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Sample records for nino southern oscillation

  1. El Nino --- Southern Oscillation Impact Prediction

    SciTech Connect

    Nicholls, N.

    1988-02-01

    The El Nino-Southern Oscillation (ENSO) phenomenon affects the atmosphere and ocean over much of the globe. The resultant atmospheric and oceanic anomalies can produce a variety of biological and societal impacts. Three examples of impacts that may be predictable by monitoring simple indices of ENSO are discussed. The advantages and disadvantages of such direct'' prediction of impacts are considered.

  2. Theory for El Nino and the Southern Oscillation

    SciTech Connect

    Cane, M.A.; Zebiak, S.E.

    1985-05-31

    A coupled atmosphere-ocean model is presented for El Nino and the Southern Oscillation that reproduces its major features, including its recurrence at irregular intervals. The interannual El Nino-Southern Oscillation cycle is maintained by deterministic interactions in the tropical Pacific region. Ocean dynamics alter sea-surface temperature, changing the atmospheric heating; the resulting changes in surface wind alter the ocean dynamics. Annually varying mean conditions largely determine the spatial pattern and temporal evolution of El Nino events. 20 references, 3 figures.

  3. El Nino: Historical and paleoclimatic aspects of the Southern Oscillation

    SciTech Connect

    Diaz, H.F.; Markgraf, V.

    1992-01-01

    This book about El Nino/Southern Oscillation is divided into the following major sections: ENSO in the modern record; the use of historical records in ENSO reconstruction; Paleoclimate reconstructions of ENSO from tree-ring records, ice cores, corals; Low resolution paleoclimatic reconstruction of ENSO from marine and terrestrial proxy indicators. The overall theme of the book is the that improved reliability of individual ENSO indices might be achieved by pooling together as many of the proxy series as feasible.

  4. The Child's Tantrum: El Nino. The Origin of the El Nino-Southern Oscillation

    NASA Technical Reports Server (NTRS)

    Picault, Joel; Hackert, Eric; Busalacchi, Antonio; Murtugudde, Ragu; Lagerloef, Gary

    2000-01-01

    In 1997, a child's tantrums caught the world's attention. These tantrums took the form not of crying and foot stamping, but of droughts and floods. Obviously, this was no ordinary child. It was, in fact, The Child, or El Nino, as it was, named in the late 1800s by South American observers, who noted that its timing coincided with the Christmas holiday. El Nino is a reversal in sea surface temperature (SST) distributions that occurs once every few years in the tropical Pacific. When it coincides with a cyclical shift in air pressure, known as the Southern Oscillation, normal weather patterns are drastically altered. The combined phenomenon is known as El Nino-Southern Oscillation (ENSO). Although ENSO is a regular phenomenon, it was unusually strong in 1997. It produced heavy rainfall and floods in California and bestowed spring-like temperatures on the Midwest during the winter. These drastic changes in normal weather patterns captured the public imagination, from news reports to jokes on late-night talk shows. Naturally, people wanted to. know as much, about El Nino as possible. Fortunately, scientists had at their disposal new satellites and ocean sensors that provided an unprecedented level of information. Consequently, not only was the 1997 ENSO the strongest in recent memory, but it was also the most thoroughly studied. Prominent groups such as the NASA Seasonalto-Interannual Prediction Project (NSIPP) combined numerous aspects of climate modeling into a single, predictive endeavor.

  5. The El Nino/Southern Oscillation and Future Soybean Prices

    NASA Technical Reports Server (NTRS)

    Keppenne, C.

    1993-01-01

    Recently, it was shown that the application of a method combining singular spectrum analysis (SSA) and the maximum entropy method to univariate indicators of the coupled ocean-atmosphere El Nino/Southern Oscillation (ENSO) phenomenon can be helpful in determining whether an El Nino (EN) or La Nina (LN) event will occur. SSA - a variant of principal component analysis applied in the time domain - filters out variability unrelated to ENSO and separates the quasi-biennial (QB), two-to-three year variability, from a lower-frequency (LF) four-to-six year EN-LN cycle; the total variance associated with ENSO combines the QB and LF modes. ENSO has been known to affect weather conditions over much of the globe. For example, EN events have been connected with unusually rainy weather over the Central and Western US, while the opposite phases of the oscillation (LN) have been plausibly associated with extreme dry conditions over much of the same geographical area...

  6. 40-50 day oscillation and the El-Nino/Southern Oscillation - a new perspective

    SciTech Connect

    Lau, K.M.; Chan, P.H.

    1986-05-01

    The tropical ocean-atmosphere exhibits two prominent modes of low-frequency oscillations, i.e, the 40-50 day oscillation and the El Nino/Southern Oscillation (ENSO). The two phenomena are viewed in the same perspective from 10 years of satellite-derived out-going-longwave-radiation data. Results reveal some interesting features that may lead to new insights into the understanding of the two phenomena.

  7. Atmospheric carbon dioxide, the southern oscillation, and the weak 1975 El Nino

    SciTech Connect

    Bacostow, R.B.; Adams, J.A.; Keeling, C.D.; Moss, D.J.; Whorf, T.P.; Wong, C.S.

    1980-10-03

    The observed rate of change of the atmospheric carbon dioxide concentration at the South Pole, Fanning Island, Hawaii, and ocean weather station P correlates with an index of the southern oscillation and with El Nino occurrences. There are changes at all four stations that seem to be in response to the weak 1975 El Nino. Thus, even poorly developed El Nino events may affect the atmospheric carbon dioxide concentration.

  8. El Nino Southern Oscillation and Tuna in the Western Pacific

    NASA Technical Reports Server (NTRS)

    Lehodey, P.; Bertignac, M.; Hampton, J.; Lewis, A.; Picaut, J.

    1997-01-01

    Nearly 70% of the world's annual tuna harvest, currently 3.2 million tonnes, comes from the Pacific Ocean. Skipjack tuna (Katsuwonus pelamis) dominate the catch. Although skipjack are distributed in the surface mixed layer throughout the equatorial and subtropical Pacific, catches are highest in the western equatorial Pacific warm pool, a region characterized by low primary productivity rates that has the warmest surface waters of the world's oceans. Assessments of tuna stocks indicate that recent western Pacific skipjack catches approaching one million tonnes annually are sustainable. The warm pool, which is fundamental to the El Nino Southern Oscillation (ENSO) and the Earth's climate in general, must therefore also provide a habitat capable of supporting this highly productive tuna population. Here we show that apparent spatial shifts in the skipjack population are linked to large zonal displacements of the warm pool that occur during ENSO events. This relationship can be used to predict (several months in advance) the region of highest skipjack abundance, within a fishing ground extending over 6,000 km along the Equator.

  9. Optimizing irrigation strategies as influenced by El Nino southern oscillation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Equatorial Pacific sea surface temperature anomalies (SSTA) can cause a systematic El Niño-Southern Oscillation (ENSO) coupling with the atmosphere to produce predictable weather patterns in much of North America. Adapting irrigation strategies for drought tolerant crops like cotton [Gossypium hirsu...

  10. El Nino-southern oscillation related fluctuations of the marine carbon cycle

    SciTech Connect

    Winguth, A.M.E.; Heimann, M.; Kurz, K.D.; Maier-Reimer, E.; Mikolajewicz, U.; Segschneider, J. )

    1994-03-01

    The yearly increase in global atmospheric carbon dioxide concentration is not constant, fluctuating around a mean growth rate. Some previous work has been done looking at the relationship of CO2 fluctuations with the El Nino-Southern Oscillation (ENSO) events in the Pacific. This paper describes the response of the three-dimensional ocean circulation model (Hamburg LSG) coupled on-line with a oceanic carbon cycle model (HAMOCC-3) to realistic wind and air temperature field anomalies. The focus is the marine carbon cycle and the interannual variations of carbon fluxes between ocean and atmosphere during the strong El Nino of 1982/83. 53 refs., 14 figs.

  11. El Nino: Historical and paleoclimatic aspects of the southern oscillation

    SciTech Connect

    Diaz, H.F.; Markgraf, V.

    1992-01-01

    This book, including 22 papers by well-known authorities, presents a balanced picture of the possible types of information that can be bound about the past occurrence of El Nino. Topics presented include the following: oxygen-isotope analyses of ice cores in the Andes; tree-ring growth; trace mineral concentrations in annual layers of coral reefs; Nile River flood records back 13 centuries. The book is accessible to outsiders whose interests require a knowledge of El Nino and its historical manifestations.

  12. Influence of El Nino Southern Oscillation on the Mesospheric Temperature

    NASA Technical Reports Server (NTRS)

    Li, Tao; Calvo, Natalia; Yue, Jia; Dou, Xiankang; Russell, J. M, III; Mlynczak, M. G.; She, Chiao-Yao; Xue, Xianghui

    2013-01-01

    Using the middle atmosphere temperature data set observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite experiment between 2002 and 2012, and temperatures simulated by the Whole Atmospheric Community Climate Model version 3.5 (WACCM3.5) between 1953 and 2005, we studied the influence of El Niño-Southern Oscillation (ENSO) on middle atmosphere temperature during the Northern Hemisphere (NH) wintertime. For the first time, a significant winter temperature response to ENSO in the middle mesosphere has been observed, with an anomalous warming of approximately 1.0 K/MEI (Multivariate ENSO Index) in the tropics and an anomalous cooling of approximately 2.0 K/MEI in the NH middle latitudes. The observed temperature responses to ENSO in the mesosphere are opposite to those in the stratosphere, in agreement with previous modeling studies. Temperature responses to ENSO observed by SABER show similar patterns to those simulated by the WACCM3.5 model. Analysis of the WACCM3.5 residual mean meridional circulation response to ENSO reveals a significant downwelling in the tropical mesosphere and upwelling in the NH middle and high latitudes during warm ENSO events, which is mostly driven by anomalous eastward gravity wave forcing in the NH mesosphere.

  13. El Nino/Southern Oscillation response to global warming.

    PubMed

    Latif, M; Keenlyside, N S

    2009-12-01

    The El Niño/Southern Oscillation (ENSO) phenomenon, originating in the Tropical Pacific, is the strongest natural interannual climate signal and has widespread effects on the global climate system and the ecology of the Tropical Pacific. Any strong change in ENSO statistics will therefore have serious climatic and ecological consequences. Most global climate models do simulate ENSO, although large biases exist with respect to its characteristics. The ENSO response to global warming differs strongly from model to model and is thus highly uncertain. Some models simulate an increase in ENSO amplitude, others a decrease, and others virtually no change. Extremely strong changes constituting tipping point behavior are not simulated by any of the models. Nevertheless, some interesting changes in ENSO dynamics can be inferred from observations and model integrations. Although no tipping point behavior is envisaged in the physical climate system, smooth transitions in it may give rise to tipping point behavior in the biological, chemical, and even socioeconomic systems. For example, the simulated weakening of the Pacific zonal sea surface temperature gradient in the Hadley Centre model (with dynamic vegetation included) caused rapid Amazon forest die-back in the mid-twenty-first century, which in turn drove a nonlinear increase in atmospheric CO(2), accelerating global warming. PMID:19060210

  14. El Nino Southern Oscillation (ENSO) impact on tuna fisheries in Indian Ocean.

    PubMed

    Kumar, Palanisamy Satheesh; Pillai, Gopalakrishna N; Manjusha, Ushadevi

    2014-01-01

    El Nino Southern Oscillation (ENSO) is an important driver of interannual variations in climate and ecosystem productivity in tropical regions. However, detailed information about this important phenomenon of the Indian Ocean is scarce. Consequently, the objective of this study is to improve understanding of the impact of warm event El Nino and cool event La Nina on annual tuna landings from the Indian Ocean from 1980 to 2010. In this study, maximum tuna landings were recorded during a weak El Nino year (1456054 t in 2006) and during a weak La Nina year (1243562 t in 2000), although the lowest tuna catch was followed during the strong El Nino year (1204119 t in 2009) and during a strong La Nina year (706546 t in 1988). Validation of predicted tuna landings and SST were showing a significant positive correlation (p < 0.01) was observed all the major tuna species except Southern Bluefin Tuna. Whereas the other relationships such as sea level pressure, Wind actions; Zonal Wind (U), Meridonial Wind (V), and Scalar Wind (W) are less well-defined. In contrast with principal component analysis we find that Principal Components 1 explains 75.5% of the total variance and suggest that sea surface temperature plays a major role in determining tuna availability in the region especially during warm event El Nino years; landings in Indian Ocean tend to be optimum SST 25 to 26°C in ENSO event. Our results confirm the ENSO impact on climate, tuna abundance and production in the Indian Ocean. However, among the oceanic variables SST explained the highest deviance in generalized additive models and therefore considered the best habitat predictor in the Indian Ocean followed by sea level pressure and Winds (U, V, W).

  15. Equatorial Pacific response to the 1982/1983 El Nino-Southern Oscillation event

    SciTech Connect

    Tang, T.Y.; Weisberg, R.H.

    1984-01-01

    The ocean's response to the 1982/83 El Nino-Southern Oscillation event was the largest ever documented. In this paper the authors explore the effects of certain details of the observed zonal wind stress anomaly field upon the ocean's response using a linear, adiabatic, reduced gravity, analytical model. The increase in magnitude of the downwelling response over the composite of previous El Nino events is attributed to the eastward translation of the observed westerly wind anomaly and the double peaked downwelling at the South American coast is attributed to the amplitude modulation of this anomaly. Effects of an easterly anomaly which appeared to the west of the dateline midway through the event are also considered.

  16. El Nino/ Southern Oscillation events and their associated midlatitude teleconnections 1531-1841

    SciTech Connect

    Hamilton, K.; Garcia, R.R.

    1986-11-01

    This paper reports on an investigation into the chronology of El Nino/Southern Oscillation (ENSO) events during the period from the arrival of Europeans in Peru in 1531 until the year 1841 when conventional barometric data became available in the tropical regions. A number of probable ENSO events can be dated from anecdotal reports of significant rainfall in the coastal desert of northern Peru. In many of the years with anomalous Peruvian rainfall it is also possible to use various types of proxy data to identify aspects of the global teleconnection patterns usually associated with tropical ENSO events.

  17. Tropical ocean-atmosphere interaction, the Pacific cold tongue, and the El Nino-Southern Oscillation

    SciTech Connect

    Jin, F.F.

    1996-10-04

    The tropical Pacific basin allows strong feedbacks among the trade winds, equatorial zonal sea surface temperature contrast, and upper ocean heat content. Coupled atmosphere-ocean dynamics produce both the strong Pacific cold tongue climate state and the El Nino-Southern Oscillation phenomenon. A simple paradigm of the tropical climate system is presented, capturing the basic physics of these two important aspects of the tropic Pacific and basic features of the climate states of the Atlantic and Indian ocean basins. 21 refs., 3 figs.

  18. El Nino-southern oscillation displacements of the western equatorial Pacific warm pool

    SciTech Connect

    McPhaden, M.J. ); Picaut, J. )

    1990-12-07

    The western equatorial Pacific warm pool (sea-surface temperatures >29C) was observed to migrate eastward across the date line during the 1986-1987 El Nino-Southern Oscillation event. Direct velocity measurements made in the upper ocean from 1986 to 1988 indicate that this migration was associated with a prolonged reversal in the South Equatorial Current forced by a large-scale relaxation of the trade winds. The data suggest that wind-forced zonal advection plays an important role in the thermodynamics of the western Pacific warm pool on interannual time scales.

  19. Rainfall shortage and El Nino-southern oscillation in New Caledonia, Southwestern Pacific

    SciTech Connect

    Morliere, A.; Rebert, J.P.

    1986-06-01

    About three months after the beginning of an El Nino/Southern Oscillation (ENSO) year, a rainfall shortage develops over all of New Caledonia (21/sup 0/S, 165/sup 0/E) and lasts for 12 months. There is, on the average, a 22% decrease over the mean monthly rainfalls for one year. This result is based on the study of a rainfall composite and of a composite obtained from the first empirical orthogonal function (EOF) extracting more than half of the variance over 30 years of measurement at 18 stations.

  20. El Nino-southern oscillation simulated in an MRI atmosphere-ocean coupled general circulation model

    SciTech Connect

    Nagai, T.; Tokioka, T.; Endoh, M.; Kitamura, Y. )

    1992-11-01

    A coupled atmosphere-ocean general circulation model (GCM) was time integrated for 30 years to study interannual variability in the tropics. The atmospheric component is a global GCM with 5 levels in the vertical and 4[degrees]latitude X 5[degrees] longitude grids in the horizontal including standard physical processes (e.g., interactive clouds). The oceanic component is a GCM for the Pacific with 19 levels in the vertical and 1[degrees]x 2.5[degrees] grids in the horizontal including seasonal varying solar radiation as forcing. The model succeeded in reproducing interannual variations that resemble the El Nino-Southern Oscillation (ENSO) with realistic seasonal variations in the atmospheric and oceanic fields. The model ENSO cycle has a time scale of approximately 5 years and the model El Nino (warm) events are locked roughly in phase to the seasonal cycle. The cold events, however, are less evident in comparison with the El Nino events. The time scale of the model ENSO cycle is determined by propagation time of signals from the central-eastern Pacific to the western Pacific and back to the eastern Pacific. Seasonal timing is also important in the ENSO time scale: wind anomalies in the central-eastern Pacific occur in summer and the atmosphere ocean coupling in the western Pacific operates efficiently in the first half of the year.

  1. The hydroclimatology of the United States during El Nino/Southern Oscillation

    SciTech Connect

    Dracup, J.A.; Piechota, T.C.; Khachikian, C.S.

    1995-12-31

    Palmer Drought Severity Index (PDSI) monthly data are analyzed, building on a previous study that investigated the influence of the El Nino/Southern Oscillation (ENSO) on US streamflow. Harmonic analysis is performed using data from 1,035 selected climatological stations, allowing observation of the biennial tendency in climate data. With the middle twelve months defined as the El Nino year (0), an idealized first harmonic fit to a 24-month ENSO composite is computed for each station. By plotting the first harmonic vectors of each station, regions of similar, or coherent, response are identified. The regions identified using PDSI data represent wet conditions in the Gulf of Mexico (Gm1 and GM2) and central (C) US, and dry conditions in the Pacific northwest (PNW) and northeast (NE) US. The PNW region exhibits the strongest interrelationship between ENSO and extreme drought events. Comparing PDSI data results with other hydroclimatic data (temperature, precipitation, and streamflow) reveals consistent responses. The most filtered response is seen in the PDSI and streamflow data, and these data are probably the best measure of the overall hydroclimatic response within a region. Results of this study suggest that conditions in the tropical Pacific (e.g., sea surface temperatures) may be excellent precursors of future climate. These conditions may also enhance long range prediction of droughts and floods for certain regions of the US.

  2. Impacts of El Nino Southern Oscillation on the Global Yields of Major Crops

    NASA Technical Reports Server (NTRS)

    Iizumi, Toshichika; Luo, Jing-Jia; Challinor, Andrew J.; Sakurai, Gen; Yokozawa, Masayuki; Sakuma, Hirofumi; Brown, Molly Elizabeth; Yamagata, Toshio

    2014-01-01

    The monitoring and prediction of climate-induced variations in crop yields, production and export prices in major food-producing regions have become important to enable national governments in import-dependent countries to ensure supplies of affordable food for consumers. Although the El Nino/Southern Oscillation (ENSO) often affects seasonal temperature and precipitation, and thus crop yields in many regions, the overall impacts of ENSO on global yields are uncertain. Here we present a global map of the impacts of ENSO on the yields of major crops and quantify its impacts on their global-mean yield anomalies. Results show that El Nino likely improves the global-mean soybean yield by 2.15.4 but appears to change the yields of maize, rice and wheat by -4.3 to +0.8. The global-mean yields of all four crops during La Nina years tend to be below normal (-4.5 to 0.0).Our findings highlight the importance of ENSO to global crop production.

  3. Excitation of the Earth's Chandler wobble by southern oscillation/El Nino, 1900-1979

    NASA Technical Reports Server (NTRS)

    Chao, B. F.

    1985-01-01

    The southern oscillation/El Nino (ENSO) is the single most prominent interannual signal in global atmospheric/oceanic fluctuations. The following question is addressed: how important is the angular momentum carried by ENSO in exciting the Earth's Chandler wobble? The question is attacked through a statistical analysis of the coherence spectra (correlation as a function of frequency) between two data sets spanning 1900 to 1979-the southern oscillation index (SOI) time series and the excitation function psi (with x-component psi sub x and y-component psi sub y) of the Chandler wobble derived from the homogeneous ILS (International Latitude Service) polar motion data. The coherence power and phase in the Chandler frequency band (approx. 0.79 to 0.89 cpy) are studied. It is found that, during 1900 to 1979 the coherence between SOI and psi sub x is significant well over the 95% confidence threshold whereas that between SOI and psi sub y is practically nil. Quantitatively, the coherence study shows that ENSO provides some 20% of the observed Chandler wobble excitation power. Since earlier investigations have shown that the total atmospheric/oceanic variation can account for the Chandler wobble excitation at about 20% level, the implication is that ENSO maybe an important (interannual) part of the atmospheric/oceanic variation that is responsible for the Chandler wobble excitation during 1900 to 1979.

  4. Use of Data to Improve El Nino Southern Oscillation Simulations and Forecasts

    NASA Technical Reports Server (NTRS)

    Perigaud, Claire

    1999-01-01

    Various data over the period 1980-1998 have been used to improve El Nino Southern Oscillation (ENSO) simulations and forecasts performed by coupled ocean/atmosphere models. For such a study, oceanic and atmospheric satellite data are necessary. Models assume a baroclinic ocean with a mixed layer coupled to a baroclinic atmosphere to simulate the anomalous fields. The various data have been used to revisit the parameterizations of the subsurface temperature in the mixed layer, atmospheric convection, and friction in the baroclinic ocean. This new model, named Tsub.Conv, simulates 4-year oscillations like the model with the original parameterization, but with anomalous thermocline and wind anomalies that agree a lot better with reality. The atmospheric model still presents some deficiencies in the eastern Pacific and when it is replaced by a statistical atmosphere, the coupled model (Tsub.Astat) performs even better. It is found that the off-equatorial ocean and wind curl anomalies play a crucial role for all these models and that Tsub.Astat simulates an ocean heat content recharge coming from the north prior to a warm event like the ones observed during the 1985-1992 period. The ENSO forecasts over 1980-1998 are considerably improved with Tsub.Astat. One needs to add the simulation of westerly wind bursts to be able to forecast the 1997 event one year in advance. Additional information is contained in the original.

  5. El Nino-southern oscillation: A coupled response to the greenhouse effect?

    SciTech Connect

    Sun, De-Zheng

    1997-11-01

    The purpose of this article to elucidate the link between the El Nino-Southern Oscillation (ENSO) and radiative forcing (of which the greenhouse effect is a major part). A unified theory for the tropical Pacific climate is developed by considering the response of the coupled ocean-atmosphere to a changing radiative forcing. The hypothesis is that both the zonal surface sea temperature (SST) gradients and ENSO are a coupled response to the strong radiative heating or the tropical warmth. Owing to ocean-atmosphere interaction, the stronger the radiative heating, the larger the zonal SST gradients. When the SST gradients exceed a critical value, however, the ocean-atmosphere interaction in the cold-tongue region is too strong for the coupled system to hold steady. Consequently, the coupled system enters an oscillatory state. These coupled dynamics are examined in a simple mathematical model whose behavior is consistent with the hypothesis. With a linear temperature profile throughout the depth of subsurface ocean, the model predicts that both the magnitude and period of the oscillation increase with increases in radiative forcing or the greenhouse effect. The increase in the magnitude of the oscillation largely comes from an enhancement of the magnitude of the cold anomalies, while the increase in the period mostly comes from a prolonged duration of the warm events. With a profile in which the lapse rate decreases with depth, the sensitivity is more moderate. The simplicity of the model prevents a quantitative simulation of the sensitivity of ENSO to increases in the greenhouse effect, but qualitatively the model results support the empirical interpretation of the prolonged duration of the 1990-1995 ENSO event. 5 refs., 7 figs.

  6. Simulated Impacts of El Nino/Southern Oscillation on United States Water Resources

    SciTech Connect

    Thomson, Allison M. ); Brown, Robert A. ); Rosenberg, Norman J. ); Izaurralde, R Cesar C. ); Legler, David; Srinivasan, Ragahvan

    2003-02-01

    The El Nino/Southern Oscillation alters global weather patterns with consequences for fresh water quality and supply. ENSO events impact regions and natural resource sectors around the globe. For example, in 1997-98, a strong El Ni?o brought warm ocean temperatures, flooding and record snowfall to the west coast of the US. Research on ENSO events and their impacts has improved long range weather predictions, potentially reducing the damage and economic cost of these anomalous weather patterns. Here, we simulate the impacts of four types of ENSO states on water resources in the conterminous United States. We distinguish between Neutral, El Ni?o, La Ni?a and strong El Ni?o years over the period of 1960-1989. Using climate statistics that characterize these ENSO states to drive the HUMUS water resources model, we examine the effects of 'pure' ENSO events, without complications from transition periods. Strong El Ni?o is not simply an amplification of El Ni?o; it leads to strikingly different consequences for climate and water resources.

  7. Influences of the El Nino Southern Oscillation and the Pacific Decadal Oscillation on the Timing of the North American Spring

    NASA Technical Reports Server (NTRS)

    McCabe, Gregory J.; Ault, Toby R.; Cook, Benjamin I.; Betancourt, Julio L.; Schwartz, Mark D.

    2012-01-01

    Detrended, modelled first leaf dates for 856 sites across North America for the period 1900-2008 are used to examine how the El Nino 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 Nino 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 significantly (at p <0.05) different than the distributions for neutral conditions. The nature of the teleconnection between Pacific SST's and first leaf dates is evident in comparable composites for detrended sea level pressure (SLP) in the spring months. During positive ENSO/PDO, there is an anomalous flow of warm air from the southwestern US into the northwestern US and an anomalous northeasterly flow of cold air from polar regions into the eastern and southeastern US. These flow patterns are reversed during negative ENSO/PDO. Although the magnitudes of first leaf date departures are not necessarily significantly related to ENSO and PDO, the spatial patterns of departures are significantly related to ENSO and PDO. These significant relations and the long-lived persistence of SSTs provide a potential tool for forecasting the tendencies for first leaf dates to be early or late.

  8. Explosive volcanic eruptions, the El Nino-southern oscillation, and U.S. climate variability

    SciTech Connect

    Portman, D.A.

    1996-01-01

    A study was conducted to identify and separate possible signals of volcanic eruptions and of the El Nino Southern Oscillation (ENSO) in U.S. surface climate records. Anomalies of monthly mean surface air temperature and total precipitation taken from the U.S. Historical Climatology Network were composited (averaged) over years of major explosive volcanic eruptions, ENSO warm events, and ENSO cold events since the year 1900. It was assumed that volcanic eruptions and ENSO events occur independently of each other. All composite anomalies were assessed for significance with regard to several statistical and physical criteria. The composite ENSO-related anomalies were then subtracted from anomalies of temperature and precipitation associated with the volcanic eruptions. Removal of large magnitude and highly significant anomalies associated with the ENSO warm and cold events is found to facilitate detection of volcanic signals in monthly records of U.S. temperature and precipitation. Volcanic signals are strongly suggested east of the Continental Divide, for example, where positive monthly temperature anomalies exceeding 1{degrees}C occur during the first fall and winter after eruptions. Negative temperature anomalies occur west of the Continental Divide during the first winter and spring after eruptions and in the southern United States during the summer of the first post-eruption calendar year. Positive monthly precipitation anomalies exceeding 15 mm in magnitude are found in the southeastern United States during the first winter and spring after eruptions. Precipitation anomalies that are smaller in magnitude and yet significant, such as positive anomalies in the northwestern United States and negative anomalies in the central and eastern United States, are found during the summer of the first post-eruption calendar year. 62 refs., 9 figs., 4 tabs.

  9. A linear, stochastic, dynamical model of El Nino-Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Thompson, Christopher J.

    1998-09-01

    Much research has been devoted to physical models of the interannual SST variability in the Pacific known as El Nino/Southern Oscillation (ENSO). The Zebiak-Cane model (ZCM, 1987) has established the dominate view of ENSO as being a coupled ocean-atmosphere phenomenon that is chaotic and linearly unstable. Recently, the idea that ENSO irregularity might be caused by stochastic forcing has gained support. Here, a variant of the ZCM is developed which is linear and stable, but displays ENSO- like variability under moderate external forcing. A linearized version of the Battisti (1988) variant of the ZCM is developed. This linear ocean-atmosphere model (LOAM) has time invariant background states, and is subject to singular vector analysis. The principle singular vector for time periods, τ, (the τ- optimals) show the following characteristics. (1) The τ-optimals grow more quickly than the most unstable mode (the ENSO mode). (2) The τ-optimals develop into the ENSO mode by 90 days. (3) Optimals were produced which used only the SST IT-optimals) and which used only the ocean dynamics (r-optimals.) For τ greater than 60 days, both optimals produce ENSO modes (of the same phase). A T-optimal pattern with a 0.1 degree anomaly maximum produces the same size ENSO as a r-optimal pattern with a 1.2 meter maximum thermocline anomaly. (4) The full optimal is the linear combination of these two sub-optimals, where their relative sizes are determined by their relative weights in the norm. (5) Neutral and damped versions of LOAM show these same properties, and still display transient growth. A version of LOAM (with an annual cycle added) is subjected to parameter studies to find plausible parameter regimes that damp the ENSO mode while preserving the transient growth of the τ-optimals. Increasing the ocean mechanical damping and decreasing the western boundary reflection has the desired effect. Four candidate models ranging from slightly damped to heavily damped are run in

  10. El-Nino Southern Oscillation simulated and predicted in SNU coupled GCMs

    NASA Astrophysics Data System (ADS)

    Ham, Yoo-Geun; Kang, In-Sik; Kim, Daehyun; Kug, Jong-Seong

    2012-06-01

    The characteristics of the El-Nino Southern Oscillation (ENSO) simulated in free integrations using two versions of the Seoul National University (SNU) ocean-atmosphere coupled global climate model (CGCM) are examined. A revised version of the SNU CGCM is developed by incorporating a reduced air-sea coupling interval (from 1 day to 2 h), a parameterization for cumulus momentum transport, a minimum entrainment rate threshold for convective plumes, and a shortened auto-conversion time scale of cloud water to raindrops. With the revised physical processes, lower tropospheric zonal wind anomalies associated with the ENSO-related sea surface temperature anomalies (SSTA) are represented with more realism than those in the original version. From too weak, the standard deviation of SST over the eastern Pacific becomes too strong in the revised version due to the enhanced air-sea coupling strength and intraseasonal variability associated with ENSO. From the oceanic side, the stronger stratification and the shallower-than-observed thermocline over the eastern Pacific also contribute to the excessive ENSO. The impacts of the revised physical processes on the seasonal predictability are investigated in two sets of the hindcast experiment performed using the two versions of CGCMs. The prediction skill measured by anomaly correlation coefficients of monthly-mean SSTA shows that the new version has a higher skill over the tropical Pacific regions compared to the old version. The better atmospheric responses to the ENSO-related SSTA in the revised version lead to the basin-wide SSTA maintained and developed in a manner that is closer to observations. The symptom of an excessively strong ENSO of the new version in the free integration is not prominent in the hindcast experiment because the thermocline depth over the eastern Pacific is maintained as initialized over the arc of time of the hindcast (7 months).

  11. Shortwave feedbacks and El Nino-Southern Oscillation: Forced ocean coupled ocean-atmosphere experiments

    NASA Technical Reports Server (NTRS)

    Waliser, Duane E.; Blanke, Bruno; Neelin, J. David; Gautier, C.

    1994-01-01

    Changes in tropical sea surface temperature (SST) can produce changes in cloudiness that modify incoming solar shortwave (SW) radiation, which in turn affects SST. The effects of this negative feedback on Pacific interannual variability are examined in forced ocean model and hybrid coupled ocean-atmosphere model simulations. Two empirical schemes are used to model the large-scale, low-frequency response of surface SW to SST anomalies. The first scheme attempts to account for the nonlocal nature of the atmospheric response to SST based patterns of covariability analyzed through singular value decomposition. In the observations the primary coupled mode of variability is composed of a SW anomaly in the central Pacific that covaries with anomalous SST in the eastern Pacific. This is applied in the model as a nonlocal feedback. The second scheme examines the effects of a purely local feedback with a spatially varying coefficient of magnitude chosen similar to the first scheme. In almost all cases the second scheme behaved similarly to the first, presumably because the correlation scale of SST is large enough for El Nino-Southern Oscillation (ENSO) dynamics that there is little sensitivity to the local approximation in the SW feedback. In simulations forced by time series of observed wind stress the SW feedback induced very minor SST damping. Results for a simpified heat budget analysis showed that while the SW feedback increased the local heat flux damping on SST, it also induced a mean shallowing of the mixed layer. The resulting changes in both the local mean vertical temperature gradient and the zonal velocity response to the wind stress acted to oppose the local heat flux damping effects. When the observed SW anomalies were applied to forced simulations, the simulated SST anomalies were modified as expected, and agreement with observed SST improved. In coupled simulations the SW feedbacks had greater impact than in the case of specified stress. The main effects were

  12. El Nino-Southern Oscillation Correlated Aerosol Angstrom Exponent Anomaly Over the Tropical Pacific Discovered in Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Li, Jing; Carlson, Barbara E.; Lacis, Andrew A.

    2011-01-01

    El Nino.Southern Oscillation (ENSO) is the dominant mode of interannual variability in the tropical atmosphere. ENSO could potentially impact local and global aerosol properties through atmospheric circulation anomalies and teleconnections. By analyzing aerosol properties, including aerosol optical depth (AOD) and Angstrom exponent (AE; often used as a qualitative indicator of aerosol particle size) from the Moderate Resolution Imaging Spectrometer, the Multiangle Imaging Spectroradiometer and the Sea ]viewing Wide Field ]of ]view Sensor for the period 2000.2011, we find a strong correlation between the AE data and the multivariate ENSO index (MEI) over the tropical Pacific. Over the western tropical Pacific (WTP), AE increases during El Nino events and decreases during La Nina events, while the opposite is true over the eastern tropical Pacific (ETP). The difference between AE anomalies in the WTP and ETP has a higher correlation coefficient (>0.7) with the MEI than the individual time series and could be considered another type of ENSO index. As no significant ENSO correlation is found in AOD over the same region, the change in AE (and hence aerosol size) is likely to be associated with aerosol composition changes due to anomalous meteorological conditions induced by the ENSO. Several physical parameters or mechanisms that might be responsible for the correlation are discussed. Preliminary analysis indicates surface wind anomaly might be the major contributor, as it reduces sea ]salt production and aerosol transport during El Nino events. Precipitation and cloud fraction are also found to be correlated with tropical Pacific AE. Possible mechanisms, including wet removal and cloud shielding effects, are considered. Variations in relative humidity, tropospheric ozone concentration, and ocean color during El Nino have been ruled out. Further investigation is needed to fully understand this AE ]ENSO covariability and the underlying physical processes responsible for

  13. Strategic adaptation of nitrogen management for el nino southern oscillation-induced winter wheat system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rainfall anomaly (RA) associated with El Niño-Southern Oscillation (ENSO) has various unwanted impacts on agricultural system globally. The loss of inorganic nitrogen (N) depending on extreme wet or dry conditions is a major concern. The main objective of this study was to adapt site-specific N ...

  14. Structure and predictability of the El Nino/Southern Oscillation phenomenon in a coupled ocean-atmosphere general circulation model

    SciTech Connect

    Latif, M.; Sterl, A.; Maier-Reimer, E.; Junge, M.M. )

    1993-04-01

    The space-time structure and predictability of the El Nino/Southern Oscillation (ENSO) phenomenon was investigated. Two comprehensive datasets were analyzed by means of an advanced statistical method, one based on observational data and other on data derived from an extended-range integration performed with a coupled ocean atmosphere general circulation model. It is shown that a considerable portion of the ENSO related low-frequency climate variability in both datasets is associated with a cycle implies the possibility of climate predictions in the tropics up to lead times of about one year. This is shown by conducting an ensemble of predictions with our coupled general circulation model. For the first time a coupled model of this type was successfully applied to ENSO predictions. 34 refs., 6 figs.

  15. Evolution of Oceanic Precipitation Anomalies During El Nino Southern Oscillation (ENSO) Events of the Last Two Decades

    NASA Technical Reports Server (NTRS)

    Yuan, Jinchun; Miller, Richard

    2001-01-01

    The Global Precipitation Climatology Program (GPCP) recently released monthly global precipitation data that allowed an analysis of oceanic precipitation anomalies before, during, and after El Nino Southern Oscillation (ENSO) events of the last two decades. During each ENSO event, a major positive precipitation anomaly was observed in the Central and Eastern Equatorial Pacific, while a major negative precipitation anomaly was observed in the Western Equatorial Pacific and Eastern Equatorial Indian Ocean. These precipitation anomalies co-varied strongly with sea surface temperature of the eastern equatorial Pacific, and may therefore be a good indicator of ENSO events. The precipitation anomaly pattern of 1997-98 differs significantly from previous ENSO events and calls certain aspects of current theories on ENSO into question.

  16. The El Nino-Southern Oscillation in the second Hadley Centre coupled model and its response to greenhouse warming

    SciTech Connect

    Collins, M.

    2000-04-01

    This paper describes El Nino-Southern Oscillation (ENSO) interannual variability simulated in the second Handley Centre coupled model under control and greenhouse warming scenarios. The model produces a very reasonable simulation of ENSO in the control experiment--reproducing the amplitude, spectral characteristics, and phase locking to the annual cycle that are observed in nature. The mechanism for the model ENSO is shown to be a mixed SST-ocean dynamics mode that can be interpreted in terms of the ocean recharge paradigm of Jin. In experiments with increased levels of greenhouse gases, no statistically significant changes in ENSO are seen until these levels approach four times preindustrial values. In these experiments, the model ENSO has an approximately 20% larger amplitude, a frequency that is approximately double that of the current ENSO (implying more frequent El Ninos and La Ninas), and phase locks to the annual cycle at a different time of year. It is shown that the increase in the vertical gradient of temperature in the thermocline region, associated with the model's response to increased greenhouse gases, is responsible for the increase in the amplitude of ENSO, while the increase in meridional temperature gradients on either side of the equator, again associated with the models response to increasing greenhouse gases, is responsible for the increased frequency of ENSO events.

  17. Central pacific seabirds and the el nino southern oscillation: 1982 to 1983 perspectives.

    PubMed

    Schreiber, R W; Schreiber, E A

    1984-08-17

    The breeding chronology and reproductive attempts of the seabird community on Christmas Island in the central Pacific Ocean (2 degrees N, 157 degrees W) were interrupted by the 1982-1983 El Niño Southern Oscillation. The resultant reproductive failure and disappearance of the entire seabird community of this equatorial atoll represents the most dramatic interruption on record of a seabird community located distant from coastal upwelling. Our data indicate the effect that the abiotic and biotic aspects of a global atmospheric-oceanic anomaly have on marine birds. The 1982-1983 El Niño Southern Oscillation provides an example of selective pressures and a natural experiment in the study of vertebrate population dynamics.

  18. Stable isotope geochemistry of corals from Costa Rica as proxy indicator of the El Nino/Southern Oscillation (ENSO)

    SciTech Connect

    Carriquiry, J.D.; Risk, M.J.; Schwarcz, H.P. )

    1994-01-01

    The authors analyzed the [delta][sup 18]O and [delta][sup 13]C time-series contained in coral skeletons collected from Isla de Cano, Costa Rica, that survived the 1982-1983 El Nino warming event. Coral [delta][sup 18]O give a record of thermal histories with a precision of [approximately]0.5[degrees]C. For this locality, the authors have determined that the average [Delta][delta][sub w] effect in the coral skeletons is equivalent to 33% of the skeletal [delta][sup 18]O range. Therefore, if [delta][sub w] effects are not compensated for, the annual skeletal-[delta][sup 18]O range displays a temperature range of 1[degrees]C lower than actual values. The isotopic record of Porites lobata skeletons shows simultaneous depletions in [sup 18]O and [sup 13]C at skeletal levels corresponding to 1983, coincident with the El Nino/Southern Oscillation (ENSO) event. Therefore, the El Nino event is not only recorded as negative [delta][sup 18]O anomalies in the skeleton, suggesting the warming of ambient waters, but also in the [delta][sup 13]C signal as negative anomalies, indicating coral bleaching. Contrary to the predictions of the [open quotes][sup 13]C-insolation model[close quotes] that the annual carbon isotope variation should be attenuated with depth in proportion to the decrease in light-intensity variation with depth, the authors found a clear trend where [Delta][delta][minus][sup 13]C increases with depth. Coral bioenergetics, which depends on both coral physiology and ecology, may adequately explain the unexpected increase in [delta][sup 13]C range with depth, without contradicting the seasonal character of [delta][sup 13]C variability with the solar irradiance cycle. Although some authors have determined the presence of hiatuses in the skeletal record due to severe stress and growth cessation, in this study it has been found that skeletal growth was not seriously diminished during the El Nino year of 1983.

  19. Correlation of interannual length-of-day variation with El Nino/Southern Oscillation, 1972-1986

    NASA Technical Reports Server (NTRS)

    Chao, B. Fong

    1988-01-01

    Correlation between interannual length-of-day (LOD) changes and an index representation of El Nino/Southern Oscillation (ENSO) for the period of 1972-1986 was examined in two ways: as the cross-correlation function in the time domain and as the complex coherence spectrum in the frequency domain. The ENSO representation was derived from barometric measurements from the Tahiti and Darwin, Australia, meteorological stations, as the difference of the sea-level pressure between the two locations. The cross correlation between this ENSO representation and LOD variation on the interannual time scale was found to have a maximum value of 0.68 and the LOD phase lag of 2 months, indicating that most of the interannual LOD variation is caused by ENSO, and that the transfer of ENSO's axial angular momentum to the solid earth lags behind the Tahiti-Darwin pressure variation by about 2 months. The corresponding coherence spectrum showed minimum correlation around biennial periods, indicating an influence of the stratospheric quasi-biennial oscillation on LOD variations.

  20. The El Nino-Southern Oscillation (ENSO)-pandemic influenza connection: coincident or causal?

    PubMed

    Shaman, Jeffrey; Lipsitch, Marc

    2013-02-26

    We find that the four most recent human influenza pandemics (1918, 1957, 1968, and 2009), all of which were first identified in boreal spring or summer, were preceded by La Niña conditions in the equatorial Pacific. Changes in the phase of the El Niño-Southern Oscillation have been shown to alter the migration, stopover time, fitness, and interspecies mixing of migratory birds, and consequently, likely affect their mixing with domestic animals. We hypothesize that La Niña conditions bring divergent influenza subtypes together in some parts of the world and favor the reassortment of influenza through simultaneous multiple infection of individual hosts and the generation of novel pandemic strains. We propose approaches to test this hypothesis using influenza population genetics, virus prevalence in various host species, and avian migration patterns.

  1. The Asian-Australian monsoon and El Nino-Southern Oscillation in the NCAR Climate System Model

    SciTech Connect

    Meehl, G.A.; Arblaster, J.M.

    1998-06-01

    Features associated with the Asian-Australian monsoon system and El Nino-Southern Oscillation (ENSO) are described in the National Center for Atmospheric Research (NCAR) global coupled Climate System Model (CSM). Simulation characteristics are compared with a version of the atmospheric component of the CSM, the NCAR CCM3, run with time-evolving SSTs from 1950 to 1994, and with observations. The CSM is shown to represent most major features of the monsoon system in terms of mean climatology, interannual variability, and connections to the tropical Pacific. This includes a representation of the Southern Oscillation links between strong Asian-Australian monsoons and associated negative SST anomalies in the eastern equatorial Pacific. The equatorial SST gradient across the Pacific in the CSM is shown to be similar to the observed with somewhat cooler mean SSTs across the entire Pacific by about 1--2 C. The seasonal cycle of SSTs in the eastern equatorial Pacific has the characteristic signature seen in the observations of relatively warmer SSTs propagating westward in the first half of the year followed by the reestablishment of the cold tongue with relatively colder SSTs propagating westward in the second half of the year. Like other global coupled models, the propagation is similar to the observed but with the establishment of the relatively warmer water in the first half of the year occurring about 1--2 months later than observed. The seasonal cycle of precipitation in the tropical eastern Pacific is also similar to other global coupled models in that there is a tendency for a stronger-than-observed double ITCZ year round, particularly in northern spring, but with a well-reproduced annual maximum of ITCZ strength north of the equator in the second half of the year.

  2. Zonal and Meridional Mass Redistribution in the Tropical Pacific During El Nino Southern Oscillation Events

    NASA Technical Reports Server (NTRS)

    Delcroix, Thierry; Gourdeau, Lionel; Rual, Pierre; Murtugudde, Raghuram

    1997-01-01

    This note aims at documenting the ENSO-related sea level changes for the whole tropical Pacific, and for the 1979-1996 period which covers numerous El Nino and La Nina events. For this purpose, we rely on (a) 0/450 dbar surface dynamic height anomaly (an alias for sea level) derived from XBT and TOGA-TAO measurements during 1979-1996, (b) TOPEX/Poseidon derived sea level anomaly during 1993-1996, and (c) Murtugudde et al. [1996] model sea level output during 1979-1995.

  3. Coupled atmosphere-ocean model simulations of El Nino/Southern Oscillation with and without an active Indian Ocean

    SciTech Connect

    Nagai, T.; Kitamura, Y.; Endoh, M.; Tokioka, T.

    1995-01-01

    An atmospheric general circulation model (GCM) was coupled with an ocean GCM covering the Pacific. This coupled model (PAC) was integrated over a 30-year period. The PAC model stimulates well the mean seasonally varying atmospheric and ocean fields and reproduces interannual variations corresponding to ENSO (El Nino/Southern Oscillation). The same atmospheric GCM was coupled with an ocean GCM covering the Indian Ocean and the tropical Pacific. This coupled model (IPC) was integrated over a 35-year period. The model climate in IPC is fairly reasonable, and its Pacific part is very similar to the Pacific climate of the PAC model. ENSO is the major interannual variability in the IPC model. The dynamics of ENSO in IPC are essentially the same as that in PAC. In the Pacific, the subsurface ocean heat content anomalies are formed by wind anomalies and show westward propagation centered off the equator. After they reach the western Pacific, they show eastward propagation along the equator. They produce changes in the thermocline structure in the eastern equatorial Pacific resulting in anomalies in SSTs. The SST anomalies provide wind anomalies, the sign of which is opposite to that of the wind anomalies in the first stage, so that this chain will continue. ENSO in the PAC and IPC models can be regarded as the {open_quotes}delayed oscillator{close_quotes} operating in the Pacific. Although the major interannual variability in the Indian Ocean is linked to ENSO in the Pacific, the Indian Ocean does not play any active role in the ENSO cycle in the IPC model. Interannual variability of monsoon activity in the IPC model is more reasonable than that in the PAC model. However, any definite mechanism for the relationship between monsoon activity and ENSO does not emerge in the present study. 31 refs., 14 figs.

  4. Modeling cotton lint yield response to irrigation management as influenced by El Nino-Southern Oscillation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The declining Ogallala Aquifer in the U.S. Southern High Plains motivates producers to optimize water use and yield of crops that can tolerate short-term water stress like cotton [Gossypium hirsutum (L.)]. Measurable and systematic sea surface temperature anomalies (SSTA) drive the El Niño-Southern ...

  5. Utilizing TRMM to Analyze Sea Breeze Thunderstorm Patterns During El Nino Southern Oscillations and Their Effects upon Available Fresh Water for South Florida Agricultural Planning and Management

    NASA Technical Reports Server (NTRS)

    Cooley, Clayton; Billiot, Amanda; Lee, Lucas; McKee, Jake

    2010-01-01

    Water is in high demand for farmers regardless of where you go. Unfortunately, farmers in southern Florida have fewer options for water supplies than public users and are often limited to using available supplies from surface and ground water sources which depend in part upon variable weather patterns. There is an interest by the agricultural community about the effect weather has on usable surface water, however, research into viable weather patterns during La Nina and El Nino has yet to be researched. Using rainfall accumulation data from NASA Tropical Rainfall Measurement Mission (TRMM) satellite, this project s purpose was to assess the influence of El Nino and La Nina Oscillations on sea breeze thunderstorm patterns, as well as general rainfall patterns during the summer season in South Florida. Through this research we were able to illustrate the spatial and temporal variations in rainfall accumulation for each oscillation in relation to major agricultural areas. The study period for this project is from 1998, when TRMM was first launched, to 2009. Since sea breezes in Florida typically occur in the months of May through October, these months were chosen to be the months of the study. During this time, there were five periods of El Nino and two periods of La Nina, with a neutral period separating each oscillation. In order to eliminate rainfall from systems other than sea breeze thunderstorms, only days that were conducive to the development of a sea breeze front were selected.

  6. Northern Hemisphere summer monsoon intensified by mega-El Nino/southern oscillation and Atlantic multidecadal oscillation.

    PubMed

    Wang, Bin; Liu, Jian; Kim, Hyung-Jin; Webster, Peter J; Yim, So-Young; Xiang, Baoqiang

    2013-04-01

    Prediction of monsoon changes in the coming decades is important for infrastructure planning and sustainable economic development. The decadal prediction involves both natural decadal variability and anthropogenic forcing. Hitherto, the causes of the decadal variability of Northern Hemisphere summer monsoon (NHSM) are largely unknown because the monsoons over Asia, West Africa, and North America have been studied primarily on a regional basis, which is unable to identify coherent decadal changes and the overriding controls on planetary scales. Here, we show that, during the recent global warming of about 0.4 °C since the late 1970s, a coherent decadal change of precipitation and circulation emerges in the entirety of the NHSM system. Surprisingly, the NHSM as well as the Hadley and Walker circulations have all shown substantial intensification, with a striking increase of NHSM rainfall by 9.5% per degree of global warming. This is unexpected from recent theoretical prediction and model projections of the 21st century. The intensification is primarily attributed to a mega-El Niño/Southern Oscillation (a leading mode of interannual-to-interdecadal variation of global sea surface temperature) and the Atlantic Multidecadal Oscillation, and further influenced by hemispherical asymmetric global warming. These factors driving the present changes of the NHSM system are instrumental for understanding and predicting future decadal changes and determining the proportions of climate change that are attributable to anthropogenic effects and long-term internal variability in the complex climate system.

  7. El Nino southern oscillation effects on dryland crop production in the Texas High Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Risk adverse dryland crop management in the US Southern High Plains may stabilize year to year productivity, however in some years the full yield potential is unrealized thereby reducing the overall cropping system productivity. Equatorial Pacific sea surface temperature anomalies (SSTA) systematica...

