نتایج جستجو برای: pdsi

تعداد نتایج: 213  

2004
Anthony L. Westerling Alexander Gershunov Daniel R. Cayan

Strong associations between observed climate anomalies at lags of one season to years in advance and normalized area burned in the western U.S. wildfire season have recently been described using a newly compiled comprehensive gridded western regional fire history (Westerling et al 2001b). Earlier studies of fire scar dendrochronologies and local fire histories have demonstrated that large-scale...

2006
ERIC J. ALFARO ALEXANDER GERSHUNOV DANIEL CAYAN

A statistical model based on canonical correlation analysis (CCA) was used to explore climatic associations and predictability of June–August (JJA) maximum and minimum surface air temperatures (Tmax and Tmin) as well as the frequency of Tmax daily extremes (Tmax90) in the central and western United States (west of 90°W). Explanatory variables are monthly and seasonal Pacific Ocean SST (PSST) an...

2006
Martin Valldor Rainer Pöttgen

The new silicide NbPdSi was prepared by melting the elements in an arc-furnace. Well-shaped single crystals were obtained by annealing the sample in an induction furnace. The structure of NbPdSi has been studied by X-ray powder and single crystal diffractometer data: TiNiSi type, Pnma, Z = 4, a= 643.0(1), b= 376.7(1), c= 744.4(2) pm, wR2= 0.0330, 346 F2 values, and 20 variables. The palladium a...

2006
Peter T. Soule

The impacts of severe droughts on human activities, terrestrial ecosystems, and hydrologic systems are wide ranging and easily discernible. Because these impacts are felt at different times by water users, various forms of drought are recognized (e.g. agricultural, hydrological). The purpose of this study is to examine spatial patterns of drought in the contiguous United States on a seasonal ba...

2008
C. P. Kempes O. B. Myers D. D. Breshears

Annual growth of semiarid tree species is generally limited by a period of water deficit and this relationship can be reflected in interannual variation in tree-ring width of semiarid species such as Pinus edulis, a piñon pine that is widely distributed across the southwestern United States. Tree-ring width of P. edulis and other semiarid tree species is most frequently related to annual precip...

2002
Tae-Woong Kim Juan B. Valdés Javier Aparicio

The temporal and spatial characteristics of droughts are investigated to provide a framework for sustainable water resources management in a semi-arid region. Using the Palmer Drought Severity Index (PDSI) as an indicator of drought severity, the characteristics of droughts are examined in the Conchos River Basin in Mexico. This basin is important to both the United States and Mexico, because t...

2015
Tianyi Zhang Hesong Wang

We identified the spatiotemporal patterns of the Normalized Difference Vegetation Index (NDVI) for the years 1982-2008 in the desert areas of Northwest China and quantified the impacts of climate and non-climate factors on NDVI changes. The results indicate that although the mean NDVI has improved in 24.7% of the study region; 16.3% among the region has been stagnating in recent years and only ...

2013
Ellis Q. Margolis Thomas W. Swetnam

Understanding relationships between variability in historical fire occurrence and ocean–atmosphere oscillations provides opportunities for fire forecasting and projecting changes in fire regimes under climate change scenarios.We analysed tree-ring reconstructed regional climate teleconnections and fire–climate relationships in upper elevation forests (.2700m) from 16 sites in eight mountain ran...

2012
Xiangtao Xu Shilong Piao Xuhui Wang Anping Chen Philippe Ciais Ranga B Myneni

Extreme climatic events like droughts, floods, heat waves and ice storms impact ecosystems as well as human societies. There is wide concern about how terrestrial ecosystems respond to extreme climatic events in the context of global warming. In this study, we used satellite-derived vegetation greenness data (Normalized Difference Vegetation Index; NDVI), in situ weather station data (temperatu...

2010
SERGIO M. VICENTE-SERRANO SANTIAGO BEGUERÍA JUAN I. LÓPEZ-MORENO

The authors propose a new climatic drought index: the standardized precipitation evapotranspiration index (SPEI). The SPEI is based on precipitation and temperature data, and it has the advantage of combining multiscalar character with the capacity to include the effects of temperature variability on drought assessment. The procedure to calculate the index is detailed and involves a climatic wa...

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