From drought to flood: A water balance analysis of the Tuolumne River basin during extreme conditions (2015–2017)     

Andrew R. Hedrick  Danny Marks  Hans-Peter Marshall  James McNamara  Scott Havens  Ernesto Trujillo  Micah Sandusky  Mark Robertson  Micah Johnson  Kat J. Bormann  Thomas H. Painter 《水文研究》2020,34(11):2560-2574

The degree to which the hydrologic water balance in a snow-dominated headwater catchment is affected by annual climate variations is difficult to quantify, primarily due to uncertainties in measuring precipitation inputs and evapotranspiration (ET) losses. Over a recent three-year period, the snowpack in California's Sierra Nevada fluctuated from the lightest in recorded history (2015) to historically heaviest (2017), with a relatively average year in between (2016). This large dynamic range in climatic conditions presents a unique opportunity to investigate correlations between annual water availability and runoff in a snow-dominated catchment. Here, we estimate ET using a water balance approach where the water inputs to the system are spatially constrained using a combination of remote sensing, physically based modelling, and in-situ observations. For all 3 years of this study, the NASA Airborne Snow Observatory (ASO) combined periodic high-resolution snow depths from airborne Lidar with snow density estimates from an energy and mass balance model to produce spatial estimates of snow water equivalent over the Tuolumne headwater catchment at 50-m resolution. Using observed reservoir inflow at the basin outlet and the well-quantified snowmelt model results that benefit from periodic ASO snow depth updates, we estimate annual ET, runoff efficiency (RE), and the associated uncertainty across these three dissimilar water years. Throughout the study period, estimated annual ET magnitudes remained steady (222 mm in 2015, 151 mm in 2016, and 299 mm in 2017) relative to the large differences in basin input precipitation (547 mm in 2015, 1,060 mm in 2016, and 2,211 mm in 2017). These values compare well with independent satellite-derived ET estimates and previously published studies in this basin. Results reveal that ET in the Tuolumne does not scale linearly with the amount of available water to the basin, and that RE primarily depends on total annual snowfall proportion of precipitation.  相似文献   

Assessing optical earth observation systems for mapping and monitoring temporary ponds in arid areas     

Valrie Soti  Annelise Tran  Jean-Stphane Bailly  Christian Puech  Danny Lo Seen  Agnes Bgu 《International Journal of Applied Earth Observation and Geoinformation》2009,11(5):344-351

Remote sensing methods for locating and monitoring temporary ponds over large areas in arid lands were tested on a study site in Northern Senegal. Three main results are presented, validated with field data and intended to highlight different spectral, spatial and temporal characteristics of the methods: (1) Among several water indices tested, two Middle Infrared-based indices (MNDWI—Modified Normalized Difference Water Index and NDWI₁—Normalized Difference Water Index) are found to be most efficient; (2) an objective method is given prescribing the necessary sensor spatial resolution in terms of minimal detected pond area; and (3) the potential of multi-temporal MODIS imagery for tracking the filling phases of small ponds is illustrated. These results should assist in epidemiological studies of vector-borne diseases that develop around these ponds, but also more generally for land and water management and preservation of threatened ecosystems in arid areas.  相似文献   

Constraining the Aerosol Radiative Forcing and Climate Sensitivity     

L. D. Danny Harvey 《Climatic change》2000,44(4):413-418

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Ground Stone Analysis: A Technological Approach, 2nd ed. Jenny L. Adams. 2014. The University of Utah Press and American Southwest,Salt Lake City, 336 pp., color, $40 (paperback).     

Danny Rosenberg 《Geoarchaeology》2015,30(5):454-455

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An annually resolved bristlecone pine carbon isotope chronology for the last millennium     

Roderick J. Bale  Iain Robertson  Neil J. Loader  Mary Gagen  Danny McCarroll 《Quaternary Research》2011,76(1):22-29

We present the first near millennium-length, annually resolved stable isotope record from bristlecone pines (Pinus longaeva, D.K Bailey). The carbon isotope ratios from the cellulose of seven trees from the White Mountains of California, corrected for anthropogenic changes in atmospheric chemistry, are used to reconstruct growing season (June through August) precipitation back to AD 1085. Extremely negative isotope results are strongly correlated with proposed severest El Niño events over the last 500 yr, and similar values in the first half of the millennium are used to reconstruct a further 13 strong El Niño events, concentrated in the 12th Century and the mid 13th and 14th Centuries. Ring-width chronologies from adjacent sites in the White Mountains demonstrate a high degree of decadal covariance with the δ¹³C series, although there are several periods of notable divergence.  相似文献   

Degree of rock surface weathering as an indicator of ice-sheet thickness along an east—west transect across southern Norway     

Atle Nesje  Danny McCarroll  Svein Olaf Dahl 《第四纪科学杂志》1994,9(4):337-347

Rock surface weathering, as reflected by rock surface hardness and roughness, was measured at six mountains along an east-west transect across southern Norway. At most sites the results show significant differences in rock surface weathering across the autochthonous blockfield boundary, suggesting that the areas above the boundary have been exposed to subaerial weathering for a considerably longer time span that the areas below. The results are interpreted as reflecting the surface profile of an asymmetric, west-centred, low-gradient ice sheet.  相似文献   

Broad-band deconvolution of GDSN data     

Danny Harvey  George L. Choy 《Geophysical Journal International》1982,69(3):659-668

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Supporting dynamic pipeline changes using Class-Based Object Versioning in Astro-WISE     

Johnson Mwebaze  Danny Boxhoorn  Idris Rai  Edwin A. Valentijn 《Experimental Astronomy》2013,35(1-2):157-186

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The Astro-WISE optical image pipeline     

John P. McFarland  Gijs Verdoes-Kleijn  Gert Sikkema  Ewout M. Helmich  Danny R. Boxhoorn  Edwin A. Valentijn 《Experimental Astronomy》2013,35(1-2):45-78

We have designed and implemented a novel way to process wide-field astronomical data within a distributed environment of hardware resources and humanpower. The system is characterized by integration of archiving, calibration, and post-calibration analysis of data from raw, through intermediate, to final data products. It is a true integration thanks to complete linking of data lineage from the final catalogs back to the raw data. This paper describes the pipeline processing of optical wide-field astronomical data from the WFI (http://www.eso.org/lasilla/instruments/wfi/) and OmegaCAM (http://www.astro-wise.org/~omegacam/) instruments using the Astro-WISE information system (the Astro-WISE Environment or simply AWE). This information system is an environment of hardware resources and humanpower distributed over Europe. AWE is characterized by integration of archiving, data calibration, post-calibration analysis, and archiving of raw, intermediate, and final data products. The true integration enables a complete data processing cycle from the raw data up to the publication of science-ready catalogs. The advantages of this system for very large datasets are in the areas of: survey operations management, quality control, calibration analyses, and massive processing.  相似文献   

Forest dynamics and the importance of place in western Honduras     

Danny Redo  J.O. Joby Bass  Andrew C. Millington 《Applied geography (Sevenoaks, England)》2009,29(1):91-110

Analyses of landscape change using remotely sensed satellite imagery constitute a large component of forest transition research, allowing for assessments of large areas. In the western highlands of Honduras is an area of complex forest dynamics (～45,000 ha) that has seen significant forest regeneration in recent years. However, analysis of the larger region (～500,000 ha) shows net forest loss. The comparative aspects highlight the importance of site selection and scale in forest transition analysis, a process often ignored in the land-use and land-cover change (LULCC) and forest transition literature. Results also highlight the importance of analyzing human-induced fragmentation at a variety of selected sites and a range of spatial scales, and producing quality, accurate forest cover and change maps.  相似文献