  8. Combined Effect of El Nino Southern Oscillation and Atlantic Multidecadal Oscillation on Lake Chad Level Variability Region

    NASA Technical Reports Server (NTRS)

    Okonkwo, Churchill; Demoz, Belay; Sakai, Ricardo; Ichoku, Charles; Anarado, Chigozie; Adegoke, Jimmy; Amadou, Angelina; Abdullahi, Sanusu Imran

    2015-01-01

    In this study, the combined effect of the Atlantic Multidecadal Oscillation (AMO) and El Niño Southern Oscillation (ENSO) on the Lake Chad (LC) level variability is explored. Our results show that the lake level at the Bol monitoring station has a statistically significant correlation with precipitation (R2 = 0.6, at the 99.5% confidence level). The period between the late 1960s and early 1970s marked a turning point in the response of the regional rainfall to climatic drivers, thereby severely affecting the LC level. Our results also suggest that the negative impact of the cold phase of AMO on Sahel precipitation masks and supersedes the positive effect of La Niña in the early the 1970s. The drop in the size of LC level from 282.5 m in the early 1960s to about 278.1 m in 1983/1984 was the largest to occur within the period of study (1900-2010) and coincides with the combined cold phase of AMO and strong El Niño phase of ENSO. Further analyses show that the current warm phase of AMO and increasing La Niña episodes appear to be playing a major role in the increased precipitation in the Sahel region. The LC level is responding to this increase in precipitation by a gradual recovery, though it is still below the levels of the 1960s. This understanding of the AMO-ENSO-rainfall-LC level association will help in forecasting the impacts of similar combined episodes in the future. These findings also have implications for long-term water resources management in the LC region.

  9. Isotope evidence of paleo - El Nino - Southern Oscillation cycles in loess-paleosol record in the central United States

    USGS Publications Warehouse

    Wang, Hongfang; Follmer, L.R.; Chao-li, Liu

    2000-01-01

    The ??13C of soil carbonate in rhizoconcretions collected from a loess-paleosol sequence in the central United States indicates that growing-season C3/C4 plant ratio oscillated by 35% on a 900 ?? 200 yr time scale during the late Wisconsinan glaciation. The pattern appears in phase with advance and retreat of the southern margin of the Laurentide ice sheet, suggesting influence by paleo-El Nin??o-Southern Oscillation cycles. The ??13C of soil organic matter indicates that the annual average C3/C4 plant ratio oscillated only by 18%, with a periodicity of 450 ?? 100 yr, and closely matched the cyclic pattern of loess-paleosol layers. It suggests a periodic enhancement of the penetration of the Gulf of Mexico air over the region during this time.

  10. Interannual variations in wheat rust development in China and the United States in relation to the El Nino/Southern oscillation

    SciTech Connect

    Scherm, H.; Yang, X.B.

    1995-09-01

    The El Nino/Southern Oscillation (ENSO) is one of the most important and best-characterized mechanisms of global climatic variation. Because regional temperature and precipitation patterns are influenced by the ENSO and plant diseases are responsive to these factors, historical disease records may contain an ENSO-related signal. We used cross-spectral analysis to establish coherence and phase relationships between the Southern Oscillation Index (SOI), which is a measure of the ENSO, and long-term (>40 years) data on wheat stripe rust in five regions of northern China and wheat stem rust in four climatic divisions of the midwestern United States. Monthly SOI values were averaged from March to June and October to March for analysis of the rust data from China and the United States, respectively, based when weather patterns in these regions are influenced by the ENSO. The coherence relationships showed consistent and significant (0.01 {le} P {le} 0.10) cooscillations between the rust and SOI series at temporal scales characteristic of the ENSO. The five stripe rust series were coherent with the SOI series at periodicities of 2.0 to 3.0 and 8.0 to 10.0 years, and three of the four stem rust series were coherent with the SOI series at a periodicity of 6.8 to 8.2 years. The phase relationships showed that, in most cases, the rust and SOI series cooscillated out of phase, suggesting that the associations between them are indirect. In a separate analysis of a shorter (18 years) stripe rust series form the Pacific Northwest of the United States, disease severity was significantly lower during El Nino years (warm phases of the ENSO) than during non-El Nino years (P {le} 0.0222) or during La Nina years (cold phases of the ENSO) (P {le}0.0253). Although no cause-and-effect relationships could be deduced, this analysis identified methods and directions for future research into relationships between climate and disease at extended temporal scales. 34 refs., 5 figs., 1 tab.

  11. Simulation of El Nino-Southern Oscillation - like variability in a global AOGCM and its response to CO{sub 2} increase

    SciTech Connect

    Tett, S.

    1995-06-01

    A 75-year integration of a coupled atmosphere-ocean model is examined for tropical interannual variability. The atmospheric model has interactive cloud and a seasonal cycle. The fluxes of heat and salinity into the ocean component of the model are flux corrected. The model has tropical variability that is qualitatively similar to that of the observed El Nino/Southern Oscillation (ENSO). The maximum amplitude of the model Nino3 signal is approximately half that observed and the modeled ENSO timescale is greater than that observed. In the first 50 years of the integration the model has eight warm events. Each event is one of two types: one characterized by a standing SST anomaly in the central and eastern Pacific and the other by a westward propagating sea surface temperature anomaly. The majority of the model warm events are of the first type. The first type of event is triggered by the eastward propagation of Kelvin waves across the Pacific, and the second by westward propagation of warm temperature anomalies through the atmospheric response to a warm anomaly causing the suppression of equatorial upwelling. There is a coupling to the seasonal cycle for the first type of event. A positive feedback through changes in marine stratocumulus in the east Pacific is an important factor in some simulated warm events. Another integration was carried out in which atmospheric CO{sub 2} was increased at a rate of 1% (compounded) per annum. There is no significant change in the one to ten year interannual variance of SST in the east Pacific, and this suggests that the size of the SST anomalies during warm or cold events in the {open_quotes}greenhouse{close_quotes} world may not be significantly different from those of today. 63 refs., 23 figs.

  12. Prediction and assessment of impacts on Asian river deltas by extreme climate events and their association with El Nino and Southern Oscillation (ENSO)

    SciTech Connect

    Chang, W.Y.B. |

    1995-12-31

    Impacts of hydrological consequences of extreme climate events such as major floods and droughts on human systems have long been among the foremost concerns of the Pacific Rim countries. Proxy climate data for the last 500 years collected form the archives of counties in the Yangtze River Delta, China, were analyzed to understand the occurrence of extreme climate events, the pattern of such occurrences and their relationships to global climate changes. There have been 16 regional (delta wide) extreme climate events during the last 500 years (since 1,500 A.D.); all occurred in conjunction with reported El Nino-Southern Oscillation (ENSO) activities. Large interannual variability in precipitation is found to occur during or immediately following the ENSO events in the Delta. Management of systems increasingly dominated by humans, such as Asian delta regions, should include consideration of major climate variability, cycle periods and the extent of climate changes, as well as the trends associated with human growth and institutional changes.

  13. Meteorological factors and El Nino Southern Oscillation are associated with paediatric varicella infections in Hong Kong, 2004-2010.

    PubMed

    Chan, J Y C; Lin, H L; Tian, L W

    2014-07-01

    Varicella accounts for substantial morbidities and remains a public health issue worldwide, especially in children. Little is known about the effect of meteorological variables on varicella infection risk for children. This study described the epidemiology of paediatric varicella notifications in Hong Kong from 2004 to 2010, and explored the association between paediatric varicella notifications in children aged <18 years and various meteorological factors using a time-stratified case-crossover model, with adjustment of potential confounding factors. The analysis found that daily mean temperature, atmospheric pressure and Southern Oscillation Index (SOI) were positively associated with paediatric varicella notifications. We found that an interquartile range (IQR) increase in temperature (8·38°C) at lag 1 day, a 9·50 hPa increase in atmospheric pressure for the current day, and a 21·91 unit increase in SOI for the current day may lead to an increase in daily cases of 5·19% [95% confidence interval (CI) 1·90-8·58], 5·77% (95% CI 3·01-8·61), and 4·32% (95% CI 2·98-5·68), respectively. An IQR increase in daily relative humidity (by 11·96%) was associated with a decrease in daily paediatric varicella (-2·79%, 95% CI -3·84 to -1·73). These findings suggest that meteorological factors might be important predictors of paediatric varicella infection in Hong Kong.

  14. Oxygen isotopes in tree rings are a good proxy for Amazon precipitation and El Nino-Southern Oscillation variability.

    PubMed

    Brienen, Roel J W; Helle, Gerd; Pons, Thijs L; Guyot, Jean-Loup; Gloor, Manuel

    2012-10-16

    We present a unique proxy for the reconstruction of variation in precipitation over the Amazon: oxygen isotope ratios in annual rings in tropical cedar (Cedrela odorata). A century-long record from northern Bolivia shows that tree rings preserve the signal of oxygen isotopes in precipitation during the wet season, with weaker influences of temperature and vapor pressure. Tree ring δ(18)O correlates strongly with δ(18)O in precipitation from distant stations in the center and west of the basin, and with Andean ice core δ(18)O showing that the signal is coherent over large areas. The signal correlates most strongly with basin-wide precipitation and Amazon river discharge. We attribute the strength of this (negative) correlation mainly to the cumulative rainout processes of oxygen isotopes (Rayleigh distillation) in air parcels during westward transport across the basin. We further find a clear signature of the El Niño-Southern Oscillation (ENSO) in the record, with strong ENSO influences over recent decades, but weaker influence from 1925 to 1975 indicating decadal scale variation in the controls on the hydrological cycle. The record exhibits a significant increase in δ(18)O over the 20th century consistent with increases in Andean δ(18)O ice core and lake records, which we tentatively attribute to increased water vapor transport into the basin. Taking these data together, our record reveals a fresh path to diagnose and improve our understanding of variation and trends of the hydrological cycle of the world's largest river catchment.

  15. Tales of volcanoes and El-Nino southern oscillations with the oxygen isotope anomaly of sulfate aerosol.

    PubMed

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L; McCabe, Justin; Savarino, Joel; Thiemens, Mark H

    2013-10-29

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher (17)O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and (17)O = 3.3‰, OEI = 11 and (17)O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that (17)O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  16. Tales of volcanoes and El-Nino southern oscillations with the oxygen isotope anomaly of sulfate aerosol.

    PubMed

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L; McCabe, Justin; Savarino, Joel; Thiemens, Mark H

    2013-10-29

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher (17)O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and (17)O = 3.3‰, OEI = 11 and (17)O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that (17)O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations.

  17. Delineating the effect of El-Nino Southern Oscillations using oxygen and sulfur isotope anomalies of sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abaunza Quintero, M. M.; Jackson, T.; McCabe, J.; Savarino, J. P.; Thiemens, M. H.

    2013-12-01

    sulfate aerosol to the stratosphere. The new results demonstrate that combined O-triple isotopes and S-quadruple isotopes may help to recognize paleo ENSO events and their impact on the oxidation history of sulfate aerosols. 1. R. Shaheen, M. A., T. Jackson, J. McCabe, J. Savarino, M. H. Thiemens. (2013) A Window to the Paleoclimate- Tales of Volcanoes and El-Ninño Southern Oscillations with the Oxygen Isotope Anomaly of Sulfate Aerosols, Proceedings of the National Academy of Sciences of the United States of America. 2. Farquhar, J., Savarino, J., Airieau, S., and Thiemens, M. H. (2001) Observation of wavelength-sensitive mass-independent sulfur isotope effects during SO2 photolysis: Implications for the early atmosphere, Journal of Geophysical Research-Planets 106, 32829-32839.

  18. Southern Peru desert shattered by the great 2001 earthquake: Implications for paleoseismic and paleo-El Nino-Southern Oscillation records

    USGS Publications Warehouse

    Keefer, David K.; Moseley, Michael E.

    2004-01-01

    In the desert region around the coastal city of Ilo, the great southern Peru earthquake of June 23, 2001 (8.2-8.4 moment magnitude), produced intense and widespread ground-failure effects. These effects included abundant landslides, pervasive ground cracking, microfracturing of surficial hillslope materials, collapse of drainage banks over long stretches, widening of hillside rills, and lengthening of first-order tributary channels. We have coined the term "shattered landscape" to describe the severity of these effects. Long-term consequences of this landscape shattering are inferred to include increased runoff and sediment transport during postearthquake rainstorms. This inference was confirmed during the first minor postearthquake rainstorm there, which occurred in June and July of 2002. Greater amounts of rainfall in this desert region have historically been associated with El Nin??o events. Previous studies of an unusual paleoflood deposit in this region have concluded that it is the product of El Nin??o-generated precipitation falling on seismically disturbed landscapes. The effects of the 2001 earthquake and 2002 rainstorm support that conclusion.

  19. Effect of the El Nino/southern oscillation on Gulf of Mexico, winter, frontal-wave cyclones: 1960-1989. (Volumes I and II)

    SciTech Connect

    Manty, R.E.

    1993-01-01

    Seasonal counts of frontal-wave cyclones forming over the Gulf of Mexico and its coastal plain show more storms in the five El Nino winters and fewer storms in the eight La Nina winters, from 1960 to 1989, significant at the .01 level by a rank sum test. This is corroborated by two results. First, during the same period, the frequency of frontal-overrunning weather conditions in the region, indicative of storms, was higher in El Nino winters and lower in La Nina winters. Second, 100 years of precipitation and temperature records show wetter, cooler El Nino winters and drier, warmer La Nina winters at gulf-region land stations and climatic divisions. A threefold explanation, based on National Meteorological Center, upper-air data, is offered for the greater frequency of gulf-region cyclogenesis during El Nino winters between 1960 and 1989. (1) The winter, mean, 250-mb jet over the southern US is intensified by 5 to 10 ms[sup [minus]1] and displaced southward between 110[degrees] and 75[degrees]W by an average of 200 to 285 km during the five El Nino winters. This implies stronger and more frequent episodes of jet-associated, upper-level troughing and divergence over the region, reinforcing surface, frontal-wave cyclones. (2) In the five El Nino winters between 1963 and 1989, seasonal average heights and temperatures of the 850-, 700-, 500-, and 200-mb surfaces are lower over the region than they are in non-El Nino winters. This implies more-common presence of cold, low-pressure troughs at upper levels, reinforcing surface cyclones. (3) A 10[degrees] eastward shift, at sea level, of the western edge of the Bermuda high during the eight El Nino winters, changes normally due-easterly trades in the northwestern Caribbean Sea to slightly south of east, allowing greater advection of moisture and heat into the gulf from the tropics, preconditioning the area for development of surface cyclones. Only winter season shows all three conditions and an increase in cyclogenesis.

  20. Florida Agriculture - Utilizing TRMM to Analyze Sea Breeze Thunderstorm Patterns During El Nino Southern Oscillations and Their Effects Upon Available Fresh Water for South Florida Agricultural Planning and Management

    NASA Technical Reports Server (NTRS)

    Billiot, Amanda; Lee, Lucas; McKee, Jake; Cooley, Zachary Clayton; Mitchell, Brandie

    2010-01-01

    This project utilizes Tropical Rainfall Measuring Mission (TRMM) and Landsat satellite data to assess the impact of sea breeze precipitation upon areas of agricultural land use in southern Florida. Water is a critical resource to agriculture, and the availability of water for agricultural use in Florida continues to remain a key issue. Recent projections of statewide water use by 2020 estimate that 9.3 billion gallons of water per day will be demanded, and agriculture represents 47% of this demand (Bronson 2003). Farmers have fewer options for water supplies than public users and are often limited to using available supplies from surface and ground water sources which depend in part upon variable weather patterns. Sea breeze thunderstorms are responsible for much of the rainfall delivered to Florida during the wet season (May-October) and have been recognized as an important overall contributor of rainfall in southern Florida (Almeida 2003). TRMM satellite data was used to analyze how sea breeze-induced thunderstorms during El Nino and La Nina affected interannual patterns of precipitation in southern Florida from 1998-2009. TRMM's Precipitation Radar and Microwave Imager provide data to quantify water vapor in the atmosphere, precipitation rates and intensity, and the distribution of precipitation. Rainfall accumulation data derived from TRMM and other microwave sensors were used to analyze the temporal and spatial variations of rainfall during each phase of the El Nino Southern Oscillation (ENSO). Through the use of TRMM and Landsat, slight variations were observed, but it was determined that neither sea breeze nor total rainfall patterns in South Florida were strongly affected by ENSO during the study period. However, more research is needed to characterize the influence of ENSO on summer weather patterns in South Florida. This research will provide the basis for continued observations and study with the Global Precipitation Measurement Mission.

  1. Roles of Various El Nino Events in Southern China Rainfall and Typhoon Landfall Activity

    NASA Astrophysics Data System (ADS)

    Wang, C.; Wang, X.

    2012-12-01

    El Nino events have been separated into canonical El Nino and El Nino Modoki because of different locations of maximum sea surface temperature (SST) anomalies and climate impacts. Based on the opposite influence on rainfall in southern China during boreal fall, this paper classifies El Nino Modoki into two groups: El Nino Modoki I and II which show different origins and patterns of SST anomalies. The warm SST anomalies originate in the equatorial central Pacific and subtropical northeastern Pacific for El Nino Modoki I and II, respectively. Thus, El Nino Modoki I shows a symmetric SST anomaly distribution about the equator with the maximum warming in the equatorial central Pacific, whereas El Nino Modoki II displays an asymmetric distribution with the warm SST anomalies extending from the northeastern Pacific to equatorial central Pacific. Additionally, the warm SST anomalies in the equatorial central Pacific extend further westward for El Nino Modoki II than El Nino Modoki I. Similar to canonical El Niño, El Nino Modoki I is associated with an anomalous anticyclone in the Philippine Sea which induces southwesterly wind anomalies along the south coast of China and carries the moisture for increasing rainfall in southern China. For El Nino Modoki II, an anomalous cyclone resides east of the Philippines, associated with northerly wind anomalies and a decrease in rainfall in southern China. Canonical El Nino and El Nino Modoki I are associated with a westward extension of the western North Pacific subtropical high (WNPSH), whereas El Nino Modoki II shifts the WNPSH eastward. Differing from canonical El Nino and El Nino Modoki I, El Nino Modoki II corresponds to northwesterly anomalies of the typhoon steering flow which are unfavorable for typhoons to make landfall in China.

  2. Canadian precipitation patterns associated with the southern oscillation

    SciTech Connect

    Shabbar, A.; Bonsal, B.; Khandekar, M.

    1997-12-01

    Precipitation responses over Canada associated with the two extreme phases of the Southern Oscillation (SO), namely El Nino and La Nina are identified. Using the best available precipitation data from 1911 to 1994, both the spatial and temporal behavior of the responses are analyzed from the El Nino/La Nino onset to several seasons afterward. Composite and correlation analyses indicate that precipitation over a large region of southern Canada extending from British Columbia, through the prairies, and into the Great Lakes region is significantly influenced by the SO phenomenon. The results show a distinct pattern of negative (positive) precipitation anomalies in this region during the first winter following the onset of El Nino (La Nina) events. During this same period, significant positive precipitation anomalies occur over the northern prairies and southeastern Northwest Territories in association with El Nino events. Statistical significance of the responses is tested by the Student`s t-test and the Wilcoxon rank-sum test, while field significance is established through the Monte Carlo procedure. All of the significant precipitation anomalies can be explained by the associated upper-atmospheric flow patterns, which during the first winter following the onset of El Nino events resemble the positive (negative) phase of the Pacific-North American (PNA) pattern. Significant correlations between Southern Oscillation index (SOI) values and the observed precipitation anomalies over southern Canada suggest the possibility of developing a long-range forecasting technique for Canadian precipitation based on the occurrence and evolution of the various phases of the SO. 31 refs., 10 figs., 3 tabs.

  3. Global Weather's Problem Child--El Nino.

    ERIC Educational Resources Information Center

    Rasmusson, Eugene M.

    1984-01-01

    Discusses the nature and effects of the El Nino/Southern Oscillation phenomenon. Indicates that new understanding of the phenomenon from current data will provide a global view of climate that has never before been within reach. (JN)

  4. El Nino During the 1990's: Harbinger of Climatic Change or Normal Fluctuation?

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2000-01-01

    Today, El Nino refers to the extreme warming episodes of the globally effective, coupled ocean-atmospheric interaction commonly known as ENSO (i.e., "El Nino-Southern Oscillation"). Concerning its observed decadal frequency and severity, El Nino during the 1990's has often been regarded as being anomalous. Results of analysis reported herein; however, appear to mitigate this belief.

  5. El Nino During the 1990s: Harbinger of Climatic Change or Normal Fluctuation

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2000-01-01

    Today, El Nino refers to the extreme warming episodes of the globally effective, coupled ocean-atmospheric interaction commonly known as ENSO (i.e., "El Nino-Southern Oscillation"). Concerning its observed decadal frequency and severity, El Nino during the 1990's has often been regarded as being anomalous. Results of analysis reported herein; however, appear to mitigate this belief.

  6. A review of the Southern Oscillation - Oceanic-atmospheric circulation changes and related rainfall anomalies

    NASA Technical Reports Server (NTRS)

    Kousky, V. E.; Kagano, M. T.; Cavalcanti, I. F. A.

    1984-01-01

    The region of South America is emphasized in the present consideration of the Southern Oscillation (SO) oceanic and atmospheric circulation changes. The persistence of climate anomalies associated with El Nino-SO events is due to strong atmosphere-ocean coupling. Once initiated, the SO follows a certain sequence of events with clearly defined effects on tropical and subtropical rainfall. Excessive rainfall related to the SO in the central and eastern Pacific, Peru, Ecuador, and southern Brazil, are complemented by drought in Australia, Indonesia, India, West Africa, and northeast Brazil. El Nino-SO events are also associated with dramatic changes in the tropospheric flow pattern over a broad area of both hemispheres.

  7. Geomorphic Effects, Chronologies, and Archaeological Significance of El Nino Floods in Southern Peru

    NASA Astrophysics Data System (ADS)

    Magilligan, F. J.; Manners, R.; Goldstein, P.

    2003-12-01

    The catastrophic effects of large floods have been well documented, on both contemporary and paleo-timecales, especially for the conterminous U.S. Less is known, however, about extreme events in hyper-arid sub-tropical climates where synoptic scale meteorological causes, such as El Nino-Southern Oscillation events, are the driving atmospheric mechanism. This research documents the geomorphic effects of extreme floods in the Moquegua River valley of southern Peru, in the core of the Atacama Desert. Using a combination of geomorphic mapping, hydrolologic modeling, aerial photography, ASTER satellite imagery, and GIS, we document the geomorphic signature of large contemporary floods within the mid-valley section (1500 masl) of the Rio Moquegua. Stratigraphic evidence and paleostage indicators of paleofloods, such as slackwater deposits and preserved high level flood gravels, are used to evidence late Holocene paleoflood magnitude-frequency relationships. On contemporary timescales, channel belt expansion by lateral erosion during large floods, such as the recent '97 and '98 floods, correspond to as much as 30-40 hectares of floodplain loss along the 20 km study reach. Sixty years of repeat aerial photography indicates that channel belt expansion and floodplain erosion commonly occurs along the Rio Moquegua. The frequent resetting of floodplain alluvium conditioned by these large floods is supported by radiocarbon dating of floodplain exposures. These dates indicate that most of the contemporary floodplain alluvium is younger that 560 14C yrs BP. The highest terrace remnants date to 3250 14C yrs BP and record a series of overbank flood gravels. Evidence for the regionally extensive Miraflores ENSO flood, ca. 1300 AD, exists in tributary and along mainstem sections. This flood has been documented along the coasts of Northern Chile to northern Peru, and has been evoked to explain significant social collapse. Our field evidence indicates that it catastrophically affected

  8. Recent variability in the Southern Oscillation: Isotopic results from a Tarawa Atoll coral

    SciTech Connect

    Cole, J.E.; Fairbanks, R.G. ); Shen, G.T. )

    1993-06-18

    In the western tropical Pacific, the interannual migration of the Indonesian Low convective system causes changes in rainfall that dominate the regional signature of the El Nino-Southern Oscillation (ENSO) system. A 96-year oxygen isotope record from a Tarawa Atoll coral (1[degrees]N, 172[degrees]E) reflects regional convective activity through rainfall-induced salinity changes. This monthly resolution record spans twice the length of the local climatological record and provides a history of ENSO variability comparable in quality with those derived from instrumental climate data. Comparison of this coral record with a historical chronology of El Nino events indicates that climate anomalies in coastal South America are occasionally decoupled from Pacific-wide ENSO extremes. Spectral analysis suggests that the distribution of variance in this record has shifted among annual to interannual periods during the present century, concurrent with observed changes in the strength of the Southern Oscillation. 28 refs., 2 figs., 1 tab.

  9. Determining the early history of El Nino

    SciTech Connect

    DeVries, T.J.; Ortlieb, L.; Diaz, A.

    1997-05-09

    This technical comment presents two analyses of Daniel H. Sandweiss article which reiterates arguments advanced a decade ago that climatic and oceanic changes 5000 years before present (B.P.) resulted in the onset of El Nino/Southern Oscillation (ENSO) events along the coast of Peru. Included is a rebuttal by the original author. 32 refs.

  10. Can El Nino Amplify the Solar Forcing of Climate?

    NASA Technical Reports Server (NTRS)

    Ruzmaikin, A.

    1999-01-01

    ENSO (El Nino and the Southern Oscillation) is considered as a stochastic driver that excites the atmospheric anomaly states, such as Pacific North American pattern. This can make the 11 year solar activity forcing feasible to climate through stochastic resonance -- a phenomenon that amplifies a weak input to a nonlinear bistable system by the assistance of noise.

  11. On the predictability of the interannual behaviour of the Madden-Julian oscillation and its relationship with El Nino

    SciTech Connect

    Sperber, K.R., LLNL

    1998-03-01

    The Madden-Julian Oscillation (MJO) is the dominant mode of tropical variability at intraseasonal timescales. It displays substantial interannual variability in intensity which may have important implications for the predictability of the coupled system. The reasons for this interannual variability are not understood. The aim of this paper is to investigate whether the interannual behavior of the MJO is related to tropical sea surface temperature (SST) anomalies, particularly El Nino, and hence whether it is predictable. The interannual behavior of the MJO has been diagnosed initially in the 40-year NCEP/ NCAR Reanalysis. The results suggest that prior to the mid-1970s the activity of the MJO was consistently lower than during the latter part of the record. This may be related to either inadequacies in the data coverage, particularly over the tropical Indian Ocean prior to the introduction of satellite observations, or to the real effects of a decadal timescale warming in the tropical SSTs. The teleconnection patterns between interannual variations in MJO activity and SST show only a weak, barely significant, influence of El Nino in which the MJO is more active during the cold phase. As well as the NCEP/NCAR Reanalysis, a 4-member ensemble of 45 year integrations with the Hadley Centre climate model (HadAM2a), forced by observed SSTs for 1949-93, has been used to investigate the relationship between MJO activity and SST. HadAM2a is known to give a reasonable simulation of the MJO and the extended record provided by this ensemble of integrations allows a more robust investigation of the predictability of MJO activity than was possible with the 40-year NCEP/NCAR Reanalysis. The results have shown that, for the uncoupled system, with the atmosphere being driven by imposed SSTS, there is no reproducibility for the activity of the MJO from year to year. The interannual behavior of the MJO is not controlled by the phase of El Nino and would appear to be chaotic in

  12. Evidence of recent warming and El Nino-related variations in ice breakup of Wisconsin lakes

    USGS Publications Warehouse

    Anderson, W.L.; Robertson, D.M.; Magnuson, J.J.

    1996-01-01

    Ice breakup dates from 1968 to 1988 were examined for 20 Wisconsin lakes to determine whether consistent interannual and long-term changes exist. Each ice record had a trend toward earlier breakup dates, as demonstrated by a negative slope with time, indicating a recent warming trend. The average change in breakup dates was 0.82 d earlier per year for the lakes in southern Wisconsin, which was more extreme than that for the northern Wisconsin lakes (0.45 d yr-1). Interannual variation in breakup dates was related to the warm phase of El Nino/Southern Oscillation (ENSO) episodes. El Nino events occurred five times during this period (1965, 1972, 1976, 1982, and 1986). Average breakup dates were significantly earlier than average (5-14 d) during the mature phase of El Nino. This variability was affected by the location of the lake: El Nino-related variation was more evident for the southern lakes than the northern lakes. This difference was caused by the average date of breakup for the southern lakes being in late March directly following the period when air temperatures were strongly related to El Nino events, whereas the average dates of breakup of the northern lakes was in mid- to late April following a period when air temperatures were not significantly related to El Nino events. Overall, the interannual and long-term patterns across Wisconsin were relatively consistent, indicating that recent warming and El Nino- related variation are regional climatic responses.

  13. Two Distinct Roles of Atlantic SSTs in ENSO Variability: North Tropical Atlantic SST and Atlantic Nino

    NASA Technical Reports Server (NTRS)

    Ham, Yoo-Geun; Kug, Jong-Seong; Park, Jong-Yeon

    2013-01-01

    Two distinct roles of the Atlantic sea surface temperatures (SSTs), namely, the North Tropical Atlantic (NTA) SST and the Atlantic Nino, on the El Nino-Southern Oscillation (ENSO) variability are investigated using the observational data from 1980 to 2010 and coupled model experiments. It appears that the NTA SST and the Atlantic Nino can be used as two independent predictors for predicting the development of ENSO events in the following season. Furthermore, they are likely to be linked to different types of El Nino events. Specifically, the NTA SST cooling during February, March, and April contributes to the central Pacific warming at the subsequent winter season, while the negative Atlantic Nino event during June, July, and August contributes to enhancing the eastern Pacific warming. The coupled model experiments support these results. With the aid of a lagged inverse relationship, the statistical forecast using two Atlantic indices can successfully predict various ENSO indices.

  14. Response of the Antarctic Stratosphere to Two Types of El Nino Events

    NASA Technical Reports Server (NTRS)

    Hurwitz, M. M.; Newman, P. A.; Oman, L. D.; Molod, A. M.

    2010-01-01

    This study is the first to identify a robust El Nino/Southern Oscillation (ENSO) signal in the Antarctic stratosphere. El Nino events are classified as either conventional "cold tongue" events (positive SST anomalies in the Nino 3 region) or "warm pool" events (positive SST anomalies in the Nino 4 region). The ERA-40, NCEP and MERRA meteorological reanalyses are used to show that the Southern Hemisphere stratosphere responds differently to these two types of El Nino events. Consistent with previous studies, "cold tongue" events do not impact temperatures in the Antarctic stratosphere. During "warm pool" El Nino events, the poleward extension and increased strength of the South Pacific Convergence Zone (SPCZ) favor an enhancement of planetary wave activity during the SON season. On average, these conditions lead to higher polar stratospheric temperatures and a weakening of the Antarctic polar jet in November and December, as compared with neutral ENSO years. The phase of the quasi-biennial oscillation (QBO) modulates the stratospheric response to "warm pool" El Nino events: the strongest planetary wave driving events are coincident with the easterly phase of the QBO.

  15. Does Terrestrial Drought Explain Global CO2 Flux Anomalies Induced by El Nino?

    NASA Technical Reports Server (NTRS)

    Schwalm. C. R.; Williams, C. A.; Schaefer, K.; Baker, I.; Collatz, G. J.; Roedenbeck, C.

    2011-01-01

    The El Nino Southern Oscillation is the dominant year-to-year mode of global climate variability. El Nino effects on terrestrial carbon cycling are mediated by associated climate anomalies, primarily drought, influencing fire emissions and biotic net ecosystem exchange (NEE). Here we evaluate whether El Nino produces a consistent response from the global carbon cycle. We apply a novel bottom-up approach to estimating global NEE anomalies based on FLUXNET data using land cover maps and weather reanalysis. We analyze 13 years (1997-2009) of globally gridded observational NEE anomalies derived from eddy covariance flux data, remotely-sensed fire emissions at the monthly time step, and NEE estimated from an atmospheric transport inversion. We evaluate the overall consistency of biospheric response to El Nino and, more generally, the link between global CO2 flux anomalies and El Nino-induced drought. Our findings, which are robust relative to uncertainty in both methods and time-lags in response, indicate that each event has a different spatial signature with only limited spatial coherence in Amazonia, Australia and southern Africa. For most regions, the sign of response changed across El Nino events. Biotic NEE anomalies, across 5 El Nino events, ranged from -1.34 to +0.98 Pg Cyr(exp -1, whereas fire emissions anomalies were generally smaller in magnitude (ranging from -0.49 to +0.53 Pg C yr(exp -1). Overall drought does not appear to impose consistent terrestrial CO2 flux anomalies during El Ninos, finding large variation in globally integrated responses from 11.15 to +0.49 Pg Cyr(exp -1). Despite the significant correlation between the CO2 flux and El Nino indices, we find that El Nino events have, when globally integrated, both enhanced and weakened terrestrial sink strength, with no consistent response across events

  16. El Nino: a chaotic dynamical system

    SciTech Connect

    Vallis, G.K.

    1986-04-11

    Most of the principal qualitative features of the El Nino-Southern Oscillation phenomenon can be explained by a simple but physically motivated theory. These features are the occurrence of sea-surface warmings in the eastern equatorial Pacific and the associated trade wind reversal; the aperiodicity of these events; the preferred onset time with respect to the seasonal cycle; and the much weaker events in the Atlantic and Indian oceans. The theory, in its simplest form, is a conceptual model for the interaction of just three variables, namely near-surface temperatures in the east and west equatorial ocean and a wind-driven current advecting the temperature field. For a large range of parameters, the model is naturally chaotic and aperiodically produces El Nino-like events. For a smaller basin, representing a smaller ocean, the events are proportionally less intense.

  17. Evolution of the Southern Oscillation as observed by the Nimbus-7 ERB experiment

    NASA Technical Reports Server (NTRS)

    Ardanuy, Philip E.; Kyle, H. Lee; Chang, Hyo-Duck

    1987-01-01

    The Nimbus-7 satellite has been in a 955-km, sun-synchronous orbit since October 1978. The Earth Radiation Budget (ERB) experiment has taken approximately 8 years of high-quality data during this time, of which seven complete years have been archived at the National Space Science Data Center. A final reprocessing of the wide-field-of-view channel dataset is underway. Error analyses indicate a long-term stability of 1 percent better over the length of the data record. As part of the validation of the ERB measurements, the archived 7-year Nimbus-7 ERB dataset is examined for the presence and accuracy of interannual variations including the Southern Oscillation signal. Zonal averages of broadband outgoing longwave radiation indicate a terrestrial response of more than 2 years to the oceanic and atmospheric manifestations of the 1982-83 El Nino/Southern Oscillation (ENSO) event, especially in the tropics. This signal is present in monthly and seasonal averages and is shown here to derive primarily from atmospheric responses to adjustments in the Pacific Ocean. The calibration stability of this dataset thus provides a powerful new tool to examine the physics of the ENSO phenomena.

  18. Impact of El Niño-southern oscillation on Indian foodgrain production

    NASA Astrophysics Data System (ADS)

    Selvaraju, R.

    2003-02-01

    The impact of El Niño-southern oscillation (ENSO) on Indian foodgrain production was analysed for the period 1950-99. The inverse relationship between sea-surface temperature (SST) anomalies from June to August (JJA) over the NINO3 sector of the tropical Pacific Ocean and Indian foodgrain production anomalies (r = -0.50) was significant at the 1% level. During the warm ENSO phase, the total foodgrain production frequently decreased (12 out of 13 years) by 1 to 15%. In 10 out of 13 cold ENSO-phase years, the total foodgrain production increased from normal. The relationship between the SST-based NINO3 ENSO index and the Kharif season (June-September) foodgrain production anomalies (r = -0.52) was greater than for the Rabi season (October-February) foodgrain production (r = -0.27). The ENSO impact on rice production was greatest among the individual crops. The average drop in rice (Kharif season crop) production during a warm ENSO-phase year was 3.4 million tonnes (7%). In a cold ENSO-phase year the average production increase was 1.3 million tones (3%). Wheat (Rabi season crop) production was also influenced by ENSO, as it depends on the carryover soil water storage from the Kharif season. Sorghum and chickpea production are not significantly influenced by ENSO extremes. Inter-annual fluctuation of the gross value of Indian foodgrain production was very large, reducing up to US2183 million in a warm ENSO year and increasing up to US1251 million in a cold ENSO year. On average, a warm ENSO year costs US773 million and a cold ENSO year had a financial gain of US437 million from normal. The cumulative probability distributions of foodgrain production anomalies during cold and warm ENSO phases are shifted positively or negatively, relative to the neutral distribution. The warm ENSO forcing significantly (1% level) reduced the probability of above-average production. The cold ENSO forcing moderately increased the above-average foodgrain production over the neutral ENSO

  19. A note on the modulation of Southern Oscillation-Southern Afican rainfall associations with the Quasi-Biennial Oscillation

    SciTech Connect

    Mason, S.J.; Lindesay, J.A. )

    1993-05-20

    The authors look at correlations between the southern oscillation and rainfall in South Africa. Since the 1950's there has been a reasonably stable correlation, but there have been times when the correlation seems to have broken down. They look at the question of whether the phase of the quasi-biennial oscillation can be involved in this correlation. There is a limited correlation found, but its evidence depends upon the westerly or easterly phase of the quasi-biennial oscillation, and only correlates certain seasonal conditions of the southern oscillation, South African rainfall data.

  20. Can the GEOS CCM Simulate the Temperature Response to Warm Pool El Nino Events in the Antarctic Stratosphere?

    NASA Technical Reports Server (NTRS)

    Hurwitz, M. M.; Song, I.-S.; Oman, L. D.; Newman, P. A.; Molod, A. M.; Frith, S. M.; Nielsen, J. E.

    2011-01-01

    "Warm pool" (WP) El Nino events are characterized by positive sea surface temperature (SST) anomalies in the central equatorial Pacific. During austral spring, WP El Nino events are associated with an enhancement of convective activity in the South Pacific Convergence Zone, provoking a tropospheric planetary wave response and thus increasing planetary wave driving of the Southern Hemisphere stratosphere. These conditions lead to higher polar stratospheric temperatures and to a weaker polar jet during austral summer, as compared with neutral ENSO years. Furthermore, this response is sensitive to the phase of the quasi-biennial oscillation (QBO): a stronger warming is seen in WP El Nino events coincident with the easterly phase of the quasi-biennial oscillation (QBO) as compared with WP El Nino events coincident with a westerly or neutral QBO. The Goddard Earth Observing System (GEOS) chemistry-climate model (CCM) is used to further explore the atmospheric response to ENSO. Time-slice simulations are forced by composited SSTs from observed NP El Nino and neutral ENSO events. The modeled eddy heat flux, temperature and wind responses to WP El Nino events are compared with observations. A new gravity wave drag scheme has been implemented in the GEOS CCM, enabling the model to produce e realistic, internally generated QBO. By repeating the above time-slice simulations with this new model version, the sensitivity of the WP El Nino response to the phase of the quasi-biennial oscillation QBO is estimated.

  1. Can the GEOS CCM Simulate the Temperature Response to Warm Pool El Nino Events in the Antarctic Stratosphere?

    NASA Technical Reports Server (NTRS)

    Hurwitz, M. M.; Song, I.-S.; Oman, L. D.; Newman, P. A.; Molod, A. M.; Frith, S. M.; Nielsen, J. E.

    2010-01-01

    "Warm pool" (WP) El Nino events are characterized by positive sea surface temperature (SST) anomalies in the central equatorial Pacific. During austral spring. WP El Nino events are associated with an enhancement of convective activity in the South Pacific Convergence Zone, provoking a tropospheric planetary wave response and thus increasing planetary wave driving of the Southern Hemisphere stratosphere. These conditions lead to higher polar stratospheric temperatures and to a weaker polar jet during austral summer, as compared with neutral ENSO years. Furthermore, this response is sensitive to the phase of the quasi-biennial oscillation (QBO): a stronger warming is seen in WP El Nino events coincident with the easterly phase of the quasi-biennial oscillation (QBO) as compared with WP El Nino events coincident with a westerly or neutral QBO. The Goddard Earth Observing System (GEOS) chemistry-climate model (CCM) is used to further explore the atmospheric response to ENSO. Time-slice simulations are forced by composited SSTs from observed WP El Nino and neutral ENSO events. The modeled eddy heat flux, temperature and wind responses to WP El Nino events are compared with observations. A new gravity wave drag scheme has been implemented in the GEOS CCM, enabling the model to produce a realistic, internally generated QBO. By repeating the above time-slice simulations with this new model version, the sensitivity of the WP El Nino response to the phase of the quasi-biennial oscillation QBO is estimated.

  2. El Nino.

    ERIC Educational Resources Information Center

    Blueford, Joyce

    1988-01-01

    Information is presented regarding "El Nino," a warm ocean current which has a profound worldwide effect on ocean life and weather patterns. Suggestions are provided for teaching students about the current and other related topics. (CB)

  3. Experiments on the Southern Oscillation with CAM3 coupled to a Mixed Layer Ocean

    NASA Astrophysics Data System (ADS)

    Monier, E.; Sokolov, A. P.

    2010-12-01

    Recent modeling studies suggest that the atmospheric component plays a dominant role in the El Nino/Southern Oscillation (ENSO) phenomenon. In particular, simulations in which an Atmospheric General Circulation Model (AGCM) is coupled to a mixed-layer ocean model can produce ‘ENSO-like’ variability with associated patterns in SST, precipitation, or atmospheric circulation similar to that of ENSO, and referred to as 'Atmospheric Walker Mode' (AWM). In the absence of Bjerknes feedback (no ocean dynamics), the AWM relies on ocean-to-atmosphere latent heat flux and cloud forcing feedback. To study the AWM, we perform a number of experiments using the Community Atmosphere Model (CAM) version 3 coupled to a mixed-layer ocean, including varying the model resolution and the depth of the mixed layer. We investigate the possible climate change impacts on the AWM by carrying out a number of equilibrium climate change simulations for a doubled CO2 with different values of the model's climate sensitivity. Results show that both the magnitude and the periodicity of the simulated AWM are rather different. This study provides further insight into the ENSO response to increasing greenhouse gas—induced radiative forcing.

  4. Interannual variability of the Indian monsoon and the Southern Oscillation

    SciTech Connect

    Wu, M.; Hastenrath, S.

    1986-01-01

    Years with abundant Southwest monsoon rainfall in India are characterized by anomalously low pressure over South Asia and the adjacent waters, enhanced cross-equatorial flow in the western, and increased cloudiness over the northern portion of the Indian Ocean, continuing from the pre-monsoon through the post-monsoon season; positive temperature anomalies over land and in the Arabian Sea in the pre-monsoon season, changing to negative departures after the monsoon onset. The following causality chain is suggested: the anomalously warm surfaces of south Asia and the adjacent ocean in the pre-monsoon season induce a thermal low, thus enhancing the northward directed pressure gradient, and favoring a vigorous cross-equatorial flow over the Indian Ocean. After the monsoon onset the land surfaces are cooled by evaporation, and the Arabian Sea surface waters by various wind stress effects. However, latent heat release over South Asia can now maintain the meridional topography gradients essential to the monsoon circulation. The positive phase of the Southern Oscillation (high pressure over the Eastern South Pacific) is associated with circulation departures in the Indian Ocean sector similar to those characteristic of years with abundant India monsoon rainfall. Abundant rainfall over India during the northern summer monsoon leads the positive mode of the southern Oscillation, and this in turn leads Java rainfall, whose peak is timed about half a year after that of India. A rising Southern Oscillation tendency presages abundant India Southwest Monsoon rainfall but a late monsoon onset. 46 references, 9 figures, 4 tables.

  5. Modulation of the Global Wind Resource by the El-Nino

    NASA Astrophysics Data System (ADS)

    Gunturu, U. B.; Yip, C. M. A.; Stenchikov, G. L.

    2014-12-01

    El-Nino is the most important climate scale oscillation in the tropical atmosphere and earlier studies have shown that it impacts weather in different parts of the world. Since the long-term stability of wind resource is a primary requirement for the reliability of wind power generation, any modulation of the wind resource by the El-Nino constitutes valuable information for efficient harvesting of wind. In this study, we construct the global wind resource as described in Gunturu & Schlosser (2012) and use the method of composites to understand the impact of the El-Nino on the global wind resource. The results show that the impact of the El-Nino is to decrease the wind resource in the central United States, southern Australia and north central Africa. Further, interestingly, the wind resource increases in the Nordic sea and the continental areas around it. The Deccan plateau region of India also has reduced WPD due to the El-Nino as shown by the composites. On the other hand, the central US and southern Australia have increased WPD due to La-Nina and the resource decreases in India. The statistically significant results will be further discussed for their implications to the long term stability of the wind resource in the different regions of the world. We also substantiate the results with other suitable metrics.

  6. El Nino and outgoing longwave radiation: An atlas of Nimbus-7 Earth radiation budget observations

    NASA Technical Reports Server (NTRS)

    Kyle, H. L.; Ardanuy, P. E.; Hucek, R. R.

    1986-01-01

    Five years of broadband Earth Radiation Budget (ERB) measurements taken by the Nimbus-7 ERB experiment have been archived. This five year period included the 1982 to 1983 El Nino/Southern Oscillation event, which reached its peak in January 1983 (near the beginning of the fifth data year). An outgoing longwave radiation subset of the data, for the period June 1980 to October 1983, was processed to enhance spatial resolution. This atlas contains the analyses of the resultant fields. In addition, a set of anomaly maps, based on a definition of pre-El Nino climatology, is included. Together, these two sets of maps provide the first broadband glimpse of the terrestrial outgoing longwave radiation response to the El Nino event.

  7. Global Precipitation during the 1997-98 El Nino and Initiation of the 1998-99 La Nina

    NASA Technical Reports Server (NTRS)

    Curtis, Scott; Adler, Robert; Huffman, George; Nelkin, Eric; Bolvin, David

    1999-01-01

    The 1997-99 ENSO (El nino Southern Oscillation) cycle was very powerful, but also well observed. The best satellite rainfall estimates combined with gauge observations allow for a global analysis of precipitation anomalies accompanying the 1997-98 El Nino and initiation of the 1998-99 La Nina. For the period April 1997 to March 1998 the central to eastern Pacific, southeastern and western U.S., Argentina, eastern Africa, South China, eastern Russia, and North Atlantic were all more than two standard deviations wetter than normal. During the same year the Maritime Continent, eastern Indian Ocean, subtropical North Pacific, northeastern South America, and much of the mid- latitude southern oceans were more than two standard deviations drier than normal. An analysis of the evolution of the El Nino and accompanying precipitation anomalies revealed that a dry Maritime Continent led the formation of the El Nino SST (Sea Surface Temperature), while in the central Pacific, precipitation anomalies lagged the El Nino SST by a season. A rapid transition from El Nino to La Nina occurred in May 1998, but as early as October-November 1997 precipitation indices captured precursor changes in Pacific rainfall anomalies. Differences were found between observed and modeled [NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis] precipitation anomalies for 1997 and 98. In particular, the model had a bias towards positive precipitation anomalies and the magnitudes of the anomalies in the equatorial Pacific were small compared to the observations. Also, the evolution of the precipitation field, including the drying of the Maritime Continent and eastward progression of rainfall in the equatorial Pacific, was less pronounced for the model compared to the observations. One degree daily estimates of rainfall show clearly the MaddenJulian Oscillation and related westerly wind burst events over the Maritime Continent, which are key

  8. The influence of different El Nino types on the northern hemisphere stratosphere simulated by the MPI-ESM

    NASA Astrophysics Data System (ADS)

    Bittner, Matthias; Timmreck, Claudia; Schmidt, Hauke

    2013-04-01

    It is known that the El Nino Southern Oscillation (ENSO), although it is mainly a tropospheric phenomenon, has an impact on the polar winter stratosphere [e.g. van Loon and Labitzke, 1987: Camp and Tung, 2007]. This has also been shown in simulations with general circulation models (GCM) [Sassi,et al. 2004, Manzini et al. 2006]. For a couple of years there are discussions about two different "flavors" of the the El Nino, the central Pacific (or Modoki) El Nino and the east Pacific El Nino [e.g. Wang and Weisberg, 2000; Yu and Kao, 2007; Ashok et al. 2007]. An observational study [Graf and Zanchettin, 2012] indicate that the polar vortex is more disturbed during EP El Ninos. Here we to investigate the influence of the equatorial sea surface temperatures on the stratosphere-troposphere coupling in the northern hemisphere winter season in a fully coupled atmosphere-ocean-land GCM. We use two versions of the Max-Planck-Institute for Meteorology model MPI-ESM, namely MPI-ESM-LR with lower T63 L47 atmosphere and GR15 ocean resolution and the MPI-ESM-MR with the same horizontal resolution in the atmosphere but a higher resolution in the vertical (L95) and in the ocean (TP04). To exclude effects of natural and anthropogenic forcing, we analyze a 1000 year coupled control simulation with pre-industrial greenhouse gas concentration and constant solar forcing (piControl). For comparison with reananlyis data we also analyze uncoupled atmosphere-only simulations with observed sea surface temperatures from 1979 until 2008 (AMIP). We compare three ways of defining El Nino: the central Pacific (CP), the east Pacific (EP) and the canonical Nino3.4 El Nino. We show to what extent the MPI-ESM is able to simulate these different types of El Nino and how they affect the polar stratosphere. The MPI-ESM model is in both versions capable of producing CP and EP El Ninos. However, the CP El Nino is dominant one in terms of magnitude and the EP El Nino has a relative small impact on global

  9. Organization of extratropical transients during El Nino

    SciTech Connect

    Hoerling, M.P. ); Ting, Mingfang )

    1994-05-01

    Four observed El Nino-Southern Oscillation (ENSO) events are studied to determine the mechanisms responsible for the anomalous extratropical atmospheric circulation during northern winter. A parallel analysis of a GCM's response to El Nino is performed in order to assess if similar mechanisms are operative in the model atmosphere. The observed stationary wave anomalies over the Pacific/North American (PNA) region are found to be similar during the four winters despite appreciable differences in sea surface temperatures. The anomalous transient vorticity fluxes are remarkably robust over the North Pacific during each even, with an eastward extension of the climatological storm track leading to strong cyclonic forcing near 40[degrees]N, 150[degrees]W. This forcing is in phase with the seasonal mean Aleutian trough anomaly suggesting the important of eddy-mean flow interaction. By comparison, the intersample variability of the GCM response over the PNA region is found to exceed the observed inter-El Nino variability. This stems primarily from a large variability in the model's anomalous transients over the North Pacific. Further analysis reveals that extratropical vorticity transients are the primary mechanism maintaining the stationary wave anomalies over the PNA region during all four observed ENSO winters. In the case of the GCM, the organization of transient eddies is ill defined over the North Pacific, a behavior indicative of model error. A physical model is proposed to explain the robustness of the tropical controlling influence of the extratropical transients in nature. A simple equatorial Pacific heat source directly forces a tropical anticyclone whose phase relative to the climatological tropical anticyclone leads to an eastward extension of the subtropical jet stream. This mechanism appears to be equally effective for a heat source located either in the central or eastern Pacific basin. 36 refs., 14 figs.

