved Parameterization of Snow Albedo in WRF + Noah: Methodology Based on a Severe Snow Event on the Tibetan Plateau
No full textSnowfall and the subsequent evolution of the snowpack have a large effect on the surface energy balance and water cycle of the Tibetan Plateau (TP). The effects of snow cover can be represented by the WRF coupled with a land surface scheme. The widely used Noah scheme is computationally efficient, but its poor representation of albedo needs considerable improvement. In this study, an improved albedo scheme is developed using a satellite-retrieved albedo that takes snow depth and age into account. Numerical experiments were then conducted to simulate a severe snow event in March 2017. The performance of the coupled WRF/Noah model, which implemented the improved albedo scheme, is compared against the model’s performance using the default Noah albedo scheme and against the coupled WRF/CLM that applied CLM albedo scheme. When the improved albedo scheme is implemented, the albedo overestimation in the southeastern TP is reduced, reducing the RMSE of the air temperature by 0.7°C. The improved albedo scheme also attains the highest correlation between the satellite-derived and the model-estimated albedo, which provides for a realistic representation of both the snow water equivalent (SWE) spatial distribution in the heavy snowbelt (SWE > 6 mm) and the maximum SWE in the eastern TP. The underestimated albedo in the coupled WRF/CLM leads to underestimating the regional maximum SWE and a consequent failure to estimate SWE in the heavy snowbelt accurately. Our study demonstrates the feasibility of improving the Noah albedo scheme and provides a theoretical reference for researchers aiming to improve albedo schemes further.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Optical and Laser Remote Sensin
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