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Title: El Nino - La Nina Implications on Flood Hazard Mitigation

Abstract

The effects of El Nino and La Nina periods on the maximum daily winter period depths of precipitation are examined using records from five precipitation gages on the Nevada Test Site. The potential implications of these effects are discussed.

Authors:
;
Publication Date:
Research Org.:
Desert Research Institute, Nevada System of Higher Education
Sponsoring Org.:
USDOE
OSTI Identifier:
881675
Report Number(s):
CONF-2006-2
TRN: US200613%%5
DOE Contract Number:
AC52-00NV13609
Resource Type:
Conference
Resource Relation:
Conference: American Society of Civil Engineers Environmental and Water Resources Conference, May 21-25, 2006, Omaha, NE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; FLOODS; MITIGATION; NEVADA TEST SITE; ATMOSPHERIC PRECIPITATIONS; SOUTHERN OSCILLATION; WATER RESOURCES; ENVIRONMENTAL IMPACTS

Citation Formats

R. French, and J. Miller. El Nino - La Nina Implications on Flood Hazard Mitigation. United States: N. p., 2006. Web.
R. French, & J. Miller. El Nino - La Nina Implications on Flood Hazard Mitigation. United States.
R. French, and J. Miller. Fri . "El Nino - La Nina Implications on Flood Hazard Mitigation". United States. doi:. https://www.osti.gov/servlets/purl/881675.
@article{osti_881675,
title = {El Nino - La Nina Implications on Flood Hazard Mitigation},
author = {R. French and J. Miller},
abstractNote = {The effects of El Nino and La Nina periods on the maximum daily winter period depths of precipitation are examined using records from five precipitation gages on the Nevada Test Site. The potential implications of these effects are discussed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Mar 31 00:00:00 EST 2006},
month = {Fri Mar 31 00:00:00 EST 2006}
}