  10. El Nino, volcanism, and global climate

    SciTech Connect

    Handler, P.; Andsager, K. )

    1994-03-01

    The June 1991 eruption of Mt. Pinatubo in the Philippines produced one of the greatest volcanic aerosols in the last hundred years. The estimated net decrease of radiation may have peaked at 10% in the tropics. What was the impact of the Pinatubo aerosol on regional and global climate Besides the expected net cooling of the average global surface temperature, correlation studies indicate that other types of climate anomalies may also be expected. These include the appearance of an El Nino event, decreased Indian monsoon rainfall, fewer tropical storms in the north Atlantic Ocean in 1991-1993, and normal to above normal winter rainfall in California in 1991/92, all of which were observed. A proposed physical mechanism for the almost-simultaneous occurrence of this constellation of climate anomalies is presented. The results of correlation studies between low-latitude volcanic aerosols and the El Nino/Southern Oscillation are presented in some detail as one example. The correlation between Indian monsoon rainfall and tropical storms in the north Atlantic Ocean is also shown and is updated for the most recent 5 years.

  11. El Nino during the 1990s: Harbinger of Climatic Change or Normal Fluctuation?

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1999-01-01

    Today, El Nino refers to the extreme warming episodes of the globally effective, coupled ocean-atmospheric interaction commonly known as ENSO (i.e., "El Nino-Southern Oscillation"). Concerning its observed decadal frequency and severity, El Nino during the 1990s has often been regarded as being anomalous. Results of analysis reported herein, however, appear to mitigate this belief. For example, regarding the frequency and severity of El Nino, the decade of the 1990s is found to compare quite favorably with that of preceding decades. Hence, the 1990s probably should not be regarded as being anomalous. On the other hand, the number of El Nino-related months per decade has sharply increased during the 1990s, as compared to the preceding four decades, hinting of a marginally significant upward trend. Perhaps, this is an indication that the Earth is now experiencing an ongoing global climatic change. Continued vigilance during the new millennium, therefore, is of paramount importance for determining whether or not this "hint" of a global change is real or if it merely reflects a normal fluctuation of climate.

  12. Disruptions of El Niño–Southern Oscillation teleconnections by the Madden–Julian Oscillation

    USGS Publications Warehouse

    Hoell, Andrew; Barlow, Mathew; Wheeler, Mathew; Funk, Christopher C.

    2014-01-01

    The El Niño–Southern Oscillation (ENSO) is the leading mode of interannual variability, with global impacts on weather and climate that have seasonal predictability. Research on the link between interannual ENSO variability and the leading mode of intraseasonal variability, the Madden–Julian oscillation (MJO), has focused mainly on the role of MJO initiating or terminating ENSO. We use observational analysis and modeling to show that the MJO has an important simultaneous link to ENSO: strong MJO activity significantly weakens the atmospheric branch of ENSO. For weak MJO conditions relative to strong MJO conditions, the average magnitude of ENSO-associated tropical precipitation anomalies increases by 63%, and the strength of hemispheric teleconnections increases by 58%. Since the MJO has predictability beyond three weeks, the relationships shown here suggest that there may be subseasonal predictability of the ENSO teleconnections to continental circulation and precipitation.

  13. The Evolution of El Nino-Precipitation Relationships from Satellites and Gauges

    NASA Technical Reports Server (NTRS)

    Curtis, Scott; Adler, Robert F.; Starr, David OC (Technical Monitor)

    2002-01-01

    This study uses a twenty-three year (1979-2001) satellite-gauge merged community data set to further describe the relationship between El Nino Southern Oscillation (ENSO) and precipitation. The globally complete precipitation fields reveal coherent bands of anomalies that extend from the tropics to the polar regions. Also, ENSO-precipitation relationships were analyzed during the six strongest El Ninos from 1979 to 2001. Seasons of evolution, Pre-onset, Onset, Peak, Decay, and Post-decay, were identified based on the strength of the El Nino. Then two simple and independent models, first order harmonic and linear, were fit to the monthly time series of normalized precipitation anomalies for each grid block. The sinusoidal model represents a three-phase evolution of precipitation, either dry-wet-dry or wet-dry-wet. This model is also highly correlated with the evolution of sea surface temperatures in the equatorial Pacific. The linear model represents a two-phase evolution of precipitation, either dry-wet or wet-dry. These models combine to account for over 50% of the precipitation variability for over half the globe during El Nino. Most regions, especially away from the Equator, favor the linear model. Areas that show the largest trend from dry to wet are southeastern Australia, eastern Indian Ocean, southern Japan, and off the coast of Peru. The northern tropical Pacific and Southeast Asia show the opposite trend.

  14. El Niño−Southern Oscillation frequency cascade

    PubMed Central

    Stuecker, Malte F.; Jin, Fei-Fei; Timmermann, Axel

    2015-01-01

    The El Niño−Southern Oscillation (ENSO) phenomenon, the most pronounced feature of internally generated climate variability, occurs on interannual timescales and impacts the global climate system through an interaction with the annual cycle. The tight coupling between ENSO and the annual cycle is particularly pronounced over the tropical Western Pacific. Here we show that this nonlinear interaction results in a frequency cascade in the atmospheric circulation, which is characterized by deterministic high-frequency variability on near-annual and subannual timescales. Through climate model experiments and observational analysis, it is documented that a substantial fraction of the anomalous Northwest Pacific anticyclone variability, which is the main atmospheric link between ENSO and the East Asian Monsoon system, can be explained by these interactions and is thus deterministic and potentially predictable. PMID:26483455

  15. El Niño-Southern Oscillation frequency cascade.

    PubMed

    Stuecker, Malte F; Jin, Fei-Fei; Timmermann, Axel

    2015-11-01

    The El Niño-Southern Oscillation (ENSO) phenomenon, the most pronounced feature of internally generated climate variability, occurs on interannual timescales and impacts the global climate system through an interaction with the annual cycle. The tight coupling between ENSO and the annual cycle is particularly pronounced over the tropical Western Pacific. Here we show that this nonlinear interaction results in a frequency cascade in the atmospheric circulation, which is characterized by deterministic high-frequency variability on near-annual and subannual timescales. Through climate model experiments and observational analysis, it is documented that a substantial fraction of the anomalous Northwest Pacific anticyclone variability, which is the main atmospheric link between ENSO and the East Asian Monsoon system, can be explained by these interactions and is thus deterministic and potentially predictable.

  16. El Nino Continues to Grow

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The latest image from NASA's Jason oceanography satellite, taken during a 10-day collection cycle ending December 2, 2002, shows the Pacific dominated by two significant areas of higher-than-normal sealevel (warmer ocean temperatures). In the central equatorial Pacific, the large area of higher than normal sea surface heights(warmer than normal sea surface temperatures) associated with growing El Nino conditions has recently migrated eastward toward the coast of South America. Meanwhile, the influence of the 20- to 30-year larger than El Nino/La Nina pattern called the Pacific Decadal Oscillation continues to create warm, higher-than-normal sea-surface heights in the north Pacific that are connected in a warm horseshoe pattern with the western and southern Pacific. Sea-surface heights are a measure of how much heat is stored in the ocean below. This heat influences both present weather and future planetary climate events.

    The image shows red areas in the north Pacific and at the equator that are about 10 centimeters (4 inches) above normal; white areas indicate sea surface heights between 14 and 32 centimeters (6 to 13 inches) above normal. These regions contrast with the western tropical Pacific, where lower-than-normal sea levels (blue areas) have developed that are between 5 and 13 centimeters (2 and 5 inches) below normal, while purple areas range from 14 to 18 centimeters (6 to 7 inches) below normal. Along the equator, the red sea surface heights equate to sea surface temperature departures greater than one degree Celsius (two degrees Fahrenheit) and the white sea surface heights are sea surface temperatures 1.5 to 2.5 degrees Celsius(three to five degrees Fahrenheit) above normal.

    The U.S. portion of the Jason mission is managed by JPL for NASA's Earth Science Enterprise, Washington, D.C. Research on Earth's oceans using Jason and other space-based capabilities is conducted by NASA's Earth Science Enterprise to better understand and protect our

  17. Proxy Records of the Indonesian Low and the El Ni{tilde n}o-Southern Oscillation (ENSO) from Stable Isotope Measurements of Indonesian Reef Corals

    SciTech Connect

    Moore, M.D.

    1995-12-31

    The Earth`s largest atmospheric convective center is the Indonesian Low. It generates the Australasian monsoon, drives the zonal tropospheric Walker Circulation, and is implicated in the genesis of the El Nino-Southern Oscillation (ENSO). The long-term variability of the Indonesian Low is poorly characterized, yet such information is crucial for evaluating whether changes in the strength and frequency of ENSO events are a possible manifestation of global warming. Stable oxygen isotope ratios ({delta}{sup 18}O) in shallow-water reef coral skeletons track topical convective activity over hundreds of years because the input of isotopically-depleted rainwater dilutes seawater {delta}{sup 18}O. Corals also impose a temperature-dependent fractionation on {delta}{sup 18}O, but where annual rainfall is high and sea surface temperature (SST) variability is low the freshwater flux effect dominates.

  18. Historical effects of El Nino and La Nina events on the seasonal evolution of the montane snowpack in the Columbia and Colorado River Basins

    USGS Publications Warehouse

    Clark, M.P.; Serreze, M.C.; McCabe, G.J.

    2001-01-01

    Snow-water equivalent (SWE) data measured at several hundred montane sites in the western United States are used to examine the historic effects of El Nino and La Nina events on seasonal snowpack evolution in the major subbasins in the Columbia and Colorado River systems. Results are used to predict annual runoff. In the Columbia River Basin, there is a general tendency for decreased SWE during El Nino years and increased SWE in La Nina years. However, the SWE anomalies for El Nino years are much less pronounced. This occurs in part because midlatitude circulation anomalies in El Nino years are located 35?? east of those in La Nina years. This eastward shift is most evident in midwinter, at which time, SWE anomalies associated with El Nino are actually positive in coastal regions of the Columbia River Basin. In the Colorado River Basin, mean anomalies in SWE and annual runoff during El Nino years depict a transition between drier-than-average conditions in the north, and wetter-than-average conditions in the southwest. Associations during La Nina years are generally opposite those in El Nino years. SWE anomalies tend to be more pronounced in spring in the Lower Colorado River Basin. Our predictions of runoff reveal modest skill for scenarios using only historic El Nino and La Nina information. Predictions based on the water stored in the seasonal snowpack are, in almost all cases, much higher than those based on El Nino-Southern Oscillation (ENSO) information alone. However, combining observed midwinter snow conditions with information on seasonal snowpack evolution associated with ENSO improves predictions for basins in which ENSO signals exhibit strong seasonality.

  19. Evolution of the 1997-98 El Nino and La Nina: the Role of Altimetry in ENSO Studies and Prediction

    NASA Technical Reports Server (NTRS)

    Busalacchi, Antonio J.

    1998-01-01

    El Nino and the Southern Oscillation (ENSO) are known to be a quasi-periodic coupled ocean-atmosphere phenomenon occurring roughly every 3-7 years. Its largest oceanic manifestations are found in the equatorial Pacific, but it is of global climatic significance. During the flight of the TOPEX]Poseidon altimeter, the equatorial Pacific was in the midst of an unusual period of prolonged ENSO warming in the mid-1990's. In 1997, the tropical Pacific witnessed the development of a major El Nino event, rivaling in strength the 1982-83 El Nino. The intensity of this El Nino, and its rapid intensification early in the calendar year, caught the scientific community by surprise. None of the forecast models, statistical or dynamical, captured these features of the 1997 El Nino, although those models that assimilated in situ ocean observations did better than most in predicting that the event would occur in 1997. The onset of the El Nino coincided with the occurrence of several westerly wind events in the western Pacific rather than to delayed oscillator physics. However, western Pacific sea levels were anomalously elevated a year and a half prior to the onset, which may have helped precondition the system to a particularly strong ENSO episode. The coming of La Nina was foreshadowed by large-scale drops in sea level in the western tropical Pacific and cyclonic wind stress curl anomalies far beyond the +\\- 8 degrees latitude bounds of the TAO mooring array. In past El Nino events, the evolution of the coupled system could only be studied from the perspective of in situ observations. The 1997-1998 El Nino event will be the first time a major El Nino event will have been observed from start to finish via remotely-sensed measurements of sea surface topography, sea surface temperature, sea surface winds, ocean color, and precipitation. These observations have considerable potential for advancing coupled climate forecasts on time scales from seasons to decades. This presentation

  20. A weak El Niño/Southern Oscillation with delayed seasonal growth around 4,300 years ago

    NASA Astrophysics Data System (ADS)

    McGregor, H. V.; Fischer, M. J.; Gagan, M. K.; Fink, D.; Phipps, S. J.; Wong, H.; Woodroffe, C. D.

    2013-11-01

    Earth's interannual climate variability is dominated by El Niño/Southern Oscillation (ENSO). Palaeoclimate records indicate a lower ENSO variance during the middle Holocene compared with today; however, model simulations have not reproduced the full magnitude of the changes, and whether external forcing drives large intrinsic ENSO variability is therefore a matter of considerable debate. Here we present a 175-year-long, monthly resolved oxygen isotope record, obtained from a Porites coral microatoll located on Kiritimati (Christmas) Island, in the NINO3.4 region of the central equatorial Pacific. Our quantitative record of ENSO variability about 4,300 years ago shows that ENSO variance was persistently reduced by 79%, compared with today, and it exhibits a dominant annual cycle. Season-specific analysis shows that El Niño events were damped during their September-November growth phase, and delayed relative to the climatological year. We suggest that the higher boreal summer insolation at the time strengthened the tropical Pacific zonal winds as well as the gradients in sea surface temperature, and thereby led to an enhanced annual cycle and suppressed ENSO. As the weak ENSO is subject to interdecadal amplitude modulation, we conclude that amplitude modulation is likely to remain robust under altered climates. Our findings show that ENSO is capable of responding to external forcing.

  1. El Niño–Southern Oscillation diversity and Southern Africa teleconnections during Austral Summer

    USGS Publications Warehouse

    Hoell, Andrew; Funk, Christopher C.; Magadzire, Tamuka; Zinke, Jens; Husak, Gregory J.

    2014-01-01

    A wide range of sea surface temperature (SST) expressions have been observed during the El Niño–Southern Oscillation events of 1950–2010, which have occurred simultaneously with different global atmospheric circulations. This study examines the atmospheric circulation and precipitation during December–March 1950–2010 over the African Continent south of 15∘S, a region hereafter known as Southern Africa, associated with eight tropical Pacific SST expressions characteristic of El Niño and La Niña events. The self-organizing map method along with a statistical distinguishability test was used to isolate the SST expressions of El Niño and La Niña. The seasonal precipitation forcing over Southern Africa associated with the eight SST expressions was investigated in terms of the horizontal winds, moisture budget and vertical motion. El Niño events, with warm SST across the east and central Pacific Ocean and warmer than average SST over the Indian Ocean, are associated with precipitation reductions over Southern Africa. The regional precipitation reductions are forced primarily by large-scale mid-tropospheric subsidence associated with anticyclonic circulation in the upper troposphere. El Niño events with cooler than average SST over the Indian Ocean are associated with precipitation increases over Southern Africa associated with lower tropospheric cyclonic circulation and mid-tropospheric ascent. La Niña events, with cool SST anomalies over the central Pacific and warm SST over the west Pacific and Indian Ocean, are associated with precipitation increases over Southern Africa. The regional precipitation increases are forced primarily by lower tropospheric cyclonic circulation, resulting in mid-tropospheric ascent and an increased flux of moisture into the region.

  2. El Niño-Southern Oscillation diversity and Southern Africa teleconnections during Austral Summer

    NASA Astrophysics Data System (ADS)

    Hoell, Andrew; Funk, Chris; Magadzire, Tamuka; Zinke, Jens; Husak, Greg

    2015-09-01

    A wide range of sea surface temperature (SST) expressions have been observed during the El Niño-Southern Oscillation events of 1950-2010, which have occurred simultaneously with different global atmospheric circulations. This study examines the atmospheric circulation and precipitation during December-March 1950-2010 over the African Continent south of 15S, a region hereafter known as Southern Africa, associated with eight tropical Pacific SST expressions characteristic of El Niño and La Niña events. The self-organizing map method along with a statistical distinguishability test was used to isolate the SST expressions of El Niño and La Niña. The seasonal precipitation forcing over Southern Africa associated with the eight SST expressions was investigated in terms of the horizontal winds, moisture budget and vertical motion. El Niño events, with warm SST across the east and central Pacific Ocean and warmer than average SST over the Indian Ocean, are associated with precipitation reductions over Southern Africa. The regional precipitation reductions are forced primarily by large-scale mid-tropospheric subsidence associated with anticyclonic circulation in the upper troposphere. El Niño events with cooler than average SST over the Indian Ocean are associated with precipitation increases over Southern Africa associated with lower tropospheric cyclonic circulation and mid-tropospheric ascent. La Niña events, with cool SST anomalies over the central Pacific and warm SST over the west Pacific and Indian Ocean, are associated with precipitation increases over Southern Africa. The regional precipitation increases are forced primarily by lower tropospheric cyclonic circulation, resulting in mid-tropospheric ascent and an increased flux of moisture into the region.

  3. Effect of salinity barrier layer in the preconditioning and onset of El Nino

    NASA Astrophysics Data System (ADS)

    Maes, C.; Picaut, J.; Belamari, S.

    2002-12-01

    Specific salinity stratification of the western Pacific warm pool known as the barrier layer has been proposed to be important in the coupling between sea surface temperature (SST) and winds leading to El Nino-Southern Oscillation. Thick barrier layer maintains surface waters warmer than 28C (the threshold for organized atmospheric convection) by reducing the entrainment cooling from below the ocean mixed layer. This mechanism allows an accumulation of heat in the upper ocean layers prior to El Nino. It also confines the forcing of westerly wind burst (WWB), the most accepted process as a trigger of El Nino, in a shallow mixed layer thus increasing the eastward displacement of the eastern edge of the warm pool. The importance of salinity barrier layer in the preconditioning phase characterized by high ocean heat content and in the onset phase characterized by high WWB activity is investigated using a general circulation coupled model of the tropical Pacific. coupled to a general circulation model. The Meteo-France/ARPEGE global atmospheric model coupled to the LODYC/OPA ocean model is able to reproduce self-sustained El Nino events together with WWBs. The methodology consists of removing the stratification effect of salinity in the vertical mixing parameterization. This cutoff is restricted to the western side of the equatorial band (4N-4S) where SST is larger than 28C. By removing the barrier layer, the main effect is to reduce the ocean heat content in the preconditioning period and to modify the ocean dynamics in response to WWBs in the onset period. Considering three El Nino events of different intensities, hindcasts show that interactions between the ocean and the atmosphere over the warm pool do not amplify and each El Nino is weakened or even aborted. A detailed analysis confirms that the physics of the warm pool such as vertical diffusion and horizontal advection is essential to set up the favorable conditions for the development of El Nino. For each event

  4. El-Niño southern oscillation and rainfall erosivity in the headwater region of the Grande River Basin, Southeast Brazil

    NASA Astrophysics Data System (ADS)

    Mello, C. R.; Norton, L. D.; Curi, N.; Yanagi, S. N. M.; Silva, A. M.

    2011-12-01

    Relationships between regional climate and oceanic and atmospheric anomalies are important tools in order to promote the development of models for predicting rainfall erosivity, especially in regions with substantial intra-annual variability in the rainfall regime. In this context, this work aimed to analyze the rainfall erosivity in headwaters of Grande River Basin, Southern Minas Gerais State, Brazil. This study considered the two most representative environments, the Mantiqueira Range (MR) and Plateau of Southern Minas Gerais (PSM). These areas are affected by the El Nino Southern Oscillation (ENSO) indicators Sea Surface Temperature (SST) for Niño 3.4 Region and Multivariate ENSO Index (MEI). Rainfall erosivity was calculated for individual rainfall events from January 2006 to December 2010. The analyses were conducted using the monthly data of ENSO indicators and the following rainfall variables: rainfall erosivity (EI30), rainfall depth (P), erosive rainfall depth (E), number of rainfall events (NRE), number of erosive rainfall events (NEE), frequency of occurrence of an early rainfall pattern (EP), occurrence of late rainfall pattern (LP) and occurrence of intermediate rainfall patter (IP). Pearson's coefficient of correlation was used to evaluate the relationships between the rainfall variables and SST and MEI. The coefficients of correlation were significant for SST in the PSM sub-region. Correlations between the rainfall variables and negative oscillations of SST were also significant, especially in the MR sub-region, however, the Person's coefficients were lesser than those obtained for the SST positive oscillations. The correlations between the rainfall variables and MEI were also significant but lesser than the SST correlations. These results demonstrate that SST positive oscillations play a more important role in rainfall erosivity, meaning they were more influenced by El-Niño episodes. Also, these results have shown that the ENSO variables have

  5. The Relationship Between El Nino/La Nina Oscillations and Recent Anomaly Time Series of OLR Determined by CERES and AIRS

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Molnar, Gyula; Iredell, Lena; Loeb, Norman G.

    2011-01-01

    This paper compares recent spatial anomaly time series of OLR (Outgoing Longwave Radiation) and OLRCLR (Clear Sky OLR) as determined using CERES and AIRS observations over the time period September 2002 through June 2010. We find excellent agreement in OLR anomaly time series of both data sets in almost every detail, down to the 1 x 1 spatial grid point level. This extremely close agreement of OLR anomaly time series derived from observations by two different instruments implies that both sets of results must be highly stable. This agreement also validates to some extent the anomaly time series of the AIRS derived products used in the computation of the AIRS OLR product. The paper then examines anomaly time series of AIRS derived products over the extended time period September 2002 through April 2011. We show that OLR anomalies during this period are closely in phase with those of an El Nino index, and that the recent global and tropical mean decreases in OLR and OLRCLR are a result of a transition from an El Nino condition at the beginning of the data record to La Nina conditions toward the end of the data period. We show that the relationship between global mean, and especially tropical mean, OLR anomalies to the El Nino index can be explained by temporal changes of the distribution of mid-tropospheric water vapor and cloud cover in two spatial regions that are in direct response to El Nino/La Nina activity which occurs outside these spatial regions.

  6. Southern Ocean Climate and Sea Ice Anomalies Associated with the Southern Oscillation

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Comiso, J. C.

    2001-01-01

    The anomalies in the climate and sea ice cover of the Southern Ocean and their relationships with the Southern Oscillation (SO) are investigated using a 17-year of data set from 1982 through 1998. We correlate the polar climate anomalies with the Southern Oscillation index (SOI) and examine the composites of these anomalies under the positive (SOI > 0), neutral (0 > SOI > -1), and negative (SOI < -1) phases of SOL The climate data set consists of sea-level pressure, wind, surface air temperature, and sea surface temperature fields, while the sea ice data set describes its extent, concentration, motion, and surface temperature. The analysis depicts, for the first time, the spatial variability in the relationship of the above variables and the SOL The strongest correlation between the SOI and the polar climate anomalies are found in the Bellingshausen, Amundsen and Ross sea sectors. The composite fields reveal anomalies that are organized in distinct large-scale spatial patterns with opposing polarities at the two extremes of SOI, and suggest oscillating climate anomalies that are closely linked to the SO. Within these sectors, positive (negative) phases of the SOI are generally associated with lower (higher) sea-level pressure, cooler (warmer) surface air temperature, and cooler (warmer) sea surface temperature in these sectors. Associations between these climate anomalies and the behavior of the Antarctic sea ice cover are clearly evident. Recent anomalies in the sea ice cover that are apparently associated with the SOI include: the record decrease in the sea ice extent in the Bellingshausen Sea from mid- 1988 through early 199 1; the relationship between Ross Sea SST and ENSO signal, and reduced sea ice concentration in the Ross Sea; and, the shortening of the ice season in the eastern Ross Sea, Amundsen Sea, far western Weddell Sea, and the lengthening of the ice season in the western Ross Sea, Bellingshausen Sea and central Weddell Sea gyre over the period 1988

  7. Rethinking the Ocean's Role in the Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Clement, A. C.; di Nezio, P. N.; Deser, C.

    2010-12-01

    The usual explanation for variability in the Southern Oscillation (SO), a shift of atmospheric mass between the Indo-Pacific warm pool region and the eastern Pacific reflected in opposite sign changes in sea level pressure, involves dynamical coupling between the atmosphere and ocean via the ‘Bjerknes feedback’ mechanism. Here we revisit this explanation using a collection of simulations with atmospheric general circulation models that have varying degrees of coupling to the ocean. The main finding is that the SO emerges as a dominant mode of tropical Pacific variability without dynamical coupling to the ocean. Atmospheric models coupled to a mixed layer ocean (i.e. with no coupled ocean dynamics) simulate what is refered to here as an ‘Atmospheric Walker Mode’ (AWM). This mode of variability has patterns in sea level pressure, sea surface temperature, and precipitation which strongly resemble observed patterns associated with the SO. The spectrum of the AWM is red out to about a decadal timescale, consistent with a stochastically forced, weakly damped process, and our analysis suggests that variability in the AWM is related to variability in the NE and SE trade winds and associated surface wind divergence in the warm pool. The main influence of ocean dynamics on the SO in fully coupled climate models is the addition power primarily at interannual timescales, as expected from the positive Bjerknes feedback. On decadal and longer timescales, ocean dynamics enhance the damping of (or act as a negative feedback on) SO variability. However, interactive ocean dynamics do not appear to be required to set the first-order spatial structure of the SO or associated patterns in SST, precipitation, or atmospheric circulation. Implications for Pacific climate variability on interannual, decadal, and century timescales are discussed.

  8. Use of Microgravity to Assess the Effects of El Nino on Ground-Water Storage in Southern Arizona

    USGS Publications Warehouse

    Parker, John T.C.; Pool, Donald R.

    1998-01-01

    The availability of ground water is of extreme importance in areas, such as southern Arizona, where it is the main supply for agricultural, industrial, or domestic purposes. Where ground-water use exceeds recharge, monitoring is critical for managing water supplies. Typically, monitoring has been done by measuring water levels in wells; however, this technique only partially describes ground-water conditions in a basin. A new application of geophysical technology is enabling U.S. Geological Survey (USGS) scientists to measure changes in the amount of water in an aquifer using a network of microgravity stations. This technique enables a direct measurement of ground-water depletion and recharge. In Tucson, Arizona, residents have relied solely upon ground water for most of their needs since the 19th century. Water levels in some wells in the Tucson area have declined more than 200 ft in the past 50 years. Similar drops in water levels have occurred elsewhere in Arizona. In response to the overdrafting of ground water, the State of Arizona passed legislation designed to attain 'safe yield,' which is defined as a balance between ground-water withdrawals and annual recharge of aquifers. To monitor progress in complying with the legislation, ground-water withdrawals are measured and estimated, and annual recharge is estimated. The Tucson Basin and Avra Valley are two ground-water basins that form the Tucson Active Management Area (TAMA), which by State statute must attain 'safe yield' by the year 2025.

  9. Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM

    NASA Technical Reports Server (NTRS)

    Hurwitz, Margaret M.; Song, In-Sun; Oman, Luke D.; Newman, Paul A.; Molod, Andrea M.; Frith, Stacey M.; Nielsen, J. Eric

    2011-01-01

    A new type of EI Nino event has been identified in the last decade. During "warm pool" EI Nino (WPEN) events, sea surface temperatures (SSTs) in the central equatorial Pacific are warmer than average. The EI Nino signal propagates poleward and upward as large-scale atmospheric waves, causing unusual weather patterns and warming the polar stratosphere. In austral summer, observations show that the Antarctic lower stratosphere is several degrees (K) warmer during WPEN events than during the neutral phase of EI Nino/Southern Oscillation (ENSO). Furthermore, the stratospheric response to WPEN events depends of the direction of tropical stratospheric winds: the Antarctic warming is largest when WPEN events are coincident with westward winds in the tropical lower and middle stratosphere i.e., the westward phase of the quasi-biennial oscillation (QBO). Westward winds are associated with enhanced convection in the subtropics, and with increased poleward wave activity. In this paper, a new formulation of the Goddard Earth Observing System Chemistry-Climate Model, Version 2 (GEOS V2 CCM) is used to substantiate the observed stratospheric response to WPEN events. One simulation is driven by SSTs typical of a WPEN event, while another simulation is driven by ENSO neutral SSTs; both represent a present-day climate. Differences between the two simulations can be directly attributed to the anomalous WPEN SSTs. During WPEN events, relative to ENSO neutral, the model simulates the observed increase in poleward planetary wave activity in the South Pacific during austral spring, as well as the relative warming of the Antarctic lower stratosphere in austral summer. However, the modeled response to WPEN does not depend on the phase of the QBO. The modeled tropical wind oscillation does not extend far enough into the lower stratosphere and upper troposphere, likely explaining the model's insensitivity to the phase of the QBO during WPEN events.

  10. The Roles of El Nino and Solar Forcing on Cloud Cover

    NASA Astrophysics Data System (ADS)

    Rohde, R. A.; Levine, J.; Muller, R. A.

    2003-12-01

    Although cloud cover has a very strong effect on climate, its behavior is so poorly understood that its role is frequently neglected. A potential breakthrough occurred with initial reports that cloud cover could be driven by variations in cosmic rays (H. Svensmark & E. Friis-Christensen, J. Atmos. Solar-Terr. Phys. v. 59, n. 11, pp 1225-32, 1997, and N.D. Marsh & H. Svensmark, Space Sci. Rev., pp 1-16, 2000). In this paper we report a detailed analysis of recently extended data now available from the International Satellite Cloud Climatology Project. In a surprise, we find that the major driving force for cloud cover is ENSO (El Nino / Southern Oscillation). In addition, we do find a weak but significant response to solar forcing; however, in contradiction to the previous reports, we find no stronger relationship to cosmic rays than to other solar parameters. For the majority of the 23 cloud types available to us, interannual variability is dominated by changes that follow the NINO3 index of Pacific sea surface temperatures. In particular, increases in high-altitude and vertically extensive cloud cover are observed to follow the motions of warm water throughout the El Nino cycle. Even far from the Pacific, many cloud cover changes are observed to correlate with El Nino, and these data provide a new and previously unexplored tool for understanding the global nature and influence of the El Nino / Southern Oscillation. In contrast, solar forcing of cloud cover is observed in, at most, a few cloud types. Only in the cloud type emphasized by Svensmark, low-altitude clouds detected in the infrared, does the dominant mode of interannual variability make a good match with solar forcing. The extended cloud record provides continued support for solar forcing of this cloud type; however, unlike Svensmark, we find no empirical reason to prefer cosmic ray flux as the forcing mechanism over any other type of solar cycle variation (e.g. irradiance or UV flux changes). Our

  11. Greenhouse warming, decadal variability, or El Nino? An attempt to understand the anomalous 1990s

    SciTech Connect

    Latif, M.; Eckert, C.; Kleeman, R.

    1997-09-01

    The dominant variability modes in the Tropics are investigated and contrasted with the anomalous situation observed during the last few years. The prime quantity analyzed is anomalous sea surface temperature (SST) in the region 30{degrees}S-60{degrees}N. Additionally, observed tropical surface wind stress fields were investigated. Further tropical atmospheric information was derived from a multidecadal run with an atmospheric general circulation model that was forced by the same SSTs. The tropical SST variability can be characterized by three modes: an interannual mode [the El Nino-Southern Oscillation (ENSO)], a decadal mode, and a trend or unresolved ultra-low-frequency variability. 48 refs., 20 figs.

  12. Geoarchaeological evidence from Peru for a 5000 years B.P. onset of El Nino

    SciTech Connect

    Sandweiss, D.H.; Richardson, J.B. III; Rollins, H.B.

    1996-09-13

    For the tropical west coast of South America, where El Nino/Southern Oscillation (ENSO) is most pronounced, archaeological and associated paleontological deposits in northern Peru revealed a major climate change at about 5000 years before the present (yr B.P.). The data implied the presence of stable, warm tropical water as far south as 10{degrees}S during the early mid-Holocene (about 8000 to 5000 yr B.P.). These data suggest that ENSO did not occur for some millennia preceding 5000 yr B.P., when global and regional climate was warmer than today. 36 refs., 1 fig., 3 tabs.

  13. Sulfate aerosol distributions and cloud variations during El Nino anomalies

    SciTech Connect

    Parungo, F. ); Hicks, B. )

    1993-02-20

    The effects of aerosols on cloud characteristics, albedo, rainfall amount, and overall climate changes were investigated by assessing the qualitative associations and quantitative correlations between the relevant variables during El Nino-Southern Oscillation (ENSO) perturbations. Both historical records and data from recent field measurements for the Pacific Ocean region were used for the investigation. The results show that ENSO perturbations could change sulfate aerosol production and distribution over the surveyed regions. Strong correlations were observed between condensation nucleus concentrations and sulfate aerosol concentrations, and between cloud amount and albedo. Weak but significant correlations were also observed between condensation nucleus concentrations and cloud amounts, and between sulfate aerosol concentrations and rainfall amounts. Although sulfate aerosols appeared to have a strong impact on cloud microphysics, the present data confirm that cloud dynamics play the pivotal role in control of cloud types and cloud amount in the studied regions. 31 refs., 5 figs., 3 tabs.

  14. Interannual variability of the coupled tropical Pacific ocean - atmosphere system associated with the El Nino-southern oscillation

    SciTech Connect

    Zhang, Rong-Hua; Levitus, S.

    1997-06-01

    Upper-ocean temperature and surface marine meteorological observations are used to examine interannual variability of the coupled tropical Pacific climate system. The basinwide structure and evolution of meteorological and oceanographic fields associated with ENSO events are described using composites, empirical orthogonal functions, and a lagged correlation analysis. The analyses reveal well-defined spatial structures and coherent phase relations among various anomaly fields.

  15. Predicting total organic carbon load with El Nino southern oscillation phase using hybrid and fuzzy logic approaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During drinking water treatment chlorine reacts with total organic carbon (TOC) to form disinfection byproducts (DBP), some of which can be carcinogenic. Additional treatment required to remove TOC before chlorination significantly increases treatment cost. There are two main sources of TOC in a wat...

  16. El Niño-Southern Oscillation and Pacific Decadal Oscillation impacts on precipitation in the southern and central United States: Evaluation of spatial distribution and predictions

    NASA Astrophysics Data System (ADS)

    Kurtzman, Daniel; Scanlon, Bridget R.

    2007-10-01

    Understanding and predicting regional impacts of El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) on winter (October-March) precipitation can provide valuable inputs to agricultural and water resources managers. Effects of ENSO and PDO on winter precipitation were assessed in 165 climate divisions throughout the southern United States. A continuous region of significantly (P < 0.05) increased (decreased) winter precipitation in response to El Niño (La Niña) conditions in the preceding summer (June-September Southern Oscillation Index (SOI)) extends across the entire southern United States and as far north as South Dakota. Within this region stronger correlations (r ≤ -0.45) are found along the Gulf of Mexico, southern Arizona, and central Nebraska. Winter precipitation differs significantly (P < 0.1) between warm and cold phase PDO periods only in the south central region, with greatest significance centered in Oklahoma. Enhanced negative La Niña anomalies during PDO cold phases are dominant in the central region (Texas to South Dakota) whereas enhanced positive El Niño anomalies during PDO warm phases are dominant in the southwest (Arizona, Nevada, and California) and southeast (Louisiana to Florida). Validation tests of winter precipitation predictions based on summer SOI and/or PDO-phase show a decrease of 9% to 16% in the relative Mean Absolute Error (MAE) from the MAE obtained by using the mean as a predictor in areas with strong correlation (r < -0.45) between SOI and precipitation. Logistic regression probability models of having above or below average winter precipitation had up to 77% successful predictions. The advantage of having probabilities of exceeding certain precipitation thresholds at the beginning of a hydrologic year makes logistic regression models attractive for decision makers.

  17. On the statistics of El Nino occurrences and the relationship of El Nino to volcanic and solar/geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1989-01-01

    El Nino is conventionally defined as an anomalous and persistent warming of the waters off the coasts of Ecuador and Peru in the eastern equatorial Pacific, having onset usually in Southern Hemispheric summer/fall. Some of the statistical aspects of El Nino occurrences are examined, especially as they relate to the normal distribution and to possible associations with volcanic, solar, and geomagnetic activity. With regard to the very strong El Nino of 1982 to 1983, it is noted that, although it may very well be related to the 1982 eruptions of El Chichon, the event occurred essentially on time (with respect to the past behavior of elapsed times between successive El Nino events; a moderate-to-stronger El Nino was expected during the interval 1978 to 1982, assuming that El Nino occurrences are normally distributed, having a mean elapsed time between successive onsets of 4 years and a standard deviation of 2 years and a last known occurrence in 1976). Also, although not widely recognized, the whole of 1982 was a record year for geomagnetic activity (based on the aa geomagnetic index, with the aa index registering an all time high in February 1982), perhaps, important for determining a possible trigger for this and other El Nino events. A major feature is an extensive bibliography (325 entries) on El Nino and volcanic-solar-geomagnetic effects on climate. Also, included is a tabular listing of the 94 major volcanic eruptions of 1835 to 1986.

  18. The Southern Oscillation, Hypoxia, and the Eastern Pacific Tuna Fishery

    NASA Astrophysics Data System (ADS)

    Webster, D.; Kiefer, D.; Lam, C. H.; Harrison, D. P.; Armstrong, E. M.; Hinton, M.; Luo, L.

    2012-12-01

    The Eastern Pacific tuna fishery, which is one of the world's major fisheries, covers thousands of square kilometers. The vessels of this fishery are registered in more than 30 nations and largely target bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis), and yellowfin (T. albacores) tuna. In both the Pelagic Habitat Analysis Module project, which is sponsored by NASA, and the Fishscape project, which is sponsored by NSF, we have attempted to define the habitat of the three species by matching a 50 year time series on fish catch and effort with oceanographic information obtained from satellite imagery and from a global circulation model. The fishery time series, which was provided by the Inter-American Tropical Tuna Commission, provided spatial maps of catch and effort at monthly time steps; the satellite imagery of the region consisted of sea surface temperature, chlorophyll, and height from GHRSST, SEAWiFS, and AVISO products, and the modeled flow field at selected depths was output from ECCO-92 simulations from 1992 to present. All information was integrated and analyzed within the EASy marine geographic information system. This GIS will also provides a home for the Fishscape spatial simulation model of the coupled dynamics of the ocean, fish, fleets, and markets. This model will then be applied to an assessment of the potential ecological and economic impacts of climate change, technological advances in fleet operations, and increases in fuel costs. We have determined by application of EOF analysis that the ECCO-2 simulation of sea surface height fits well with that of AVISO imagery; thus, if driven properly by predictions of future air-sea exchange, the model should provide good estimates of circulation patterns. We have also found that strong El Nino events lead to strong recruitment of all three species and strong La Nina events lead to weak recruitment. Finally, we have found that the general spatial distribution of the Eastern Pacific fishing grounds

  19. Forecast EL NIÑO–Southern oscillation phases and best irrigation strategies to increase cotton yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Equatorial Pacific sea surface temperatures cause a systematic El Niño-Southern Oscillation (ENSO) coupling with the atmosphere to produce predictable weather patterns in much of North America. Forecast ENSO phases and associated rainfall frequency and amount were related to modeled dual purpose whe...

  20. Prediction, Assessment of the Rift Valley fever Activity in East and Southern Africa 2006 - 2008 and Possible Vector Control Strategies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Historical outbreaks of Rift Valley fever (RVF) since the early 1950s have been associated with cyclical patterns of the El Nino/Southern Oscillation (ENSO) phenomenon which results in elevated and widespread rainfall over the RVF endemic areas of Africa. Using satellite measurements of global and ...

  1. Antarctic warming driven by internal Southern Ocean deep convection oscillations

    NASA Astrophysics Data System (ADS)

    Martin, Torge; Pedro, Joel B.; Steig, Eric J.; Jochum, Markus; Park, Wonsun; Rasmussen, Sune O.

    2016-04-01

    Simulations with the free-running, complex coupled Kiel Climate Model (KCM) show that heat release associated with recurring Southern Ocean deep convection can drive centennial-scale Antarctic temperature variations of 0.5-2.0 °C. We propose a mechanism connecting the intrinsic ocean variability with Antarctic warming that involves the following three steps: Preconditioning: heat supplied by the lower branch of the Atlantic Meridional Overturning Circulation (AMOC) accumulates at depth in the Southern Ocean, trapped by the Weddell Gyre circulation; Convection onset: wind and/or sea-ice changes tip the preconditioned, thermally unstable system into the convective state; Antarctic warming: fast sea-ice-albedo feedbacks (on annual to decadal timescales) and slower Southern Ocean frontal and sea-surface temperature adjustments to the convective heat release (on multi-decadal to centennial timescales), drive an increase in atmospheric heat and moisture transport towards Antarctica resulting in warming over the continent. Further, we discuss the potential role of this mechanism to explain climate variability observed in Antarctic ice-core records.

  2. El Niño-Southern Oscillation and snow level in the western United States

    NASA Astrophysics Data System (ADS)

    Svoma, Bohumil M.

    2011-12-01

    The relationship between El Niño-Southern Oscillation and the elevation of snow level in the western United States is established. Snow level variability is quantified from records of (1) wet-bulb zero heights at ten rawinsonde sites (1957-2010), (2) empirically estimated snow levels over ten adjacent watersheds from precipitation and snowfall observations (˜1924-2009), and (3) 850-700 hPa thicknesses (1948-2010). The statistical relationship between these variables and the Southern Oscillation Index is established through the examination of the change in the empirical probability density function from moderate values of the Southern Oscillation Index to extreme values of the Southern Oscillation Index. For all data sources, results suggest that El Niño events are linked to higher snow levels across much of the western United States. Considering the known effects of El Niño on airflow over the western United States, the elevated snow levels are likely due to the more maritime characteristics of midlatitude cyclones. The strength of this signal decreases with distance from the Pacific Ocean and the southern Rockies display slightly decreased snow levels during El Niño events, likely due to the transition of maritime air masses to continental air masses. A snow covered area analysis derived from the Terra MODIS observations supports this El Niño signal in snow level. There is little evidence for a significant and spatially coherent La Niña relationship with snow level. This ENSO signal in snow level is apparent in the data with trend removed and for the cold and warm phases of the Pacific Decadal Oscillation.

  3. El Niño-Southern Oscillation and Snow Level in the western United States

    NASA Astrophysics Data System (ADS)

    Svoma, B. M.

    2013-12-01

    Snow level, the elevation that snowfall transitions to rainfall, is directly related to the snow covered area resulting from a given snowfall event. With snow level variability quantified from records of (1) wet-bulb zero heights at ten rawinsonde sites (1957-2010), (2) empirical snow level estimates from precipitation and snowfall observations in ten watersheds (~1924-2009), and (3) 850-700 hPa thicknesses (1948-2010), the relationship between El Niño-Southern Oscillation and the elevation of snow level in the western United States is established. The statistical relationship between the Southern Oscillation Index and these snow level proxies is determined by the change in the empirical probability density function from moderate values of the Southern Oscillation Index to extreme values of the Southern Oscillation Index. For all three data sources, the results suggest that El Niño events are linked to higher snow levels across nearly the entire western United States. The strength of this signal generally decreases with distance from the Pacific Ocean and results suggest that the southern Rockies experience slightly decreased snow levels during El Niño events. A snow covered area analysis derived from observations by NASA's Moderate Resolution Imaging Spectrometer (MODIS) supports this El Niño signal in snow level. There is little evidence for a significant and spatially coherent La Niña relationship with snow level. It is likely that the elevated snow levels are due to the tendency for more maritime characteristics of mid-latitude cyclones during El Niño events while decreased snow levels in the southern Rockies are likely due to the transition of maritime air masses to continental air masses along with deeper troughs. To lend support for this hypothesis, the leading modes of synoptic scale flow during winter precipitation events will be identified for separate regions of the western United States using the North American Regional Reanalysis dataset.

  4. Effect of El-Nino on Southwest Monsoon 2015

    NASA Astrophysics Data System (ADS)

    K. U., Vidhulakshmi; Mrudula, G.

    2016-05-01

    Indian Summer Monsoon Rainfall (ISMR) of 2015 showed a deficit of 14% in the seasonal rainfall. Many researchers connected this deficit to the El-Nino which developed in late May. In this study an analysis of major ENSO events and its influence on ISMR during the period 1975 till present have been carried out. The behavior of ISMR during the previous El-Nino/La-Nina years has been compared with that of 2015. Preliminary analysis shows the effects of El-Nino on ISMR of 2015 started mainly from July. This is attributed to Madden Julian Oscillation (MJO) by many scientists. Analysis of spatial and temporal correlations of SST of various Nino regions with the ISMR and of MJO will also be presented in detail.

  5. Effects of 1997-1998 El Nino on Tropospheric Ozone and Water Vapor

    NASA Technical Reports Server (NTRS)

    Chandra, S.; Ziemke, J. R.; Min, W.; Read, W. G.

    1998-01-01

    This paper analyzes the impact of the 1997-1998 El Nino on tropospheric column ozone and tropospheric water vapor derived respectively from the Total Ozone Mapping Spectrometer (TOMS) on Earth Probe and the Microwave Limb Scanning instrument on the Upper Atmosphere Research Satellite. The 1997-1998 El Nino, characterized by an anomalous increase in sea-surface temperature (SST) across the eastern and central tropical Pacific Ocean, is one of the strongest El Nino Southern Oscillation (ENSO) events of the century, comparable in magnitude to the 1982-1983 episode. The major impact of the SST change has been the shift in the convection pattern from the western to the eastern Pacific affecting the response of rain-producing cumulonimbus. As a result, there has been a significant increase in rainfall over the eastern Pacific and a decrease over the western Pacific and Indonesia. The dryness in the Indonesian region has contributed to large-scale burning by uncontrolled wildfires in the tropical rainforests of Sumatra and Borneo. Our study shows that tropospheric column ozone decreased by 4-8 Dobson units (DU) in the eastern Pacific and increased by about 10-20 DU in the western Pacific largely as a result of the eastward shift of the tropical convective activity as inferred from National Oceanic and Atmospheric Administration (NOAA) outgoing longwave radiation (OLR) data. The effect of this shift is also evident in the upper tropospheric water vapor mixing ratio which varies inversely as ozone (O3). These conclusions are qualitatively consistent with the changes in atmospheric circulation derived from zonal and vertical wind data obtained from the Goddard Earth Observing System data assimilation analyses. The changes in tropospheric column O3 during the course of the 1997-1998 El Nino appear to be caused by a combination of large-scale circulation processes associated with the shift in the tropical convection pattern and surface/boundary layer processes associated with

  6. The southern oscillation and prediction of Der season rainfall in Somalia

    SciTech Connect

    Hutchinson, P. )

    1992-05-01

    Somalia survives in semiarid to and conditions, with annual rainfall totals rarely exceeding 700 mm, which are divided between two seasons. Many areas are arid, with negligible precipitation. Seasonal totals are highly variable. Thus, any seasonal rainfall forecast would be of significant importance to both the agricultural and animal husbandry communities. An investigation was carried out to determine whether there is a relationship between the Southern Oscillation and seasonal rainfall. No relationship exists between the Southern Oscillation and rainfall during the midyear [open quotes]Gu[close quotes] season, but it is shown that the year-end [open quotes]Der[close quotes] season precipitation is affected by the Southern Oscillation in southern and central areas of Somalia. Three techniques were used: correlation, regression, and simple contingency tables. Correlations between the SOI (Southern Oscillation index) and seasonal rainfall vary from zero up to about -0.8, with higher correlations in the south, both for individual stations and for area-averaged rainfall. Regression provides some predictive capacity, but the [open quotes]explanation[close quotes] of the variation in rainfall is not particularly high. The contingency tables revealed that there were very few occasions of both high SOI and high seasonal rainfall, although there was a wide scatter of seasonal rainfall associated with a low SOI. It is concluded that the SOI would be useful for planners, governments, and agencies as one tool in food/famine early warning but that the relationships are not strong enough for the average farmer to place much reliance on forecasts produced solely using the SOI.

  7. Late Pleistocene oscillations of the Drau Glacier (southern Austria)

    NASA Astrophysics Data System (ADS)

    Karnitschar, Christina; Reitner, Jürgen; Draganits, Erich

    2016-04-01

    The Drau Glacier was the largest Pleistocene glacier in the southeastern part of the Alps and significantly shaped the landscape in this region. The study area is located at the termination of the Drau Glacier in the southern part of Austria (Carinthia). The investigation aims to decipher glacial dynamics during the Late Pleistocene glacial advance, stabilisation and final recession of this glacier based on geological/geomorphological mapping, interpretation of airborne laser scan (ALS) topographic data and lithostratigraphic investigations of glacial and periglacial sediments. Special emphasis is laid on the reconstruction of the maximum extent of the glaciation (LGM). Based on previous mapping by Bobek (1959) and Ucik (1996-1998) more details have been gained for the paleogeographic reconstruction based on glacial and non-glacial erosion and accumulation features. These include traces of pre-Upper Pleistocene glaciation, drumlins, terminal moraines and kettle holes. Paleogeographic reconstruction was done with correlation of different outcrops based on lithostratigraphy and ALS topography. Sequences of gravel related to glacial advance covered by till, followed by periglacial sediments allowed detailed reconstruction of the glacial sequence in this area and the complex succession of various extents of the Drau Glacier. References Bobek, Hans. 1959: Der Eisrückgang im östlichen Klagenfurter Becken. In: Mitteilungen der österreichischen geographischen Gesellschaft, Wien. Ucik, Friedrich Hans. 1996: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 141, S. 340, Wien. Ucik, Friedrich Hans. 1997: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 141, S. 325-326, Wien. Ucik, Friedrich Hans. 1998: Bericht über geologische Aufnahmen im Quartär auf Blatt 204 Völkermarkt, Jb. Geol. B.-A., 142, S. 333-334, Wien.

  8. Recent variability in the southern oscillation: isotopic results from a tarawa atoll coral.

    PubMed

    Cole, J E; Fairbanks, R G; Shen, G T

    1993-06-18

    In the western tropical Pacific, the interannual migration of the Indonesian Low convective system causes changes in rainfall that dominate the regional signature of the El Niño-Southern Oscillation (ENSO) system. A 96-year oxygen isotope record from a Tarawa Atoll coral (1 degrees N, 172 degrees E) reflects regional convective activity through rainfall-induced salinity changes. This monthly resolution record spans twice the length of the local climatological record and provides a history of ENSO variability comparable in quality with those derived from instrumental climate data. Comparison of this coral record with a historical chronology of EI Niño events indicates that climate anomalies in coastal South America are occasionally decoupled from Pacific-wide ENSO extremes. Spectral analysis suggests that the distribution of variance in this record has shifted among annual to interannual periods during the present century, concurrent with observed changes in the strength of the Southern Oscillation. PMID:17793658

  9. Precursory signals of the major El Niño Southern Oscillation events

    NASA Astrophysics Data System (ADS)

    Varotsos, C. A.; Tzanis, C.; Cracknell, A. P.

