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Henry F. Diaz

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The Salt and Verde river basins in northeastern Arizona are a vital source of fresh water for the greater Phoenix metropolitan area and for two Native American tribes who rely on the basins’ natural resources for their livelihoods. The region depends on winter rain and snow to replenish the river basins’ water supply. Atmospheric rivers – long, narrow channels in the atmosphere that carry water vapor from the Pacific Ocean – supply a substantial portion of this winter precipitation. While atmospheric rivers are critical for maintaining water resources and preventing drought, they occasionally cause extreme storms that lead to flooding. Scientists project that climate change will affect the intensity and frequency...
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In the expectation that global climate will change steadily in the coming decades, this research project had the goal to obtain a more detailed view of the climatic changes that Hawai’i could experience by the mid and late 21st century. Given the importance of rainfall for Hawaiian ecosystems and freshwater reserves, this project investigated past seasonal rainfall pattern and developed a statistical model to estimate future rainfall changes for the major islands. As a result of this research, high-resolution maps and data are now available that researchers can use to study potential impacts on endangered species, or use the rainfall changes as input in decision-support tools.This data product provides data files...
Abstract: The aim of this paper is to present a statistical downscaling method in which the relationships between present-day daily weather patterns and local rainfall data are derived and used to project future shifts in the frequency of heavy rainfall events under changing global climate conditions. National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) reanalysis data from wet season months (November to April) 1958–2010 are composited for heavy rain days at 12 rainfall stations in the Hawaiian Islands. The occurrence of heavy rain events (days with amounts above the 90th percentile estimated from all wet season rain days 1958–2010) was found to be strongly correlated...
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The overall amount of precipitation deposited along the West Coast and western cordillera of North America from 25??to 55??N varies from year to year, and superimposed on this domain-average variability are varying north-south contrasts on timescales from at least interannual to interdecadal. In order to better understand the north-south precipitation contrasts, their interannual and decadal variations are studied in terms of how much they affect overall precipitation amounts and how they are related to large-scale climatic patterns. Spatial empirical orthogonal functions (EOFs) and spatial moments (domain average, central latitude, and latitudinal spread) of zonally averaged precipitation anomalies along the westernmost...
Categories: Publication; Types: Citation; Tags: Journal of Climate
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Monthly stream flow series from 1345 sites around the world are used to characterize geographic differences in the seasonality and year-to-year variability of stream flow. Stream flow seasonality varies regionally, depending on the timing of maximum precipitation, evapotranspiration, and contributions from snow and ice. Lags between peaks of precipitation and stream flow vary smoothly from long delays in high-latitude and mountainous regions to short delays in the warmest sectors. Stream flow is most variable from year to year in dry regions of the southwest United States and Mexico, the Sahel, and southern continents, and it varies more (relatively) than precipitation in the same regions. Tropical rivers have the...
Categories: Publication; Types: Citation; Tags: Journal of Hydrometeorology
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