Conference:
Other availability
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  • Streamflows in the Pacific Southwest of the United States in relation to the tropical Type 1 El Nino-Southern Oscillation (T1ENSO) and La Nina events are examined using composite and harmonic analyses for each event during a 24-month evolution period. The hydroclimatic signals associated with either extreme phase of the Southern Oscillation (SO) are explored based on data from 50 streamflow stations in California, Arizona, New Mexico, Colorado, and Utah. A significant level for the results is assessed by the use of a hypergeometric distribution. Highly significant, coherent signals are demonstrated to exist for both events, with opposite sign and almostmore » identical timing. Pacific Southwest streamflow responses to the T1ENSO thermal forcing are characterized by a wet December-July season in the subsequent year of the event. Similarly, a dry February-July season is detected as a period at which the La Nina-streamflow relationship is strong and spatially coherent. An index time series is plotted to determine the temporal consistency of the signal. It was found that the respective seasonal signal for each event was confirmed by all episodes. Amplification (suppression) of the regional annual streamflow cycle is noticed during the subsequent year of the typical T1ENSO (La Nina) event. A lag cross-correlation analysis is conducted between the time series of the seasonal December-July streamflow index and the SO index. The March-May season in the previous year of the seasonal T1ENSO signal was determined to be the logical period in which the SO index can be averaged to obtain the highest correlation and the maximum time lag. A Mann-Whitney U test reveals statistically significant differences in the means of seasonal streamflows associated with T1ENSO and La Nina events. Plausible explanations for the observed teleconnections are presented. 34 refs., 7 figs., 2 tabs.« less
  • The Zebiak and Cane model is used in its {open_quotes}uncoupled mode,{close_quotes} meaning that the oceanic model component is driven by the Florida State University (FSU) wind stress anomalies over 1980-93 to simulate sea surface temperature anomalies, and these are used in the atmospheric model component to generate wind anomalies. Simulations are compared with data derived from FSU winds, International Satellite Cloud Climatology Project cloud convection, Advanced Very High Resolution Radiometer SST, Geosat sea level, 20{degrees}C isotherm depth derived from an expendable bathythermograph, and current velocities estimated from drifters or current-meter moorings. Forced by the simulated SST, the atmospheric model ismore » fairly successful in reproducing the observed westerlies during El Nino events. The model fails to simulate the easterlies during La Nina 1988. The simulated forcing of the atmosphere is in very poor agreement with the heating derived from cloud convection data. Similarly, the model is fairly successful in reproducing the warm anomalies during El Nino events. However, it fails to simulate the observed cold anomalies. Simulated variations of thermocline depth agree reasonably well with observations. The model simulates zonal current anomalies that are reversing at a dominant 9-month frequency. Projecting altimetric observations on Kelvin and Rossby waves provides an estimate of zonal current anomalies, which is consistent with the ones derived from drifters or from current meter moorings. Unlike the simulated ones, the observed zonal current anomalies reverse from eastward during El Nino events to westward during La Nina events. The simulated 9-month oscillations correspond to a resonant mode of the basin. They can be suppressed by cancelling the wave reflection at the boundaries, or they can be attenuated by increasing the friction in the ocean model. 58 refs., 14 figs., 6 tabs.« less
  • Monthly total precipitation and mean temperature data records extending from the late nineteenth century to 1990 were collected for 147 stations in South Dakota, North Dakota, and portions of adjacent states and provinces. This region, defined as the Northern Plains region (NPR), was examined for patterns associated with the warm phase (ENSO) and the cold phase (LNSO) of the Southern Oscillation. Based on a correlation analysis, the NPR was treated as having one spatial degree of freedom. Using Monte Carlo simulations of the Student`s t-test statistic, four seasons with significant changes in mean precipitation or temperature during either ENSO ormore » LNSO were identified. A highly significant signal was evident during the ENSO April to October season for precipitation, where the mean precipitation increased 7.21 cm for the 23 events studied. Here 20 of these 23 ENSO events exhibited precipitation above the median value, and 14 of the 23 events were in the upper quartile. In contrast, a strong signal for decreased LNSO precipitation was noted where May to August precipitation averaged 3.91 cm lower during the 17 events, with similar significance values. Complementing the enhanced ENSO warm season precipitation, the August to October temperature decreased by 2.17{degrees}C, with a significant number of events in both the lowest half and lowest quartile. Finally, temperature averaged 4.67{degrees}C cooler during LNSO winters. These results will be useful for limited-season prediction of precipitation and temperature tendencies across the NPR. It is interesting to note that the initial ENSO years did not reveal a significant temperature increase during the NPR winter in contrast to similar studies. However, by slightly modifying the years that were classified as ENSO years, a significant winter temperature response was indicated. 37 refs., 11 figs., 2 tabs.« less
  • Radiolarian distributions and physical oceanographic data from the Santa Barbara basin indicate the following. Strong anti-El Nino periods can be characterized by (1) intermediate radiolarian density, (2) high percentage of transition-central radiolarian fauna, and (3) low percentage and number of warm-water radiolarian fauna. This distribution pattern is attributed to strong wind-driven upwelling and reduced northward transport by the California Countercurrent during anti-El Nino periods. Strong El Nino periods are typically (1) high in radiolarian density, and (2) low in percentage but high in number of warm-water fauna. This distribution is attributed to reduced wind-driven upwelling, enhanced northward countercurrent transport, andmore » geostrophic doming of the cold-water masses in the shear zone between the California Current and California Countercurrent.« less
  • Significant precipitation along the north-central coast of Peru (lat 5{degree}-10{degree}S) occurs exclusively during El Nino incursions of warm water into the Peruvian littoral. Flood deposits from this region therefore provide a proxy record of extreme El Nino events. The author presents a 3,500 yr chronology of the extreme events based on radiocarbon dating of overbank flood sediments from the Rio Casma (lat 9.2{degree}S). The flood-plain stratigraphy suggests that the El Nino phenomenon has occurred throughout the Holocene and that flood events much larger than that which occurred during 1982-1983 occur here at least once very 1,000 yr.