    2016-05-01

    An exploration of the temporal evolution of the El Niño Southern Oscillation (ENSO) from January 1876 to November 2011 by means of a new time domain called natural time reveals that the major ENSO extremes provide precursory signals that are maximized in a time window of almost 2 years. This finding may be used to improve the accuracy of the short-term prediction models of the ENSO extremes, thus enabling steps to be taken to ameliorate its disastrous impacts.

  10. On the Cause of Eastern Equatorial Pacific Ocean T-S Variations Associated with El Nino

    NASA Technical Reports Server (NTRS)

    Wang, Ou; Fukumori, Ichiro; Lee, Tong; Cheng, Benny

    2004-01-01

    The nature of observed variations in temperature-salinity (T-S) relationship between El Nino and non-El Nino years in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5(deg)S-5(deg)N, 150(deg)W-90(deg)W) is investigated using an ocean general circulation model. The origin of the subject water mass is identified using the adjoint of a simulated passive tracer. The higher salinity during El Nino is attributed to larger convergence of saltier water from the Southern Hemisphere and smaller convergence of fresher water from the Northern Hemisphere.

  11. El Niño Southern Oscillation (ENSO) and dysentery in Shandong province, China.

    PubMed

    Zhang, Ying; Bi, Peng; Wang, Guoyong; Hiller, Janet E

    2007-01-01

    To investigate the impact of the El Niño Southern Oscillation (ENSO) on dysentery transmission, the relationship between monthly dysentery cases in Shandong Province of China and the monthly Southern Oscillation Index (SOI), a broad index of ENSO, was examined over the period 1991-2003. Spearman correlations and generalized linear models were calculated to detect the association between the SOI and dysentery cases. Data from 1991 to 2001 were used to estimate the parameters, while data from 2002 to 2003 were used to test the forecasting ability of the model. After controlling for seasonality, autocorrelation, and a time-lagged effect, the results indicate that there was a significant negative association between the number of dysentery cases and the SOI, with a lagged effect of 2 months. A one-standard-deviation decrease in the SOI might cause up to 207 more dysentery cases per month in Shandong Province. This is the first report of the impact of the Southern Oscillation on dysentery risk in China, indicating that the SOI may be a useful early indicator of potential dysentery risk in Shandong Province.

  12. Coherent Modes of Global SST and Summer Rainfall over China: An Assessment of the Regional Impacts of the 1997-98 El Nino/ La Nina

    NASA Technical Reports Server (NTRS)

    Lau, K.-M.; Weng, Hengyi

    1999-01-01

    In this paper, we have identified three principal modes of summertime rainfall variability over China and global sea surface temperature (SST) for the period 1955-1998. Using these modes, we have assessed the impact of the El Nino/La Nina on major drought and flood occurrence over China during 1997-1998. The first mode can be identified with the growth phase of El Nino superimposed on a linear warming trend since the mid-1950s. This mode strongly influences rainfall over northern China. The second mode comprises of a quasi-biennial tendency manifested in alternate wet and dry years over the Yangtze River Valley (YRV) of central China. The third mode is dominated by a quasi-decadal oscillation in eastern China between the Yangtze River and the Yellow River. Using a mode-by-mode reconstruction, we evaluate the impacts of the various principal modes on the 1997 and 1998 observed rainfall anomaly. We find that the severe drought in northern China, and to a lesser degree the flood in southern China, in 1997 is likely a result of the influence of anomalous SST forcing during the growth phase of the El Nino. In addition, rainfall in southern China may be influenced by the decadal or long-term SST variability. The severe flood over the Yangtze River Valley in 1998 is associated with the biennial tendency of basin scale SST during the transition from El Nino to La Nina in 1997-98. Additionally, the observed prolonged drought over northern China and increasing flooding over the YRV since the 1950s may be associated with a long-term warming trend in the tropical Indian and western Pacific ocean. During 1997, the El Nino SST exacerbated the drought situation over northern China. In 1998, the drought appeared to get temporary relief from the La Nina anomalous SST forcing.

  13. O the Interannual Variability of the Indian Monsoon and the Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Wu, Ming Chin

    The mechanisms of the interannual variability of the Indian monsoon and the Southern Oscillation are investigated from observations in the Indian Ocean sector. On this diagnostic basis, a statistical forecasting scheme is developed for all-India rainfall anomalies. A good summer monsoon is characterized by the following aspects. (1) Arabian Sea: higher sea surface temperature (SST) in the pre-monsoon season but lower SST in the monsoon and post -monsoon seasons, lower sea level pressure (SLP) throughout the year, strong surface wind and more cloudiness from the pre-monsoon through the post-monsoon seasons; (2) Indian subcontinent: higher surface temperature in the pre-monsoon season but lower surface temperature afterward, decreased lower-tropospheric constant pressure topographies and higher in the North but lower in the South upper-tropospheric topographies, stronger lower-tropospheric inflow from the South and upper-tropospheric outflow toward the South, and more northward position of the upper-air ridge; and (3) Tibetan Plateau: a warm and dry concurrent summer and a warm and wet preceding winter. An early monsoon onset is heralded by oceanic -atmospheric conditions around the Indian subcontinent similar to those for a good monsoon year. However, conditions immediately following an early monsoon onset are characterized in the Arabian Sea by high SST, strong surface wind, less cloudiness, and high SLP, and in India by an anomalously cold and then warm surface environment. A cool equatorial Pacific Ocean episode of the southern Oscillation is characterized in the Indian Ocean by higher SST in the antecedent seasons but lower SST in the concurrent and following seasons, lower SLP from the preceding throughout the following seasons, stronger surface wind in the western part of the ocean but weaker surface wind in the eastern part during the summer, and more cloudiness. Both large positive values of the Southern Oscillation index and its tendency foreshadow a good

  14. Northern Hemisphere summer monsoon intensified by mega-El Niño/southern oscillation and Atlantic multidecadal oscillation

    PubMed Central

    Wang, Bin; Liu, Jian; Kim, Hyung-Jin; Webster, Peter J.; Yim, So-Young; Xiang, Baoqiang

    2013-01-01

    Prediction of monsoon changes in the coming decades is important for infrastructure planning and sustainable economic development. The decadal prediction involves both natural decadal variability and anthropogenic forcing. Hitherto, the causes of the decadal variability of Northern Hemisphere summer monsoon (NHSM) are largely unknown because the monsoons over Asia, West Africa, and North America have been studied primarily on a regional basis, which is unable to identify coherent decadal changes and the overriding controls on planetary scales. Here, we show that, during the recent global warming of about 0.4 °C since the late 1970s, a coherent decadal change of precipitation and circulation emerges in the entirety of the NHSM system. Surprisingly, the NHSM as well as the Hadley and Walker circulations have all shown substantial intensification, with a striking increase of NHSM rainfall by 9.5% per degree of global warming. This is unexpected from recent theoretical prediction and model projections of the 21st century. The intensification is primarily attributed to a mega-El Niño/Southern Oscillation (a leading mode of interannual-to-interdecadal variation of global sea surface temperature) and the Atlantic Multidecadal Oscillation, and further influenced by hemispherical asymmetric global warming. These factors driving the present changes of the NHSM system are instrumental for understanding and predicting future decadal changes and determining the proportions of climate change that are attributable to anthropogenic effects and long-term internal variability in the complex climate system. PMID:23509281

  15. Long-term stationarity of El Niño-Southern Oscillation teleconnections in southeastern Australia

    NASA Astrophysics Data System (ADS)

    Ashcroft, Linden; Gergis, Joëlle; Karoly, David John

    2016-05-01

    The El Niño-Southern Oscillation (ENSO) phenomenon plays a large role in the modulation of Australian rainfall, particularly in the highly populated southeast. However, this influence is not stationary over time: weak ENSO teleconnections in Australia have been identified during 1920-1950, and palaeoclimate reconstructions indicate that a breakdown in global ENSO teleconnections may have also occurred in the early to mid-1800s. A lack of long-term instrumental data has prevented detailed examination of this intriguing earlier period. This study uses newly recovered instrumental rainfall observations to determine whether the weakening of ENSO teleconnections in the nineteenth century is apparent in eastern and southern southeastern Australia (SEA). Quantitative rainfall and rainday data from 1788 to 2012 are compared with three ENSO indices derived from palaeoclimate data. Statistical analysis suggests a weakening of the relationship between ENSO and SEA rainfall in the early nineteenth century data (~1835-1850), supporting results reported in previous global and regional studies based on palaeoclimate and documentary rainfall reconstructions. Possible causes of this weakening in teleconnection strength are then explored by examining a range of Southern Hemisphere circulation indices. The 1835-1850 period of low ENSO-SEA rainfall correlations appears to be characterised by a combination of reduced La Niña events and ENSO variance associated with a positive phase of the Interdecadal Pacific Oscillation, with the possible influence of a predominately negative phase of the Southern Annular Mode. However, current temporal and geographical data limitations prevent definitive conclusions from being drawn. Despite these caveats, this study illustrates the considerable value of historical instrumental climate data in assessing long-term variations in climate mode teleconnections, particularly in the data-poor Southern Hemisphere.

  16. Correlation between solar activity and El Niño Southern Oscillation (ENSO)

    NASA Astrophysics Data System (ADS)

    Mumtahana, Farahhati; Sulistiani, Santi; Kesumaningrum, Rasdewita

    2015-09-01

    ENSO (El Niño Southern Oscillation) is an oceanic anomaly and atmospheric phenomenon in equatorial pacific indicated by Southern Oscillation Index (SOI). It describes the air pressure between Darwin (Australia) and Tahiti (Southern Pacific Ocean). ENSO occurs at irregular interval between 3 and 7 years causing global climate system variation. Considering this event occurs periodically, it might be triggered by the 11-years of solar cycle as an energy source. In this case, the solar activity is represented by the variability of the periodical Sunspot number (R). Changes in the rate of heating and the amount of solar energy package is presumed to be the cause of the ENSO phenomenon. In this work, we use the data of Sunspot number (R) and SOI from 1870 to 2013. Derived from those data, spectral analysis of the output energy package is analyzed by using WWZ (Weighted Wavelet Z-Transform). Then we correlate with the periodicity and condition of ENSO phenomenon to obtain the prediction of occurrence interval.

  17. Assessing the persistence of millennial-scale oscillations during the penultimate glacial phase in southern Europe

    NASA Astrophysics Data System (ADS)

    Wilson, Graham; Frogley, Mick; Jones, Tim; Leng, Melanie

    2016-04-01

    There is growing evidence that millennial-scale climate oscillations are a pervasive feature of glacial intervals. During the last glaciation (Marine Isotope Stage (MIS) 2-4), incursions of cold water into the North Atlantic appeared to coincide with abrupt reductions in southern European tree populations (Tzedakis et al., 2004: Geology 32, 109-112), suggesting down-stream impacts on continental temperature and hydroclimate. Ice-rafting into the North Atlantic during the penultimate glacial (MIS 6) is thought to be less extensive than at times during MIS 2-4, perhaps resulting in more subdued climate oscillations. Published pollen data from Lake Ioannina core I-284 (Epirus, NW Greece) suggest pronounced oscillations in tree population extent during early MIS 6 (185-155 ka), followed by much-reduced tree populations and subdued oscillations throughout late MIS 6 (155-135 ka) (Roucoux et al., 2011: Journal of Quaternary Science 26, 616-626). Previous studies of the diatom and isotope records from the MIS 7/6, 6/5e and 2/1 transitions, and from MIS 5e and 1 in Lake Ioannina core I-284 demonstrate the sensitivity of these proxies to changes in regional climate. Here we apply a combined diatom and stable isotope (carbon and oxygen) approach to evaluate the influence of millennial-scale oscillations on southern Europe hydroclimate during MIS 6. The new isotope data from Lake Ioannina core I-284 demonstrates higher precipitation / evaporation (P/E) ratios between c. 178 and 164 ka, associated with peak insolation during MIS 6e, and episodes of planktonic diatom expansion likely reflecting the interstadials of the 6e complex. Close correspondence between diatom planktonic frequencies, arboreal pollen and regional sea-surface temperatures together provide strong evidence for millennial-scale oscillations in regional precipitation at times during the early‒mid MIS 6. The isotope data suggest overall cooler and drier conditions during the mid-late MIS 6, consistent with

  18. Influence of southern oscillation on autumn rainfall in Iran (1951-2011)

    NASA Astrophysics Data System (ADS)

    Roghani, Rabbaneh; Soltani, Saeid; Bashari, Hossein

    2016-04-01

    This study aimed to investigate the relationships between southern oscillation and autumn (October-December) rainfall in Iran. It also sought to identify the possible physical mechanisms involved in the mentioned relationships by analyzing observational atmospheric data. Analyses were based on monthly rainfall data from 50 synoptic stations with at least 35 years of records up to the end of 2011. Autumn rainfall time series were grouped by the average Southern Oscillation Index (SOI) and SOI phase methods. Significant differences between rainfall groups in each method were assessed by Kruskal-Wallis and Kolmogorov-Smirnov non-parametric tests. Their relationships were also validated using the linear error in probability space (LEPS) test. The results showed that average SOI and SOI phases during July-September were related with autumn rainfall in some regions located in the west and northwest of Iran, west coasts of the Caspian Sea and southern Alborz Mountains. The El Niño (negative) and La Niña (positive) phases were associated with increased and decreased autumn rainfall, respectively. Our findings also demonstrated the persistence of Southern Pacific Ocean's pressure signals on autumn rainfall in Iran. Geopotential height patterns were totally different in the selected El Niño and La Niña years over Iran. During the El Niño years, a cyclone was formed over the north of Iran and an anticyclone existed over the Mediterranean Sea. During La Niña years, the cyclone shifted towards the Mediterranean Sea and an anticyclone developed over Iran. While these El Niño conditions increased autumn rainfall in Iran, the opposite conditions during the La Niña phase decreased rainfall in the country. In conclusion, development of rainfall prediction models based on the SOI can facilitate agricultural and water resources management in Iran.

  19. Coastal vulnerability across the Pacific dominated by El Niño-Southern Oscillation

    USGS Publications Warehouse

    Barnard, Patrick L.; Short, Andrew D.; Harley, Mitchell D.; Splinter, Kristen D.; Vitousek, Sean; Turner, Ian L.; Allan, Jonathan; Banno, Masayuki; Bryan, Karin R.; Doria, André; Hansen, Jeff E.; Kato, Shigeru; Kuriyama, Yoshiaki; Randall-Goodwin, Evan; Ruggiero, Peter; Walker, Ian J.; Heathfield, Derek K.

    2015-01-01

    To predict future coastal hazards, it is important to quantify any links between climate drivers and spatial patterns of coastal change. However, most studies of future coastal vulnerability do not account for the dynamic components of coastal water levels during storms, notably wave-driven processes, storm surges and seasonal water level anomalies, although these components can add metres to water levels during extreme events. Here we synthesize multi-decadal, co-located data assimilated between 1979 and 2012 that describe wave climate, local water levels and coastal change for 48 beaches throughout the Pacific Ocean basin. We find that observed coastal erosion across the Pacific varies most closely with El Niño/Southern Oscillation, with a smaller influence from the Southern Annular Mode and the Pacific North American pattern. In the northern and southern Pacific Ocean, regional wave and water level anomalies are significantly correlated to a suite of climate indices, particularly during boreal winter; conditions in the northeast Pacific Ocean are often opposite to those in the western and southern Pacific. We conclude that, if projections for an increasing frequency of extreme El Niño and La Niña events over the twenty-first century are confirmed, then populated regions on opposite sides of the Pacific Ocean basin could be alternately exposed to extreme coastal erosion and flooding, independent of sea-level rise.

  20. Coastal vulnerability across the Pacific dominated by El Niño/Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Barnard, Patrick L.; Short, Andrew D.; Harley, Mitchell D.; Splinter, Kristen D.; Vitousek, Sean; Turner, Ian L.; Allan, Jonathan; Banno, Masayuki; Bryan, Karin R.; Doria, André; Hansen, Jeff E.; Kato, Shigeru; Kuriyama, Yoshiaki; Randall-Goodwin, Evan; Ruggiero, Peter; Walker, Ian J.; Heathfield, Derek K.

    2015-10-01

    To predict future coastal hazards, it is important to quantify any links between climate drivers and spatial patterns of coastal change. However, most studies of future coastal vulnerability do not account for the dynamic components of coastal water levels during storms, notably wave-driven processes, storm surges and seasonal water level anomalies, although these components can add metres to water levels during extreme events. Here we synthesize multi-decadal, co-located data assimilated between 1979 and 2012 that describe wave climate, local water levels and coastal change for 48 beaches throughout the Pacific Ocean basin. We find that observed coastal erosion across the Pacific varies most closely with El Niño/Southern Oscillation, with a smaller influence from the Southern Annular Mode and the Pacific North American pattern. In the northern and southern Pacific Ocean, regional wave and water level anomalies are significantly correlated to a suite of climate indices, particularly during boreal winter; conditions in the northeast Pacific Ocean are often opposite to those in the western and southern Pacific. We conclude that, if projections for an increasing frequency of extreme El Niño and La Niña events over the twenty-first century are confirmed, then populated regions on opposite sides of the Pacific Ocean basin could be alternately exposed to extreme coastal erosion and flooding, independent of sea-level rise.

  1. The effect of El Niño - Southern Oscillation events on CO2 and H2O fluxes in a mountainous tropical rainforest in equatorial Indonesia

    NASA Astrophysics Data System (ADS)

    Olchev, Alexander; Ibrom, Andreas; Panferov, Oleg; Gushchina, Darija; Kreilein, Heinrich; Popov, Victor; Propastin, Pavel; June, Tania; Rauf, Abdul; Gravenhorst, Gode; Knohl, Alexander

    2016-04-01

    The possible impact of El Niño-Southern Oscillation (ENSO) events on the main components of CO2 and H2O fluxes between the tropical rainforest and the atmosphere was investigated. The fluxes were continuously measured in an old-growth mountainous tropical rainforest in Central Sulawesi in Indonesia (1°39.47'S and 120°10.409'E) using the eddy covariance method for the period from January 2004 to June 2008 (Ibrom et al. 2007). During the period of measurements two episodes of El Niño and one episode of La Niña were observed. All these ENSO episodes had moderate intensity and were of the central Pacific type. To quantify the ENSO impacts on meteorological parameters and fluxes and to distinguish them from effects caused by the seasonal migration of the Intertropical Convergence Zone (ITCZ) we analyzed the correlation between the deviations of monthly meteorological parameter and flux values from their monthly averages over the entire measuring period and the Nino4 and Nino3.4 indexes. The typical timescale of the full ENSO cycle is estimated to be about 48-52 months (Setoh et al., 1999), whereas the timescale of the main meteorological parameters (global solar radiation (G), precipitation amount (P), air temperature (T)) is characterized by much higher month-to-month variability even after annual trend filtering. In order to filter the high-frequency oscillation in the time series of atmospheric characteristics and monthly Net Ecosystem Exchange of CO2 (NEE), Gross Primary Production (GPP), Ecosystem Respiration (RE) and evapotranspiration (ET) anomalies, the simple centered moving average smoothing procedure was applied. The moving averages of variables were calculated over 7 months (centered value ± 3 months). Statistical analysis included both simple correlation and cross-correlation analysis. Analysis of the temporal variability of CO2 and H2O fluxes showed a high sensitivity of monthly GPP and ET of the mountainous tropical rainforest to ENSO intensity

  2. The effect of El Niño - Southern Oscillation events on CO2 and H2O fluxes in a mountainous tropical rainforest in equatorial Indonesia

    NASA Astrophysics Data System (ADS)

    Olchev, Alexander; Ibrom, Andreas; Panferov, Oleg; Gushchina, Darija; Kreilein, Heinrich; Popov, Victor; Propastin, Pavel; June, Tania; Rauf, Abdul; Gravenhorst, Gode; Knohl, Alexander

    2016-04-01

    The possible impact of El Niño-Southern Oscillation (ENSO) events on the main components of CO2 and H2O fluxes between the tropical rainforest and the atmosphere was investigated. The fluxes were continuously measured in an old-growth mountainous tropical rainforest in Central Sulawesi in Indonesia (1°39.47'S and 120°10.409'E) using the eddy covariance method for the period from January 2004 to June 2008 (Ibrom et al. 2007). During the period of measurements two episodes of El Niño and one episode of La Niña were observed. All these ENSO episodes had moderate intensity and were of the central Pacific type. To quantify the ENSO impacts on meteorological parameters and fluxes and to distinguish them from effects caused by the seasonal migration of the Intertropical Convergence Zone (ITCZ) we analyzed the correlation between the deviations of monthly meteorological parameter and flux values from their monthly averages over the entire measuring period and the Nino4 and Nino3.4 indexes. The typical timescale of the full ENSO cycle is estimated to be about 48-52 months (Setoh et al., 1999), whereas the timescale of the main meteorological parameters (global solar radiation (G), precipitation amount (P), air temperature (T)) is characterized by much higher month-to-month variability even after annual trend filtering. In order to filter the high-frequency oscillation in the time series of atmospheric characteristics and monthly Net Ecosystem Exchange of CO2 (NEE), Gross Primary Production (GPP), Ecosystem Respiration (RE) and evapotranspiration (ET) anomalies, the simple centered moving average smoothing procedure was applied. The moving averages of variables were calculated over 7 months (centered value ± 3 months). Statistical analysis included both simple correlation and cross-correlation analysis. Analysis of the temporal variability of CO2 and H2O fluxes showed a high sensitivity of monthly GPP and ET of the mountainous tropical rainforest to ENSO intensity

  3. El Niño-Southern Oscillation, local weather and occurrences of dengue virus serotypes

    PubMed Central

    Huang, Xiaodong; Clements, Archie C.A.; Williams, Gail; Devine, Gregor; Tong, Shilu; Hu, Wenbiao

    2015-01-01

    Severe dengue fever is usually associated with secondary infection by a dengue virus (DENV) serotype (1 to 4) that is different to the serotype of the primary infection. Dengue outbreaks only occur following importations of DENV in Cairns, Australia. However, the majority of imported cases do not result in autochthonous transmission in Cairns. Although DENV transmission is strongly associated with the El Niño-Southern Oscillation (ENSO) climate cycle and local weather conditions, the frequency and potential risk factors of infections with the different DENV serotypes, including whether or not they differ, is unknown. This study used a classification tree model to identify the hierarchical interactions between Southern Oscillation Index (SOI), local weather factors, the presence of imported serotypes and the occurrence of the four autochthonous DENV serotypes from January 2000–December 2009 in Cairns. We found that the 12-week moving average of SOI and the 2-week moving average of maximum temperature were the most important factors influencing the variation in the weekly occurrence of the four DENV serotypes, the likelihoods of the occurrence of the four DENV serotypes may be unequal under the same environmental conditions, and occurrence may be influenced by changes in global and local environmental conditions in Cairns. PMID:26581295

  4. El Niño-Southern Oscillation, local weather and occurrences of dengue virus serotypes.

    PubMed

    Huang, Xiaodong; Clements, Archie C A; Williams, Gail; Devine, Gregor; Tong, Shilu; Hu, Wenbiao

    2015-11-19

    Severe dengue fever is usually associated with secondary infection by a dengue virus (DENV) serotype (1 to 4) that is different to the serotype of the primary infection. Dengue outbreaks only occur following importations of DENV in Cairns, Australia. However, the majority of imported cases do not result in autochthonous transmission in Cairns. Although DENV transmission is strongly associated with the El Niño-Southern Oscillation (ENSO) climate cycle and local weather conditions, the frequency and potential risk factors of infections with the different DENV serotypes, including whether or not they differ, is unknown. This study used a classification tree model to identify the hierarchical interactions between Southern Oscillation Index (SOI), local weather factors, the presence of imported serotypes and the occurrence of the four autochthonous DENV serotypes from January 2000-December 2009 in Cairns. We found that the 12-week moving average of SOI and the 2-week moving average of maximum temperature were the most important factors influencing the variation in the weekly occurrence of the four DENV serotypes, the likelihoods of the occurrence of the four DENV serotypes may be unequal under the same environmental conditions, and occurrence may be influenced by changes in global and local environmental conditions in Cairns.

  5. El Niño-Southern Oscillation, local weather and occurrences of dengue virus serotypes

    NASA Astrophysics Data System (ADS)

    Huang, Xiaodong; Clements, Archie C. A.; Williams, Gail; Devine, Gregor; Tong, Shilu; Hu, Wenbiao

    2015-11-01

    Severe dengue fever is usually associated with secondary infection by a dengue virus (DENV) serotype (1 to 4) that is different to the serotype of the primary infection. Dengue outbreaks only occur following importations of DENV in Cairns, Australia. However, the majority of imported cases do not result in autochthonous transmission in Cairns. Although DENV transmission is strongly associated with the El Niño-Southern Oscillation (ENSO) climate cycle and local weather conditions, the frequency and potential risk factors of infections with the different DENV serotypes, including whether or not they differ, is unknown. This study used a classification tree model to identify the hierarchical interactions between Southern Oscillation Index (SOI), local weather factors, the presence of imported serotypes and the occurrence of the four autochthonous DENV serotypes from January 2000-December 2009 in Cairns. We found that the 12-week moving average of SOI and the 2-week moving average of maximum temperature were the most important factors influencing the variation in the weekly occurrence of the four DENV serotypes, the likelihoods of the occurrence of the four DENV serotypes may be unequal under the same environmental conditions, and occurrence may be influenced by changes in global and local environmental conditions in Cairns.

  6. TOPEX/El Nino Watch - El Nino Moisture in the Atmosphere, February 22, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image shows differences in atmospheric water vapor relative to a normal (average) year in the Earth's upper troposphere about 10 kilometers (6 miles) above the surface. These measurements were made by the Microwave Limb Sounder (MLS) instrument aboard NASA's Upper Atmosphere Research Satellite (UARS). This image, obtained on February 22, 1998, shows that high levels of atmospheric water vapor (red) continue to persist above the warm water pool, commonly referred to as El Nino, in the eastern equatorial Pacific Ocean. This image also shows high levels of atmospheric moisture above Southern California. The extent of this high moisture area along the equator has slightly decreased since late January, which corresponds to the shrinking volume of the warm water pool on the ocean's surface. During El Nino, the warmer ocean water off the coast of Peru evaporates at a higher rate, and the resulting warm moist air rises, forming tall cloud towers. In the tropics, the warm water and the resulting tall cloud towers typically produce large amounts of rain. These data show a new formation of high levels of moisture off the coast of Japan in an area that is the typical breeding ground for winter storms. Storms produced off the coast of Japan normally migrate eastward toward the western United States. During this El Nino condition, the southern tropical jet stream has shifted northward, bringing additional moisture from the tropics. When these two sources of moisture converge near California, they produce storms with higher-than-normal rainfall.

  7. Bifurcation analysis of delay-induced resonances of the El-Niño Southern Oscillation

    PubMed Central

    Krauskopf, Bernd; Sieber, Jan

    2014-01-01

    Models of global climate phenomena of low to intermediate complexity are very useful for providing an understanding at a conceptual level. An important aspect of such models is the presence of a number of feedback loops that feature considerable delay times, usually due to the time it takes to transport energy (for example, in the form of hot/cold air or water) around the globe. In this paper, we demonstrate how one can perform a bifurcation analysis of the behaviour of a periodically forced system with delay in dependence on key parameters. As an example, we consider the El-Niño Southern Oscillation (ENSO), which is a sea-surface temperature (SST) oscillation on a multi-year scale in the basin of the Pacific Ocean. One can think of ENSO as being generated by an interplay between two feedback effects, one positive and one negative, which act only after some delay that is determined by the speed of transport of SST anomalies across the Pacific. We perform here a case study of a simple delayed-feedback oscillator model for ENSO, which is parametrically forced by annual variation. More specifically, we use numerical bifurcation analysis tools to explore directly regions of delay-induced resonances and other stability boundaries in this delay-differential equation model for ENSO. PMID:25197254

  8. Bifurcation analysis of delay-induced resonances of the El-Niño Southern Oscillation.

    PubMed

    Krauskopf, Bernd; Sieber, Jan

    2014-09-01

    Models of global climate phenomena of low to intermediate complexity are very useful for providing an understanding at a conceptual level. An important aspect of such models is the presence of a number of feedback loops that feature considerable delay times, usually due to the time it takes to transport energy (for example, in the form of hot/cold air or water) around the globe. In this paper, we demonstrate how one can perform a bifurcation analysis of the behaviour of a periodically forced system with delay in dependence on key parameters. As an example, we consider the El-Niño Southern Oscillation (ENSO), which is a sea-surface temperature (SST) oscillation on a multi-year scale in the basin of the Pacific Ocean. One can think of ENSO as being generated by an interplay between two feedback effects, one positive and one negative, which act only after some delay that is determined by the speed of transport of SST anomalies across the Pacific. We perform here a case study of a simple delayed-feedback oscillator model for ENSO, which is parametrically forced by annual variation. More specifically, we use numerical bifurcation analysis tools to explore directly regions of delay-induced resonances and other stability boundaries in this delay-differential equation model for ENSO.

  9. Bifurcation analysis of delay-induced resonances of the El-Niño Southern Oscillation.

    PubMed

    Krauskopf, Bernd; Sieber, Jan

    2014-09-01

    Models of global climate phenomena of low to intermediate complexity are very useful for providing an understanding at a conceptual level. An important aspect of such models is the presence of a number of feedback loops that feature considerable delay times, usually due to the time it takes to transport energy (for example, in the form of hot/cold air or water) around the globe. In this paper, we demonstrate how one can perform a bifurcation analysis of the behaviour of a periodically forced system with delay in dependence on key parameters. As an example, we consider the El-Niño Southern Oscillation (ENSO), which is a sea-surface temperature (SST) oscillation on a multi-year scale in the basin of the Pacific Ocean. One can think of ENSO as being generated by an interplay between two feedback effects, one positive and one negative, which act only after some delay that is determined by the speed of transport of SST anomalies across the Pacific. We perform here a case study of a simple delayed-feedback oscillator model for ENSO, which is parametrically forced by annual variation. More specifically, we use numerical bifurcation analysis tools to explore directly regions of delay-induced resonances and other stability boundaries in this delay-differential equation model for ENSO. PMID:25197254

  10. Variations in the tropical greenhouse effect during El Nino

    SciTech Connect

    Soden, B.J.

    1997-05-01

    Observations of the clear-sky outgoing longwave radiation and sea surface temperature are combined to examine the evolution of the tropical greenhouse effect from colder La Nina conditions in early 1985 to warmer El Nino conditions in late 1987. Although comparison of individual months can suggest a decrease in greenhouse trapping from cold to warm conditions, when the entire 4-yr record is considered a distinct increase in tropical-mean greenhouse trapping of {approximately}2 W m{sup -2} is observed in conjunction with a {approximately}0.4 K increase in tropical-mean sea surface temperature. This observed increase compares favorably with GCM simulations of the change in the clear-sky greenhouse effect during El Nifio-Southern Oscillation (ENSO). Superimposed on top of the SST-driven change in greenhouse trapping are dynamically induced changes in tropical moisture apparently associated with a redistribution of SST during ENSO. The GCM simulations also successfully reproduce this feature, providing reassurance in the ability of GCMs to predict both dynamically and thermodynamically driven changes in greenhouse trapping. 25 refs., 3 figs., 1 tab.

  11. TOPEX/El Nino Watch - El Nino Moisture in the Atmosphere, January and February, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This series of six images shows the evolution of atmospheric water vapor over the Pacific Ocean during the 1998 El Nino condition. Higher than normal ocean water temperatures increase the rate of evaporation, and the resulting warm moist air rises into the atmosphere, altering global weather patterns. Data obtained by the Microwave Limb Sounder (MLS) on NASA's Upper Atmosphere Research Satellite (UARS) during January and February 1998 show a decrease in the extent of high levels of water vapor (red) over the eastern equatorial Pacific and an increase in water vapor (yellow to red) over the northwestern Pacific off the coast of Japan. This area is a breeding ground for winter storms that move eastward toward North America. During this El Nino condition, the southern tropical jet stream has shifted northward, bringing additional moisture from the tropics. When these two sources of moisture converge near California, they produce storms with higher-than-normal rainfall.

  12. Long-term variability of the southern Adriatic circulation in relation to North Atlantic Oscillation

    NASA Astrophysics Data System (ADS)

    Shabrang, L.; Menna, M.; Pizzi, C.; Lavigne, H.; Civitarese, G.; Gačić, M.

    2016-02-01

    The interannual variability of the South Adriatic Gyre and its relation to the wind vorticity and the large-scale climatic pattern (North Atlantic Oscillation - NAO) was studied using the time series of satellite altimetric data and ocean surface wind products. The cyclonic circulation observed in the southern Adriatic area was partly sustained by the local wind forcing, as suggested by the positive correlation between the rate of change of the current vorticity and the wind-stress vorticity. Nevertheless, the influence of vorticity advection from the adjacent area (northern Ionian Sea) cannot be ignored and it is more significant during the anticyclonic phase of Adriatic-Ionian Bimodal Oscillation System. The geostrophic current vorticities of the southern Adriatic and northern Ionian seas are correlated with a time lag of 14 months, which approximately corresponds to an advection speed of ˜ 1 cm s-1. The different wind patterns observed during two NAO phases in the winter revealed a stronger positive vorticity during the negative NAO phase. Conversely, during the wintertime positive NAO phase the wind vorticity is characterized by lower positive or slightly negative values. Despite a statistically significant negative correlation between the NAO index and the wind vorticity, no unequivocal relationship between large climatic system and the interannual variability of the South Adriatic Gyre intensity was found due to additional effects of the vorticity advection from the Ionian. This can be explained by the fact that the Ionian circulation mode does not depend on the NAO variations. Therefore, the main result of this study is that the interannual variability of the southern Adriatic cyclonic circulation is a result of the combined influence of the vorticity advection from the Ionian and the local wind-curl effect.

  13. Climate Variability Drives Plankton Community Composition Changes: the 2010-2011 El Nino to La Nina Transition Around Australia

    NASA Technical Reports Server (NTRS)

    Thompson, Peter A.; Bonham, Pru; Thomson, Paul; Rochester, Wayne; Doblin, Martina A.; Waite, Anya M.; Richardson, Anthony; Rousseaux, Cecile S.

    2015-01-01

    The strong La Nina of 2010-2011 provided an opportunity to investigate the ecological impacts of El Nino-Southern Oscillation on coastal plankton communities using the nine national reference stations around Australia. Based on remote sensing and across the entire Australian region 2011 (La Nina) was only modestly different from 2010 (El Nino) with the average temperature declining 0.2 percent surface chlorophyll a up 3 percent and modelled primary production down 14 percent. Other changes included a poleward shift in Prochlorococcus and Synechococcus. Along the east coast, there was a reduction in salinity, increase in nutrients, Chlorophytes and Prasinophytes (taxa with chlorophyll b, neoxanthin and prasinoxanthin). The southwest region had a rise in the proportion of 19-hexoyloxyfucoxanthin; possibly coccolithophorids in eddies of the Leeuwin Current and along the sub-tropical front. Pennate diatoms increased, Ceratium spp. decreased and Scrippsiella spp. increased in 2011. Zooplankton biomass declined significantly in 2011. There was a reduction in the abundance of Calocalanus pavo and Temora turbinata and increases in Clausocalanus farrani, Oncaea scottodicarloi and Macrosetella gracilis in 2011. The changes in the plankton community during the strong La Nina of 2011 suggest that this climatic oscillation exacerbates the tropicalization of Australia.

  14. Stratospheric geoengineering impacts on El Niño/Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Gabriel, C. J.; Robock, A.

    2015-03-01

    To examine the impact of proposed stratospheric geoengineering schemes on the amplitude and frequency of El Niño/Southern Oscillation (ENSO) variations we examine climate model simulations from the Geoengineering Model Intercomparison Project (GeoMIP) G1-G4 experiments. Here we compare tropical Pacific behavior under anthropogenic global warming (AGW) using the representative concentration pathway resulting in 4.5 W m-2 radiative forcing at the end of the 21st Century, the RCP4.5 scenario, with that under G1-G4 and under historical model simulations. Climate models under AGW project relatively uniform warming across the tropical Pacific over the next several decades. We find no statistically significant change in ENSO frequency or amplitude under stratospheric geoengineering as compared with those that would occur under ongoing AGW.

  15. Reduced El Niño-Southern Oscillation during the Last Glacial Maximum.

    PubMed

    Ford, Heather L; Ravelo, A Christina; Polissar, Pratigya J

    2015-01-16

    El Niño-Southern Oscillation (ENSO) is a major source of global interannual variability, but its response to climate change is uncertain. Paleoclimate records from the Last Glacial Maximum (LGM) provide insight into ENSO behavior when global boundary conditions (ice sheet extent, atmospheric partial pressure of CO2) were different from those today. In this work, we reconstruct LGM temperature variability at equatorial Pacific sites using measurements of individual planktonic foraminifera shells. A deep equatorial thermocline altered the dynamics in the eastern equatorial cold tongue, resulting in reduced ENSO variability during the LGM compared to the Late Holocene. These results suggest that ENSO was not tied directly to the east-west temperature gradient, as previously suggested. Rather, the thermocline of the eastern equatorial Pacific played a decisive role in the ENSO response to LGM climate.

  16. Meteorological factors and El Niño Southern Oscillation are independently associated with dengue infections.

    PubMed

    Earnest, A; Tan, S B; Wilder-Smith, A

    2012-07-01

    Our objective was to determine the association between temperature, humidity, rainfall and dengue activity in Singapore, after taking into account lag periods as well as long-term climate variability such as the El Niño Southern Oscillation Index (SOI). We used a Poisson model which allowed for autocorrelation and overdispersion in the data. We found weekly mean temperature and mean relative humidity as well as SOI to be significantly and independently associated with dengue notifications. There was an interaction effect by periods of dengue outbreaks, but periods where El Niño was present did not moderate the relationship between humidity and temperature with dengue notifications. Our results help to understand the temporal trends of dengue in Singapore, and further reinforce the findings that meteorological factors are important in the epidemiology of dengue.

  17. Precipitation change in Southern Italy linked to global scale oscillation indexes

    NASA Astrophysics Data System (ADS)

    Caloiero, T.; Coscarelli, R.; Ferrari, E.; Mancini, M.

    2009-09-01

    Hydrological impacts from climate change are of principal interest to water resources policy-makers and practising engineers. Climate change has attracted extensive attention from every sector of the society because of the potentially large scale negative environmental and economic consequences. Particularly the analysis of the temporal evolution of precipitation is fundamental to evaluate water resources availability, especially in areas with a marked orography like in Southern Italy. To this aim several statistical tests can be used for exploratory analyses and detection of monotonic trends in time series data. Moreover rainfall amounts occurred in seasonal periods, directly responsible for availability of water resources on a specified area, are strongly dependent on climate system. In order to highlight some features of such dependence, planetary-scale indexes based on the difference in the sea level pressure between two geographic areas tagging centres of climatic action have been taken into account. Such procedure, called teleconnection, shows that climatic conditions in different geographical areas, even relatively far from each other, can be interdependent. For instance, the conditions of the Atlantic, Pacific and Indian Oceans, which constitute heat and steam sources for the masses of air which cross them, in the intertropical zone are related to the precipitation regime, while at the latitudes of the temperate zones they modulate the circulation of the western winds, the high and low pressure zones distribution and the track of the low pressure areas responsible for the atmospheric phenomena. Within this purview, some authors have drawn correlations between precipitation and indexes describing some planetary-scale oscillations, like the well-known El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). As example, several analyses of the relationships between large-scale pressure fields, such as the NAO, and European climate have

  18. Reduced El Niño-Southern Oscillation during the Last Glacial Maximum.

    PubMed

    Ford, Heather L; Ravelo, A Christina; Polissar, Pratigya J

    2015-01-16

    El Niño-Southern Oscillation (ENSO) is a major source of global interannual variability, but its response to climate change is uncertain. Paleoclimate records from the Last Glacial Maximum (LGM) provide insight into ENSO behavior when global boundary conditions (ice sheet extent, atmospheric partial pressure of CO2) were different from those today. In this work, we reconstruct LGM temperature variability at equatorial Pacific sites using measurements of individual planktonic foraminifera shells. A deep equatorial thermocline altered the dynamics in the eastern equatorial cold tongue, resulting in reduced ENSO variability during the LGM compared to the Late Holocene. These results suggest that ENSO was not tied directly to the east-west temperature gradient, as previously suggested. Rather, the thermocline of the eastern equatorial Pacific played a decisive role in the ENSO response to LGM climate. PMID:25593181

  19. An Examination of the Hadley Sea-Surface Temperature Time Series for the Nino 3.4 Region

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2010-01-01

    The Hadley sea-surface temperature (HadSST) dataset is investigated for the interval 1871-2008. The purpose of this investigation is to determine the degree of success in identifying and characterizing El Nino (EN) southern (ENSO) extreme events, both EN and La Nina (LN) events. Comparisons are made against both the Southern Oscillation Index for the same time interval and with published values of the Oceanic Nino Index for the interval since 1950. Some 60 ENSO extreme events are identified in the HadSST dataset, consisting of 33 EN and 27 LN events. Also, preferential associations are found to exist between the duration of ENSO extreme events and their maximum anomalous excursion temperatures and between the recurrence rate for an EN event and the duration of the last known EN event. Because the present ongoing EN is a strong event, it should persist 11 months or longer, inferring that the next EN event should not be expected until June 2012 or later. Furthermore, the decadal sum of EN-related months is found to have increased somewhat steadily since the decade of 1920-1929, suggesting that the present decade (2010-2019) possibly will see about 3-4 EN events, totaling about 37 +/- 3 EN-related months (i.e., months that meet the definition for the occurrence of an EN event).

  20. Teleconnections of the Southern Oscillation in the tropical Atlantic sector in the OSU coupled upper ocean-atomosphere GCM

    SciTech Connect

    Hameed, S.; Meinster, A. ); Sperber, K.R. )

    1993-03-01

    The Oregon State University coupled upper ocean-atmosphere GCM has been shown to qualitatively simulate the Southern Oscillation. A composite analysis of the warm and cold events simulated in this 23-year integration has been performed. During the low phase of the Southern Oscillation, when warm anomalies occur in the eastern Pacific, the model simulates for the Atlantic region during March-May (1) a deficit of precipitation over the tropical South American continent, (2) Caribbean and Gulf of Mexico sea level pressure and sea surface temperature are in phase with the eastern Pacific anomalies, while those east of the Nordeste region are out of phase, and (3) northeast trade winds are anomalously weak and southwest trade winds are anomalously strong (as inferred from surface current anomalies). The anomalies in the oceanic processes are induced by perturbations in the atmospheric circulation over the Atlantic and are coupled to changes in the Walker circulation. During the high phase of the simulated Southern Oscillation, conditions in the atmosphere and ocean are essentially the reverse of the low phase. The model produces a response in the South American region during the opposing phases of the Southern Oscillation that is in general agreement with observations. The interannual variation of Nordeste rainfall is shown to be dominated by a few band-limited frequencies. These frequencies are found in the SST series of those regions of the Atlantic and Pacific oceans where strong correlations with Nordeste precipitation exist.

  1. El Niño-Southern Oscillation and dengue early warning in Ecuador

    NASA Astrophysics Data System (ADS)

    Stewart, A. M.; Lowe, R.

    2012-04-01

    Dengue fever, a mosquito-borne viral disease, is one of the most important emerging tropical diseases. Dengue is hyper-endemic in coastal Ecuador, where all four serotypes co-circulate. The El Niño-Southern Oscillation (ENSO) influences climate in Ecuador, with positive phase ENSO (El Niño) associated with wetter and warmer conditions over the southern coastal region. In turn, greater rainfall increases the availability of mosquito breeding sites for the dengue mosquito (Aedes aegypti), while warmer temperatures increase rates of larval development, mosquito biting, and viral replication in the mosquito. We report a statistical model for assessing the importance of climate as a driver for inter-annual variability in dengue fever in southern coastal Ecuador. Climate variables from a local meteorology station (precipitation, number of rainy days, minimum/maximum/mean air temperature), combined with gridded climate products, and anomalies of Pacific sea surface temperatures (Oceanic Niño Index, ONI) were used to predict monthly dengue standardized morbidity ratios (SMR) (1995-2010). Non-climatic confounding factors such as serotype introduction and vector control effort were also considered. Preliminary results indicated a statistically significant positive association between dengue risk and the number of rainy days during the previous month. Both the number of rainy days and dengue SMR were positively associated with the Pacific SST anomalies with a lead time of several months. Due to time lags involved in the climate-disease transmission system, monitoring El Niño / La Niña evolution in the Pacific Ocean could provide some predictive lead time for forecasting dengue epidemics. This is the first study of dengue fever and climate in this region. This research provides the foundation to develop a climate-driven early warning system for dengue fever in Ecuador.

  2. Modulation of the Southern Africa precipitation response to the El Niño Southern Oscillation by the subtropical Indian Ocean Dipole

    NASA Astrophysics Data System (ADS)

    Hoell, Andrew; Funk, Chris; Zinke, Jens; Harrison, Laura

    2016-06-01

    The climate of Southern Africa, defined as the land area bound by the region 15°S-35°S; 12.5°E-42.5°E, during the December-March rainy season is driven by Indo-Pacific sea surface temperature (SST) anomalies associated with the El Niño Southern Oscillation (ENSO) and the Subtropical Indian Ocean Dipole (SIOD). The observed December-March 1979-2014 Southern Africa precipitation during the four ENSO and SIOD phase combinations suggests that the phase of the SIOD can disrupt or enhance the Southern Africa precipitation response to ENSO. Here, we use a large ensemble of model simulations driven by global SST and ENSO-only SST to test whether the SIOD modifies the relationship between Southern Africa precipitation and ENSO. Since ENSO-based precipitation forecasts are used extensively over Southern Africa, an improved understanding of how other modes of SST variability modulate the regional response to ENSO is important. ENSO, in the absence of the SIOD, forces an equivalent barotropic Rossby wave over Southern Africa that modifies the regional mid-tropospheric vertical motions and precipitation anomalies. El Niño (La Niña) is related with high (low) pressure over Southern Africa that produces anomalous mid-tropospheric descent (ascent) and decreases (increases) in precipitation relative to average. When the SIOD and ENSO are in opposite phases, the SIOD compliments the ENSO-related atmospheric response over Southern Africa by strengthening the regional equivalent barotropic Rossby wave, anomalous mid-tropospheric vertical motions and anomalous precipitation. By contrast, when the SIOD and ENSO are in the same phase, the SIOD disrupts the ENSO-related atmospheric response over Southern Africa by weakening the regional equivalent barotropic Rossby wave, anomalous mid-tropospheric vertical motions and anomalous precipitation.

  3. Climate Regimes, El Niño-Southern Oscillation, and Meningococcal Meningitis Epidemics

    PubMed Central

    Oluwole, Olusegun Steven Ayodele

    2015-01-01

    Meningococcal meningitis is a major public health problem that kills thousands annually in Africa, Europe, North, and South America. Occurrence is, however, highest during the dry seasons in Sahel Africa. Interannual changes in precipitation correlate with interannual changes in El Niño-Southern Oscillation (ENSO), while interdecadal changes in precipitation correlate with Pacific Decadal Oscillation (PDO). The objective of the study was to determine if there is spectral coherence of seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis in Sahel, Central, and East Africa with interannual and interdecadal changes of PDO and ENSO. Time series were fitted to occurrence of meningococcal meningitis in Sahel, Central, and East Africa, to indices of precipitation anomalies in the Sahel, and to indices of ENSO and PDO anomalies. Morlet wavelet was used to transform the time series to frequency-time domain. Wavelet spectra and coherence analyses were performed. Occurrence of meningococcal meningitis showed seasonal, interannual, and interdecadal changes. The magnitude of occurrence was higher during warm climate regime, and strong El Niños. Spectra coherence of interannual and interdecadal changes of ENSO and PDO with occurrence of meningococcal meningitis in Sahel, Central, and East Africa were significant at p < 0.0001. Precipitation in Sahel was low during warm climate regimes. Spectra coherence of changes in precipitation in Sahel with ENSO was significant at p < 0.0001. ENSO and PDO are determinants of the seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis. Public health management of epidemics of meningococcal meningitis should include forecast models of changes in ENSO to predict periods of low precipitation, which initiate occurrence. PMID:26284234

  4. Climate Regimes, El Niño-Southern Oscillation, and Meningococcal Meningitis Epidemics.

    PubMed

    Oluwole, Olusegun Steven Ayodele

    2015-01-01

    Meningococcal meningitis is a major public health problem that kills thousands annually in Africa, Europe, North, and South America. Occurrence is, however, highest during the dry seasons in Sahel Africa. Interannual changes in precipitation correlate with interannual changes in El Niño-Southern Oscillation (ENSO), while interdecadal changes in precipitation correlate with Pacific Decadal Oscillation (PDO). The objective of the study was to determine if there is spectral coherence of seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis in Sahel, Central, and East Africa with interannual and interdecadal changes of PDO and ENSO. Time series were fitted to occurrence of meningococcal meningitis in Sahel, Central, and East Africa, to indices of precipitation anomalies in the Sahel, and to indices of ENSO and PDO anomalies. Morlet wavelet was used to transform the time series to frequency-time domain. Wavelet spectra and coherence analyses were performed. Occurrence of meningococcal meningitis showed seasonal, interannual, and interdecadal changes. The magnitude of occurrence was higher during warm climate regime, and strong El Niños. Spectra coherence of interannual and interdecadal changes of ENSO and PDO with occurrence of meningococcal meningitis in Sahel, Central, and East Africa were significant at p < 0.0001. Precipitation in Sahel was low during warm climate regimes. Spectra coherence of changes in precipitation in Sahel with ENSO was significant at p < 0.0001. ENSO and PDO are determinants of the seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis. Public health management of epidemics of meningococcal meningitis should include forecast models of changes in ENSO to predict periods of low precipitation, which initiate occurrence.

