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Detrended, modelled first leaf dates for 856 sites across North America for the period 1900–2008 are used to examine how the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) separately and together might influence the timing of spring. Although spring (mean March through April) ENSO and PDO signals are apparent in first leaf dates, the signals are not statistically significant (at a 95% confidence level (p < 0.05)) for most sites. The most significant ENSO/PDO signal in first leaf dates occurs for El Niño and positive PDO conditions. An analysis of the spatial distributions of first leaf dates for separate and combined ENSO/PDO conditions features a northwest–southeast dipole that is...
Categories: Publication; Types: Citation; Tags: ENSO, PDO, phenology, spring
Precipitation varied substantially in the Mojave Desert through the 20th century in a manner broadly similar to the other warm North American deserts. Episodes of drought and prolonged dry conditions (1893–1904, ca. 1942–1975, and 1999-present) alternated with relatively wet periods (1905–ca. 1941 and ca. 1976–1998), probably because of global-scale climate fluctuations. These are the El Niño-Southern Oscillation that affects interannual climate and the Pacific Decadal Oscillation that evidently causes decadal-scale variability such as prolonged dry and wet episodes. Studies done in the late 20th century demonstrate that precipitation fluctuations affected populations of perennial vegetation, annuals, and small...
The influence of the Pacific decadal oscillation (PDO) on important hydroclimatic variables during years of neutral ENSO for 84 climate divisions in the western United States is analyzed from 1925 to 1998. When the 34 neutral ENSO years are split by cold (12 yr) and warm (22 yr) PDOs, the resulting winter precipitation patterns are spatially similar to those that occur during years of La Ni�a?cold PDO and, to a lesser extent, years of El Ni�o?warm PDO, respectively, although the characteristic ENSO dipole is not evident. The PDO influence is similar when the winter Palmer drought severity index is analyzed, although the core area of influence moves from the Southwest to the northern Rockies. Correlations between...
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The study presented here utilized long-term streamflow records (over 500 years) to investigate the influence of interannual/interdecadal climate variability on the Colorado River basin. 19 unimpaired water year streamflow stations were reconstructed utilizing partial least square regression using standard tree ring chronologies. The spatial and temporal variability of drought was evaluated for all the stations for the different centuries in the record. Finally, the relationship between individual impact of ENSO, PDO, and AMO and its combined effect on streamflow was determined using the non parametric Rank Sum test for different lag years (0, +1, +2, and +3) of streamflow. This research also determined the change...
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The Colorado River is the dominant water source for the southwestern United States, crossing through seven states before reaching Mexico. The river supplies water to approximately 36 million people, irrigates nearly six million acres of farmland within and beyond the basin, and contributes an estimated 26 billion dollars each year to the region’s recreational economy. Yet the Colorado River’s water supply is already fully allocated, meaning that the economic and environmental health of the region is closely tied to the river’s streamflow. Climate projections for the Southwest show a future marked by chronic drought and substantial reductions in streamflow. The region has already been impacted by climate change,...
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As elevation increases, both temperature and moisture availability decrease. In many parts of the world, this decrease in temperature is a limiting factor for vegetation—at certain elevations, the temperature becomes too cold for plants to survive. However in the tropics, moisture availability may play a more important role than temperature in determining the altitude at which forests can grow. For example on Haleakalā, a volcano on the Hawaiian Island of Mauʻi, the forest line is not found at the same elevation everywhere, as you would expect if it were controlled by temperature. Rather, the forest line is highest in the wetter eastern-most end and lower on the drier, western end of the volcano. Research also...
Detrended, modelled first leaf dates for 856 sites across North America for the period 1900–2008 are used to examine how the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) separately and together might influence the timing of spring. Although spring (mean March through April) ENSO and PDO signals are apparent in first leaf dates, the signals are not statistically significant (at a 95% confidence level (p < 0.05)) for most sites. The most significant ENSO/PDO signal in first leaf dates occurs for El Niño and positive PDO conditions. An analysis of the spatial distributions of first leaf dates for separate and combined ENSO/PDO conditions features a northwest–southeast dipole that is...
Categories: Publication; Types: Citation; Tags: ENSO, PDO, phenology, spring


map background search result map search result map Associations of interdecadal/interannual climate variability and long-term colorado river basin streamflow Projecting Future Streamflow in the Colorado River Basin Measurement of El Niño Southern Oscillation (ENSO)-related Climate Conditions and Ecosystem Responses in Hawaiʻi Measurement of El Niño Southern Oscillation (ENSO)-related Climate Conditions and Ecosystem Responses in Hawaiʻi Projecting Future Streamflow in the Colorado River Basin Associations of interdecadal/interannual climate variability and long-term colorado river basin streamflow