  5. Influence of El Niño Southern Oscillation on global scale flood and drought risk

    NASA Astrophysics Data System (ADS)

    Ward, Philip; Jongman, Brenden; Veldkamp, Ted; Kummu, Matti; Dettinger, Michael; Sperna Weiland, Frederiek; Winsemius, Hessel

    2015-04-01

    In this contribution we demonstrate the influence of climate variability on flood and drought risk. El Niño Southern Oscillation (ENSO) is the most dominant interannual signal of climate variability, and has a strong influence on climate over large parts of the world. In turn, it strongly influences many extreme hazards and their resulting socioeconomic impacts, including economic damage and loss of life. Whilst ENSO is known to influence hydrology in many regions of the world, little is known about its influence on the socioeconomic impacts of either floods or droughts. To address this, we developed new modelling frameworks to assess ENSO's influence on both flood risk and drought risk at the global scale. Flood risk is expressed in terms of annual expected damages and annual affected population. Drought risk is expressed in terms of water shortage and water stress. We show that ENSO exerts strong and widespread influences on flood hazard and risk, as well as drought risk. Reliable anomalies of flood risk exist during El Niño or La Niña years, or both, in basins spanning almost half (44%) of Earth's land surface. Significant correlations between ENSO and water scarcity conditions were found for 43% of the global land area, meaning that more than half of the global population is effectively affected by water shortage and stress events under 2010 conditions. Our results show that climate variability, especially from ENSO, should be incorporated into disaster risk analyses and policies. Since ENSO has some predictive skill with lead times of several seasons, the findings suggest the possibility to develop probabilistic risk projections, which could be used for improved disaster planning. The findings are also relevant in the context of climate change. If the frequency and/or magnitude of ENSO events were to change in the future, this could imply changes in flood and drought risk variations across almost half of the world's terrestrial regions. The flood part of

  6. A RETROSPECTIVE ANALYSIS OF THE EFFECT OF EL NINO-SOUTHERN OSCILLATION EVENTS ON COASTAL WATER QUALITY IN SOUTHWEST FLORIDA. (R825197)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  7. The 1997-98 El Nino Event and Related Wintertime Lightning Variations in the Southeastern United States

    NASA Technical Reports Server (NTRS)

    Goodman, S. J.; Buechler, D. E.; Knupp, K.; Driscoll, K.; McCaul, E. W.

    1999-01-01

    The El Nino Southern Oscillation (ENSO) is a climate anomaly responsible for world-wide weather impacts ranging from droughts to floods. In the United States, warm episode years are known to produce above normal rainfall along the Southeast US Gulf Coast and into the Gulf of Mexico, with the greatest response observed in the October-March period of the latest warm-episode year. The 1997-98 warm episode, notable for being the strongest event since 1982-83, presents our first opportunity to examine the response to a major ENSO event and determine the variation of wintertime thunderstorm activity in this part of the world. Due to the recent launch of a lightning sensor on NASA's Tropical Rainfall Measuring Mission (TRMM) in November 1997 and the expanded coverage of the National Lightning Detection Network (NLDN), we are able to examine such year-to-year changes in lightning activity with far greater detail than ever before.

  8. The 1997-98 El-Nino Event and Related Lightning Variations in the Southeastern United States

    NASA Technical Reports Server (NTRS)

    Buechler, D. E.; Goodman, S. J.; McCaul, E. W.; Knupp, K.

    1999-01-01

    The El Nino Southern Oscillation (ENSO) is a climate anomaly responsible for world-wide weather impacts ranging from droughts to floods. In the United States, warm episode years are known to produce above normal rainfall along the Southeast US Gulf Coast and into the Gulf of Mexico, with the greatest response observed in the October-March period of the current warm-episode year. The 1997-98 warm episode, notable for being the strongest event since 1982-83, presents our first opportunity to examine the response to a major ENSO event and determine the variation of wintertime thunderstorm activity in this part of the world. Due to the recent launch of a lightning sensor on NASA's Tropical Rainfall Measuring Mission (TRMM) in November 1997 and the expanded coverage of the National Lightning Detection Network (NLDN), we are able to examine such year-to-year changes in lightning activity with far greater detail than ever before.

  9. El Niño-Southern oscillation variability from the late cretaceous marca shale of California

    USGS Publications Warehouse

    Davies, Andrew; Kemp, Alan E.S.; Weedon, Graham P.; Barron, John A.

    2012-01-01

    Changes in the possible behavior of El Niño–Southern Oscillation (ENSO) with global warming have provoked interest in records of ENSO from past “greenhouse” climate states. The latest Cretaceous laminated Marca Shale of California permits a seasonal-scale reconstruction of water column flux events and hence interannual paleoclimate variability. The annual flux cycle resembles that of the modern Gulf of California with diatoms characteristic of spring upwelling blooms followed by silt and clay, and is consistent with the existence of a paleo–North American Monsoon that brought input of terrigenous sediment during summer storms and precipitation runoff. Variation is also indicated in the extent of water column oxygenation by differences in lamina preservation. Time series analysis of interannual variability in terrigenous sediment and diatom flux and in the degree of bioturbation indicates strong periodicities in the quasi-biennial (2.1–2.8 yr) and low-frequency (4.1–6.3 yr) bands both characteristic of ENSO forcing, as well as decadal frequencies. This evidence for robust Late Cretaceous ENSO variability does not support the theory of a “permanent El Niño,” in the sense of a continual El Niño–like state, in periods of warmer climate.

  10. Impacts of El Niño Southern Oscillation on the global yields of major crops.

    PubMed

    Iizumi, Toshichika; Luo, Jing-Jia; Challinor, Andrew J; Sakurai, Gen; Yokozawa, Masayuki; Sakuma, Hirofumi; Brown, Molly E; Yamagata, Toshio

    2014-05-15

    The monitoring and prediction of climate-induced variations in crop yields, production and export prices in major food-producing regions have become important to enable national governments in import-dependent countries to ensure supplies of affordable food for consumers. Although the El Niño/Southern Oscillation (ENSO) often affects seasonal temperature and precipitation, and thus crop yields in many regions, the overall impacts of ENSO on global yields are uncertain. Here we present a global map of the impacts of ENSO on the yields of major crops and quantify its impacts on their global-mean yield anomalies. Results show that El Niño likely improves the global-mean soybean yield by 2.1-5.4% but appears to change the yields of maize, rice and wheat by -4.3 to +0.8%. The global-mean yields of all four crops during La Niña years tend to be below normal (-4.5 to 0.0%). Our findings highlight the importance of ENSO to global crop production.

  11. El Niño Southern Oscillation and leptospirosis outbreaks in New Caledonia.

    PubMed

    Weinberger, Daniel; Baroux, Noémie; Grangeon, Jean-Paul; Ko, Albert I; Goarant, Cyrille

    2014-04-01

    Leptospirosis is an important cause of seasonal outbreaks in New Caledonia and the tropics. Using time series derived from high-quality laboratory-based surveillance from 2000-2012, we evaluated whether climatic factors, including El Niño Southern Oscillation (ENSO) and meteorological conditions allow for the prediction of leptospirosis outbreaks in New Caledonia. We found that La Niña periods are associated with high rainfall, and both of these factors were in turn, temporally associated with outbreaks of leptospirosis. The sea surface temperature in El Niño Box 4 allowed forecasting of leptospirosis outbreaks four months into the future, a time lag allowing public health authorities to increase preparedness. To our knowledge, our observations in New Caledonia are the first demonstration that ENSO has a strong association with leptospirosis. This association should be tested in other regions in the South Pacific, Asia or Latin America where ENSO may drive climate variability and the risk for leptospirosis outbreaks.

  12. El Niño/Southern Oscillation response to global warming

    PubMed Central

    Latif, M.; Keenlyside, N. S.

    2009-01-01

    The El Niño/Southern Oscillation (ENSO) phenomenon, originating in the Tropical Pacific, is the strongest natural interannual climate signal and has widespread effects on the global climate system and the ecology of the Tropical Pacific. Any strong change in ENSO statistics will therefore have serious climatic and ecological consequences. Most global climate models do simulate ENSO, although large biases exist with respect to its characteristics. The ENSO response to global warming differs strongly from model to model and is thus highly uncertain. Some models simulate an increase in ENSO amplitude, others a decrease, and others virtually no change. Extremely strong changes constituting tipping point behavior are not simulated by any of the models. Nevertheless, some interesting changes in ENSO dynamics can be inferred from observations and model integrations. Although no tipping point behavior is envisaged in the physical climate system, smooth transitions in it may give rise to tipping point behavior in the biological, chemical, and even socioeconomic systems. For example, the simulated weakening of the Pacific zonal sea surface temperature gradient in the Hadley Centre model (with dynamic vegetation included) caused rapid Amazon forest die-back in the mid-twenty-first century, which in turn drove a nonlinear increase in atmospheric CO2, accelerating global warming. PMID:19060210

  13. El Niño Southern Oscillation and Leptospirosis Outbreaks in New Caledonia

    PubMed Central

    Weinberger, Daniel; Baroux, Noémie; Grangeon, Jean-Paul; Ko, Albert I.; Goarant, Cyrille

    2014-01-01

    Leptospirosis is an important cause of seasonal outbreaks in New Caledonia and the tropics. Using time series derived from high-quality laboratory-based surveillance from 2000–2012, we evaluated whether climatic factors, including El Niño Southern Oscillation (ENSO) and meteorological conditions allow for the prediction of leptospirosis outbreaks in New Caledonia. We found that La Niña periods are associated with high rainfall, and both of these factors were in turn, temporally associated with outbreaks of leptospirosis. The sea surface temperature in El Niño Box 4 allowed forecasting of leptospirosis outbreaks four months into the future, a time lag allowing public health authorities to increase preparedness. To our knowledge, our observations in New Caledonia are the first demonstration that ENSO has a strong association with leptospirosis. This association should be tested in other regions in the South Pacific, Asia or Latin America where ENSO may drive climate variability and the risk for leptospirosis outbreaks. PMID:24743322

  14. Estimates of the water vapor climate feedback during the El Niño Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Dessler, A. E.; Wong, S.

    2009-12-01

    We have estimated the strength of the water vapor feedback by analyzing the changes in tropospheric specific humidity during El Niño Southern Oscillation (ENSO) cycles. We do this analysis in climate models and in two reanalysis products, the European Center for Medium-Range Weather Forecasts Reanalysis (ERA40) and the NASA Modern Era Retrospective-analysis for Research and Applications (MERRA). The water vapor feedback during ENSO in the models ranges from 1.4 to 3.9 W/m^2/K, and in the ERA40 and MERRA it is 3.7 and 4.7 W/m^2/K, respectively. Taken as a group, these values are higher than previous estimates of the water vapor feedback in response to century-long global warming, suggesting that the ENSO water vapor feedback may be stronger than the water vapor feedback in response to long-term global warming. We also examine the reason for the large spread in the ENSO-driven water vapor feedback among the models and between the models and the reanalyses. We show that the spread is not related to the variation in the simulation of water vapor, but are due to differing estimates of extratropical surface temperature variations during ENSO. The models and the reanalyses show a consistent relationship between the variations in the tropical surface temperature over an ENSO cycle and the radiative response to the associated changes in q.

  15. Reconstructing El Niño-Southern Oscillation (ENSO) from high-resolution palaeoarchives

    NASA Astrophysics Data System (ADS)

    Gergis, Joëlle; Braganza, Karl; Fowler, Anthony; Mooney, Scott; Risbey, James

    2006-10-01

    El Niño-Southern Oscillation (ENSO) is one of the most important coupled ocean-atmospheric phenomena to cause global climate variability on interannual timescales. Efforts to understand recent, apparently anomalous ENSO behaviour are hampered by the phenomenon's unstable (non-stationary) nature and the limitations inherent in palaeoclimate records. In this paper, the complexities associated with isolating ENSO signals in observational and palaeoclimate records are reviewed. The utility and limitations of high-resolution (tree-ring, coral, speleothems, ice and documentary) proxy data for ENSO reconstruction are discussed. To overcome the regional biases contained within each palaeoclimatic source, it is necessary to compare complementary signals derived from multiple proxy climate records. To date, there have been limited attempts to reconstruct large-scale ENSO using these multiproxy methodologies. A critique of the complexities associated with previous approaches of reconstructing discrete ENSO events and atmospheric/oceanic indices is provided. Abundant potential remains to better characterise teleconnection patterns, propagation signatures and non-stationary features of large-scale ENSO behaviour. If key uncertainties in ENSO dynamics (such as the response of extreme events to natural/human forcing) are to be adequately assessed, then complementary attempts must be made to model the historic synoptic conditions with apparent changes in reconstructed indices. Copyright

  16. The El Niño Southern Oscillation and malaria epidemics in South America

    NASA Astrophysics Data System (ADS)

    Gagnon, Alexandre S.; Smoyer-Tomic, Karen E.; Bush, Andrew B.

    2002-05-01

    A better understanding of the relationship between the El Niño Southern Oscillation (ENSO), the climatic anomalies it engenders, and malaria epidemics could help mitigate the world-wide increase in incidence of this mosquito-transmitted disease. The purpose of this paper is to assess the possibility of using ENSO forecasts for improving malaria control. This paper analyses the relationship between ENSO events and malaria epidemics in a number of South American countries (Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela). A statistically significant relationship was found between El Niño and malaria epidemics in Colombia, Guyana, Peru, and Venezuela. We demonstrate that flooding engenders malaria epidemics in the dry coastal region of northern Peru, while droughts favor the development of epidemics in Colombia and Guyana, and epidemics lag a drought by 1 year in Venezuela. In Brazil, French Guiana, and Ecuador, where we did not detect an ENSO/malaria signal, non-climatic factors such as insecticide sprayings, variation in availability of anti-malaria drugs, and population migration are likely to play a stronger role in malaria epidemics than ENSO-generated climatic anomalies. In some South American countries, El Niño forecasts show strong potential for informing public health efforts to control malaria.

  17. An analysis of high cloud variability: imprints from the El Niño-Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Li, King-Fai; Su, Hui; Mak, Sze-Ning; Chang, Tiffany M.; Jiang, Jonathan H.; Norris, Joel R.; Yung, Yuk L.

    2016-03-01

    Using data from the International Satellite Cloud Climatology Project (ISCCP), we examine how near-global (60°N-60°S) high cloud fraction varies over time in the past three decades. Our focus is on identifying dominant modes of variability and associated spatial patterns, and how they are related to sea surface temperature. By performing the principal component analysis, we find that the first two principal modes of high cloud distribution show strong imprints of the two types of El Niño-Southern Oscillation (ENSO)—the canonical ENSO and the ENSO Modoki. Comparisons between ISCCP data and 14 models from the Atmospheric Model Intercomparison Project Phase 5 (AMIP5) show that models simulate the spatial pattern and the temporal variations of high cloud fraction associated with the canonical ENSO very well but the magnitudes of the canonical ENSO vary among the models. Furthermore, the multi-model mean of the second principal mode in the AMIP5 simulations appears to capture the temporal behavior of the second mode but individual AMIP5 models show large discrepancies in capturing observed temporal variations. A new metric, defined by the relative variances of the first two principal components, suggests that most of the AMIP5 models overestimate the second principal mode of high clouds.

  18. The Role of Tide-induced Vertical Mixing in Modulating the Decadal Change of El Nino

    NASA Astrophysics Data System (ADS)

    Peng, S.; Chen, S.

    2014-12-01

    The El Nino-South Oscillation (ENSO) is an important phenomenon occurring every 3-7 years in the tropical Pacific Ocean and plays a role in the regional and global climate changeThe conventional El Nino is characterized by the maximum sea surface temperature (SST) anomalies located at the eastern tropical Pacific. Recent studies have suggested that a different type of El Nino, characterized by a westward shift of the maximum SST anomalies to the central Pacific and thus called central Pacific (CP) El Nino, has occurred more frequently since 1990s and has different weather /climate impacts on the countries surrounding the Pacific However, the mechanism of this decadal change of El Nino is still elusive. In this study, we first report evidence that the tide energy has decreased over the past several decades as observed by the tidal stations at western Pacific, which is consistent with the weakening of the lunar tidal forcing during the same period as determined by the relative position of the moon, the earth and the sun. We then hypothesize that the decrease of tidal energy is responsible for the more frequent occurrence of CP El Nino through the role of tidal mixing in the ocean during the past several decades. The GFDL coupled model is employed to test this hypothesis through sensitivity experiments on the change of tidal mixing. The experimental results as well as the corresponding analysis demonstrate that the weakening of the tidal mixing does lead to the more frequent occurrence of CP El Nino. This finding makes a significant contribution to the understanding of the mechanism of decadal variability of El Nino observed in recent decades and the future projection of the decadal change of El Nino.

  19. On the interannual variability of ocean temperatures around South Georgia, Southern Ocean: Forcing by El Niño/Southern Oscillation and the Southern Annular Mode

    NASA Astrophysics Data System (ADS)

    Meredith, Michael P.; Murphy, Eugene J.; Hawker, Elizabeth J.; King, John C.; Wallace, Margaret I.

    2008-09-01

    The ocean around South Georgia, in the southwest Atlantic sector of the Southern Ocean, is highly productive, with large stocks of Antarctic krill supporting extensive colonies of marine- and land-based predators. The operation of this ecosystem is strongly influenced by physical forcings, and the role of the El Niño/Southern Oscillation (ENSO) phenomenon has been highlighted previously. Here we examine in detail the transmission of ENSO signals to South Georgia, and investigate other sources of interannual variability. ENSO variability generates anomalies in sea-surface temperature (SST) across the South Pacific via atmospheric teleconnections. These anomalies are advected toward South Georgia within the Antarctic Circumpolar Current (ACC), and previous studies have focussed on long-period advection (order of 2-3 years) from the southwest Pacific. We observe here, however, that the region close to the Antarctic Peninsula in the southeast Pacific is especially susceptible to ENSO forcing via anomalous meridional winds; this induces SST anomalies that are advected to South Georgia on a much more rapid timescale (order 5-6 months). The phasing of these teleconnections is such that anomalies that reach the southeast Pacific from farther west tend to be reinforced here by air-sea-ice interaction. We also find an important role for the Southern Annular Mode (SAM) in determining SST variability at South Georgia. This is a circumpolar mode of climate variability, and thus can readily influence local SST at South Georgia directly. The SAM is, however, not perfectly zonally symmetric, and (like ENSO) has a particular impact on meridional winds in the southeast Pacific. The average timescale for SAM influence on South Georgia SST is shorter than that of ENSO, since it includes a stronger component of direct local forcing. The South Georgia ecosystem is not self-sustaining, with import of krill from breeding and nursery grounds upstream in the ACC being important. We

  20. Detection of Characteristic Precipitation Anomaly Patterns of El Nino / La Nina in Time- variable Gravity Fields by GRACE

    NASA Astrophysics Data System (ADS)

    Heki, K.; Morishita, Y.

    2007-12-01

    GRACE (Gravity Recovery and Climate Experiment) satellites, launched in March 2002, have been mapping monthly gravity fields of the Earth, allowing us to infer changes in surface mass, e.g. water and ice. Past findings include the ice mass loss in southern Greenland (Luthcke et al., 2006) and its acceleration in 2004 (Velicogna and Wahr, 2006), crustal dilatation by the 2004 Sumatra Earthquake (Han et al., 2006) and the postseismic movement of water in mantle (Ogawa and Heki, 2007). ENSO (El Nino and Southern Oscillation) brings about global climate impacts, together with its opposite phenomenon, La Nina. Ropelewski and Halpert (1987) showed typical precipitation patterns in ENSO years; characteristic regional-scale precipitation anomalies occur in India, tropical and southern Africa and South America. Nearly opposite precipitation anomalies are shown to occur in La Nina years (Ropelewski and Halpert, 1988). Here we report the detection of such precipitation anomaly patterns in the GRACE monthly gravity data 2002 - 2007, which includes both La Nina (2005 fall - 2006 spring) and El Nino (2006 fall - 2007 spring) periods. We modeled the worldwide gravity time series with constant trends and seasonal changes, and extracted deviations of gravity values at two time epochs, i.e. February 2006 and 2007, and converted them into the changes in equivalent surface water mass. East Africa showed negative gravity deviation (-20.5 cm in water) in 2006 February (La Nina), which reversed to positive (18.7 cm) in 2007 February (El Nino). Northern and southern parts of South America also showed similar see-saw patterns. Such patterns closely resemble to those found meteorologically (Ropelewski and Halpert, 1987; 1988), suggesting the potential of GRACE as a sensor of inter-annual precipitation anomalies through changes in continental water storage. We performed numerical simulations of soil moisture changes at grid points in land area incorporating the CMAP precipitation data, NCEP

  1. Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - VIII. VW Hyi in outburst observed with the Southern African Large Telescope

    NASA Astrophysics Data System (ADS)

    Woudt, P. A.; Warner, B.; O'Donoghue, D.; Buckley, D. A. H.; Still, M.; Romero-Colemero, E.; Väisänen, P.

    2010-01-01

    We analyse four light curves obtained at high time resolution (~0.1s) with the 11-m Southern African Large Telescope, at the ends of two normal outbursts and one superoutburst of the dwarf nova VW Hyi. All of these contain at least some Dwarf Nova Oscillations (DNOs), which, when at their highest amplitudes, are seen in unprecedented detail. In addition to the expected DNOs with periods >20 s, we find a previously unknown modulation at 13.39s, but none at shorter periods. The various DNOs and their interaction with the longer period quasi-periodic oscillations are interpreted in terms of the model of magnetically controlled flow from an accretion disc proposed earlier in this series of papers. Our observations include rare DNOs very late in outburst; we find that the fundamental period does not increase beyond ~90 s, which is the same value that the independent `longer period DNOs' converge on. Based on observations made with the Southern African Large Telescope (SALT). E-mail: Patrick.Woudt@uct.ac.za

  2. Strong influence of El Niño Southern Oscillation on flood risk around the world

    PubMed Central

    Ward, Philip J.; Jongman, Brenden; Kummu, Matti; Dettinger, Michael D.; Sperna Weiland, Frederiek C.; Winsemius, Hessel C.

    2014-01-01

    El Niño Southern Oscillation (ENSO) is the most dominant interannual signal of climate variability and has a strong influence on climate over large parts of the world. In turn, it strongly influences many natural hazards (such as hurricanes and droughts) and their resulting socioeconomic impacts, including economic damage and loss of life. However, although ENSO is known to influence hydrology in many regions of the world, little is known about its influence on the socioeconomic impacts of floods (i.e., flood risk). To address this, we developed a modeling framework to assess ENSO’s influence on flood risk at the global scale, expressed in terms of affected population and gross domestic product and economic damages. We show that ENSO exerts strong and widespread influences on both flood hazard and risk. Reliable anomalies of flood risk exist during El Niño or La Niña years, or both, in basins spanning almost half (44%) of Earth’s land surface. Our results show that climate variability, especially from ENSO, should be incorporated into disaster-risk analyses and policies. Because ENSO has some predictive skill with lead times of several seasons, the findings suggest the possibility to develop probabilistic flood-risk projections, which could be used for improved disaster planning. The findings are also relevant in the context of climate change. If the frequency and/or magnitude of ENSO events were to change in the future, this finding could imply changes in flood-risk variations across almost half of the world’s terrestrial regions. PMID:25331867

  3. Analysis of the Non-Linearity of El Niño Southern Oscillation Teleconnections

    NASA Astrophysics Data System (ADS)

    Frauen, Claudia; Dommenget, Dietmar; Rezny, Michael; Wales, Scott

    2014-05-01

    The El Niño Southern Oscillation (ENSO) has significant variations and non-linearities in its pattern and strength. ENSO events are shifted along the equator, with some located in the central Pacific (CP) and others in the east Pacific (EP). To study how these variations are reflected in global ENSO teleconnections we analyze observations and idealized atmospheric general circulation model (AGCM) simulations. Clear non-linearities exist in observed teleconnections of sea level pressure (SLP) and precipitation. However, it is difficult to distinguish if these are caused by the different signs, strengths or spatial patterns of events (strong El Niño events mostly being EP events and strong La Niña events mostly being CP events) or by combinations of these. Therefore, sensitivity experiments are performed with an AGCM forced with idealized EP and CP ENSO sea surface temperature (SST) patterns with varying signs and strengths. It can be shown that in general the response is stronger for warm events than for cold events and the teleconnections shift following the SST anomaly patterns. EP events show stronger non-linearities than CP events. The non-linear responses to ENSO events can be explained as a combination of non-linear responses to a linear ENSO (fixed pattern but varying signs and strengths) and a linear response to a non-linear ENSO (varying patterns). Any observed event is a combination of these aspects. While in most tropical regions these add up leading to stronger non-linear responses than expected from the single components, in some regions they cancel each other resulting in little overall non-linearity. This leads to strong regional differences in ENSO teleconnections.

  4. Stratospheric geoengineering impacts on El Niño/Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Gabriel, C. J.; Robock, A.

    2015-10-01

    To examine the impact of proposed stratospheric geoengineering schemes on the amplitude and frequency of El Niño/Southern Oscillation (ENSO) variations we examine climate model simulations from the Geoengineering Model Intercomparison Project (GeoMIP) G1-G4 experiments. Here we compare tropical Pacific behavior under anthropogenic global warming (AGW) using several scenarios: an instantaneous quadrupling of the atmosphere's CO2 concentration, a 1 % annual increase in CO2 concentration, and the representative concentration pathway resulting in 4.5 W m-2 radiative forcing at the end of the 21st century, the Representative Concentration Pathway 4.5 scenario, with that under G1-G4 and under historical model simulations. Climate models under AGW project relatively uniform warming across the tropical Pacific over the next several decades. We find no statistically significant change in ENSO frequency or amplitude under stratospheric geoengineering as compared with those that would occur under ongoing AGW, although the relative brevity of the G1-G4 simulations may have limited detectability of such changes. We also find that the amplitude and frequency of ENSO events do not vary significantly under either AGW scenarios or G1-G4 from the variability found within historical simulations or observations going back to the mid-19th century. Finally, while warming of the Niño3.4 region in the tropical Pacific is fully offset in G1 and G2 during the 40-year simulations, the region continues to warm significantly in G3 and G4, which both start from a present-day climate.

  5. Strong influence of El Niño Southern Oscillation on flood risk around the world.

    PubMed

    Ward, Philip J; Jongman, Brenden; Kummu, Matti; Dettinger, Michael D; Sperna Weiland, Frederiek C; Winsemius, Hessel C

    2014-11-01

    El Niño Southern Oscillation (ENSO) is the most dominant interannual signal of climate variability and has a strong influence on climate over large parts of the world. In turn, it strongly influences many natural hazards (such as hurricanes and droughts) and their resulting socioeconomic impacts, including economic damage and loss of life. However, although ENSO is known to influence hydrology in many regions of the world, little is known about its influence on the socioeconomic impacts of floods (i.e., flood risk). To address this, we developed a modeling framework to assess ENSO's influence on flood risk at the global scale, expressed in terms of affected population and gross domestic product and economic damages. We show that ENSO exerts strong and widespread influences on both flood hazard and risk. Reliable anomalies of flood risk exist during El Niño or La Niña years, or both, in basins spanning almost half (44%) of Earth's land surface. Our results show that climate variability, especially from ENSO, should be incorporated into disaster-risk analyses and policies. Because ENSO has some predictive skill with lead times of several seasons, the findings suggest the possibility to develop probabilistic flood-risk projections, which could be used for improved disaster planning. The findings are also relevant in the context of climate change. If the frequency and/or magnitude of ENSO events were to change in the future, this finding could imply changes in flood-risk variations across almost half of the world's terrestrial regions.

  6. Annual flood sensitivities to El Niño-Southern Oscillation at the global scale

    USGS Publications Warehouse

    Ward, Philip J.; Eisner, S.; Flörke, M.; Dettinger, Michael D.; Kummu, M.

    2013-01-01

    Floods are amongst the most dangerous natural hazards in terms of economic damage. Whilst a growing number of studies have examined how river floods are influenced by climate change, the role of natural modes of interannual climate variability remains poorly understood. We present the first global assessment of the influence of El Niño–Southern Oscillation (ENSO) on annual river floods, defined here as the peak daily discharge in a given year. The analysis was carried out by simulating daily gridded discharges using the WaterGAP model (Water – a Global Assessment and Prognosis), and examining statistical relationships between these discharges and ENSO indices. We found that, over the period 1958–2000, ENSO exerted a significant influence on annual floods in river basins covering over a third of the world's land surface, and that its influence on annual floods has been much greater than its influence on average flows. We show that there are more areas in which annual floods intensify with La Niña and decline with El Niño than vice versa. However, we also found that in many regions the strength of the relationships between ENSO and annual floods have been non-stationary, with either strengthening or weakening trends during the study period. We discuss the implications of these findings for science and management. Given the strong relationships between ENSO and annual floods, we suggest that more research is needed to assess relationships between ENSO and flood impacts (e.g. loss of lives or economic damage). Moreover, we suggest that in those regions where useful relationships exist, this information could be combined with ongoing advances in ENSO prediction research, in order to provide year-to-year probabilistic flood risk forecasts.

  7. Multiproxy reconstructions of the El Niño-Southern Oscillation: progress and challenges (Invited)

    NASA Astrophysics Data System (ADS)

    Emile-Geay, J.; Comboul, M.; Guillot, D.; Cobb, K.; Evans, M. N.; Correge, T.; Carré, M.; Driscoll, R. E.; Elliot, M.; Mcgregor, H. V.; Tudhope, A. W.; Cole, J. E.; Rajaratnam, B.

    2013-12-01

    A major source of uncertainty in climate model projections of the twenty-first century is the evolution of the tropical Pacific ocean/atmosphere system, home to the El Niño-Southern Oscillation (ENSO), the dominant mode of global climate variability on interannual to decadal timescales. Indeed, there is no consensus among models as to how its mean state, amplitude, frequency, spatial structure, and atmospheric teleconnections will evolve with continued anthropogenic forcing. Since the instrumental record is too short to usefully characterize low-frequency climate variability, one must turn to the paleoclimate record for a longer view. Because each paleo archive is limited by its own sets of errors and biases, it is generally believed that a multiproxy approach holds the best promise in estimating past climate variations. However, multiproxy-based estimates of past tropical Pacific climate, in particular ENSO, are hindered by three main challenges: - weighing information from different proxy types - treating uncertainties due to chronological errors - treating uncertainties due to the statistical calibration process These sources of uncertainty complicate the interpretation of multiproxy reconstructions, prompting inquiries as to whether reconstructed variations reflect a true change in the phenomenon of interest (here, ENSO), or merely a change in the relative contribution of different observations, sensors, archives, observing sites, or statistical artifacts due to the extremely illl-posed nature of the multivariate estimation problem. In this presentation, I will synthesize lessons gleaned from recent multiproxy studies I have led - univariate and multivariate, coral-only and multiproxy, and explicitly quantifying age errors. The comparison will illustrate how the challenges identified above play out in different settings over the last millennium and Holocene, and how the resulting uncertainties may be quantified and communicated to end-users of such

  8. Strong influence of El Niño Southern Oscillation on flood risk around the world

    USGS Publications Warehouse

    Ward, Philip J.; Jongman, B; Kummu, M.; Dettinger, Mike; Sperna Weiland, F.C; Winsemius, H.C

    2014-01-01

    El Niño Southern Oscillation (ENSO) is the most dominant interannual signal of climate variability and has a strong influence on climate over large parts of the world. In turn, it strongly influences many natural hazards (such as hurricanes and droughts) and their resulting socioeconomic impacts, including economic damage and loss of life. However, although ENSO is known to influence hydrology in many regions of the world, little is known about its influence on the socioeconomic impacts of floods (i.e., flood risk). To address this, we developed a modeling framework to assess ENSO’s influence on flood risk at the global scale, expressed in terms of affected population and gross domestic product and economic damages. We show that ENSO exerts strong and widespread influences on both flood hazard and risk. Reliable anomalies of flood risk exist during El Niño or La Niña years, or both, in basins spanning almost half (44%) of Earth’s land surface. Our results show that climate variability, especially from ENSO, should be incorporated into disaster-risk analyses and policies. Because ENSO has some predictive skill with lead times of several seasons, the findings suggest the possibility to develop probabilistic flood-risk projections, which could be used for improved disaster planning. The findings are also relevant in the context of climate change. If the frequency and/or magnitude of ENSO events were to change in the future, this finding could imply changes in flood-risk variations across almost half of the world’s terrestrial regions.

  9. El Niño-Southern Oscillation Impacts on Winter Vegetable Production in Florida*.

    NASA Astrophysics Data System (ADS)

    Hansen, James W.; Jones, James W.; Kiker, Clyde F.; Hodges, Alan W.

    1999-01-01

    Florida's mild winters allow the state to play a vital role in supplying fresh vegetables for U.S. consumers. Producers also benefit from premium prices when low temperatures prevent production in most of the country. This study characterizes the influence of the El Niño-Southern Oscillation (ENSO) on the Florida vegetable industry using statistical analysis of the response of historical crop (yield, prices, production, and value) and weather variables (freeze hazard, temperatures, rainfall, and solar radiation) to ENSO phase and its interaction with location and time of year. Annual mean yields showed little evidence of response to ENSO phase and its interaction with location. ENSO phase and season interacted to influence quarterly yields, prices, production, and value. Yields (tomato, bell pepper, sweet corn, and snap bean) were lower and prices (bell pepper and snap bean) were higher in El Niño than in neutral or La Niña winters. Production and value of tomatoes were higher in La Niña winters. The yield response can be explained by increased rainfall, reduced daily maximum temperatures, and reduced solar radiation in El Niño winters. Yield and production of winter vegetables appeared to be less responsive to ENSO phase after 1980; for tomato and bell pepper, this may be due to improvements in production technology that mitigate problems associated with excess rainfall. Winter yield and price responses to El Niño events have important implications for both producers and consumers of winter vegetables, and suggest opportunities for further research.

  10. Influence of El Niño Southern Oscillation on global hydropower production

    NASA Astrophysics Data System (ADS)

    Ng, Jia Yi; Turner, Sean; Galelli, Stefano

    2016-04-01

    Hydropower contributes significantly to meeting the world's energy demand, accounting for at least 16% of total electrical output. Its role as a mature and cost competitive renewable energy source is expected to become increasingly important as the world transits to a low-carbon economy. A key component of hydropower production is runoff, which is highly dependent on precipitation and other climate variables. As such, it becomes critical to understand how the drivers of climate variability impact hydropower production. One globally-important driver is the El Niño Southern Oscillation (ENSO). While it is known that ENSO influences hydrological processes, the potential value of its associated teleconnection in design related tasks has yet to be explored at the global scale. Our work seeks to characterize the impact of ENSO on global hydropower production so as to quantify the potential for increased production brought about by incorporating climate information within reservoir operating models. We study over 1,500 hydropower reservoirs - representing more than half the world's hydropower capacity. A historical monthly reservoir inflow time series is assigned to each reservoir from a 0.5 degree gridded global runoff dataset. Reservoir operating rules are designed using stochastic dynamic programming, and storage dynamics are simulated to assess performance under the climate conditions of the 20th century. Results show that hydropower reservoirs in the United States, Brazil, Argentina, Australia, and Eastern China are strongly influenced by ENSO episodes. Statistically significant lag correlations between ENSO indicators and hydropower production demonstrate predictive skill with lead times up to several months. Our work highlights the potential for using these indicators to increase the contribution of existing hydropower plants to global energy supplies.

  11. Investigations of the middle atmospheric thermal structure and oscillations over sub-tropical regions in the Northern and Southern Hemispheres

    NASA Astrophysics Data System (ADS)

    Sharma, Som; Kumar, Prashant; Jethva, Chintan; Vaishnav, Rajesh; Bencherif, Hassan

    2016-08-01

    The temperature retrieved from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite during January 2002 to September 2015 are used in this study to delineate the differences of middle atmospheric thermal structure in the Northern Hemisphere (NH) and Southern Hemisphere (SH). Two stations namely Mt. Abu (24.59°N, 72.70°E) in NH and Reunion Island (21.11°S, 55.53°E) in SH are chosen over sub-tropical regions. Temperature climatology from SABER observations suggests that stratopause is warmer, and upper mesosphere is cooler in NH as compared to SH. Three atmospheric models are used to understand the monthly thermal structure differences for different altitudes. Moreover, semi-annual, annual and quasi-biennial oscillations are studied using Lomb Scargle Periodogram and Wavelet transform techniques. Over NH, summer and winter season are warmer (~4 K) and cooler (~3 K) respectively in stratosphere as compared to SH. It is important to note here that Mt. Abu temperature is warmer (~9 K) than Reunion Island in winter but in summer season Mt. Abu temperature is cooler in upper mesosphere and above mesosphere NH shows warming. Results show that annual oscillations are dominated in both hemisphere as compared to semi-annual and quasi-biennial oscillations. In upper mesosphere, strength of annual oscillations is substantial in NH, while semi-annual oscillations are stronger in SH. Wavelet analyses found that annual oscillations are significant in NH near mesopause, while semi-annual oscillations are strengthening in SH.

  12. Data Assimilation Into a Coupled Ocean Atmosphere Model: Application to the 1997-1998 El Nino

    NASA Technical Reports Server (NTRS)

    Lee, Tong

    1999-01-01

    As part of JPL's ocean data assimilation effort to study ocean circulation and seasonal-interannual climate variability, sea level anomaly observed by TOPEX altimeter, together with sea surface temperature and wind stress data, are assimilated into a simple coupled ocean atmosphere model of the tropical Pacific. Model-data consistency is examined. Impact of the assimilation (as initialization) on El Nino Southern Oscillation (ENSO) forecasts is evaluated. The coupled model consists of a shallow water component with two baroclinic modes, an Ekman shear layer, a simplified mixed-layer temperature equation, and a statistical atmosphere based on dominant correlations between historical surface temperature and wind stress anomaly data. The adjoins method is used to fit the coupled model to the data over various six-month periods from late 1996 to early 1998 by optimally adjusting the initial state, model parameters, and basis functions of the statistical atmosphere. On average, the coupled model can be fitted to the data to approximately within the data and representation errors (5 cm, 0.5 C, and 10 sq m/sq m for sea level, surface temperature, and pseudo wind stress anomalies, respectively). The estimated fields resemble observed spatio-temporal structure reasonably well. Hindcasts/forecasts of the 1997/1998 El Nino initialized from forced estimated ocean states and parameters are much more realistic than those simply initialized from ocean states (see figure below). In particular, the ability of the model to produce significant warming beyond the initial state is dramatically improved. Parameter estimation, which compensates for some model errors, is found to be important to obtaining better fits of the model to data and to improving forecasts.

  13. The Impact of the El Niño-Southern Oscillation and Atlantic Meridional Mode on Seasonal Atlantic Tropical Cyclone Activity

    NASA Astrophysics Data System (ADS)

    Chang, P.; Patricola, C. M.; Saravanan, R.

    2013-05-01

    The influence of the El Nino-Southern Oscillation (ENSO) on Atlantic tropical cyclone (TC) activity on the interannual timescale is well understood, with El Niño (La Niña) inhibiting (promoting) TC activity through enhanced (reduced) vertical wind shear in the Atlantic main development region (MDR). The switch from relatively inactive to active Atlantic TC seasons in the mid-1990's has highlighted the relationship of Atlantic TC activity to interannual to decadal modes of Atlantic climate variability, including the Atlantic Multidecadal Oscillation (AMO) and the Atlantic Meridional Mode (AMM). This study investigates the influence of concurrent strong (exceeding the 90th percentile) positive and negative phases of ENSO and the AMM/AMO on seasonal Atlantic TC activity using a 27-km resolution regional climate model that represents the observed 1980-2000 interannual variability of Atlantic accumulated cyclone energy (ACE; 104 kt2) with a correlation of R=0.58 when observed Atlantic and eastern tropical Pacific sea surface temperature (SST) and lateral boundary conditions (LBCs) are prescribed. Experiments are designed by forcing the model with a strong El Niño or La Niña by prescribing LBCs and eastern tropical Pacific SST of 1987 and 1999 respectively, in combination with strongly positive, neutral/weakly positive, and strongly negative phases of the AMM through prescribed Atlantic SST of 2005, 1987 or 1999, and 1984, respectively. Two ensembles of each experiment are run. During the strong El Niño, simulated Atlantic ACE is weaker than the simulated 1980-2000 mean of 112 regardless of the AMM phase. The ACE changes relatively little between the negative (48) and neutral (59) AMM, but increases moderately between the neutral and positive (87) AMM during the El Niño. This, together with the response in MDR vertical wind shear suggests that the threshold MDR shear for TC suppression occurs between the neutral and positive AMM phase during an El Niño. During the

  14. Extended-range forecast of spring rainfall in southern China based on the Madden-Julian Oscillation

    NASA Astrophysics Data System (ADS)

    Li, Wenkai; Hsu, Pang-chi; He, Jinhai; Zhu, Zhiwei; Zhang, Wenjun

    2016-06-01

    Spring (March-May) rainfall after a dry period in winter has a substantial impact on agriculture and water management in populous southern China. The occurrence of low-frequency spring rainfall anomalies has been linked with the tropical Madden-Julian Oscillation (MJO) through its modulation of large-scale circulation and moisture supply over southern China. Using the spatial and temporal information of the MJO as a predictor, an empirical model for extended-range forecasting of spring rainfall in southern China was constructed. We first obtained the coupled patterns between the preceding MJO evolutions (real-time multivariate MJO index) and the succeeding rainfall variability in southern China based on singular value decomposition analysis. Then, a prediction was carried out by projecting the predictor onto the spatiotemporal coupled patterns. Useful skill, in terms of the temporal correlation coefficient (TCC) between the predicted and observed rainfall over southern China, persisted up to a forecast lead-time of six pentads. The forecast amplitude bias in terms of root-mean-square error was around 1.0 standard deviation. Also, the forecast skill was highly dependent on the strength of the MJO signal. During active MJO periods, the TCC skill was around twofold larger than that during weak MJO periods. The current statistical model shows encouraging ability, but additional work is required to improve its forecasting skill.

  15. El Nino's Family Tree (Invited)

    NASA Astrophysics Data System (ADS)

    Philander, S. G.

    2013-12-01

    Fluctuations in tropical Pacific rainfall and sea surface temperature (SST) patterns involve different processes on different timescales, but nonetheless have certain features (traits) in common so that all can be viewed as members of the same family. Best-known are the children El Niño and La Niña who, in their performance of the Southern Oscillation, move warm surface waters adiabatically back and forth across the Pacific. They and their nephews and nieces in the Atlantic and Indian Ocean all depend on favorable background conditions, especially a suitable depth for the thermocline whose tilt they oscillate to produce SST changes. The parents El Padre and La Madre are in control of that depth and invoke diabatic processes to change it gradually over the course of decades, at times making it so deep that El Niño becomes permanent. This is the spontaneous, natural branch of the family. Another branch responds to external forcing (externally imposed variations in sunlight) and has as members the cycles of the seasons, of obliquity, and of the precession of the equinoxes. These cousins, aunts and uncles of El Niño are protagonists in the drama of the recurrent Ice Ages.

  16. The Relation between Indian Monsoon Rainfall, the Southern Oscillation, and Hemispheric Air and Sea Temperature: 1884-1984.

    NASA Astrophysics Data System (ADS)

    Elliott, W. P.; Angell, J. K.

    1987-08-01

    Correlations between the June-September Indian monsoon rainfall and Santiago minus Darwin pressure, Tahiti minus Darwin pressure, and Wright's Southern Oscillation index, as well as the individual station pressure deviations themselves, show that the monsoon rainfall anticipates the Southern Oscillation Indices and the individual pressure deviations with the exception of the pressure at Santiago. Monsoon rainfall is also negatively correlated with sea surface temperatures in the eastern equatorial Pacific one to two seasons later. The correlations suggest that above average monsoon rainfall is associated with below average Southern Hemisphere temperatures two to three seasons later, whereas above average Northern Hemisphere winter temperatures-particularly continental temperatures-anticipate above average rainfall. The correlations with hemispheric temperatures are significant only since about 1947, however. A strong negative correlation (0.64) between the seasonal change in Darwin's pressure deviation from December-February to March-May prior to the monsoon, and monsoon rainfall is found in the period 1947-84, but only weakly in the period before 1947.

  17. Evidence for multiple refugia at different time scales during Pleistocene climatic oscillations in southern Australia inferred from phylogeography

    NASA Astrophysics Data System (ADS)

    Byrne, M.

    2008-12-01

    Phylogeography uses the spatial distribution of genealogical lineages to deduce the influence of historical processes on the evolution of species, and can be informative in regard to location of refugia during extreme climatic conditions. Southern Australia is an ancient landscape with generally low geological relief that was not glaciated but did experience significant climatic oscillations from warm wet conditions in interglacials to cool dry environments during glacial maxima. Phylogeographic patterns in many of the biota of southern Australia reveal evidence of geographically structured divergent lineages indicative of contraction to, and expansion from, major refugia. The time frame for this divergence corresponds with mid Pleistocene climatic oscillations that became more extreme with greater amplitude, and with increased aridity and the formation of sandy deserts. Within lineages there is high haplotype diversity that is generally locally distributed, often specific to populations. These patterns do not reveal specific locations of major refugia that have high diversity and acted as an origin for recent range expansion, as has been observed in Northern Hemisphere glaciated regions. Rather it appears there have been multiple localised refugia throughout the distributions of the species, allowing them to persist through multiple climatic cycles in heterogeneous environments. Phylogeographic patterns in southern Australia indicate that major biotic responses to climatic change involve persistence and resilience rather than large-scale migration, indicating the importance of dynamic evolutionary processes and a mosaic of habitats in heterogeneous landscapes for species to persist though changing environmental conditions.

  18. El Niño Southern Oscillation Influences River Bank Erosion on the Lower Mekong River

    NASA Astrophysics Data System (ADS)

    Darby, S. E.; Trieu, H. Q.; Carling, P. A.

    2009-12-01

    . However, both simulated time series exhibit quasi-periodic oscillations about these means. The Mekong’s flow regime is controlled by variations in meltwater regime, the intensity of the SE Asian monsoon, and the frequency and intensity of tropical cyclones that penetrate inland from the South China Sea. Since melt contributes only to (non-erosive) base flows, variability in glacier and snow melt contributions from Himalayan source areas are unlikely to significantly impact inter-annual variations in river bank erosion. However, inter-annual variability in the SE Asian monsoon and tropical cyclone dynamics may both be related, albeit in a complex manner, to the El Niño Southern Oscillation (ENSO). Cross-wavelet transform and wavelet coherence analyses indicate statistically significant (at 95% limit) coherence between ENSO and simulated river bank erosion, but at both sites only since about 1980. During this recent period the ENSO and fluvial erosion time series are in anti-phase; that is ENSO cold phases are associated with enhanced rates of river bank erosion. This is as expected, since ENSO cold phases are associated with earlier onset and enhanced intensity of the monsoon, while the number of intense tropical storm systems making landfall over Vietnam and moving across the Lower Mekong Basin is also higher.

  19. El Nino winners and losers declared

    SciTech Connect

    Kerr, R.A.

    1991-03-08

    Last spring human forecasters thought they saw signs of an imminent warming of the tropical Pacific, a classic El Nino, that could wreak havoc with weather around the globe. Researchers running computer models, on the other hand, saw a slight warming but not enough for an El Nino. The modelers were right. The season for El Ninos has ended and nothing happened. Since the models came online about 5 years ago, there have been two contests to predict El Ninos, which occur every 3 to 7 years, and the models have won both. The models are still experimental, but the general feeling is that they're indicating the right trends. The prospect of having reliable El Nino prediction models is good news beyond the small coterie of tropical Pacific specialists. Worldwide weather patterns are closely tied to El Nino cycles.

  20. A nonlinear characteristic of El Niño-Southern Oscillation events

    NASA Astrophysics Data System (ADS)

    Duan, Wansuo; Xue, Feng; Mu, Mu

    2010-05-01

    We use the approach of conditional nonlinear optimal perturbation (CNOP) to investigate the optimal precursory disturbances in a theoretical El Niño-Southern Oscillation (ENSO) model and then an intermediate model. By exploring the dynamical behaviors of the El Niño events caused by these CNOP-type precursors, a characteristic for this kind of theoretical El Niño events is shown, i.e., the stronger El Niño events tend to decay faster and have shorter durations of the decaying phase. By examining the observed El Niño events, it is found that the Niño-3.4 SSTA are more potential than the Niño-3 SSTA in illustrating the decaying characteristic of the theoretical El Niño events. In particular, it is the Niño-3.4 indices for the strong El Niño events during 1981-2007 that roughly show the decaying characteristic. Based on the physics of the theoretical model, the mechanism responsible for the above decaying characteristic of strong El Niño events is explored. The analysis demonstrates that the property of the stronger El Niño event decaying faster can be realized only through the linear dynamics with the combined effects of the rising of thermocline and the mean upwelling, but that of the stronger El Niño event having a shorter duration of the decaying phase results from a nonlinear mechanism. It is shown that the nonlinearity related to the anomalous temperature advection in the tropical Pacific shortens the duration of the decaying phase for El Niño event. The stronger the El Niño event, the stronger the nonlinearity, then the more considerable the suppressing of the nonlinearity on the duration of the decaying phase for El Niño event. This explains why the stronger El Niño events have shorter durations of the decaying phase. Also, this sheds light on why the observed strong El Niño events are more likely to show this characteristic.

  1. El Nino-like events during Miocene

    SciTech Connect

    Casey, R.E.; Nelson, C.O.; Weinheimer, A.L.; Oeth, P.A.; Swanson, R.J.

    1988-03-01

    El Nino-like events have been recorded from the Miocene laminated siliceous facies of the Monterey Formation. These El Nino-like Miocene events are compared to El Nino events recorded from Holocene varved sediments deposited within the anoxic Santa Barbara basin. Strong El Nino events can be recognized from Holocene Santa Barbara basin sediments by increases in radiolarian flux to the sea floor during those events. For the last 100-plus years, frequency of strong El Ninos has been on the order of one extremely strong event about every 100 years, and one easily recognizable event about every 18 years. Frequencies in the laminated (varved) Miocene range from about every 4-5 years to over 20 years. The higher frequencies occur within generally warm intervals and the lower frequencies within generally cold intervals. Perhaps the frequencies of these events may, in fact, be an important indicator in determining whether the intervals were cold or warm. Reconstructions of the paleo-California Current system during El Nino-like periods have been made for the west coast from the Gulf of California to northern California. Strong El Nino-like events occurred 5.5 and 8 Ma, and a strong anti-El Nino-like event occurred at about 6.5 Ma. Evidence from the 5.5 and 8 Ma events combined with other evidence suggests that modern El Ninos, similar to today's, were initiated at 5.5 Ma or earlier.

  2. Reconstruction of the El Nino attractor with neural networks

    SciTech Connect

    Grieger, B.; Latif, M.

    1994-09-01

    Based on a combined data set of sea surface temperature, zonal surface wind stress and upper ocean heat content the dynamics of the El Nino phenomenon is investigated. In a reduced phase space spanned by the first four EOFs two different stochastic models are estimated from the data. A nonlinear model represented by a simulated neural network is compared with a linear model obtained with the principal oscillation pattern (POP) analysis. While the linear model is limited to damped oscillations onto a fix point attractor, the nonlinear model recovers a limit cycle attractor. This indicates that the real system is located above the bifurcation point in parameter space supporting self-sustained oscillations. The results are discussed with respect to consistency with current theory. 21 refs., 10 figs.

  3. Interannual Atmospheric Oscillations and Their Gravitational Effects

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.; Au, A. Y.

    2000-01-01

    Past studies have examined the effects of the interannual atmospheric oscillations (IAO), or often called teleconnection patterns, on the Earth's rotation, such as El Nino/Southern Oscillation (ENSO), the quasi-biennial oscillation, and to a lesser extent the North Atlantic Oscillation (NAO). The present study focuses on IAO's effects on the gravitational field and geocenter; the purpose is to be able to identify and isolate the contributions of each prominent IAO in relation to the total contribution of the atmosphere, in terms of their magnitudes, their geographical patterns, and their interannual time history. We use the 40-year NCEP reanalysis of the monthly, global atmospheric surface pressure field as our basic data set. The method we apply to isolate the IAOs is the empirical orthogonal function (EOF) decomposition which is widely used in meteorological investigations. We do the EOF analysis first on IAOs' seasonal signals (by "collapsing" the 40-year series into 12 mean-months for each grid point) and obtain estimates for their respective contributions. Then we remove these seasonal signals from the data to focus on the (broad-band) interannual EOFs. We examine ENSO, NAO, North Pacific Oscillation, and other less prominent IAOs that can be identified from our data set, and compute their respective contributions to the variation of global gravitational field and geocenter motion. Finally, we compare the results with the available observational data, and discuss the implications w.r.t. the upcoming space missions such as GRACE.

  4. Combined effects of the Pacific Decadal Oscillation and El Niño-Southern Oscillation on global land dry-wet changes.

    PubMed

    Wang, Shanshan; Huang, Jianping; He, Yongli; Guan, Yuping

    2014-10-17

    The effects of natural variability, especially El Niño-Southern Oscillation (ENSO) effects, have been the focus of several recent studies on the change of drought patterns with climate change. The interannual relationship between ENSO and the global climate is not stationary and can be modulated by the Pacific Decadal Oscillation (PDO). However, the global land distribution of the dry-wet changes associated with the combination of ENSO and the PDO remains unclear. In the present study, this is investigated using a revised Palmer Drought Severity Index dataset (sc_PDSI_pm). We find that the effect of ENSO on dry-wet changes varies with the PDO phase. When in phase with the PDO, ENSO-induced dry-wet changes are magnified with respect to the canonical pattern. When out of phase, these dry-wet variations weaken or even disappear. This remarkable contrast in ENSO's influence between the two phases of the PDO highlights exciting new avenues for obtaining improved global climate predictions. In recent decades, the PDO has turned negative with more La Niña events, implying more rain and flooding over land. La Niña-induced wet areas become wetter and the dry areas become drier and smaller due to the effects of the cold PDO phase.

  5. Is There Any Teleconnection Between Surface Hydrology in Poland and El Niño/Southern Oscillation?

    NASA Astrophysics Data System (ADS)

    Niedzielski, Tomasz

    2011-05-01

    The objective of the work discussed in this paper was to seek possible links between surface hydrology in Southwestern (SW) Poland and El Niño/Southern Oscillation (ENSO). Although the impact of ENSO on hydrology in Europe has been investigated by many researchers, no clear picture demonstrating spatial variability of such a teleconnection has yet been unequivocally reported. In particular, there is no comprehensive study on ENSO-streamflow links for Polish rivers. Herein, discharge time series from 15 sites located at lowland and mountain rivers in SW Poland and different ENSO indices are examined. They include atmospheric time series (axial component of atmospheric angular momentum, Southern Oscillation Index), oceanic indices (Niño 3.4 Index, Global SST Index), geodetic data (length-of-day), and the combined index (Multivariate ENSO Index). The data span the period from November 1971 to October 2006. On the basis of cross-correlation and wavelet analyses it was found that there is a weak but significant link between ENSO and surface hydrology in SW Poland. It is inferred that ENSO episodes may be among a few factors affecting winter and early spring discharges of rivers in SW Poland and may have a (probably limited) impact on snow-melt flood generation.

  6. Geosat-derived sea level and surface current anomalies in the equatorial Pacific during the 1986-1989 El Nino and La Nina

    NASA Technical Reports Server (NTRS)

    Delcroix, Thierry; Boulanger, Jean-Philippe; Masia, F.; Menkes, C.

    1994-01-01

    Equatorial wave dynamics are essential in most oceanic models for reproducing aspects of the El Nino-Southern Oscillation (ENSO) phenomenon. Observational evidence of first baroclinic equatorial Kelvin and first symmetric meridional Rossby waves is found in Geosat-derived sea level anomalies (SLA) and surface zonal current anomalies (ZCA) in the equatorial Pacific ocean during the 1986-1987 El Nino and the ensuing 1988-1989 La Nina. This was made possible after extensive quality control and specific processing of the recently improved Geosat geophysical data records pertaining to the 17-day Exact Repeat Mission. In particular, the processing was made so that the Geosat-derived ZCA best fit near-surface zonal currents from three equatorial moorings at 165 deg E, 140 deg W, and 110 deg W. The Geosat-derived SLA and ZCA are decomposed into first baroclinic equatorial Kelvin and gravest Rossby modes. The emphasis is then put on the chronology of the ZCA at the equator where the currents are the most energetic and where Kelvin and first symmetric Rossby waves explain most of the variance in ZCA, in similar proportion. The 1986-1987 El Nino is mostly characterized by a strong downwelling Kelvin wave in December 1986, a series of downwelling Kelvin waves in March-October 1987, and a strong upwelling Rossby wave in March-September 1987. These waves are consistent with wind forcing, and all give rise to notable eastward ZCA for almost an entire year. During El Nino-La Nina transition period there is the occurrence of two downwelling Rossby waves originating from the eastern Pacific at times of favorable wind forcing. These Rossby waves switch the basin-wide ZCA from eastward to westward, terminating the warm event. Then, the 1988-1989 La Nina shows the generation of a series of upwelling Kelvin waves which are clearly identified in March/April and September/October 1988. These upwelling Kelvin waves are apparently related to the enhencement of the trade wind in the western

  7. The 1982-1983 El Nino Atlas: Nimbus-7 microwave radiometer data

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy

    1987-01-01

    Monthly maps of sea surface temperature, atmospheric water vapor, and surface level wind speed as measured by the Scanning Multichannel Microwave Radiometer (SMMR) on the Nimbus-7 satellite for the tropical Pacific from June 1982 to October 1983, during one of the most intense El Nino Southern Oscillations (ENSO) episodes, are presented. The non-ENSO annual cycle was compiled by averaging the 1980 and 1981 data for each calendar month and was removed from monthly fields of 1982 and 1983 to reveal the anomalous distributions. The anomaly fields and part of the non-ENSO annual cycle are also presented. This study and earlier evaluations demonstrate that the Nimbus/SMMR can be used to monitor large scale and low frequency variabilities in the tropical ocean. The SMMR data support and extend conventional measurements. The variabilities of the three parameters are found to represent various aspects of ENSO related through ocean atmosphere interaction. Their simultaneous and quantitative descriptions pave the way for the derivation of ocean atmosphere latent heat exchange and further the understanding of the coupled atmospheric and oceanic thermodynamics.

  8. Relationships between El Niño-Southern Oscillation and nitrogen concentrations in a Western Mediterranean river

    NASA Astrophysics Data System (ADS)

    Sigro, J.; Vegas-Vilarrúbia, T.; Giralt, S.; Brunet, M.

    2010-05-01

    El Niño-Southern Oscillation (ENSO) is the dominating mode of interannual climate variability at global scale (Brönnimann, 2007). ENSO extreme negative and positive phases can significantly influence on climatic conditions in Europe, affecting precipitation mainly in spring and autumn (Mariotti et al., 2002; Moron and Ward 1998), but also during winter (Brönnimann et al., 2007; Pozo-Vázquez et al., 2005). Over the Iberian Peninsula (IP), ENSO teleconnections can modulate the frequency and intensity of precipitation (Brunet and López, 1991; Rodó et al., 1997; Rodríguez-Puebla et al., 1998), with a time-lag between the ENSO and its effect on precipitation ranging from 3 to 21 months (Rodó et al., 1997). Large areas of the IP are also affected by severe droughts during the final months of La Niña years and the initial months of the following year, while other areas are affected by dry conditions during the first months of El Niño years, as well as during the summers and autumns of the following year (Muñoz-Diaz and Rodrigo, 2005; Vicente-Serrano, 2005). Here we explore the possibility that nitrate concentration in the Llobregat River (North-eastern Spain) is influenced by ENSO events, which are modulating precipitation variability over the Western Mediterranean basin. The Southern Oscillation Index during La Niña years, the self-calibrating Palmer Hydrological Drought Index (van der Schrier et al., 2006; Wells et al., 2004), and nitrate concentrations were significantly correlated on a seasonal basis in the Llobregat River, with both drought and nitrate concentrations increasing during positive ENSO phases. Our hypothesis is that initially unusual within-stream nitrate increases would take place, owing to higher-than-normal evaporation from the river. During drought periods, the hydrological deficit favours nitrate accumulation in the catchment's soils and, thus, a decline in allochthonous inputs to the river water would be expectable. Besides, on the late

  9. The influence of the North Atlantic Oscillation and El Niño-Southern Oscillation on mean and extreme values of column ozone over the United States

    NASA Astrophysics Data System (ADS)

    Petropavlovskikh, I.; Evans, R.; McConville, G.; Manney, G. L.; Rieder, H. E.

    2015-02-01

    Continuous measurements of total ozone (by Dobson spectrophotometers) across the contiguous United States began in the early 1960s. Here, we analyze temporal and spatial variability and trends in total ozone from the five US sites with long-term records. While similar long-term ozone changes are detected at all five sites, we find differences in the patterns of ozone variability on shorter timescales. In addition to standard evaluation techniques, STL-decomposition methods (Seasonal Trend decomposition of time series based on LOESS (LOcally wEighted Scatterplot Smoothing)) are used to address temporal variability and "fingerprints" of dynamical features in the Dobson data. Methods from statistical extreme value theory (EVT) are used to characterize days with high and low total ozone (termed EHOs and ELOs, respectively) at each station and to analyze temporal changes in the frequency of ozone extremes and their relationship to dynamical features such as the North Atlantic Oscillation (NAO) and El Niño-Southern Oscillation. A comparison of the fingerprints detected in the frequency distribution of the extremes with those for standard metrics (i.e., the mean) shows that more fingerprints are found for the extremes, particularly for the positive phase of the NAO, at all five US monitoring sites. Results from the STL decomposition support the findings of the EVT analysis. Finally, we analyze the relative influence of low- and high-ozone events on seasonal mean column ozone at each station. The results show that the influence of ELOs and EHOs on seasonal mean column ozone can be as much as ±5 %, about as large as the overall long-term decadal ozone trends.

  10. The influence of the North Atlantic Oscillation and El Niño-Southern Oscillation on mean and extreme values of column ozone over the United States

    NASA Astrophysics Data System (ADS)

    Petropavlovskikh, I.; Evans, R.; McConville, G.; Manney, G. L.; Rieder, H. E.

    2014-08-01

    Continuous measurements of total ozone (by Dobson spectrophotometers) across the contiguous United States (US) began in the early 1960s. Here, we analyze temporal and spatial variability and trends in total ozone from the five US sites with long-term records. While similar long-term ozone changes are detected at all five sites, we find differences in the patterns of ozone variability on shorter time scales. In addition to standard evaluation techniques, STL-decomposition methods (Seasonal Trend decomposition of time series based on LOcally wEighted Scatterplot Smoothing, LOESS) are used to address temporal variability and trends in the Dobson data. The LOESS-smoothed trend components show a decline of total ozone between the 1970s and 2000s and a "stabilization" at lower levels in recent years, which is also confirmed by linear trend analysis. Methods from statistical extreme value theory (EVT) are used to characterize days with high and low total ozone (termed EHOs and ELOs, respectively) at each station and to analyze temporal changes in the frequency of ozone extremes and their relationship to dynamical features such as the North Atlantic Oscillation and El Niño Southern Oscillation. A comparison of the "fingerprints" detected in the frequency distribution of the extremes with those for standard metrics (i.e., the mean) shows that more "fingerprints" are found for the extremes, particularly for the positive phase of the NAO, at all five US monitoring sites. Results from the STL-decomposition support the findings of the EVT analysis. Finally, we analyze the relative influence of low and high ozone events on seasonal mean column ozone at each station. The results show that the influence of ELOs and EHOs on seasonal mean column ozone can be as much as ±5%, or about twice as large as the overall long-term decadal ozone trends.

  11. Forecasting Andean rainfall and crop yield from the influence of El Nino on Pleiades visibility

    PubMed

    Orlove; Chiang; Cane

    2000-01-01

    Farmers in drought-prone regions of Andean South America have historically made observations of changes in the apparent brightness of stars in the Pleiades around the time of the southern winter solstice in order to forecast interannual variations in summer rainfall and in autumn harvests. They moderate the effect of reduced rainfall by adjusting the planting dates of potatoes, their most important crop. Here we use data on cloud cover and water vapour from satellite imagery, agronomic data from the Andean altiplano and an index of El Nino variability to analyse this forecasting method. We find that poor visibility of the Pleiades in June-caused by an increase in subvisual high cirrus clouds-is indicative of an El Nino year, which is usually linked to reduced rainfall during the growing season several months later. Our results suggest that this centuries-old method of seasonal rainfall forecasting may be based on a simple indicator of El Nino variability.

  12. The El Niño–Southern Oscillation (ENSO)–pandemic Influenza connection: Coincident or causal?

    PubMed Central

    Shaman, Jeffrey; Lipsitch, Marc

    2013-01-01

    We find that the four most recent human influenza pandemics (1918, 1957, 1968, and 2009), all of which were first identified in boreal spring or summer, were preceded by La Niña conditions in the equatorial Pacific. Changes in the phase of the El Niño–Southern Oscillation have been shown to alter the migration, stopover time, fitness, and interspecies mixing of migratory birds, and consequently, likely affect their mixing with domestic animals. We hypothesize that La Niña conditions bring divergent influenza subtypes together in some parts of the world and favor the reassortment of influenza through simultaneous multiple infection of individual hosts and the generation of novel pandemic strains. We propose approaches to test this hypothesis using influenza population genetics, virus prevalence in various host species, and avian migration patterns. PMID:22308322

  13. Does El Niño-Southern Oscillation affect the precipitation in Korea on seasonal time scales?

    NASA Astrophysics Data System (ADS)

    Ho, Chang-Hoi; Choi, Woosuk; Kim, Jinwon; Kim, Maeng-Ki; Yoo, Hee-Dong

    2016-08-01

    A number of studies in the past two decades have attempted to find the relationship between the precipitation in Korea and the El Niño-Southern Oscillation (ENSO) on various time scales. Comprehensive analyses of station precipitation data in Korea for the 61-year period, 1954-2014, in this study show that the effects of ENSO on the seasonal precipitation in Korea are practically negligible. The correlation between summer precipitation and ENSO is insignificant regardless of the intensity, type (e.g., eastern-Pacific or central-Pacific), and stage (e.g., developing, mature, or decaying) of ENSO. Somewhat meaningful correlation between ENSO and precipitation in Korea occurs only in the ENSO-developing fall. Because summer rainfall accounts for over half of the annual total and fall is a dry season in Korea, the overall effects of ENSO on precipitation in Korea are practically nonexistent.

  14. Reconstruction of El Niño Southern Oscillation using data from ships' logbooks, 1750-1855

    NASA Astrophysics Data System (ADS)

    Barrett, Hannah; Jones, Julie; Bigg, Grant

    2016-04-01

    The logbooks from ships which historically travelled the World's oceans contain a vast amount of meteorological information useful for studies of historical climate. They provide daily, marine-based weather observations from the pre-instrumental era. The Climatological Database for the World's Oceans (CLIWOC) and digitised English East India Company (EEIC) logbooks have been used to investigate the climate during the period 1750-1855. A statistical-based reconstruction of El Niño Southern Oscillation (ENSO) has been carried out using these databases, focusing on observations from the Indo-Pacific region. The coherency between previous ENSO reconstructions and this new, logbook ENSO reconstruction has been assessed. By uncovering the potential uses of ships' logbook data, and establishing methodologies to reconstruct climate indices, it is hoped that further efforts will be made to digitise ship logbook. Further digitisation would make this unique data source even more valuable to historical climatology.

  15. Palaeoclimate reconstructions reveal a strong link between El Niño-Southern Oscillation and Tropical Pacific mean state.

    PubMed

    Sadekov, Aleksey Yu; Ganeshram, Raja; Pichevin, Laetitia; Berdin, Rose; McClymont, Erin; Elderfield, Henry; Tudhope, Alexander W

    2013-01-01

    The El Niño-Southern Oscillation (ENSO) is one of the most important components of the global climate system, but its potential response to an anthropogenic increase in atmospheric CO2 remains largely unknown. One of the major limitations in ENSO prediction is our poor understanding of the relationship between ENSO variability and long-term changes in Tropical Pacific oceanography. Here we investigate this relationship using palaeorecords derived from the geochemistry of planktonic foraminifera. Our results indicate a strong negative correlation between ENSO variability and zonal gradient of sea-surface temperatures across the Tropical Pacific during the last 22 ky. This strong correlation implies a mechanistic link that tightly couples zonal sea-surface temperature gradient and ENSO variability during large climate changes and provides a unique insight into potential ENSO evolution in the future by suggesting enhanced ENSO variability under a global warming scenario.

  16. Using transfer functions to quantify El Niño Southern Oscillation dynamics in data and models

    PubMed Central

    MacMartin, Douglas G.; Tziperman, Eli

    2014-01-01

    Transfer function tools commonly used in engineering control analysis can be used to better understand the dynamics of El Niño Southern Oscillation (ENSO), compare data with models and identify systematic model errors. The transfer function describes the frequency-dependent input–output relationship between any pair of causally related variables, and can be estimated from time series. This can be used first to assess whether the underlying relationship is or is not frequency dependent, and if so, to diagnose the underlying differential equations that relate the variables, and hence describe the dynamics of individual subsystem processes relevant to ENSO. Estimating process parameters allows the identification of compensating model errors that may lead to a seemingly realistic simulation in spite of incorrect model physics. This tool is applied here to the TAO array ocean data, the GFDL-CM2.1 and CCSM4 general circulation models, and to the Cane–Zebiak ENSO model. The delayed oscillator description is used to motivate a few relevant processes involved in the dynamics, although any other ENSO mechanism could be used instead. We identify several differences in the processes between the models and data that may be useful for model improvement. The transfer function methodology is also useful in understanding the dynamics and evaluating models of other climate processes. PMID:25197250

  17. Using transfer functions to quantify El Niño Southern Oscillation dynamics in data and models.

    PubMed

    MacMartin, Douglas G; Tziperman, Eli

    2014-09-01

    Transfer function tools commonly used in engineering control analysis can be used to better understand the dynamics of El Niño Southern Oscillation (ENSO), compare data with models and identify systematic model errors. The transfer function describes the frequency-dependent input-output relationship between any pair of causally related variables, and can be estimated from time series. This can be used first to assess whether the underlying relationship is or is not frequency dependent, and if so, to diagnose the underlying differential equations that relate the variables, and hence describe the dynamics of individual subsystem processes relevant to ENSO. Estimating process parameters allows the identification of compensating model errors that may lead to a seemingly realistic simulation in spite of incorrect model physics. This tool is applied here to the TAO array ocean data, the GFDL-CM2.1 and CCSM4 general circulation models, and to the Cane-Zebiak ENSO model. The delayed oscillator description is used to motivate a few relevant processes involved in the dynamics, although any other ENSO mechanism could be used instead. We identify several differences in the processes between the models and data that may be useful for model improvement. The transfer function methodology is also useful in understanding the dynamics and evaluating models of other climate processes.

  18. Centennial-scale vegetation and North Atlantic Oscillation changes during the Late Holocene in the southern Iberia

    NASA Astrophysics Data System (ADS)

    Ramos-Román, M. J.; Jiménez-Moreno, G.; Anderson, R. S.; García-Alix, A.; Toney, J. L.; Jiménez-Espejo, F. J.; Carrión, J. S.

    2016-07-01

    High-reso CE to lution pollen analysis, charcoal, non-pollen palynomorphs and magnetic susceptibility have been analyzed in the sediment record of a peat bog in Sierra Nevada in southern Iberia. The study of these proxies provided the reconstruction of vegetation, climate, fire and human activity of the last ∼4500 cal yr BP. A progressive trend towards aridification during the late Holocene is observed in this record. This trend is interrupted by millennial- and centennial-scale variability of relatively more humid and arid periods. Arid conditions are recorded between ∼4000 and 3100 cal yr BP, being characterized by a decline in arboreal pollen and with a spike in magnetic susceptibility. This is followed by a relatively humid period from ∼3100 to 1600 cal yr BP, coinciding partially with the Iberian-Roman Humid Period, and is indicated by the increase of Pinus and the decrease in xerophytic taxa. The last 1500 cal yr BP are characterized by several centennial-scale climatic oscillations. Generally arid conditions from ∼450 to 1300 CE, depicted by a decrease in Pinus and an increase in Artemisia, comprise the Dark Ages and the Medieval Climate Anomaly. Since ∼ 1300 to 1850 CE pronounced oscillations occur between relatively humid and arid conditions. Four periods depicted by relatively higher Pinus coinciding with the beginning and end of the Little Ice Age are interrupted by three arid events characterized by an increase in Artemisia. These alternating arid and humid shifts could be explained by centennial-scale changes in the North Atlantic Oscillation and solar activity.

  19. Indian Ocean Dipole and El Niño/Southern Oscillation impacts on regional chlorophyll anomalies in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Currie, J. C.; Lengaigne, M.; Vialard, J.; Kaplan, D. M.; Aumont, O.; Naqvi, S. W. A.; Maury, O.

    2013-03-01

    The Indian Ocean Dipole (IOD) and the El Niño-Southern Oscillation (ENSO) frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled bio-physical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely-sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997-1998 ENSO and IOD event. Results show that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing. IOD depresses integrated chlorophyll in the 5° S-10° S thermocline ridge region, even though the signal is negligible in surface chlorophyll. A previously-unreported negative influence of IOD on chlorophyll concentrations is also shown in a region around the southern tip of India. The only investigated region where ENSO has a greater influence on chlorophyll than does IOD, is in the Somalia upwelling region, where it causes a decrease in fall and winter chlorophyll by reducing local upwelling winds. Lastly, we show that the chlorophyll impact of climate indices is frequently asymmetric, with a general tendency for larger positive than negative chlorophyll anomalies. ENSO and IOD cause significant and predictable regional re-organisation of phytoplankton productivity via their influence on near-surface oceanography. Resolving the details of these effects should improve our understanding, and eventually gain predictability, of interannual changes in Indian Ocean productivity, fisheries, ecosystems and carbon budgets.

  20. Indian Ocean Dipole and El Niño/Southern Oscillation impacts on regional chlorophyll anomalies in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Currie, J. C.; Lengaigne, M.; Vialard, J.; Kaplan, D. M.; Aumont, O.; Naqvi, S. W. A.; Maury, O.

    2013-10-01

    The Indian Ocean Dipole (IOD) and the El Niño/Southern Oscillation (ENSO) are independent climate modes, which frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled biophysical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997/1998 ENSO and IOD event. Results suggest that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing. A negative influence of IOD on chlorophyll concentrations is shown in a region around the southern tip of India in fall. IOD also depresses depth-integrated chlorophyll in the 5-10° S thermocline ridge region, yet the signal is negligible in surface chlorophyll. The only investigated region where ENSO has a greater influence on chlorophyll than does IOD, is in the Somalia upwelling region, where it causes a decrease in fall and winter chlorophyll by reducing local upwelling winds. Yet unlike most other regions examined, the combined explanatory power of IOD and ENSO in predicting depth-integrated chlorophyll anomalies is relatively low in this region, suggestive that other drivers are important there. We show that the chlorophyll impact of climate indices is frequently asymmetric, with a general tendency for larger positive than negative chlorophyll anomalies. Our results suggest that ENSO and IOD cause significant and predictable regional re-organisation of chlorophyll via their influence on near-surface oceanography. Resolving the details of these effects should improve our understanding, and eventually gain predictability, of interannual changes in Indian Ocean productivity, fisheries, ecosystems and carbon

  1. El Nino and the Teacher at Sea.

    ERIC Educational Resources Information Center

    Johnson, Kerry Anne

    1998-01-01

    Details the experiences of a teacher who spent a month on a National Oceanic and Atmospheric Administration (NOAA) ship. Reports observations of developing El Nino conditions and presents related classroom activities. (DDR)

  2. Differential modulation of eastern oyster ( Crassostrea virginica) disease parasites by the El-Niño-Southern Oscillation and the North Atlantic Oscillation

    NASA Astrophysics Data System (ADS)

    Soniat, Thomas M.; Hofmann, Eileen E.; Klinck, John M.; Powell, Eric N.

    2009-02-01

    The eastern oyster ( Crassostrea virginica) is affected by two protozoan parasites, Perkinsus marinus which causes Dermo disease and Haplosporidium nelsoni which causes MSX (Multinucleated Sphere Unknown) disease. Both diseases are largely controlled by water temperature and salinity and thus are potentially sensitive to climate variations resulting from the El Niño-Southern Oscillation (ENSO), which influences climate along the Gulf of Mexico coast, and the North Atlantic Oscillation (NAO), which influences climate along the Atlantic coast of the United States. In this study, a 10-year time series of temperature and salinity and P. marinus infection intensity for a site in Louisiana on the Gulf of Mexico coast and a 52-year time series of air temperature and freshwater inflow and oyster mortality from Delaware Bay on the Atlantic coast of the United States were analyzed to determine patterns in disease and disease-induced mortality in C. virginica populations that resulted from ENSO and NAO climate variations. Wavelet analysis was used to decompose the environmental, disease infection intensity and oyster mortality time series into a time-frequency space to determine the dominant modes of variability and the time variability of the modes. For the Louisiana site, salinity and Dermo disease infection intensity are correlated at a periodicity of 4 years, which corresponds to ENSO. The influence of ENSO on Dermo disease along the Gulf of Mexico is through its effect on salinity, with high salinity, which occurs during the La Niña phase of ENSO at this location, favoring parasite proliferation. For the Delaware Bay site, the primary correlation was between temperature and oyster mortality, with a periodicity of 8 years, which corresponds to the NAO. Warmer temperatures, which occur during the positive phase of the NAO, favor the parasites causing increased oyster mortality. Thus, disease prevalence and intensity in C. virginica populations along the Gulf of Mexico

  3. Possible impacts of mega-El Niño/Southern Oscillation and Atlantic multidecadal oscillation on Eurasian heat wave frequency variability

    NASA Astrophysics Data System (ADS)

    Zhou, Yefan; Wu, Zhiwei

    2016-04-01

    Identifying predictability sources of heat wave variations is a scientific challenge and of practical importance. This study investigates the summertime heat wave frequency (HWF) over Eurasia for 19502014. The Eurasian HWF is dominated by two distinct modes: the interdecadal (ID) mode featured by an increasing pattern overall, centered around eastern Europe-central Asia and Mongolia-southwestern China; the interannual (IA) mode resembling a tri-pole anomaly pattern with three centers over western-northern Europe, northeastern Asia and East Asia. The ID mode is found to be influenced by mega-El Niño/Southern Oscillation (mega-ENSO) and the Atlantic multidecadal oscillation (AMO), and the latter has far more effect, whereas the IA mode is connected with mega-ENSO. Further analysis suggests that mega-ENSO variations can incite a Gill-type response spreading to Eurasia, while the AMO changes cause eastward-propagating Rossby wave trains toward Eurasia. These two teleconnection patterns together contribute to the large-scale circulation anomalies of the ID mode, and those related to the IA mode arise from the teleconnection pattern excited by mega-ENSO. A strong mega-ENSO triggers subsidence with high pressure anomalies, warms the surface and increases the HWF significantly over northeastern Asia particularly. Likewise, the warm AMO-induced circulation anomalies engender surface radiative heating and HWF growth in most of Eurasian continent except some localized Siberian and Asian regions. The situation is opposite for a weak mega-ENSO and AMO. Those models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) which realistically capture the features of the ID mode can reproduce the AMO-like sea surface temperature anomalies (SSTAs), while signals resembling mega-ENSO are found in those with favorable capability of simulating the IA mode. On the contrary, these relevant SSTAs linked to the respective modes vanish in the models with little skills. Thus

  4. Factors contributing to a decadal oscillation in South African rainfall

    NASA Astrophysics Data System (ADS)

    Jury, Mark R.

    2015-04-01

    South African rainfall in the period 1960-2010 exhibits ˜12-year oscillations of similar amplitude to those at 2-5 years. Corresponding global climate signals, as deduced from principal component analysis, include ocean heat content (HC2) and upper zonal winds (2U1) primarily in the Pacific sector. Composites of wet and dry summers are analyzed as depth and height sections to understand the ocean-atmosphere coupling that generates low frequency oscillations. Point-to-field correlations with respect to decadal-filtered South African rainfall (SA1) reveal how the Pacific signals connect with Africa through upper zonal winds, vorticity cells, sea temperature, and aerosol concentration. A regression algorithm of HC2 and 2U1 explains 58 % of the decadal SA1 variance and peak years 1976 and 2000. Although the HC2 pattern is asymmetric and independent, 2U1 principal component time scores follow the Multivariate El Nino Southern Oscillation Index and Pacific Decadal Oscillation. The conveyor of tropical easterlies that dips over the SW Indian Ocean subsequently rises over southern Africa bringing rain with a decadal frequency.

  5. Multi-decadal variability and trends in the El Niño-Southern Oscillation and tropical Pacific fisheries implications

    NASA Astrophysics Data System (ADS)

    Harrison, D. E.; Chiodi, Andrew M.

    2015-03-01

    Extremes of the El Niño-Southern Oscillation (ENSO) are known to have various socio-economic impacts, including effects on several Pacific fisheries. The 137-year-long record of Darwin sea-level pressure offers a uniquely long-term perspective on ENSO and provides important insight into various aspects of interannual to century-scale variability that affects these fisheries. One particular issue of interest is whether there is a centennial-scale (or longer) trend that can be expected to alter the future distributions of these fisheries. Since most tropical Pacific fishery records are no longer than a few decades, another issue is the extent to which trends over these recent decades are a good basis for detecting the presence of long-term (e.g., centennial-scale) deterministic changes, and perhaps thereby projecting future conditions. We find that the full 137-yr trend cannot be distinguished from zero with 95% confidence, and also that the ENSO variance in recent decades is very similar to that of the early decades of the record, suggesting that ENSO has not fundamentally changed over the period of large increase in atmospheric CO2. However, the strong multi-decadal variability in ENSO is reflected in decades with quite different levels of ENSO effects on the ecosystem. Many multi-decadal subsets of the full record have statistically significant trends, using standard analysis techniques. These multi-decadal trends are not; however, representative of the record-length trend, nor are they a useful basis for projecting conditions in subsequent decades. Trend statistical significance is not a robust foundation for speculation about the future. We illustrate how the difficulties involved in determining whether a trend is statistically significant or not mean that, even after careful consideration, an unexpectedly large number of trends may reach standard statistical significance levels over the time spans for which many newer records are available, but still not

  6. Early-season warning of soybean rust regional epidemics using El Niño Southern/Oscillation information

    NASA Astrophysics Data System (ADS)

    Del Ponte, Emerson M.; Maia, Aline De H. N.; Dos Santos, Thiago V.; Martins, Eduardo J.; Baethgen, Walter E.

    2011-07-01

    Soybean rust (SBR) is a disease of significant impact to Brazilian soybean production. Twenty-four locations in a major growing region in southern Brazil, where long-term (30 years) weather information was available, were selected to estimate the risk of SBR epidemics and identify potential predictors derived from El Niño 3.4 region. A rainfall-based model was used to predict SBR severity in an "epidemic development window" (the months of February and March for the studied region) in the time series. Twenty-eight daily simulations for each year-location ( n = 720) were performed considering each day after 31 January as a hypothetical detection date (HDD) to estimate a severity index (SBRindex). The mean SBRindex in a single year was defined as the `growing season severity index' (GSSI) for that year. A probabilistic risk assessment related GSSI and sea surface temperatures (SST) at the El Niño 3.4. region (here categorized as warm, cold or neutral phase) in October-November-December (OND) of the same growing season. Overall, the median GSSI across location-years was 34.5%. The risk of GSSI exceeding 60% was generally low and ranged from 0 to 20 percentage points, with the higher values found in the northern regions of the state when compared to the central-western. During a warm OND-SST phase, the probability of GSSI exceeding its overall mean (locations pooled) increased significantly by around 25 percentage points compared to neutral and cold SST phases, especially over the central western region. This study demonstrates the potential to use El Niño/Southern Oscillation information to anticipate the risk of SBR epidemics up to 1 month in advance at a regional scale.

  7. Impacts of El Niño Southern Oscillation and Indian Ocean Dipole on dengue incidence in Bangladesh.

    PubMed

    Banu, Shahera; Guo, Yuming; Hu, Wenbiao; Dale, Pat; Mackenzie, John S; Mengersen, Kerrie; Tong, Shilu

    2015-11-05

    Dengue dynamics are driven by complex interactions between hosts, vectors and viruses that are influenced by environmental and climatic factors. Several studies examined the role of El Niño Southern Oscillation (ENSO) in dengue incidence. However, the role of Indian Ocean Dipole (IOD), a coupled ocean atmosphere phenomenon in the Indian Ocean, which controls the summer monsoon rainfall in the Indian region, remains unexplored. Here, we examined the effects of ENSO and IOD on dengue incidence in Bangladesh. According to the wavelet coherence analysis, there was a very weak association between ENSO, IOD and dengue incidence, but a highly significant coherence between dengue incidence and local climate variables (temperature and rainfall). However, a distributed lag nonlinear model (DLNM) revealed that the association between dengue incidence and ENSO or IOD were comparatively stronger after adjustment for local climate variables, seasonality and trend. The estimated effects were nonlinear for both ENSO and IOD with higher relative risks at higher ENSO and IOD. The weak association between ENSO, IOD and dengue incidence might be driven by the stronger effects of local climate variables such as temperature and rainfall. Further research is required to disentangle these effects.

  8. Impacts of El Niño Southern Oscillation and Indian Ocean Dipole on dengue incidence in Bangladesh

    NASA Astrophysics Data System (ADS)

    Banu, Shahera; Guo, Yuming; Hu, Wenbiao; Dale, Pat; MacKenzie, John S.; Mengersen, Kerrie; Tong, Shilu

    2015-11-01

    Dengue dynamics are driven by complex interactions between hosts, vectors and viruses that are influenced by environmental and climatic factors. Several studies examined the role of El Niño Southern Oscillation (ENSO) in dengue incidence. However, the role of Indian Ocean Dipole (IOD), a coupled ocean atmosphere phenomenon in the Indian Ocean, which controls the summer monsoon rainfall in the Indian region, remains unexplored. Here, we examined the effects of ENSO and IOD on dengue incidence in Bangladesh. According to the wavelet coherence analysis, there was a very weak association between ENSO, IOD and dengue incidence, but a highly significant coherence between dengue incidence and local climate variables (temperature and rainfall). However, a distributed lag nonlinear model (DLNM) revealed that the association between dengue incidence and ENSO or IOD were comparatively stronger after adjustment for local climate variables, seasonality and trend. The estimated effects were nonlinear for both ENSO and IOD with higher relative risks at higher ENSO and IOD. The weak association between ENSO, IOD and dengue incidence might be driven by the stronger effects of local climate variables such as temperature and rainfall. Further research is required to disentangle these effects.

  9. Interannual variation of stable isotopes in precipitation at Bangkok in response to El Ñino Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Ichiyanagi, Kimpei; Yamanaka, Manabu D.

    2005-11-01

    Evidence for a close relationship between the interannual variation of stable isotopes in precipitation and the El Ñino Southern Oscillation (ENSO) is presented for Bangkok, Thailand. Anomalies of sea surface temperature in the Niño-3 region of the equatorial Pacific (ENSO index) and 18O in precipitation in Bangkok were positively correlated for May and October. The composite mean precipitation was much greater in the isotopic low phase than in the high phase for both May and October. This suggests that the amount of precipitation is the main factor determining the observed variation of stable isotopes in precipitation in Bangkok. Composite analyses of 850 hPa temperature, evaporation, outgoing longwave radiation (OLR), and precipitation showed that the variation in the amount of precipitation in Bangkok is a response to the ENSO-Asian summer monsoon coupling in May, and a direct response to ENSO in October. The composite mean d-excess values in both the low and high phases in October and in the low phase in May were about 10, and were less than 7 during the high phase in May. A large difference in the evaporation field between the low and high phases of May exists over the Indian Ocean, suggesting that evaporation was not in equilibrium during the high phase in May. Future studies will consider the precipitation amount effect based on daily or event-based sampling. Copyright

  10. Influence of El Niño–Southern Oscillation (ENSO) events on the evolution of central California's shoreline

    USGS Publications Warehouse

    Storlazzi, Curt D.; Griggs, Gary B.

    2000-01-01

    Significant sea-cliff erosion and storm damage occurred along the central coast of California during the 1982–1983 and 1997–1998 El Niño winters. This generated interest among scientists and land-use planners in how historic El Niño–Southern Oscillation (ENSO) winters have affected the coastal climate of central California. A relative ENSO intensity index based on oceanographic and meteorologic data defines the timing and magnitude of ENSO events over the past century. The index suggests that five higher intensity (relative values 4–6) and 17 lower intensity (relative values 1–3) ENSO events took place between 1910 and 1995. The ENSO intensity index correlates with fluctuations in the time series of cyclone activity, precipitation, detrended sea level, wave height, sea-surface temperature, and sea-level barometric pressure. Wave height, sea level, and precipitation, which are the primary external forcing parameters in sea-cliff erosion, increase nonlinearly with increasing relative ENSO event intensity. The number of storms that caused coastal erosion or storm damage and the historic occurrence of large-scale sea-cliff erosion along the central coast also increase nonlinearly with increasing relative event intensity. These correlations and the frequency distribution of relative ENSO event intensities indicate that moderate- to high-intensity ENSO events cause the most sea-cliff erosion and shoreline recession over the course of a century.

  11. Is there a linkage between the tropical cyclone activity in the southern Indian Ocean and the Antarctic Oscillation?

    NASA Astrophysics Data System (ADS)

    Mao, Rui; Gong, Dao-Yi; Yang, Jing; Zhang, Zi-Yin; Kim, Seong-Joong; He, Hao-Zhe

    2013-08-01

    this article, the relationship between the Antarctic Oscillation (AAO) and the tropical cyclone (TC) activity in the southern Indian Ocean (SIO) was examined. It was found that on the interannual time scale, the AAO is well linked with the TC activity in the SIO during TC season (December-March). The rank correlation coefficient between the AAO index and the TC frequency (TCF) in the SIO is 0.37, which is significant at the 95% confidence level. When the AAO is in a positive phase, TC passage in the northwestern coast of Australia (100E°-120°E and 10°S-30°S) increases by approximately 50%-100% from the climatology. The increase in the TC passage is primarily the result of more frequent TCs originating in this region due to enhanced water vapor convergence and ascending motions, which are caused by a cyclonic height anomaly over the western coast of Australia associated with the positive AAO phases. In addition, the AAO-height covariations, which are essential to the formation of the AAO-TC links in the SIO, were investigated through a historical climate simulation using the Community Climate System Model 4 from the Coupled Model Intercomparison Project Phase 5. The AAO-height links were well reproduced in the simulation. The similarity in the AAO-height links between the observation and the simulation supports the physical robustness of the AAO-TC links in the SIO.

  12. People, El Niño southern oscillation and fire in Australia: fire regimes and climate controls in hummock grasslands.

    PubMed

    Bliege Bird, Rebecca; Bird, Douglas W; Codding, Brian F

    2016-06-01

    While evidence mounts that indigenous burning has a significant role in shaping pyrodiversity, the processes explaining its variation across local and external biophysical systems remain limited. This is especially the case with studies of climate-fire interactions, which only recognize an effect of humans on the fire regime when they act independently of climate. In this paper, we test the hypothesis that an anthropogenic fire regime (fire incidence, size and extent) does not covary with climate. In the lightning regime, positive El Niño southern oscillation (ENSO) values increase lightning fire incidence, whereas La Niña (and associated increases in prior rainfall) increase fire size. ENSO has the opposite effect in the Martu regime, decreasing ignitions in El Niño conditions without affecting fire size. Anthropogenic ignition rates covary positively with high antecedent rainfall, whereas fire size varies only with high temperatures and unpredictable winds, which may reduce control over fire spread. However, total area burned is similarly predicted by antecedent rainfall in both regimes, but is driven by increases in fire size in the lightning regime, and fire number in the anthropogenic regime. We conclude that anthropogenic regimes covary with climatic variation, but detecting the human-climate-fire interaction requires multiple measures of both fire regime and climate.This article is part of the themed issue 'The interaction of fire and mankind'.

  13. Flood frequencies and durations and their response to El Niño Southern Oscillation: Global analysis

    NASA Astrophysics Data System (ADS)

    Ward, P. J.; Kummu, M.; Lall, U.

    2016-08-01

    Floods are one of the most serious forms of natural hazards in terms of the damages they cause. In 2012 alone, flood damages exceeded 19 billion. A large proportion of the damages from several recent major flood disasters, such as those in South India and South Carolina (2015), England and Wales (2014), the Mississippi (2012), Thailand (2011), Queensland (Australia) (2010-2011), and Pakistan (2010), were related to the long duration of those flood events. However, most flood risk studies to date do not account for flood duration. In this paper, we provide the first global modelling exercise to assess the link between interannual climate variability and flood duration and frequency. Specifically, we examine relationships between simulated flood events and El Niño Southern Oscillation (ENSO). Our results show that the duration of flooding appears to be more sensitive to ENSO than is the case for flood frequency. At the globally aggregated scale, we found floods to be significantly longer during both El Niño and La Niña years, compared to neutral years. At the scale of individual river basins, we found strong correlations between ENSO and both flood frequency and duration for a large number of basins, with generally stronger correlations for flood duration than for flood frequency. Future research on flood impacts should attempt to incorporate more information on flood durations.

  14. Predicting stochastic systems by noise sampling, and application to the El Niño-Southern Oscillation.

    PubMed

    Chekroun, Mickaël David; Kondrashov, Dmitri; Ghil, Michael

    2011-07-19

    Interannual and interdecadal prediction are major challenges of climate dynamics. In this article we develop a prediction method for climate processes that exhibit low-frequency variability (LFV). The method constructs a nonlinear stochastic model from past observations and estimates a path of the "weather" noise that drives this model over previous finite-time windows. The method has two steps: (i) select noise samples--or "snippets"--from the past noise, which have forced the system during short-time intervals that resemble the LFV phase just preceding the currently observed state; and (ii) use these snippets to drive the system from the current state into the future. The method is placed in the framework of pathwise linear-response theory and is then applied to an El Niño-Southern Oscillation (ENSO) model derived by the empirical model reduction (EMR) methodology; this nonlinear model has 40 coupled, slow, and fast variables. The domain of validity of this forecasting procedure depends on the nature of the system's pathwise response; it is shown numerically that the ENSO model's response is linear on interannual time scales. As a result, the method's skill at a 6- to 16-month lead is highly competitive when compared with currently used dynamic and statistic prediction methods for the Niño-3 index and the global sea surface temperature field. PMID:21730171

  15. People, El Niño southern oscillation and fire in Australia: fire regimes and climate controls in hummock grasslands.

    PubMed

    Bliege Bird, Rebecca; Bird, Douglas W; Codding, Brian F

    2016-06-01

    While evidence mounts that indigenous burning has a significant role in shaping pyrodiversity, the processes explaining its variation across local and external biophysical systems remain limited. This is especially the case with studies of climate-fire interactions, which only recognize an effect of humans on the fire regime when they act independently of climate. In this paper, we test the hypothesis that an anthropogenic fire regime (fire incidence, size and extent) does not covary with climate. In the lightning regime, positive El Niño southern oscillation (ENSO) values increase lightning fire incidence, whereas La Niña (and associated increases in prior rainfall) increase fire size. ENSO has the opposite effect in the Martu regime, decreasing ignitions in El Niño conditions without affecting fire size. Anthropogenic ignition rates covary positively with high antecedent rainfall, whereas fire size varies only with high temperatures and unpredictable winds, which may reduce control over fire spread. However, total area burned is similarly predicted by antecedent rainfall in both regimes, but is driven by increases in fire size in the lightning regime, and fire number in the anthropogenic regime. We conclude that anthropogenic regimes covary with climatic variation, but detecting the human-climate-fire interaction requires multiple measures of both fire regime and climate.This article is part of the themed issue 'The interaction of fire and mankind'. PMID:27216513

  16. Magmatic heat and the El Nino cycle

    USGS Publications Warehouse

    Shaw, H.R.; Moore, J.G.

    1988-01-01

    Large submarine lava flows with apparent volumes exceeding 10 km3 have recently been imaged on the deep ocean floor in various parts of the Pacific by means of GLORIA and SeaMarc side-looking sonar surveys. Such flows may produce thermal anomalies large enough to perturb the cyclic processes of the ocean and could be a factor in the genesis of El Nino phenomena. We find that known volume rates of mid-ocean magma production could generate repetitive thermal anomalies as large as 10% of the average El Nino sea surface anomaly at intervals of about 5 years (the mean interval of El Nino events between 1935 and 1984). Likewise, estimated rates of eruption, cooling of lava on the seafloor, and transfer of heat to the near-surface environment could reasonably produce a thermal anomaly comparable to that associated with El Nino. Larger magmatic events, associated with fluctuations in the total magmatic power and seismicity along the East Pacific Rise, are possible at longer intervals and may explain the extreme size of some El Nino events, such as that of 1982-1983. -Authors

  17. The 1997-98 El Nino Event and Related Wintertime Lightning Variations in the Southeastern United States

    NASA Technical Reports Server (NTRS)

    Goodman, S. J.; Buechler, D. E.; Knupp, K.; Driscoll, K.; McCaul, E. W.

    1999-01-01

    The El Nino Southern Oscillation (ENSO) is a climate anomaly responsible for world-wide weather impacts ranging from droughts to floods. In the United States, warm episode years are known to produce above normal rainfall along the Southeast US Gulf Coast and into the Gulf of Mexico, with the greatest response observed in the October-March period of the latest warm-episode year. The 1997-98 warm episode is notable for being the strongest event since 1982-83. With the recent launch of a lightning sensor on NASA's Tropical Rainfall Measuring Mission (TRMM) in November 1997 and the expanded coverage of the National Lightning Detection Network (NLDN), such year-to-year changes in lightning activity can be examined with far greater detail than ever before. For the recent ENSO event the greatest year-to-year changes in lightning frequency occur within a broad swath across the northern Gulf of Mexico basin where there is nearly a 200% increase in lightning days year-to-year (35 days in 1997-98 vs. 13 days in 1996-97) and a 200% increase in lightning hours (150 hours vs. 50). These changes occur in association with a 100% increase in the number of synoptic scale cyclones and an anomalously strong jet stream encompassing much of the Gulf basin.

  18. Inter-decadal change in El Niño-Southern Oscillation examined with Bjerknes stability index analysis

    NASA Astrophysics Data System (ADS)

    An, Soon-Il; Bong, Hayoung

    2016-08-01

    Characteristics of El Niño-Southern Oscillation (ENSO) have changed since the late 1970s as it synchronized with the Pacific Decadal Oscillation (PDO). In order to investigate the primary feedback process responsible for the interdecadal change in ENSO characteristics according to the PDO, using the ocean assimilation data (SODA) and the reanalysis data (NCEP/NCAR), we performed Bjerknes linear stability index (BJ index) analysis of two decadal periods: one before the late 1970s (the nPDO period) and the other after the late 1970s (the pPDO period). The BJ index for the pPDO period (-0.07 year-1 for the growth rate of the eastern Pacific SST anomaly) is significantly larger than that for the nPDO period (-0.25 year-1). The larger BJ index value is primarily due to the enhanced zonal advection feedback (ZA; +0.44 year-1), thermocline feedback (TH; +0.33 year-1), and the reduced damping by the mean meridional current (MD; +0.16 year-1). The increases in ZA and TH are mainly attributed to the shoaling of the mean thermocline depth, which increased the sensitivity of the ocean dynamic fields to the wind forcing; and the reduced MD is related to the reduced mean meridional current associated with the weakened trade wind. The enhanced positive feedback is partly compensated by the enhanced thermodynamic damping including the shortwave, sensible heat flux and latent heat flux (collectively, -0.88 year-1). Interestingly, the change in air-sea coupling strength from the nPDO to the pPDO period was small. Without the two extreme El Niño events (1982-1983 and 1997-1998) in the pPDO period (pPDO_noBIG), the difference in BJ index between nPDO and pPDO_noBIG periods became smaller (~0.07 year-1), indicating that the two extreme El Niño events largely contribute to the larger ENSO variability of the pPDO period, possibly due to nonlinear feedback processes. Nevertheless, qualitative similarity in each of the feedback and damping components of BJ index exists between the p

  19. Coupled decadal variability of the North Atlantic Oscillation, regional rainfall and spring discharges in the Campania region (Southern Italy)

    NASA Astrophysics Data System (ADS)

    de Vita, P.; Allocca, V.; Manna, F.; Fabbrocino, S.

    2011-12-01

    Climate change is one of the issues most debated by the scientific community with a special focus to the combined effects of anthropogenic modifications of the atmosphere and the natural climatic cycles. Various scenarios have been formulated in order to forecast the global atmospheric circulation and consequently the variability of the global distribution of air temperature and rainfall. The effects of climate change have been analysed with respect to the risks of desertification, droughts and floods, remaining mainly limited to the atmospheric and surface components of the hydrologic cycle. Consequently the impact of the climate change on the recharge of regional aquifers and on the groundwater circulation is still a challenging topic especially in those areas whose aqueduct systems depend basically on springs or wells, such as the Campania region (Southern Italy). In order to analyse the long-term climatic variability and its influence on groundwater circulation, we analysed decadal patterns of precipitation, air temperature and spring discharges in the Campania region (Southern Italy), coupled with the North Atlantic Oscillation (NAO). The time series of precipitation and air temperature were gathered over 90 yr, in the period from 1921 to 2010, choosing 18 rain gauges and 9 air temperature stations among those with the most continuous functioning as well as arranged in a homogeneous spatial distribution. Moreover, for the same period, we gathered the time series of the winter NAO index (December to March mean) and of the discharges of the Sanità spring, belonging to an extended carbonate aquifer (Cervialto Mount) located in the central-eastern area of the Campania region, as well as of two other shorter time series of spring discharges. The hydrogeological features of this aquifer, its relevance due to the feeding of an important regional aqueduct system, as well as the unique availability of a long-lasting time series of spring discharges, allowed us to

  20. Exploring impacts of El Niño Southern Oscillation on Meteorological Forcing within the Glaciated Llanganuco Valley, Peru

    NASA Astrophysics Data System (ADS)

    Covert, J. M.; Hellstrom, R. A.

    2015-12-01

    El Niño Southern Oscillation (ENSO) is known to be the primary modulator of inter-annual weather patterns in the Andes, but its impact in the Cordillera Blanca (White Range) is not fully understood. In 2004 an autonomous sensor network (ASN) was installed in the Llanganuco Valley in the Cordillera Blanca, Peru consisting of two automatic weather stations (AWS) located at the base and upper ridge of the valley connected by four air temperature/humidity micro-loggers at equal elevation intervals. The ASN permits high resolution evaluations of the micro-scale meteorology within the valley. Twenty-four hour composites and monthly averages of wind, solar insolation, air temperature profiles, and precipitation obtained from the ASN were analyzed for the historical wet and dry seasons between the years of 2005 and 2015. The evidence suggests that teleconnections exist between eastern equatorial Pacific Ocean sea surface temperatures and meteorological forcing within the Valley. Comparisons between the two AWS units reveal similar ENSO impacts during the wet season that are not replicated in the dry season. We found that warm and cold ENSO create anomalies that appear unique to this region of the outer Tropics. Warm ENSO phases promote wetter than normal dry seasons and dryer than normal wet seasons and visa versa for cold phases of ENSO. Air temperature is strongly positively correlated to warm ENSO phases during the wet season and depends on elevation during the dry season. Insolation is negatively correlated to warm ENSO phases at higher elevations with weak positive correlation at lower elevations. We attribute observed seasonality, in part, to interactions between channeling of synoptic flow and thermally driven winds. Although the sporadic availability of data prevents definitive conclusions at this time, recent improvements in the ASN infrastructure will facilitate deeper understanding of ENSO impacts on meteorological forcing within pro-glacial valleys of the

  1. Tales of volcanoes and El-Niño southern oscillations with the oxygen isotope anomaly of sulfate aerosol

    PubMed Central

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L.; McCabe, Justin; Savarino, Joel; Thiemens, Mark H.

    2013-01-01

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth’s system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980–2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher ∆17O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and ∆17O = 3.3‰, OEI = 11 and ∆17O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that ∆17O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  2. El Niño Southern Oscillation and vegetation dynamics as predictors of dengue fever cases in Costa Rica

    NASA Astrophysics Data System (ADS)

    Fuller, D. O.; Troyo, A.; Beier, J. C.

    2009-01-01

    Dengue fever (DF) and dengue hemorrhagic fever (DHF) are growing health concerns throughout Latin America and the Caribbean. This study focuses on Costa Rica, which experienced over 100 000 cases of DF/DHF from 2003 to 2007. We utilized data on sea-surface temperature anomalies related to the El Niño Southern Oscillation (ENSO) and two vegetation indices derived from the Moderate Resolution Imaging Spectrometer (MODIS) from the Terra satellite to model the influence of climate and vegetation dynamics on DF/DHF cases in Costa Rica. Cross-correlations were calculated to evaluate both positive and negative lag effects on the relationships between independent variables and DF/DHF cases. The model, which utilizes a sinusoid and non-linear least squares to fit case data, was able to explain 83% of the variance in weekly DF/DHF cases when independent variables were shifted backwards in time. When the independent variables were shifted forward in time, consistently with a forecasting approach, the model explained 64% of the variance. Importantly, when five ENSO and two vegetation indices were included, the model reproduced a major DF/DHF epidemic of 2005. The unexplained variance in the model may be due to herd immunity and vector control measures, although information regarding these aspects of the disease system are generally lacking. Our analysis suggests that the model may be used to predict DF/DHF outbreaks as early as 40 weeks in advance and may also provide valuable information on the magnitude of future epidemics. In its current form it may be used to inform national vector control programs and policies regarding control measures; it is the first climate-based dengue model developed for this country and is potentially scalable to the broader region of Latin America and the Caribbean where dramatic increases in DF/DHF incidence and spread have been observed.

  3. Analysis of El Niño-Southern Oscillation Phenomena's Effect on the Gross Domestic Product of Western Pacific Nations

    NASA Astrophysics Data System (ADS)

    O'Connell, M.; Lewis, A.; Mezzafonte, D.

    2014-12-01

    El Niño Southern Oscillation (ENSO) is a climatological phenomenon that occurs in the tropical Pacific Ocean which has a direct influence on the climate of western Pacific nations. This study evaluated the meteorological effects of ENSO on the economies of Indonesia and the Philippines. It was hypothesized that decreased precipitation in the western Tropical Pacific region during El Niño events causes decreases in agricultural production in the region resulting in a negative effect on a nation's Gross Domestic Product (GDP). Furthermore, during La Niña events, when precipitation increases, an increase in the nation's agricultural GDP and overall GDP is expected. Annual GDP data were obtained from the World Bank and the Bank of Indonesia for 1960-2012. Sea surface temperatures (SST) data, in the Niño 3.4 region, were obtained from the National Oceanic and Atmospheric Administration (NOAA) National Climate Data Center. Data of the agricultural and total GDP of Indonesia and the Philippines had inconclusive correlations with ENSO signal data. By examining data between smaller time segments of the overall 1960-2012 timeframe, more conclusive results could not be discerned. Indonesia's quarterly non-oil GDP for 2000-2009 was independently correlated with ENSO providing better insight on the variables' relationship during discrete ENSO phenomena. The results provided strong correlation coefficients of 0.831 and 0.624 in support of the antithesis as well as -0.421 in support of the hypothesis. An economic anomaly known as the East Asian Financial Crisis may have been the cause of the unexpected correlations however more data is needed to be certain. Overall, the results demonstrated weak to moderate correlations between studied variables. However, more data is needed to reach substantial conclusions.

  4. El Niño-Southern Oscillation is linked to decreased energetic condition in long-distance migrants

    USGS Publications Warehouse

    Paxton, Kristina L.; Cohen, Emily B.; Paxton, Eben; Németh, Zoltan; Moore, Frank R.

    2014-01-01

    Predicting how migratory animals respond to changing climatic conditions requires knowledge of how climatic events affect each phase of the annual cycle and how those effects carry-over to subsequent phases. We utilized a 17-year migration dataset to examine how El Niño-Southern Oscillation climatic events in geographically different regions of the Western hemisphere carry-over to impact the stopover biology of several intercontinental migratory bird species. We found that migratory birds that over-wintered in South America experienced significantly drier environments during El Niño years, as reflected by reduced Normalized Difference Vegetation Index (NDVI) values, and arrived at stopover sites in reduced energetic condition during spring migration. During El Niño years migrants were also more likely to stopover immediately along the northern Gulf coast of the southeastern U.S. after crossing the Gulf of Mexico in small suboptimal forest patches where food resources are lower and migrant density often greater than larger more contiguous forests further inland. In contrast, NDVI values did not differ between El Niño and La Niña years in Caribbean-Central America, and we found no difference in energetic condition or use of coastal habitats for migrants en route from Caribbean-Central America wintering areas. Birds over-wintering in both regions had consistent median arrival dates along the northern Gulf coast, suggesting that there is a strong drive for birds to maintain their time program regardless of their overall condition. We provide strong evidence that not only is the stopover biology of migratory landbirds influenced by events during the previous phase of their life-cycle, but where migratory birds over-winter determines how vulnerable they are to global climatic cycles. Increased frequency and intensity of ENSO events over the coming decades, as predicted by climatic models, may disproportionately influence long-distance migrants over-wintering in

  5. El Niño-Southern Oscillation-based index insurance for floods: Statistical risk analyses and application to Peru

    NASA Astrophysics Data System (ADS)

    Khalil, Abedalrazq F.; Kwon, Hyun-Han; Lall, Upmanu; Miranda, Mario J.; Skees, Jerry

    2007-10-01

    Index insurance has recently been advocated as a useful risk transfer tool for disaster management situations where rapid fiscal relief is desirable and where estimating insured losses may be difficult, time consuming, or subject to manipulation and falsification. For climate-related hazards, a rainfall or temperature index may be proposed. However, rainfall may be highly spatially variable relative to the gauge network, and in many locations, data are inadequate to develop an index because of short time series and the spatial dispersion of stations. In such cases, it may be helpful to consider a climate proxy index as a regional rainfall index. This is particularly useful if a long record is available for the climate index through an independent source and it is well correlated with the regional rainfall hazard. Here El Niño-Southern Oscillation (ENSO) related climate indices are explored for use as a proxy to extreme rainfall in one of the districts of Peru, Piura. The ENSO index insurance product may be purchased by banks or microfinance institutions to aid agricultural damage relief in Peru. Crop losses in the region are highly correlated with floods but are difficult to assess directly. Beyond agriculture, many other sectors suffer as well. Basic infrastructure is destroyed during the most severe events. This disrupts trade for many microenterprises. The reliability and quality of the local rainfall data are variable. Averaging the financial risk across the region is desirable. Some issues with the implementation of the proxy ENSO index are identified and discussed. Specifically, we explore (1) the reliability of the index at different levels of probability of exceedance of maximum seasonal rainfall, (2) the effect of sampling uncertainties and the strength of the proxy's association to local outcome, (3) the potential for clustering of payoffs, (4) the potential that the index could be predicted with some lead time prior to the flood season, and (5) evidence

  6. El Niño-Southern Oscillation is linked to decreased energetic condition in long-distance migrants.

    PubMed

    Paxton, Kristina L; Cohen, Emily B; Paxton, Eben H; Németh, Zoltán; Moore, Frank R

    2014-01-01

    Predicting how migratory animals respond to changing climatic conditions requires knowledge of how climatic events affect each phase of the annual cycle and how those effects carry-over to subsequent phases. We utilized a 17-year migration dataset to examine how El Niño-Southern Oscillation climatic events in geographically different regions of the Western hemisphere carry-over to impact the stopover biology of several intercontinental migratory bird species. We found that migratory birds that over-wintered in South America experienced significantly drier environments during El Niño years, as reflected by reduced Normalized Difference Vegetation Index (NDVI) values, and arrived at stopover sites in reduced energetic condition during spring migration. During El Niño years migrants were also more likely to stopover immediately along the northern Gulf coast of the southeastern U.S. after crossing the Gulf of Mexico in small suboptimal forest patches where food resources are lower and migrant density often greater than larger more contiguous forests further inland. In contrast, NDVI values did not differ between El Niño and La Niña years in Caribbean-Central America, and we found no difference in energetic condition or use of coastal habitats for migrants en route from Caribbean-Central America wintering areas. Birds over-wintering in both regions had consistent median arrival dates along the northern Gulf coast, suggesting that there is a strong drive for birds to maintain their time program regardless of their overall condition. We provide strong evidence that not only is the stopover biology of migratory landbirds influenced by events during the previous phase of their life-cycle, but where migratory birds over-winter determines how vulnerable they are to global climatic cycles. Increased frequency and intensity of ENSO events over the coming decades, as predicted by climatic models, may disproportionately influence long-distance migrants over-wintering in

  7. Asynchronous food-web pathways could buffer the response of Serengeti predators to El Niño Southern Oscillation.

    PubMed

    Sinclair, A R E; Metzger, Kristine L; Fryxell, John M; Packer, Craig; Byrom, Andrea E; Craft, Meggan E; Hampson, Katie; Lembo, Tiziana; Durant, Sarah M; Forrester, Guy J; Bukombe, John; Mchetto, John; Dempewolf, Jan; Hilborn, Ray; Cleaveland, Sarah; Nkwabi, Ally; Mosser, Anna; Mduma, Simon A R

    2013-05-01

    Understanding how entire ecosystems maintain stability in the face of climatic and human disturbance is one of the most fundamental challenges in ecology. Theory suggests that a crucial factor determining the degree of ecosystem stability is simply the degree of synchrony with which different species in ecological food webs respond to environmental stochasticity. Ecosystems in which all food-web pathways are affected similarly by external disturbance should amplify variability in top carnivore abundance over time due to population interactions, whereas ecosystems in which a large fraction of pathways are nonresponsive or even inversely responsive to external disturbance will have more constant levels of abundance at upper trophic levels. To test the mechanism underlying this hypothesis, we used over half a century of demographic data for multiple species in the Serengeti (Tanzania) ecosystem to measure the degree of synchrony to variation imposed by an external environmental driver, the El Niño Southern Oscillation (ENSO). ENSO effects were mediated largely via changes in dry-season vs. wet-season rainfall and consequent changes in vegetation availability, propagating via bottom-up effects to higher levels of the Serengeti food web to influence herbivores, predators and parasites. Some species in the Serengeti food web responded to the influence of ENSO in opposite ways, whereas other species were insensitive to variation in ENSO. Although far from conclusive, our results suggest that a diffuse mixture of herbivore responses could help buffer top carnivores, such as Serengeti lions, from variability in climate. Future global climate changes that favor some pathways over others, however, could alter the effectiveness of such processes in the future.

  8. Tales of volcanoes and El-Niño southern oscillations with the oxygen isotope anomaly of sulfate aerosol

    NASA Astrophysics Data System (ADS)

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L.; McCabe, Justin; Savarino, Joel; Thiemens, Mark H.

    2013-10-01

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher ∆17O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and ∆17O = 3.3‰, OEI = 11 and ∆17O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that ∆17O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations.

  9. El Niño-Southern Oscillation Is Linked to Decreased Energetic Condition in Long-Distance Migrants

    PubMed Central

    Paxton, Kristina L.; Cohen, Emily B.; Paxton, Eben H.; Németh, Zoltán; Moore, Frank R.

    2014-01-01

    Predicting how migratory animals respond to changing climatic conditions requires knowledge of how climatic events affect each phase of the annual cycle and how those effects carry-over to subsequent phases. We utilized a 17-year migration dataset to examine how El Niño-Southern Oscillation climatic events in geographically different regions of the Western hemisphere carry-over to impact the stopover biology of several intercontinental migratory bird species. We found that migratory birds that over-wintered in South America experienced significantly drier environments during El Niño years, as reflected by reduced Normalized Difference Vegetation Index (NDVI) values, and arrived at stopover sites in reduced energetic condition during spring migration. During El Niño years migrants were also more likely to stopover immediately along the northern Gulf coast of the southeastern U.S. after crossing the Gulf of Mexico in small suboptimal forest patches where food resources are lower and migrant density often greater than larger more contiguous forests further inland. In contrast, NDVI values did not differ between El Niño and La Niña years in Caribbean-Central America, and we found no difference in energetic condition or use of coastal habitats for migrants en route from Caribbean-Central America wintering areas. Birds over-wintering in both regions had consistent median arrival dates along the northern Gulf coast, suggesting that there is a strong drive for birds to maintain their time program regardless of their overall condition. We provide strong evidence that not only is the stopover biology of migratory landbirds influenced by events during the previous phase of their life-cycle, but where migratory birds over-winter determines how vulnerable they are to global climatic cycles. Increased frequency and intensity of ENSO events over the coming decades, as predicted by climatic models, may disproportionately influence long-distance migrants over-wintering in

  10. El Niño-Southern Oscillation (ENSO) effects on Hessian fly (Diptera: Cecidomyiidae) infestation in the southeastern United States.

    PubMed

    Woli, P; Ortiz, B V; Buntin, D; Flanders, K

    2014-12-01

    Climate variability is expected to have an influence on the population of Hessian fly, Mayetiola destructor Say (Diptera: Cecidomyiidae), a serious insect pest of winter wheat in the southeastern United States. This study had two objectives: 1) to examine the effects of El Niño-Southern Oscillation (ENSO) on Hessian fly infestation and 2) to develop a weather-based Hessian fly infestation model for wheat yield loss prediction. At least 20 years of Hessian fly infestation and wheat yield records from two locations in South Georgia were used for this study. The yearly values of infestation were separated by ENSO phase and tested to assess the infestation differences across ENSO phases. Each year, yield losses from infestation were calculated by subtracting the yields of resistant varieties from those of susceptible ones. The yield losses were then separated by ENSO phase and tested. Multiple regression analyses were conducted to identify the contribution of monthly weather variables and changes in wheat acreage to Hessian fly infestation. Results showed that Hessian fly infestation and yield losses were greatest during the La Niña and least during the El Niño phase. The weather conditions that significantly increased the risk for infestation were those of the August-February period. The risk of infestation was higher during August-September under wetter, cooler conditions and during October-February under drier, warmer conditions. These findings could help wheat growers reduce the risk of infestation in the years that are expected to have more infestation through the adoption of necessary mitigation measures before the crop season.

  11. Interannual and interdecadal oscillation patterns in sea level

    SciTech Connect

    Unal, Y.S.; Ghil, M.

    1995-07-01

    Relative sea-level height (RSLH) data at 213 tide-gauge stations have been analyzed on a monthly an an annual basis to study interannual and interdecadal oscillations. The main tools of the study are similar spectrum analysis (SSA) and multichannel SSA (M-SSA). Very-low-frequency variability of RSLH was filtered by SSA to estimate the linear trend at each station. Global sea-level rise, after post-glacial rebound corrections, has been found to equal 1.62{+-}0.38 mm/y, by averaging over 175 stations. The study identified two dominant time scales of El Nino-Southern Oscillation (ENSO) variability, quasi-biennial and low-frequency, in the RSLH data at almost all stations. However, the amplitudes of both ENSO signals are higher in the equatorial Pacific and along the west coast of North America. Throughout the Pacific, the study found three dominant spatio-temporal oscillatory patterns, associated with time scales of ENSO variability; their periods are 2.2.5-3 and 4-6 y. Strong and weak El Nino years are evident in the sea-level time series reconstructed from the quasi-biennial and low-frequency modes. Interannual variability with periods of 3 and 4-8 y is detected in the Atlantic RSLH data. In the eastern Atlantic region, we have found slow propagation of both modes northward and southward, away from 40-45{degrees}N. Interdecadal oscillations were studied using 81 stations with sufficiently long and continuous records. Most of these have variability at 9-13 and some at 18 y. Two significant eigenmode pairs, corresponding to periods of 11.6 and 12.8 y, are found in the eastern and western Atlantic ocean at latitudes 40{degrees}N-70{degrees}N and 10{degrees}N-50{degrees}N, respectively. 60 refs., 23 figs., 3 tabs.

  12. Angular momentum exchange among the solid Earth, atmosphere, and oceans: A case study of the 1982-1983 El Nino event

    NASA Technical Reports Server (NTRS)

    Dickey, J. O.; Marcus, S. L.; Hide, R.; Eubanks, T. M.; Boggs, D. H.

    1994-01-01

    The 1982-1983 El Nino/Southern Oscillation (ENSO) event was accompanied by the largest interannual variation in the Earth's rotation rate on record. In this study we demonstrate that atmospheric forcing was the dominant cause for this rotational anomaly, with atmospheric angular momentum (AAM) integrated from 1000 to 1 mbar (troposphere plus stratosphere) accounting for up to 92% of the interannual variance in the length of day (LOD). Winds between 100 and 1 mbar contributed nearly 20% of the variance explained, indicating that the stratosphere can play a significant role in the Earth's angular momentum budget on interannual time scales. Examination of LOD, AAM, and Southern Oscillation Index (SOI) data for a 15-year span surrounding the 1982-1983 event suggests that the strong rotational response resulted from constructive interference between the low-frequency (approximately 4-6 year) and quasi-biennial (approximately 2-3 year) components of the ENSO phenomenon, as well as the stratospheric Quasi-Biennial Oscillation (QBO). Sources of the remaining LOD discrepancy (approximately 55 and 64 microseconds rms residual for the European Centre for Medium-Range Forecasting (EC) and U.S. National Meteorological Center (NMC) analyses) are explored; noise and systematic errors in the AAM data are estimated to contribute 18 and 33 microseconds, respectively, leaving a residual (rms) of 40 (52) microseconds unaccounted for by the EC (NMC) analysis. Oceanic angular momentum contributions (both moment of inertia changes associated with baroclinic waves and motion terms) are shown to be candidates in closing the interannual axial angular momentum budget.

  13. A study of quasi-millennial extratropical winter cyclone activity over the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Xia, Lan; von Storch, Hans; Feser, Frauke; Wu, Jian

    2016-10-01

    The winter extratropical cyclone activity in the Southern Hemisphere during the last one thousand years within a global climate simulation was analyzed by tracking cyclones, and then clustering them into ten clusters consecutively for each hundred years. There is very strong year-to-year variability for Southern Hemispheric winter extratropical cyclone numbers and larger variations on centennial time scale, more so than for its Northern Hemispherical counterparts. However, no obvious trend can be found. The mean tracks of clusters over the Southern Indian Ocean and near New Zealand shift poleward from the eleventh to the twentieth century while the clusters in the central Southern Pacific shift equatorward. Storm track clusters with largest deepening rates are found over the Southwestern Indian Ocean. In the twentieth century, rapidly deepening cyclones appear more often while long lifespan cyclones appear less frequently. The winter storm activity in the Southern Hemisphere is closely related to the Antarctic Oscillation. The cyclone frequency over the Indian Ocean and South Pacific Ocean can be associated with the Indian Ocean Dipole and El Nino-Southern Oscillation respectively.

  14. Section on Observed Impacts on El Nino

    NASA Technical Reports Server (NTRS)

    Rosenzweig, Cynthia

    2000-01-01

    Agricultural applications of El Nino forecasts are already underway in some countries and need to be evaluated or re-evaluated. For example, in Peru, El Nino forecasts have been incorporated into national planning for the agricultural sector, and areas planted with rice and cotton (cotton being the more drought-tolerant crop) are adjusted accordingly. How well are this and other such programs working? Such evaluations will contribute to the governmental and intergovernmental institutions, including the Inter-American Institute for Global Change Research and the US National Ocean and Atmospheric Agency that are fostering programs to aid the effective use of forecasts. As El Nino climate forecasting grows out of the research mode into operational mode, the research focus shifts to include the design of appropriate modes of utilization. Awareness of and sensitivity to the costs of prediction errors also grow. For example, one major forecasting model failed to predict the very large El Nino event of 1997, when Pacific sea-surface temperatures were the highest on record. Although simple correlations between El Nino events and crop yields may be suggestive, more sophisticated work is needed to understand the subtleties of the interplay among the global climate system, regional climate patterns, and local agricultural systems. Honesty about the limitations of an forecast is essential, especially when human livelihoods are at stake. An end-to-end analysis links tools and expertise from the full sequence of ENSO cause-and-effect processes. Representatives from many disciplines are needed to achieve insights, e.g, oceanographers and atmospheric scientists who predict El Nino events, climatologists who drive global climate models with sea-surface temperature predictions, agronomists who translate regional climate connections in to crop yield forecasts, and economists who analyze market adjustments to the vagaries of climate and determine the value of climate forecasts

  15. The role of ENSO in the Tropical Intra-seasonal Oscillation

    NASA Astrophysics Data System (ADS)

    Jung, E.; Kirtman, B. P.

    2015-12-01

    Deep convection over the tropics initiates over the Indian Ocean and propagates into the Pacific on intra-seasonal (30-90 days) timescales. This so-called Tropical Intra-Seasonal Oscillations (TISO) impacts on global weather and climate, such as El Nino/Southern Oscillation (ENSO), extreme weather in northern hemisphere, Asian and Australian monsoon, so on. However, the individual TISO events are unpredictable beyond 20 days. In the Pacific, on the other hand, ENSO occurs on intra-annual (2-7 years) timescales with significant global socio-economic and environmental impact, and has a predictability of 8-10 months prior to its mature stage. Here we use NCAR Community Climate System Model (CCSM4) forecasts and observational estimates to show the roles of ENSO in the TISO. This study shows that mixed layer depth in the southwestern Indian Ocean, which is known to be one of the TISO onset regions, deepens (shoals) during El-Nino (La-Nina) through the low frequency modulation. The deeper (shallower) mixed layer reduces (enhanced) TISO-associated Sea surface temperature (SST) and wind variability, which leads to less (more) favorable conditions for TISO onset over the Indian Ocean.

  16. How ENSO Modifies the Quasi-Biennial Oscillation in a General Circulation Model

    NASA Astrophysics Data System (ADS)

    Schirber, S.

    2014-12-01

    El Nino / Southern Oscillation (ENSO) and the Quasi-biennial Oscillation (QBO) in the stratosphere are two prominent tropical phenomena on the interannual timescale. In this work, we analyze the effect of ENSO on the QBO utilizing an atmospheric general circulation model in a comprehensive experimental setup. We construct two ensembles of different QBO initial conditions, with the onset of a westerly (QBOW) and easterly (QBOE) jet at 10 hPa. In the course of a 18 months simulation period, the two sets of initial conditions experience each El Nino (EL) and La Nina (LA) SSTs as boundary conditions. Due to the increased tropospheric temperatures during EL conditions compared to LA conditions, the simulation shows an increase in tropospheric wave activity which increases QBO forcing in the stratosphere in EL. The underlying easterly jet of QBOW is weaker during EL compared to LA, while the underlying westerly jet of QBOE is stronger during EL compared to LA. On one hand, the weaker underlying jet in QBOW and the increase in QBO forcing due to waves cause a faster downward propagation of the westerly jet of QBOW during EL. On the other hand, the stronger underlying jet of QBOE opposes the increased QBO forcing due to waves for QBOE during EL. Therefore the downward propagation speed of the easterly jet of QBOE is similar during EL and LA conditions. Changes in stratospheric tropical upwelling associated with EL and LA do not affect QBO properties in the simulation.

  17. Initialized decadal prediction for transition to positive phase of the Interdecadal Pacific Oscillation

    DOE PAGES

    Meehl, Gerald A.; Hu, Aixue; Teng, Haiyan

    2016-06-02

    The negative phase of the Interdecadal Pacific Oscillation (IPO), a dominant mode of multi-decadal variability of sea surface temperatures (SSTs) in the Pacific, contributed to the reduced rate of global surface temperature warming in the early 2000s. Here, a proposed mechanism for IPO multidecadal variability indicates that the presence of decadal timescale upper ocean heat content in the off-equatorial western tropical Pacific can provide conditions for an interannual El Nino/Southern Oscillation event to trigger a transition of tropical Pacific SSTs to the opposite IPO phase. Here we show that a decadal prediction initialized in 2013 simulates predicted Nino3.4 SSTs thatmore » have qualitatively tracked the observations through 2015. The year three to seven average prediction (2015-2019) from the 2013 initial state shows a transition to the positive phase of the IPO from the previous negative phase and a resumption of larger rates of global warming over the 2013-2022 period consistent with a positive IPO phase.« less

  18. Coral luminescence identifies the Pacific Decadal Oscillation as a primary driver of river runoff variability impacting the southern Great Barrier Reef.

    PubMed

    Rodriguez-Ramirez, Alberto; Grove, Craig A; Zinke, Jens; Pandolfi, John M; Zhao, Jian-xin

    2014-01-01

    The Pacific Decadal Oscillation (PDO) is a large-scale climatic phenomenon modulating ocean-atmosphere variability on decadal time scales. While precipitation and river flow variability in the Great Barrier Reef (GBR) catchments are sensitive to PDO phases, the extent to which the PDO influences coral reefs is poorly understood. Here, six Porites coral cores were used to produce a composite record of coral luminescence variability (runoff proxy) and identify drivers of terrestrial influence on the Keppel reefs, southern GBR. We found that coral skeletal luminescence effectively captured seasonal, inter-annual and decadal variability of river discharge and rainfall from the Fitzroy River catchment. Most importantly, although the influence of El Niño-Southern Oscillation (ENSO) events was evident in the luminescence records, the variability in the coral luminescence composite record was significantly explained by the PDO. Negative luminescence anomalies (reduced runoff) were associated with El Niño years during positive PDO phases while positive luminescence anomalies (increased runoff) coincided with strong/moderate La Niña years during negative PDO phases. This study provides clear evidence that not only ENSO but also the PDO have significantly affected runoff regimes at the Keppel reefs for at least a century, and suggests that upcoming hydrological disturbances and ecological responses in the southern GBR region will be mediated by the future evolution of these sources of climate variability.

  19. Coral Luminescence Identifies the Pacific Decadal Oscillation as a Primary Driver of River Runoff Variability Impacting the Southern Great Barrier Reef

    PubMed Central

    Rodriguez-Ramirez, Alberto; Grove, Craig A.; Zinke, Jens; Pandolfi, John M.; Zhao, Jian-xin

    2014-01-01

    The Pacific Decadal Oscillation (PDO) is a large-scale climatic phenomenon modulating ocean-atmosphere variability on decadal time scales. While precipitation and river flow variability in the Great Barrier Reef (GBR) catchments are sensitive to PDO phases, the extent to which the PDO influences coral reefs is poorly understood. Here, six Porites coral cores were used to produce a composite record of coral luminescence variability (runoff proxy) and identify drivers of terrestrial influence on the Keppel reefs, southern GBR. We found that coral skeletal luminescence effectively captured seasonal, inter-annual and decadal variability of river discharge and rainfall from the Fitzroy River catchment. Most importantly, although the influence of El Niño-Southern Oscillation (ENSO) events was evident in the luminescence records, the variability in the coral luminescence composite record was significantly explained by the PDO. Negative luminescence anomalies (reduced runoff) were associated with El Niño years during positive PDO phases while positive luminescence anomalies (increased runoff) coincided with strong/moderate La Niña years during negative PDO phases. This study provides clear evidence that not only ENSO but also the PDO have significantly affected runoff regimes at the Keppel reefs for at least a century, and suggests that upcoming hydrological disturbances and ecological responses in the southern GBR region will be mediated by the future evolution of these sources of climate variability. PMID:24416214

  20. Extreme Winter Precipitation Events in the Western United States: The impact of ENSO and the Madden-Julian Oscillation

    NASA Astrophysics Data System (ADS)

    Schubert, S.; Chang, Y.; Suarez, M.; Pegion, P.

    2005-05-01

    The west coast of the United States occasionally experiences intense winter storms that account for a major fraction of the total seasonal rain(snow)fall. In some cases, it is not a single storm, but a series of storms, that batter the west coast in a matter of few weeks. These storms, unfortunately, are often associated with flooding, mudslides and other disasters that can lead to extensive property damage and even loss of life. In this talk, I will review our current understanding of the nature of these storms and the extent to which their occurrence is impacted by El Nino/Southern Oscillation and the Madden Julian Oscillation. The results are based on 50 years of precipitation observations, NCEP/NCAR reanalyses, and idealized experiments with a global atmospheric general circulation model.

  1. El Nino as an element of a global-scale wave in the atmosphere-ocean system

    NASA Astrophysics Data System (ADS)

    Serykh, Ilya; Sonechkin, Dmitry

    2016-04-01

    The analyses of the real meteorological and oceanographical data, and long runs of the coupled atmosphere-ocean hydro- thermodynamical models identify a spatial-temporal structure of the main mode of the interannual to decadal climatic variations. This mode looks like a global-scale wave that extends from West to East around the Earth, and varies rhythmically. In fact, the establishment of this wave is a generalization and development of the well-known structures of the so-called "teleconnections" in the ocean-atmosphere system. The known regional structures like ENSO, IOD, PDO, IPO, PNA, NAO, AO, ACW and other can be considered as parts of this global-scale wave. Moving eastward around the Earth, this wave triggers El Nino - Southern oscillation events. An index of this wave is proposed as a sum of normalized anomalies of the sea level pressure and the near-surface temperature in 20 locations around the globe. It is proven that the power spectrum of this index is not continuous but discrete in its character. Thus, one can suppose that the dynamics of the global-scale wave is nonchaotic, and so predictable with no limit in principle. The index power spectrum reveals statistically significant peaks at the same periods that are inherent to the power spectra of the traditional ENSO indices. The main peaks are at the sub-harmonics of the well-known Chandler wobble (of the ~1.2 year period) in the Earth's pole motion: 3.6; 4.8; 2.4 years. Some other statistically significant peaks also are seen at the super-harmonics of the Luni-Solar nutation (of the ~18.6 year period), and combinational harmonics of the Schwabe's and Hale's solar activity cycles. Based on the eastward propagation of the global-scale wave, a predictor of ENSO events was suggested. It has high correlation (about 0.7) with Nino indices but leads them on about 12 months. The use of this predictor opens a possibility to overcome the Spring Predictability Barrier in ENSO forecasting.

  2. El Nino north - Nino effects in the eastern subarctic Pacific ocean

    SciTech Connect

    Wooster, W.S.; Fluharty, D.L.

    1985-01-01

    This book represents the proceedings of a meeting on El Nino effects in the eastern subarctic Pacific, held on 12-13 September 1984 at the Pacific Marine Environmental Laboratory, Seattle, Washington. The papers of the first day focused on the physical environment; the second day was devoted to examining the biological response. These papers show how an El Nino event such as that of 1982-1983 can perturb the ocean and its biota far from the equator and provide some insight into the research required if the environmental effects and their biological consequences are to be successfully predicted.

  3. El Niño-Southern Oscillation determines the salinity of the freshwater lens under a coral atoll in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    van der Velde, M.; Javaux, M.; Vanclooster, M.; Clothier, B. E.

    2006-11-01

    The freshwater resources of coral atolls occur mainly as lenses floating on salt water underneath the islands. The size and shape of these lenses are determined by hydrogeologic characteristics, the rainfall recharge rate and its temporal variation, plus extractions (Underwood et al., 1992; Jones and Banner, 2003; Jocson et al., 2002). In the South Pacific, rainfall exhibits seasonal as well as interannual variability related to the El Niño-Southern Oscillation (ENSO) (Ropelewski and Halpert, 1987). We used electric conductivity measurements from pumped wells on Tongatapu to show a moderate ENSO control on the temporal fluctuation of the pumped freshwater salinity. The salinity dynamics depended on low or increased rainfall recharge during respectively dry El Niño periods or wet La Niña events. ENSO events cause a large variation around the mean salinity and determine the relative salinity over the time-scale of several years, while a smaller variation is introduced by seasonal rainfall. The Southern Oscillation Index (SOI) (Troup, 1965; Stone et al., 1996) was used to predict freshwater salinity with a lag time of 10 months.

  4. Short-term effect of El Niño-Southern Oscillation on pediatric hand, foot and mouth disease in Shenzhen, China.

    PubMed

    Lin, Hualiang; Zou, Hong; Wang, Qinzhou; Liu, Chunxiao; Lang, Lingling; Hou, Xuexin; Li, Zhenjun

    2013-01-01

    Hand, foot and mouth disease (HFMD) was an emerging viral infectious disease in recent years in Shenzhen. The underlying risk factors have not yet been systematically examined. This study analyzed the short-term effect of El Niño-Southern Oscillation on pediatric HFMD in Shenzhen, China. Daily count of HFMD among children aged below 15 years old, Southern Oscillation Index (SOI), and weather variables were collected to construct the time series. A distributed lag non-linear model was applied to investigate the effect of daily SOI on pediatric HFMD occurrence during 2008-2010. We observed an acute effect of SOI variation on HFMD occurrence. The extremely high SOI (SOI = 45, with 0 as reference) was associated with increased HFMD, with the relative risk (RR) being 1.66 (95% Confidence Interval [CI]: 1.34-2.04). Further analyses of the association between HFMD and daily mean temperature and relative humidity supported the correlation between pediatric HFMD and SOI. Meteorological factors might be important predictors of pediatric HFMD occurrence in Shenzhen.

  5. The influences of Type 1 El Nino and La Nina events on streamflows in the Pacific Southwest of the United States

    SciTech Connect

    Kahya, E.; Dracup, J.A. )

    1994-06-01

    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 almost 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.

  6. Aerosol-climate interactions over southern Africa: the ENSO signal and interannual variability

    NASA Astrophysics Data System (ADS)

    Tummon, Fiona

    2010-05-01

    Southern Africa is a region that experiences high interannual climatic variability. It is also a region that, in general is poorly developed, has a high population growth rate and is at times politically unstable. As a whole, the region is extremely vulnerable to climatic changes, with a large proportion of the population depending on rain-fed agriculture as a source of income and subsistence. It is well known that the El-Nino/La-Nina oscillation contributes significantly to the climate variability over much of southern Africa; with El-Nino years generally being dry and warm in the southeastern parts and unusually wet in the eastern equatorial regions, whilst La-Nina years are generally wet and cool in the southeast, but dry in the eastern tropics. This in turn effects vegetation growth, and as a result the extent of biomass burning in the following dry season; with above-average wet seasons leading to increased burning, and drier than average seasons being followed by less extensive burning. The savannas of Africa experience some of the most extensive burning in the world, and contribute a very significant portion of the aerosol loading over southern Africa during the dry austral winter season, from June through October. At present, however, the climatic impact of aerosols over southern Africa is poorly understood, particularly in terms of the interannual variability of these impacts. The regional climate model RegCM3 is used to investigate the climatic impacts of the aerosol burden over southern African further, with particular focus on interannual variability and the role of ENSO. Preliminary results indicate that the impacts of the direct and semi-direct aerosol-effects on regional temperature, precipitation and circulation patterns vary between dry (El-Nino) and wet (La-Nina) years. There is a strong seasonality to these effects, with significant impacts occurring only during the austral winter, when biomass burning peaks throughout the southern Africa

  7. Decadal Variation of the Number of El Nino Onsets and El Nino-Related Months and Estimating the Likelihood of El Nino Onset in a Warming World

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2009-01-01

    Examination of the decadal variation of the number of El Nino onsets and El Nino-related months for the interval 1950-2008 clearly shows that the variation is better explained as one expressing normal fluctuation and not one related to global warming. Comparison of the recurrence periods for El Nino onsets against event durations for moderate/strong El Nino events results in a statistically important relationship that allows for the possible prediction of the onset for the next anticipated El Nino event. Because the last known El Nino was a moderate event of short duration (6 months), having onset in August 2006, unless it is a statistical outlier, one expects the next onset of El Nino probably in the latter half of 2009, with peak following in November 2009-January 2010. If true, then initial early extended forecasts of frequencies of tropical cyclones for the 2009 North Atlantic basin hurricane season probably should be revised slightly downward from near average-to-above average numbers to near average-to-below average numbers of tropical cyclones in 2009, especially as compared to averages since 1995, the beginning of the current high-activity interval for tropical cyclone activity.

  8. Pastoral del Nino: Bringing the Abundant Life to Paraguayan Children

    ERIC Educational Resources Information Center

    Austin, Ann Berghout; Aquino, Cyle; Burro, Elizabeth

    2007-01-01

    Pastoral del Nino is transforming children's lives in rural Paraguay. Part of Pastoral Social (Catholic Social Services), Pastoral del Nino's primary focus is to bring "vida en abundancia" (the abundant life) to families by ensuring that mothers survive childbirth and children reach their first birthdays. In addition, the organization promotes…

  9. What Is El Nino and How Does It Affect Us?

    ERIC Educational Resources Information Center

    Biachi, Janine; Nutter, Ann; Price, Jon

    This teaching unit provides materials and information about the effects of El Nino on people, the economy, and nature around the world. It is important for students to know the impact El Nino has had on the world. The unit presents information that builds student's interest in other environmental phenomena as well. This unit offers information on…

  10. El Nino influence on Holocene reef accretion in Hawai'i

    USGS Publications Warehouse

    Rooney, J.; Fletcher, C.; Grossman, E.; Engels, M.; Field, M.

    2004-01-01

    intertidal zone. We infer that forcing other than relative sea-level rise has altered the natural ability to support reef accretion on Hawaiian insular shelves. The limiting factor in these areas today is wave energy. Numbers of both large North Pacific swell events and hurricanes in Hawai'i are greater during El Nino years. We infer that if these major reef-limiting forces were suppressed, net accretion would occur in some areas in Hawai'i that are now wave-limited. Studies have shown that El Nino/Southern Oscillation (ENSO) was significantly weakened during early-mid Holocene time, only attaining an intensity similar to the current one ca. 5000 yr ago. We speculate that this shift in ENSO may assist in explaining patterns of Holocene Hawaiian reef accretion that are different from those of the present and apparently not related to relative sen-level rise.

  11. Long-term data reveal a population decline of the tropical lizard Anolis apletophallus, and a negative affect of el nino years on population growth rate.

    PubMed

    Stapley, Jessica; Garcia, Milton; Andrews, Robin M

    2015-01-01

    Climate change threatens biodiversity worldwide, however predicting how particular species will respond is difficult because climate varies spatially, complex factors regulate population abundance, and species vary in their susceptibility to climate change. Studies need to incorporate these factors with long-term data in order to link climate change to population abundance. We used 40 years of lizard abundance data and local climate data from Barro Colorado Island to ask how climate, total lizard abundance and cohort-specific abundance have changed over time, and how total and cohort-specific abundance relate to climate variables including those predicted to make the species vulnerable to climate change (i.e. temperatures exceeding preferred body temperature). We documented a decrease in lizard abundance over the last 40 years, and changes in the local climate. Population growth rate was related to the previous years' southern oscillation index; increasing following cooler-wetter, la niña years, decreasing following warmer-drier, el nino years. Within-year recruitment was negatively related to rainfall and minimum temperature. This study simultaneously identified climatic factors driving long-term population fluctuations and climate variables influencing short-term annual recruitment, both of which may be contributing to the population decline and influence the population's future persistence.

  12. The 1997-98 El Nino Event and Related Wintertime Lightning Variations in the Southeastern United States

    NASA Technical Reports Server (NTRS)

    Goodman, S. J.; Buechler, D. E.; Knupp, K.; Driscoll, K.; McCaul, E. W., Jr.

    2000-01-01

    The El Nino Southern Oscillation (ENSO) is a climate anomaly responsible for worldwide weather impacts ranging from droughts to floods. In the United States, warm episode years are known to produce above normal rainfall along the Southeast U.S. Gulf Coast and into the Gulf of Mexico, with the greatest response observed in the October-March period of the warm episode year. The 1997-98 warm episode is notable for being the strongest event since 198283. With the recent launch of a lightning sensor on NASA's Tropical Rainfall Measuring Mission (TRMM) in November 1997 and the detailed coverage of the U.S. National Lightning Detection Network (NLDN), such interannual changes in lightning activity can be examined with far greater detail than ever before. For the 1997-98 ENSO event the most significant year-to-year changes in lightning frequency worldwide occurred along the Gulf Coast and within the Gulf of Mexico basin during the Northern Hemisphere winter. Within a broad swath across the northern Gulf of Mexico basin there is a 100-150% increase in lightning days year-to-year (a peak of 33 days in the winter of 1997-98 vs. only 15 days or fewer in both the 1996-97 and 1998-99 winter). In addition, there is a nearly 200% increase in lightning hours (a peak of 138 hours in 1996-97 vs. 50 hours in both 1996-97 and 1998-99). The increase in lightning activity during ENSO occurs in association with a 100% increase in the number of synoptic scale cyclones that developed within or moved through the Gulf basin. The primary variables controlling these enhancements in thunderstorm activity are the position and strength of the jet stream.

  13. Watching for the Next El Nino

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Topex/Poseidon image of sea-surface heights was taken during a 10-day collection cycle ending August 7, 2002. Sea-surface heights are a measure of how much heat is stored in the ocean below to influence future planetary climate events. Since May 2001, there have been a series of warm Kelvin waves--eastward-moving ocean waves that cross the equatorial Pacific in about two months. A sizable one arrived at the South American coast last February, raising the ocean temperature by 2 degrees Celsius (3.6 degrees Fahrenheit) and triggering the National Oceanic and Atmospheric Administration's forecast for a mild El Nino in 2002. There was another wave in June, followed by the current large pool of warm water in the tropical Pacific that is now moving toward the coast of South America at a speed of 215 kilometers (134 miles) a day and will arrive there in three to four weeks, raising ocean temperatures. Scientists will continue to monitor the Pacific closely for further signs of El Nino formation and intensity.

  14. El Nino Threatens, but Fizzles (for Now)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    For the first two weeks in June, the surface winds and sea surface temperatures across the Pacific Ocean began to display an all-too-familiar pattern. Normally, the trade winds in the equatorial Pacific blow from east to west and push warm surface waters from the eastern Pacific westward. As is indicated by the arrows displaying wind speed and direction in the above Quick Scatterometer (QuikScat) satellite data, the trade winds stopped and in some cases reversed course across the equatorial Pacific in early June. Consequently, the waters in the eastern Pacific grew warmer than usual. If this trend continued or intensified, another El Nino would have settled in by fall 2002 and rainfall and atmospheric circulation patterns would have begun to change across North and South America. However, in the later half of June conditions returned to normal. Scientists hope that satellite data from QuikScat will help them to study and even forecast future El Nino events. Launched aboard the SeaWinds satellite in 1999, the QuickScat instrument essentially sends out high frequency radio waves to detect the frothiness of ocean water. Since choppy ocean water is created almost solely by the surface winds blowing across the ocean, scientists can obtain an accurate measure of wind speed and direction from these data. Image courtesy NASA JPL Air-Sea Interaction and Climate Team

  15. ENSO dynamics and diversity resulting from the recharge oscillator interacting with the slab ocean

    NASA Astrophysics Data System (ADS)

    Yu, Yanshan; Dommenget, Dietmar; Frauen, Claudia; Wang, Gang; Wales, Scott

    2016-03-01

    El Nino-Southern Oscillation (ENSO) is the leading mode of interannual global climate variability, which in its essence is often described by the equatorial dynamics of the recharge oscillator with a fixed pattern. Here we explore the idea that ENSO can be simulated in a model with a fixed pattern of sea surface temperature variability following the recharge oscillator mechanism, which interacts with the thermodynamic red noise of a slab ocean. This model is capable of simulating the leading modes of sea surface temperature variability in the tropical Pacific in good agreement with the observations and most coupled general circulation models. ENSO dynamics, amplitude, seasonality, the structure of the leading patterns, its meridional extension, its variations in an eastern and central Pacific pattern and associated positive feedbacks are all influenced and simulated well by including the interaction of recharge oscillator and the thermodynamic coupling to the slab ocean model. We further point out that much of the ENSO diversity in the spatial structure is a reflection of this interaction. However, it also has to be noted that some equatorial dynamics are missing in this model and in coupled general circulation models that are important for the ENSO diversity.

  16. ENSO dynamics and diversity resulting from the recharge oscillator interacting with the slab ocean

    NASA Astrophysics Data System (ADS)

    Yu, Yanshan; Dommenget, Dietmar; Frauen, Claudia; Gang, Wang; Wales, Scott

    2015-04-01

    El Nino-Southern Oscillation (ENSO) is the leading mode of interannual global climate variability, which in its essence is often described by the equatorial dynamics of the recharge oscillator with a fixed pattern. Here we explore the idea that ENSO can be simulated in a model with a fixed pattern of sea surface temperature variability following the recharge oscillator mechanism, which interacts with the thermodynamic red noise of a slab ocean. This model is capable of simulating the leading modes of sea surface temperature variability in the tropical Pacific in good agreement with the observations and most coupled general circulation models. ENSO dynamics, amplitude, seasonality, the structure of the leading patterns, its meridional extension, its variations in an eastern and central Pacific pattern and associated positive feedbacks are all influenced and simulated well by including the interaction of recharge oscillator and the thermodynamic coupling to the slab ocean model. We further point out that much of the ENSO diversity in the spatial structure is a reflection of this interaction. However, it also has to be noted that some equatorial dynamics are missing in this model and in coupled general circulation models that are important for the ENSO diversity.

  17. TOPEX/El Nino Watch - El Nino Rhythm, Dec, 10, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Dec.10, 1997 and sea surface height is an indicator of the heat content of the ocean. The volume and area of the warm water pool related to El Nino has increased again after reaching a temporary low around Dec. 1. TOPEX/Poseidon has been tracking the fluctuations of the El Nino warm pool since it began early this year. Oceanographers believe the recent increases and decreases in the size of the warm water pool at the equator are part of the natural rhythm of El Nino and that the warm pool is occasionally pumped up by wind bursts blowing from the western and central Pacific Ocean. Each wind burst has triggered a temporary increase in area and volume of the warm pool. These data collected throughout 1997 have provided scientists with their first detailed view of how El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream

  18. Sea level response to the 1986-1987 El Niño-Southern Oscillation Event in the western Pacific in the vicinity of Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Ridgway, K. R.; Godfrey, J. S.; Meyers, G.; Bailey, R.

    1993-01-01

    Sea levels at the Papua New Guinea coast responded to the 1986-87 El Niño-Southern Oscillation (ENSO) event much as would be expected for points on the inshore edge of a western boundary current driven by remote sea level disturbances. The first empirical orthogonal function of sea level in the region accounts for 60% of the variance, and shows a clear western boundary current signal. Sea level observations from tide gauges and estimates from adjacent expendable bathythermographs (XBTs) are in good agreement, so XBT data are used to supplement sea level results; specifically, we obtain an estimate of the western boundary current as a function of depth. The anomalous transport through Vitiaz Strait varied by about 15 Sv during the event, with possibly more following the eastern New Ireland coast. The western boundary current response appears to be located entirely equatorward of the inflow feeding it, as expected from linear theory. The boundary current followed the Trobriand Island ridge, rather than the main Papua New Guinea coastline, and appears to bifurcate along southern New Britain. A maximum response to the ENSO occurred south of New Ireland, where steric sea level appeared to vary by up to 45 cm due to the ENSO event; this may be an inertial feature.

  19. Influence of the El Niño southern oscillation on the total ozone column and clear-sky ultraviolet radiation over China

    NASA Astrophysics Data System (ADS)

    Zhang, Jiankai; Tian, Wenshou; Xie, Fei; Li, Yuanpu; Wang, Feiyang; Huang, Jinlong; Tian, Hongying

    2015-11-01

    The influence of the El Niño Southern Oscillation (ENSO) on the total ozone column (TOC) and clear-sky ultraviolet (UV) radiation over China is analysed using various datasets and a chemistry-climate model. Higher TOC values than normal are found over most parts of China during El Niño events. La Niña events have almost the opposite effect on TOC anomalies over China. It is particularly noticeable that the maximum response of the TOC to ENSO shifts northward from southern China in winter to northern China in summer. The seasonal shift of the centre of TOC anomalies is related to the seasonal shift of the location of the East Asia westerly jet, accompanied by tropopause height changes and anomalous circulations induced by Rossby wave trains along the jet. The differences in the TOC between El Niño and La Niña events can cause up to 6-10% clear-sky erythemal UV changes over the middle and lower reaches of the Yangtze River in winter and the northwestern Tibetan Plateau during spring, which may have public health consequences.

  20. Atmospheric and Oceanic Response to Southern Ocean Deep Convection Oscillations on Decadal to Centennial Time Scales in Climate Models

    NASA Astrophysics Data System (ADS)

    Martin, T.; Reintges, A.; Park, W.; Latif, M.

    2014-12-01

    Many current coupled global climate models simulate open ocean deep convection in the Southern Ocean as a recurring event with time scales ranging from a few years to centennial (de Lavergne et al., 2014, Nat. Clim. Ch.). The only observation of such event, however, was the occurrence of the Weddell Polynya in the mid-1970s, an open water area of 350 000 km2 within the Antarctic sea ice in three consecutive winters. Both the wide range of modeled frequency of occurrence and the absence of deep convection in the Weddell Sea highlights the lack of understanding concerning the phenomenon. Nevertheless, simulations indicate that atmospheric and oceanic responses to the cessation of deep convection in the Southern Ocean include a strengthening of the low-level atmospheric circulation over the Southern Ocean (increasing SAM index) and a reduction in the export of Antarctic Bottom Water (AABW), potentially masking the regional effects of global warming (Latif et al., 2013, J. Clim.; Martin et al., 2014, Deep Sea Res. II). It is thus of great importance to enhance our understanding of Southern Ocean deep convection and clarify the associated time scales. In two multi-millennial simulations with the Kiel Climate Model (KCM, ECHAM5 T31 atmosphere & NEMO-LIM2 ~2˚ ocean) we showed that the deep convection is driven by strong oceanic warming at mid-depth periodically overriding the stabilizing effects of precipitation and ice melt (Martin et al., 2013, Clim. Dyn.). Sea ice thickness also affects location and duration of the deep convection. A new control simulation, in which, amongst others, the atmosphere grid resolution is changed to T42 (~2.8˚), yields a faster deep convection flip-flop with a period of 80-100 years and a weaker but still significant global climate response similar to CMIP5 simulations. While model physics seem to affect the time scale and intensity of the phenomenon, the driving mechanism is a rather robust feature. Finally, we compare the atmospheric and

  1. Interdecadal changes in the co-variability of North Pacific Oscillation and Pacific Meridional Mode and their impact on the tropical Pacific climate variability

    NASA Astrophysics Data System (ADS)

    Shin, So-Jung; An, Soon-Il

    2016-04-01

    North Pacific Oscillation (NPO) and Pacific Meridional Mode (PMM) are known as the representatives of extratropical stochastic forcings to influence the tropical Pacific climate, especially El Nino-Southern Oscillation (ENSO), through a wind-evaporation-SST (WES) feedback mechanism (a.k.a. 'seasonal footprinting'). NPO and PMM are obviously independent phenomena, but sometimes they occur together. Here, we explore the concurrence of NPO and PMM for the period of 1872 - 2012, and found that the concurrence of NPO and PMM is related to the eastward migration of Aleutian Low. A conditional composite analysis showed that only when NPO and PMM occurred together, the El Nino-like SST anomalies were significantly induced in the following winter. Furthermore, the co-variability between NPO and PMM shows the noticeable interdecadal variations, which is somehow related to the change in the mean North Pacific upper-level jet stream. This is because the mean jet stream affects the location and intensity of Aleutian Low. We further analyzed the various coupled model simulations, and found that the model simulations provide consistent results to the observation.

  2. Remote Sensing the Patterns of Vector-borne Disease in El Nino and non-El Nino Years

    NASA Technical Reports Server (NTRS)

    Wood, B. L.; Chang, J.; Lobitz, B.; Beck, L.; DAntoni, Hector (Technical Monitor)

    1997-01-01

    The relationship between El Nino and non-El Nino and the patterns of vector-borne disease can be viewed at a variety of spatial and temporal scales. At one extreme are long term predictions of changing precipitation and temperature patterns at continental and global scales. At the opposite extreme are the local or site specific ecological changes associated with the long term events. In order to understand and address the human health consequences of El Nino events, especially the patterns of vector-borne diseases, it is necessary to combine both scales of observation. At a local or regional scale the patterns of vector-borne diseases are determined by temperature, precipitation, and habitat availability. These factors, as well as disease incidence can be altered by El Nino events. Remote sensing data such as that acquired by the NOAA AVHRR and Landsat TM sensors can be used to characterize and monitor changing ecological conditions and therefore predict vector-borne disease patterns. The authors present the results of preliminary work on the analysis of historical AVHRR and TM data acquired during El Nino and nonfatal Nino years to characterize ecological conditions in Peru on a monthly basis. This information will then be combined with disease data to determine the relationship between changes in ecological conditions and disease incidence. Our goal is to produce a sequence of remotely sensed images which can be used to show the ecological and disease patterns associated with long term El Nino events and predictions.

  3. Influence of El Nino and ITCZ on Brazilian River Streamflows

    NASA Astrophysics Data System (ADS)

    Lopes, A.; Dracup, J. A.

    2010-12-01

    This study analyzes effects of climatic phenomena El Nino and ITCZ latitudinal movements on streamflow patterns in major Brazilian river basins: Amazon (north), Araguaia-Tocantins (central-north), Parana (central-south) and Sao Francisco (central-northeast). Multiple correlation between annual streamflows and the NINO 3.4 and North Tropical Atlantic SST indexes (NTA) were analyzed for each river basin using different annual periods in order to account for the delay in streamflow response. The data consists of unimpaired river discharge time series at key points (from the Brazilian National Water Agency (ANA)); normalized yearly averaged NINO3.4 index characterizing El Nino (from NOAA); and NTA index (from NOAA), as a surrogate of the latitudinal movement of the ITCZ, since it is correlated to the Atlantic SST gradient. As a result, each river basin showed a different response. At the Amazon river basin, almost all dry years occurred when NINO3.4 was above average (El Nino years). Moreover, in almost every year when NINO3.4 was below average (La Nina) the streamflows were above average. Thus, it seems that La Nina have strong effects in floods in Amazon river. Moreover, El Nino events seem to be a necessary, but not sufficient condition for low streamflows at Amazon river. A weaker relationship was found for Xingu river basin, since it is probably affected by cold fronts from the south. As the location of river basins changes towards the south, the effect of El Nino events gets weaker as for Araguaia-Tocantins and Sao Francisco river basins. At the Parana river basin, the relationship is reversed. Almost all extreme wet years occurred during El Nino years. The correlation between streamflows and the NTA indexes were very weak for all river basins except for the Amazon. When the NTA anomaly is negative, wet years occurs, since the ITCZ moves southwards and stays longer at that position, increasing rainfall over the Amazon and Northeast of Brazil. In contrast, almost

  4. Southern Peru desert shattered by the great 2001 earthquake: Implications for paleoseismic and paleo-El Niño–Southern Oscillation records

    PubMed Central

    Keefer, David K.; Moseley, Michael E.

    2004-01-01

    In the desert region around the coastal city of Ilo, the great southern Peru earthquake of June 23, 2001 (8.2–8.4 moment magnitude), produced intense and widespread ground-failure effects. These effects included abundant landslides, pervasive ground cracking, microfracturing of surficial hillslope materials, collapse of drainage banks over long stretches, widening of hillside rills, and lengthening of first-order tributary channels. We have coined the term “shattered landscape” to describe the severity of these effects. Long-term consequences of this landscape shattering are inferred to include increased runoff and sediment transport during postearthquake rainstorms. This inference was confirmed during the first minor postearthquake rainstorm there, which occurred in June and July of 2002. Greater amounts of rainfall in this desert region have historically been associated with El Niño events. Previous studies of an unusual paleoflood deposit in this region have concluded that it is the product of El Niño-generated precipitation falling on seismically disturbed landscapes. The effects of the 2001 earthquake and 2002 rainstorm support that conclusion. PMID:15263069

  5. TOPEX/El Nino Watch - El Nino is Still Lingering in the Pacific May 3, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea-surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea-surface height relative to normal ocean conditions on May 3, 1998, and sea-surface height is an indicator of the heat content of the ocean. The image shows that sea-surface height along the central and eastern equatorial Pacific has maintained a near normal state since March 1998. However, the western equatorial Pacific, shown here in purple, has not returned to a normal state and is still about 30 centimeters (12 inches) below normal sea level. Remnants of the El Nino warm water pool, shown in red and white, are situated to the north of the equator. Oceanographers indicate these measurements show that the Pacific has not yet fully recovered from this large El Nino event. These sea-surface height measurements have provided scientists with a detailed view of how the 1997-98 El Nino's warm water pool behaves because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National

  6. The Origins of Mexico's Universidad de los Ninos.

    ERIC Educational Resources Information Center

    Levy, Raquel

    1989-01-01

    The article describes an after school program, the Universidad de los Ninos, in Mexico City, for children with special abilities. The program stresses development of individual potential, a flexible curriculum, parent involvement, and development of social responsibility. (DB)

  7. El Nino - La Nina Implications on Flood Hazard Mitigation

    SciTech Connect

    R. French; J. Miller

    2006-03-31

    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.

  8. TOPEX/El Nino Watch - El Nino Warm Water Pool Decreasing, Jan, 08, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Jan. 8, 1998, and sea surface height is an indicator of the heat content of the ocean. The volume of the warm water pool related to the El Nino has decreased by about 40 percent since its maximum in early November, but the area of the warm water pool is still about one and a half times the size of the continental United States. The volume measurements are computed as the sum of all the sea surface height changes as compared to normal ocean conditions. In addition, the maximum water temperature in the eastern tropical Pacific, as measured by the National Oceanic and Atmospheric Administration (NOAA), is still higher than normal. Until these high temperatures diminish, the El Nino warm water pool still has great potential to disrupt global weather because the high water temperatures directly influence the atmosphere. Oceanographers believe the recent decrease in the size of the warm water pool is a normal part of El Nino's natural rhythm. TOPEX/Poseidon has been tracking these fluctuations of the El Nino warm pool since it began in early 1997. These sea surface height measurements have provided scientists with their first detailed view of how El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds

  9. Volcanos and El Nino: Signal separation in northern hemisphere winter

    SciTech Connect

    Kirchner, I.; Graf, H.F.

    1995-08-01

    The frequent coincidence of volcanic forcing with El Nino events disables the clear assignment of climate anomalies to either volcanic or El Nino forcing. In order to select the signals, a set of four different perpetual January GCM experiments was performed (control, volcano case, El Nino case and combined volcano/El Nino case) and studied with advanced statistical methods for the Northern Hemisphere winter. The results were compared with observations. The signals for the different forcings are discussed for three variables (temperature, zonal wind and geopotential height) and five levels (surface, 850 hPa. 500 hPa, 200 hPa and 50 hPa). The global El Nino signal can be selected more clearly in the troposphere than in the stratosphere. In contrast, the global volcano signal is strongest in the stratospheric temperature field. The amplitude of the perturbation for the volcano case is largest in the Atlantic region. The observed effect of local cooling due to the volcanic reduction of short-wave radiation over large land areas (like Asia) in sub-tropical regions, the observed advective warming over Eurasia and the advective cooling over Greenland are well simulated in the model. The radiative cooling near the surface is important for the volcano signal in the subtropics, but it is weak in high latitudes during winter. A statistically significant tropospheric signal of El Nino forcing occurs in the subtropics and in the mid-latitudes of the North Pacific. The local anomalies in the El Nino forcing region in the tropics, and the warming over North America in middle and high latitudes are simulated as observed. The combined signal is different from a simple linear combination of the separate signals. It leads to a climate perturbation stronger than for forcing with El Nino or stratospheric aerosol alone and to a somewhat modified pattern. 73 refs., 16 figs., 2 tabs.

  10. Pacific Decadal Variability in the Southern Indian Ocean: A 1 ky Interdecadal Pacific Oscillation and Australian Megadrought Reconstruction from Law Dome, East Antarctica.

    NASA Astrophysics Data System (ADS)

    Vance, T.; Roberts, J. L.; Plummer, C. T.; Kiem, A.; van Ommen, T. D.

    2014-12-01

    The Interdecadal Pacific Oscillation (IPO) is a multidecadal mode of Pacific basin SST anomalies, and is the basin-wide, bi-hemispheric expression of the Pacific Decadal Oscillation (PDO). The two indices are highly correlated, but the extent to which they are merely low frequency ENSO is debated. Nonetheless, the IPO/PDO significantly influences interannual rainfall variability and drought risk across and beyond the Pacific region on multi-decadal timescales, thus an understanding of long-term IPO/PDO variability will help with assessing past and future drought risk. A new and highly accurate 1 ky IPO reconstruction has been produced from the Law Dome ice core (East Antarctica). Law Dome is a high accumulation site on the coast of Antarctica in the Indian Ocean sector of the Southern Ocean, and the Law Dome record is directly related to atmospheric anomalies across a broad mid-latitude swathe of this region. The reconstruction utilizes both the accumulation (snowfall) and sea salt (wind proxy) records to produce a reconstruction that is highly calibrated to the instrumental IPO record from 1870-2009 and shows excellent skill (reduction of error value of 0.86). We then super-imposed the 1 ky IPO on a Law Dome proxy for rainfall in eastern subtropical Australia (previously shown to represent rainfall with high significance during IPO positive phases (r =0.406-0.677, p <0.0001-0.01) to identify eight Australian 'mega-droughts' (dry periods >5 y duration) over the last millennium. Six mega-droughts occur between AD 1000-1320 including one 39 y drought (AD 1174-1212). Water resources and infrastructure planning in Australia has been based on very limited statistical certainty around drought risk due to the short instrumental record and lack of rainfall proxies. A recent drought (the 'Big Dry' ~1995-2009) brought both agricultural and urban water supplies to critically low levels, while the Murray-Darling Basin river system, which provides 65% of the water used for

  11. Bacterial community composition and physiological shifts associated with the El Niño Southern Oscillation (ENSO) in the Patos Lagoon estuary.

    PubMed

    They, Ng Haig; Ferreira, Lise Maria Holanda; Marins, Luís Fernando; Abreu, Paulo Cesar

    2015-04-01

    The Patos Lagoon estuary is a microtidal system that is strongly regulated by atmospheric forces, including remote large-scale phenomena such as the El Niño Southern Oscillation (ENSO), which affects precipitation patterns in the region. In this study, we investigated whether the bacterial community composition (BCC), community-level physiological profiles (CLPP), and a set of environmental variables were affected by the transition from a moderate El Niño to a strong La Niña event (June 2010 to May 2011). We identified two distinct periods: a period following El Niño that was characterized by low salinity and high concentrations of NO3(-) and PO4(-3) and low molecular weight (LMW) substances and a period following La Niña during which salinity, temperature, and transparency increased and the concentrations of nutrients and LMW substances decreased. The BCC and CLPP were significantly altered in response to this transition. This is the first study addressing the effect of ENSO on bacteria at the community level in an estuarine system. Our results suggest that there is a link between ENSO and bacteria, indicating the role of climate variability in bacterial activities and, hence, the cycling of organic matter by these microorganisms. PMID:25339307

  12. Changes in the apparent survival of a tropical bird in response to the El Niño Southern Oscillation in mature and young forest in Costa Rica.

    PubMed

    Wolfe, Jared D; Ralph, C John; Elizondo, Pablo

    2015-07-01

    The effects of habitat alteration and climatic instability have resulted in the loss of bird populations throughout the globe. Tropical birds in particular may be sensitive to climate and habitat change because of their niche specialization, often sedentary nature, and unique life-cycle phenologies. Despite the potential influence of habitat and climatic interactions on tropical birds, we lack comparisons of avian demographics from variably aged forests subject to different climatic phenomena. Here, we measured relationships between forest type and climatic perturbations on White-collared Manakin (Manacus candei), a frugivorous tropical bird, by using 12 years of capture data in young and mature forests in northeastern Costa Rica. We used Cormack-Jolly-Seber models and an analysis of deviance to contrast the influence of the El Niño Southern Oscillation (ENSO) on manakin survival. We found that ENSO had little effect on manakin survival in mature forests. Conversely, in young forests, ENSO explained 79% of the variation where dry El Niño events negatively influenced manikin survival. We believe mature forest mitigated negative effects of dry El Niño periods and can serve as refugia for some species by buffering birds from climatic instability. Our results represent the first published documentation that ENSO influences the survival of a resident Neotropic landbird. PMID:25687831

  13. Extreme rainfall activity in the Australian tropics reflects changes in the El Niño/Southern Oscillation over the last two millennia

    PubMed Central

    Denniston, Rhawn F.; Villarini, Gabriele; Gonzales, Angelique N.; Wyrwoll, Karl-Heinz; Polyak, Victor J.; Ummenhofer, Caroline C.; Lachniet, Matthew S.; Wanamaker, Alan D.; Humphreys, William F.; Woods, David; Cugley, John

    2015-01-01

    Assessing temporal variability in extreme rainfall events before the historical era is complicated by the sparsity of long-term “direct” storm proxies. Here we present a 2,200-y-long, accurate, and precisely dated record of cave flooding events from the northwest Australian tropics that we interpret, based on an integrated analysis of meteorological data and sediment layers within stalagmites, as representing a proxy for extreme rainfall events derived primarily from tropical cyclones (TCs) and secondarily from the regional summer monsoon. This time series reveals substantial multicentennial variability in extreme rainfall, with elevated occurrence rates characterizing the twentieth century, 850–1450 CE (Common Era), and 50–400 CE; reduced activity marks 1450–1650 CE and 500–850 CE. These trends are similar to reconstructed numbers of TCs in the North Atlantic and Caribbean basins, and they form temporal and spatial patterns best explained by secular changes in the dominant mode of the El Niño/Southern Oscillation (ENSO), the primary driver of modern TC variability. We thus attribute long-term shifts in cyclogenesis in both the central Australian and North Atlantic sectors over the past two millennia to entrenched El Niño or La Niña states of the tropical Pacific. The influence of ENSO on monsoon precipitation in this region of northwest Australia is muted, but ENSO-driven changes to the monsoon may have complemented changes to TC activity. PMID:25825740

  14. Extreme rainfall activity in the Australian tropics reflects changes in the El Niño/Southern Oscillation over the last two millennia.

    PubMed

    Denniston, Rhawn F; Villarini, Gabriele; Gonzales, Angelique N; Wyrwoll, Karl-Heinz; Polyak, Victor J; Ummenhofer, Caroline C; Lachniet, Matthew S; Wanamaker, Alan D; Humphreys, William F; Woods, David; Cugley, John

    2015-04-14

    Assessing temporal variability in extreme rainfall events before the historical era is complicated by the sparsity of long-term "direct" storm proxies. Here we present a 2,200-y-long, accurate, and precisely dated record of cave flooding events from the northwest Australian tropics that we interpret, based on an integrated analysis of meteorological data and sediment layers within stalagmites, as representing a proxy for extreme rainfall events derived primarily from tropical cyclones (TCs) and secondarily from the regional summer monsoon. This time series reveals substantial multicentennial variability in extreme rainfall, with elevated occurrence rates characterizing the twentieth century, 850-1450 CE (Common Era), and 50-400 CE; reduced activity marks 1450-1650 CE and 500-850 CE. These trends are similar to reconstructed numbers of TCs in the North Atlantic and Caribbean basins, and they form temporal and spatial patterns best explained by secular changes in the dominant mode of the El Niño/Southern Oscillation (ENSO), the primary driver of modern TC variability. We thus attribute long-term shifts in cyclogenesis in both the central Australian and North Atlantic sectors over the past two millennia to entrenched El Niño or La Niña states of the tropical Pacific. The influence of ENSO on monsoon precipitation in this region of northwest Australia is muted, but ENSO-driven changes to the monsoon may have complemented changes to TC activity. PMID:25825740

  15. Bacterial community composition and physiological shifts associated with the El Niño Southern Oscillation (ENSO) in the Patos Lagoon estuary.

    PubMed

    They, Ng Haig; Ferreira, Lise Maria Holanda; Marins, Luís Fernando; Abreu, Paulo Cesar

    2015-04-01

    The Patos Lagoon estuary is a microtidal system that is strongly regulated by atmospheric forces, including remote large-scale phenomena such as the El Niño Southern Oscillation (ENSO), which affects precipitation patterns in the region. In this study, we investigated whether the bacterial community composition (BCC), community-level physiological profiles (CLPP), and a set of environmental variables were affected by the transition from a moderate El Niño to a strong La Niña event (June 2010 to May 2011). We identified two distinct periods: a period following El Niño that was characterized by low salinity and high concentrations of NO3(-) and PO4(-3) and low molecular weight (LMW) substances and a period following La Niña during which salinity, temperature, and transparency increased and the concentrations of nutrients and LMW substances decreased. The BCC and CLPP were significantly altered in response to this transition. This is the first study addressing the effect of ENSO on bacteria at the community level in an estuarine system. Our results suggest that there is a link between ENSO and bacteria, indicating the role of climate variability in bacterial activities and, hence, the cycling of organic matter by these microorganisms.

  16. Changes in the apparent survival of a tropical bird in response to the El Niño Southern Oscillation in mature and young forest in Costa Rica.

    PubMed

    Wolfe, Jared D; Ralph, C John; Elizondo, Pablo

    2015-07-01

    The effects of habitat alteration and climatic instability have resulted in the loss of bird populations throughout the globe. Tropical birds in particular may be sensitive to climate and habitat change because of their niche specialization, often sedentary nature, and unique life-cycle phenologies. Despite the potential influence of habitat and climatic interactions on tropical birds, we lack comparisons of avian demographics from variably aged forests subject to different climatic phenomena. Here, we measured relationships between forest type and climatic perturbations on White-collared Manakin (Manacus candei), a frugivorous tropical bird, by using 12 years of capture data in young and mature forests in northeastern Costa Rica. We used Cormack-Jolly-Seber models and an analysis of deviance to contrast the influence of the El Niño Southern Oscillation (ENSO) on manakin survival. We found that ENSO had little effect on manakin survival in mature forests. Conversely, in young forests, ENSO explained 79% of the variation where dry El Niño events negatively influenced manikin survival. We believe mature forest mitigated negative effects of dry El Niño periods and can serve as refugia for some species by buffering birds from climatic instability. Our results represent the first published documentation that ENSO influences the survival of a resident Neotropic landbird.

  17. Influence of El Niño-Southern Oscillation on the population structure of a sea lion breeding colony in the Gulf of California

    NASA Astrophysics Data System (ADS)

    Shirasago-Germán, Bernardo; Pérez-Lezama, Edgar L.; Chávez, Ernesto A.; García-Morales, Ricardo

    2015-03-01

    The El Niño-Southern Oscillation (ENSO) phenomenon has a significant influence on Pacific marine ecosystems from primary trophic levels to top predators that cause fluctuations in their populations. Based on this fact we analyzed the sea lion Zalophus californianus population structure variability using censuses performed from 1979 to 2004 in Los Islotes breeding colony located at La Paz Bay as well as concomitant the ENSO phenomenon variability. To discriminate variations in the population structure not ascribable to the population attributes, a virtual population was created and compared to the census population. The residuals obtained from this comparison were correlated with the MEI (Multivariate ENSO Index) and BEST (Bivariate ENSO Time Series) indices, descriptors of the ENSO variability. The results showed that the population structure is an adequate descriptor of the conditions of the population instead of the abundance, and the total population is affected by the ENSO. The adult, subadult and pup male groups were the most sensitive groups to this phenomenon due to their intrinsic development and behavior. Likewise the BEST index is a better descriptor than the MEI index of the ENSO influence in the region where the breeding colony Los Islotes resides. Therefore we demonstrate in this work that changes caused by the ENSO not directly affect the sea lion due to its homeothermic capacity but affects the habitat where this organism performs its biological functions, producing behavioral changes in the population.

  18. Extreme rainfall activity in the Australian tropics reflects changes in the El Niño/Southern Oscillation over the last two millennia.

    PubMed

    Denniston, Rhawn F; Villarini, Gabriele; Gonzales, Angelique N; Wyrwoll, Karl-Heinz; Polyak, Victor J; Ummenhofer, Caroline C; Lachniet, Matthew S; Wanamaker, Alan D; Humphreys, William F; Woods, David; Cugley, John

    2015-04-14

    Assessing temporal variability in extreme rainfall events before the historical era is complicated by the sparsity of long-term "direct" storm proxies. Here we present a 2,200-y-long, accurate, and precisely dated record of cave flooding events from the northwest Australian tropics that we interpret, based on an integrated analysis of meteorological data and sediment layers within stalagmites, as representing a proxy for extreme rainfall events derived primarily from tropical cyclones (TCs) and secondarily from the regional summer monsoon. This time series reveals substantial multicentennial variability in extreme rainfall, with elevated occurrence rates characterizing the twentieth century, 850-1450 CE (Common Era), and 50-400 CE; reduced activity marks 1450-1650 CE and 500-850 CE. These trends are similar to reconstructed numbers of TCs in the North Atlantic and Caribbean basins, and they form temporal and spatial patterns best explained by secular changes in the dominant mode of the El Niño/Southern Oscillation (ENSO), the primary driver of modern TC variability. We thus attribute long-term shifts in cyclogenesis in both the central Australian and North Atlantic sectors over the past two millennia to entrenched El Niño or La Niña states of the tropical Pacific. The influence of ENSO on monsoon precipitation in this region of northwest Australia is muted, but ENSO-driven changes to the monsoon may have complemented changes to TC activity.

  19. Recharge beneath low-impact design rain gardens and the influence of El Niño Southern Oscillation on urban, coastal groundwater resources

    NASA Astrophysics Data System (ADS)

    Newcomer, M. E.; Gurdak, J. J.

    2011-12-01

    Groundwater resources in urban, coastal environments are highly vulnerable to increased human pressures and climate variability. Impervious surfaces, such as buildings, roads, and parking lots prevent infiltration, reduce recharge to underlying aquifers, and increase contaminants in surface runoff that often overflow sewage systems. To mitigate these effects, cities worldwide are adopting low impact design (LID) approaches that direct runoff into natural vegetated systems, such as rain gardens that reduce, filter, and slow stormwater runoff, and are hypothesized to increase infiltration and recharge rates to aquifers. The effects of LID on recharge rates and quality is unknown, particularly during intense precipitation events for cities along the Pacific coast in response to interannual variability of the El Niño Southern Oscillation (ENSO). Using vadose zone monitoring sensors and instruments, I collected and monitored soil, hydraulic, and geochemical data to quantify the rates and quality of infiltration and recharge to the California Coastal aquifer system beneath a LID rain garden and traditional turf-lawn setting in San Francisco, CA. The data were used to calibrate a HYDRUS-3D model to simulate recharge rates under historical and future variability of ENSO. Understanding these processes has important implications for managing groundwater resources in urban, coastal environments.

  20. El Niño-Southern Oscillation influence on the dust storm activity in Australia: Can the past provide a key to the future?

    NASA Astrophysics Data System (ADS)

    Pudmenzky, C.; Stone, R.; Allan, R.; Butler, H.

    2011-12-01

    Wind erosion is an internationally recognised land degradation problem and affects approximately 28% of the global land area. The Australian continent is the largest dust source in the Southern Hemisphere with an emission rate of around 100 Tg yr-1 or approximate 5% of the global total. The climate (especially eastern Australian climate) is greatly influenced by the El Niño-Southern Oscillation (ENSO) which is the strongest natural fluctuation of climate on interannual time-scales and also affects climate conditions globally. ENSO is the core driver of extreme weather events such as drought, flooding, bushfires, dust storms and tropical cyclones and up to 50% of annual rainfall variability in northern and eastern Australia is linked to ENSO. These drier conditions will reduce vegetation cover and result in an increased dust storm activity in the future in central eastern Australia during dry El Niño phases of the Southern Oscillation. The Lake Eyre Basin, Channel Country and the Mallee region are the main dust source areas and severe dust storms have the potential to transport millions of tonnes of fertile topsoil from inland Australia to places as far as New Zealand, New Caledonia and Antarctic. The research project will investigate the influence of the ENSO on dust storm activity in Australia. This will be achieved through major reanalysis of past climate conditions for the past 150 years or more using the global 'Atmospheric Circulation Reconstruction over the Earth' (ACRE) project outputs which will reconstruct both upper-air dynamics, surface conditions and then all major dust storm events of the past. Australia has one of the most variable rainfall climates in the world and observational and modelling results suggest that more frequent or stronger ENSO events are possible in the future. Drought in Australia is probably the most economically costly climate event and has environmental and social impacts by reducing agricultural output and having social

  1. TOPEX/El Nino Watch - Moisture in the Atmosphere, Jan & Feb, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    his series of six images shows the evolution of atmospheric water vapor over the Pacific Ocean during the 1998 El Nino condition. Higher than normal ocean water temperatures increase the rate of evaporation, and the resulting warm moist air rises into the atmosphere, altering global weather patterns. Data obtained by the Microwave Limb Sounder (MLS) on NASA's Upper Atmosphere Research Satellite (UARS) during January and February 1998 show a decrease in the extent of high levels of water vapor (red) over the eastern equatorial Pacific and an increase in water vapor (yellow to red) over the northwestern Pacific off the coast of Japan. This area is a breeding ground for winter storms that move eastward toward North America. During this El Nino condition, the southern tropical jet stream has shifted northward, bringing additional moisture from the tropics. When these two sources of moisture converge near California, they produce storms with higher-than-normal rainfall.

    For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

  2. Farming and fishing in the wake of El Nino

    SciTech Connect

    Tibbetts, J.

    1996-09-01

    How does the periodic warming of the waters of the central Pacific relate to global climate change and food production? In Queensland, Australia, savvy farmers keep a sharp eye on signs of El Nino, which usually brings drought that withers the state`s winter wheat crop. Returning every four years on average and usually lasting approximately a year, El Nino is an unusual warming in the central Pacific that builds storms and disrupts wind patterns, turning weather upside down in far-removed regions. But El Nino took scientists by surprise when it persisted from 1991 to 1995. This was the first time that El Nino had lasted for more than three years since monitoring began in the 1870s. And true to form, El Nino of 1991-1995 brought extreme drought to Queensland, in north-eastern Australia, drying out farmland and costing the state economy approximately $1 billion (Australian) a year. The drought, for example, dropped rainfall levels to all-time lows in Toowoomba, one of the state`s prime cereal-growing regions.

  3. Precipitation Anomalies in the Tropical Indian Ocean and Possible Links to the Initiation of El Nino

    NASA Technical Reports Server (NTRS)

    Curtis, Scott; Adler, Robert F.; Huffman, George J.; Starr, David OC. (Technical Monitor)

    2001-01-01

    A pattern of variability in precipitation and 1000mb zonal winds for the tropical Indian Ocean during, 1979 to 1999 (AtmIO mode) is described using EOFs. The AtmIO mode consists of a cross-equatorial gradient of precipitation anomalies and equatorial wind anomalies of alternating signs on the Equator. The positive phase is defined as enhanced precipitation to the In "n south of the equator, suppressed precipitation to the north, and anomalous westerlies centered on the island of Sumatra. In September-October 1981, February-March 1990, and October-December 1996 the AtmIO mod-, was positive and there was a significant 30-60 day variability in the gradient of precipitation anomalies. These cases coincided with moderate to heavy ,activity in the Madden-Jullan Oscillation (MJO). Links between the AtmIO, MJO, and El Nino are discussed.

  4. TOPEX/El Nino Watch - El Nino in Retreat, Pacific in Transition, June 14, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea-surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea-surface height relative to normal ocean conditions on June 14, 1998, and sea-surface height is an indicator of the heat content of the ocean. This image shows that the tropical Pacific has been switching from warm to cold during the last few months. The purple area in the center of the image is a pulse of cold water moving across the equator which the satellite measures as a region of lower than normal sea level. Scientists indicate that it appears that the central equatorial Pacific ocean will stay colder than normal for some time to come because sea level is about 18 centimeters (7 inches) below normal, creating a deficit in the heat supply to the surface waters. It is not certain yet, if this current cooling trend (shown in purple) will eventually evolve into a long-lasting La Nina situation. Remnants of the El Nino warm water pool, shown here in red and white, are still lingering north of the equator in the center of this image. The effects of El Nino can remain in the climate system for a long time and could still impact weather conditions around the world. The satellite's sea-surface height measurements have provided scientists with a detailed view of the 1997-98 El Nino because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision. In this image, the white areas show the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The purple areas are 14 to 18 centimeters (6 to 7 inches) below normal and the blue areas are 5 to 13 centimeters (2 to 5 inches) below normal. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a

  5. Insights into Tropical Tropospheric Ozone from the 1998-2000 SHADOZ (Southern Hemisphere Additional Ozonesondes) Data Record

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Schmidlin, Francis J.; Volker, W.; Kirchhoff, J. H.; Posny, Franaoise; Gert, J.; Coetzee, R.; Hoegger, Bruno; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    We describe the first overview of total, stratospheric and tropospheric ozone in the southern hemisphere tropics based on a three year, ten site record of ozone soundings from the Southern Hemisphere Additional Ozonesondes (SHADOZ) network. Observations covering 1998-2000 were made over Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. The ozone data, with simultaneous temperature profiles to approximately 7 hPa and relative humidity to approximately 200 hPa, are at an archive: http://code9l6. gsfc.nasa.gov/Data_services/shadoz. Prominent features are highly variable tropospheric ozone, a zonal wave-one pattern in total (and tropospheric) column ozone, and signatures of the Quasi-Biennial Oscillation (QBO) in stratospheric ozone. Total, stratospheric and tropospheric column ozone amounts usually peak between August and November and are lowest in the first half of the year. Tropospheric ozone variability over the Indian and Pacific Ocean displays influences of the waning 1997-1998 Indian Ocean Dipole and ENSO (El Nino / Southern Oscillation), seasonal convection and pollution transport from Africa. Tropospheric ozone over the Atlantic Basin reflects regional subsidence and recirculation as well as pollution ozone from biomass burning.

  6. An improved procedure for El Nino forecasting: Implications for predictability

    SciTech Connect

    Chen, D.; Zebiak, S.E.; Cane, M.A.

    1995-09-22

    A coupled ocean-atmosphere data assimilation procedure yields improved forecasts of El Nino for the 1980s compared with previous forecasting procedures. As in earlier forecasts with the same model, no oceanic data were used, and only wind information was assimilated. The improvement is attributed to the explicit consideration of air-sea interaction in the initialization. These results suggest that El Nino is more predictable than previously estimated, but that predictability may vary on decadal or longer time scales. This procedure also eliminates the well-known spring barrier to El Nino prediction, which implies that it may not be intrinsic to the real climate system. 24 refs., 5 figs., 1 tab.

  7. Ocean wave dynamics and El Nino

    SciTech Connect

    Schneider, E.K.; Huang, B.; Shukla, J.

    1995-10-01

    The response of an ocean general circulation model to specified wind stress is used to understand the role of ocean wave propagation in the evolution of El Nino events in sea surface temperatures (SST) in the equatorial Pacific Ocean. In a control experiment the ocean model reproduces observed equatorial Pacific interannual variability in response to forcing by the observed wind stress. The ocean model is then forced with the same wind stress but with the time evolution of the wind stress forcing reversed. An analysis of the anomalies from the annual cycle in these two experiments delineates the parts of the response that are in equilibrium with and out of equilibrium with the wind stress forcing. The experiment demonstrates that the heat content is not in equilibrium with the wind stress forcing either on or near the equator. Very close to the equator the slope of the thermocline is in equilibrium with the wind stress, but the mean heat content is far from equilibrium. Slightly off of the equator in the western Pacific westward propagating heat content anomalies appear to originate in regions of strong wind stress forcing and then propagate to the western boundary. These westward propagating anomalies also depart significantly from equilibrium with the wind stress forcing. Additional experiments allow these westward propagating anomalies to be identified as freely propagating Rossby waves. The Rossby waves are shown to determine the equatorial heat content response to the wind stress forcing when they arrive at the western boundary and to be responsible for the nonequilibrium behavior of the equatorial mean heat content. A simplified coupled model is derived by fitting the results and estimating parameter values from the numerical experiments. 45 refs., 16 figs.

  8. Tolerance of sponge assemblages to temperature anomalies: resilience and proliferation of sponges following the 1997-8 El-Niño southern oscillation.

    PubMed

    Kelmo, Francisco; Bell, James J; Attrill, Martin J

    2013-01-01

    Coral reefs across the world are under threat from a range of stressors, and while there has been considerable focus on the impacts of these stressors on corals, far less is known about their effect on other reef organisms. The 1997-8 El-Niño Southern Oscillation (ENSO) had notable and severe impacts on coral reefs worldwide, but not all reef organisms were negatively impacted by this large-scale event. Here we describe how the sponge fauna at Bahia, Brazil was influenced by the 1997-8 ENSO event. Sponge assemblages from three contrasting reef habitats (reef tops, walls and shallow banks) at four sites were assessed annually from 1995 to 2011. The within-habitat sponge diversity did not vary significantly across the study period; however, there was a significant increase in density in all habitats. Multivariate analyses revealed no significant difference in sponge assemblage composition (ANOSIM) between pre- and post-ENSO years for any of the habitats, suggesting that neither the 1997-8 nor any subsequent smaller ENSO events have had any measurable impact on the reef sponge assemblage. Importantly, this is in marked contrast to the results previously reported for a suite of other taxa (including corals, echinoderms, bryozoans, and ascidians), which all suffered mass mortalities as a result of the ENSO event. Our results suggest that of all reef taxa, sponges have the potential to be resilient to large-scale thermal stress events and we hypothesize that sponges might be less affected by projected increases in sea surface temperature compared to other major groups of reef organisms.

  9. Tolerance of Sponge Assemblages to Temperature Anomalies: Resilience and Proliferation of Sponges following the 1997–8 El-Niño Southern Oscillation

    PubMed Central

    Kelmo, Francisco; Bell, James J.; Attrill, Martin J.

    2013-01-01

    Coral reefs across the world are under threat from a range of stressors, and while there has been considerable focus on the impacts of these stressors on corals, far less is known about their effect on other reef organisms. The 1997–8 El-Niño Southern Oscillation (ENSO) had notable and severe impacts on coral reefs worldwide, but not all reef organisms were negatively impacted by this large-scale event. Here we describe how the sponge fauna at Bahia, Brazil was influenced by the 1997–8 ENSO event. Sponge assemblages from three contrasting reef habitats (reef tops, walls and shallow banks) at four sites were assessed annually from 1995 to 2011. The within-habitat sponge diversity did not vary significantly across the study period; however, there was a significant increase in density in all habitats. Multivariate analyses revealed no significant difference in sponge assemblage composition (ANOSIM) between pre- and post-ENSO years for any of the habitats, suggesting that neither the 1997–8 nor any subsequent smaller ENSO events have had any measurable impact on the reef sponge assemblage. Importantly, this is in marked contrast to the results previously reported for a suite of other taxa (including corals, echinoderms, bryozoans, and ascidians), which all suffered mass mortalities as a result of the ENSO event. Our results suggest that of all reef taxa, sponges have the potential to be resilient to large-scale thermal stress events and we hypothesize that sponges might be less affected by projected increases in sea surface temperature compared to other major groups of reef organisms. PMID:24116109

  10. Interannual variability of summertime aerosol optical depth over East Asia during 2000-2011: a potential influence from El Niño Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Liu, Yikun; Liu, Junfeng; Tao, Shu

    2013-12-01

    Aerosols degrade air quality, perturb atmospheric radiation, and impact regional and global climate. Due to the rapid increase in anthropogenic emissions, aerosol loading over East Asia (EA) is markedly higher than other industrialized regions, which motivates a need to characterize the evolution of aerosols and understand the associated drivers. Based on the MISR satellite data during 2000-2011, a wave-like interannual variation of summertime aerosol optical depth (SAOD) is observed over the highly populated North China Plain (NCP) in East Asia. Specifically, the peak-to-trough ratio of SAOD ranges from 1.4 to 1.6, with a period of 3-4 years. This variation pattern differs apparently from what has been seen in EA emissions, indicating a periodic change in regional climate pattern during the past decade. Investigations of meteorological fields over the region reveal that the high SAOD is generally associated with the enhanced Philippine Sea Anticyclone Anomaly (PSAA) which weakens southeasterlies over northeastern EA and depresses air ventilation. Alternatively, higher temperature and lower relative humidity are found to be coincident with reduced SAOD. The behavior of PSAA has been found previously to be modulated by the El Niño Southern Oscillations (ENSO), therefore ENSO could disturb the EA SAOD as well. Rather than changing coherently with the ENSO activity, the SAOD peaks over NCP are found to be accompanied by the rapid transition of El Niño warm to cold phases developed four months ahead. An index measuring the development of ENSO during January-April is able to capture the interannual variability of SAOD over NCP during 2000-2011. This finding indicates a need to integrate the large-scale periodic climate variability in the design of regional air quality policy.

  11. A long-term trend in precipitation of different spatial regions of Bangladesh and its teleconnections with El Niño/Southern Oscillation and Indian Ocean Dipole

    NASA Astrophysics Data System (ADS)

    Ahmed, Md. Kawser; Alam, Mohammad Samsul; Yousuf, Abu Hena Muhammad; Islam, Md. Monirul

    2016-04-01

    A long-term (1948 to 2012) trend of precipitation (annual, pre-monsoon, monsoon, and post-monsoon seasons) in Bangladesh was analyzed in different regions using both parametric and nonparametric approaches. Moreover, the possible teleconnections of precipitation (annual and monsoon) variability with El Niño/Southern Oscillation (ENSO) episode and Indian Ocean Dipole (IOD) were investigated using both average and individual (both positive and negative) values of ENSO index and IOD. Our findings suggested that for annual precipitation, a significant increasing monotonic trend was found in whole Bangladesh (4.87 mm/year), its western region (5.82 mm/year) including Rangpur (9.41 mm/year) and Khulna (4.95 mm/year), and Sylhet (10.12 mm/year) and Barisal (6.94 mm/year) from eastern region. In pre-monsoon, only Rangpur (2.88 mm/year) showed significant increasing trend, while in monsoon, whole Bangladesh (3.04 mm/year), Sylhet (7.17 mm/year), and Barisal (6.94 mm/year) showed similar trend. In post-monsoon, there was no significant trend. Our results also revealed that the precipitation (annual or monsoon) of whole Bangladesh and almost all of the spatial regions did not show any significant correlation with ENSO events, whereas the average IOD values showed significant correlation only in monsoon precipitation of western region. The individual positive IODs showed significant correlation in whole Bangladesh, western region, and its two divisions (Rajshahi and Khulna). So, in the context of Bangladesh climate, IOD has the more teleconnection to precipitation than that of ENSO. Our findings indicate that the co-occurrence of ENSO and IOD events may suppress their influence on each other.

  12. The relationship between the Southern Oscillation Index, rainfall and the occurrence of canine tick paralysis, feline tick paralysis and canine parvovirus in Australia.

    PubMed

    Rika-Heke, Tamara; Kelman, Mark; Ward, Michael P

    2015-07-01

    The aim of this study was to describe the association between climate, weather and the occurrence of canine tick paralysis, feline tick paralysis and canine parvovirus in Australia. The Southern Oscillation Index (SOI) and monthly average rainfall (mm) data were used as indices for climate and weather, respectively. Case data were extracted from a voluntary national companion animal disease surveillance resource. Climate and weather data were obtained from the Australian Government Bureau of Meteorology. During the 4-year study period (January 2010-December 2013), a total of 4742 canine parvovirus cases and 8417 tick paralysis cases were reported. No significant (P ≥ 0.05) correlations were found between the SOI and parvovirus, canine tick paralysis or feline tick paralysis. A significant (P < 0.05) positive cross-correlation was found between parvovirus occurrence and rainfall in the same month (0.28), and significant negative cross-correlations (-0.26 to -0.36) between parvovirus occurrence and rainfall 4-6 months previously. Significant (P < 0.05) negative cross-correlations (-0.34 to -0.39) were found between canine tick paralysis occurrence and rainfall 1-3 months previously, and significant positive cross-correlations (0.29-0.47) between canine tick paralysis occurrence and rainfall 7-10 months previously. Significant positive cross-correlations (0.37-0.68) were found between cases of feline tick paralysis and rainfall 6-10 months previously. These findings may offer a useful tool for the management and prevention of tick paralysis and canine parvovirus, by providing an evidence base supporting the recommendations of veterinarians to clients thus reducing the impact of these diseases.

  13. The influence of El Niño-Southern Oscillation (ENSO) cycles on wave-driven sea-floor sediment mobility along the central California continental margin

    USGS Publications Warehouse

    Storlazzi, Curt D.; Reid, Jane A.

    2010-01-01

    Ocean surface waves are the dominant temporally and spatially variable process influencing sea floor sediment resuspension along most continental shelves. Wave-induced sediment mobility on the continental shelf and upper continental slope off central California for different phases of El Niño-Southern Oscillation (ENSO) events was modeled using monthly statistics derived from more than 14 years of concurrent hourly oceanographic and meteorologic data as boundary input for the Delft SWAN wave model, gridded sea floor grain-size data from the usSEABED database, and regional bathymetry. Differences as small as 0.5 m in wave height, 1 s in wave period, and 10° in wave direction, in conjunction with the spatially heterogeneous unconsolidated sea-floor sedimentary cover, result in significant changes in the predicted mobility of continental shelf surficial sediment in the study area. El Niño events result in more frequent mobilization on the inner shelf in the summer and winter than during La Niña events and on the outer shelf and upper slope in the winter months, while La Niña events result in more frequent mobilization on the mid-shelf during spring and summer months than during El Niño events. The timing and patterns of seabed mobility are addressed in context of geologic and biologic processes. By understanding the spatial and temporal variability in the disturbance of the sea floor, scientists can better interpret sedimentary patterns and ecosystem structure, while providing managers and planners an understanding of natural impacts when considering the permitting of offshore activities that disturb the sea floor such as trawling, dredging, and the emplacement of sea-floor engineering structures.

  14. Spatial and Temporal Analysis of Drought in the Western United States in Relation to Oceanic Oscillations

    NASA Astrophysics Data System (ADS)

    Ross, L.; Scuderi, L. A.

    2014-12-01

    Drought, a natural phenomenon that has affected western North America for millennia, is characterized by significant changes in precipitation with rapid shifts between wet and dry states. General Circulation Model projections indicate increased aridity in the 21st century for the Western U.S., and as such the impact of drought will likely become more significant on the environment and the economy. In the pursuit of improving drought predictability, as well as increasing our ability to better characterize the onset of drought, we ask whether defined climate regime shift signals can be identified and if there are variations in this signal for different drought periods, and if so, whether these shifts may be periodic. Annual growth rings of precipitation sensitive trees in the upper and lower Colorado River Basin regions are analyzed using 1) edge detection filters to determine the timing and significance of climate regime induced precipitation shifts, 2) digital filters to identify long and short-term precipitation variability within the site mean chronologies, and 3) wavelet analysis to determine the presence of significant periodicities in the chronologies. Results show that the edge detection algorithms are successful in identifying significant shifts in climatic regimes, and wavelet analysis indicates that some of these shifts may be periodic, suggesting larger scale atmospheric circulation forcing on timescales of decades to centuries. These results are used to identify specific patterns and timing of drought over the upper and lower Colorado River Basins in relation to oceanic oscillations such as the Pacific Decadal Oscillation, the Atlantic Multidecadal Oscillation, and El Nino Southern Oscillation. Establishing a relationship between the timing and pattern of the drought and the timing of the oceanic oscillations can lead to improved drought predictability in this region and increase our ability to respond to the environmental and economic impacts of drought.

  15. Radiolarian indicators of El Nino and anti-El Nino events in Holocene sediments of Santa Barbara basin

    SciTech Connect

    Weinheimer, A.L.

    1986-04-01

    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, and geostrophic doming of the cold-water masses in the shear zone between the California Current and California Countercurrent.

  16. El Nino--An Example of Ocean/Atmosphere Interactions.

    ERIC Educational Resources Information Center

    O'Brien, James J.

    1978-01-01

    El Nino is a complex periodic oceanographic event that occurs off the west coast of South America, adversely affecting climate not only in the local area but in other regions of the world. There is evidence that the equatorial regions hold the key to predicting this economically destructive phenomenon. (Author/BB)

  17. The Ninos Especiales Outreach Training Project (NEOTP). Final Report.

    ERIC Educational Resources Information Center

    Bruder, Mary Beth; And Others

    The Ninos Especiales Outreach Training Project was a 3-year federally funded project to provide information, training, and evaluation related to a culturally sensitive, family-focused model of early intervention services for infants with severe disabilities and their families of Puerto Rican heritage. Implementation occurred through three major…

  18. On the Nature of the Arctic Oscillation and Its Diverse Influence on Surface Temperature

    NASA Astrophysics Data System (ADS)

    Dai, P.; Tan, B.

    2015-12-01

    What physical process that the Arctic oscillation (AO) describes is still unclear and under debate since Thompson and Wallace's pioneering work. By applying a cluster analysis to daily NCEP/NCAR reanalysis data, present study found that the AO pattern can be resolved into two families with five family members and each member has a timescale of one week or so. One family takes a form of mixed NAO and Pacific center, and another takes a form of double-wavetrain which has a projection of PNA over Pacific-North America and of NAO over North Atlantic. Different family members have different influence on northern Hemisphere surface temperature, which should be taken into consideration when one makes weather prediction based on AO. Due to the projection of family members on PNA and NAO, AO shows somehow correlation with PNA or NAO. It is also shown that one of the members is strongly modulated by the El Nino-Southern oscillation (ENSO) and shows an upward (downward) trend in its frequency of occurrence between 1958-2005.

  19. The Interdecadal Pacific Oscillation and mid-stratospheric tropical ozone trends

    NASA Astrophysics Data System (ADS)

    Iglesias-Suarez, Fernando; Young, Paul J.; Wild, Oliver; Kinnison, Douglas E.

    2016-04-01

    In recent years, the global ozone layer has started to show the first signs of recovery, but puzzlingly tropical mid-stratospheric ozone has decreased since the beginning of the 90s. This is a key region of the stratosphere where most ozone is produced. Previous studies have shown that interannual variability in the troposphere (e.g. El Nino-Southern Oscillation) can affect the lower stratosphere, both dynamics and composition. Here for the first time, we show how multidecadal internal climate variability - in the Pacific Ocean's sea surface temperatures (i.e. the Interdecadal Pacific Oscillation, IPO) - have an impact in mid-stratospheric tropical ozone, and account for the observed trends. We suggest a mechanism that involves dynamical (i.e. Brewer Dobson circulation) and chemical (i.e. ozone loss chemistry via NOy chemistry) processes to explain this IPO-ozone link. Understanding internally generated multidecadal variability in this region of the stratosphere is crucial to distinguish between forced and unforced signals and better describe ozone recovery.

  20. The Impact of the El Niño-Southern Oscillation and Atlantic Meridional Mode on Seasonal Atlantic Tropical Cyclone Activity

    NASA Astrophysics Data System (ADS)

    Patricola, C. M.; Saravanan, R.; Chang, P.

    2012-12-01

    The influence of the El Niño-Southern Oscillation (ENSO) on Atlantic tropical cyclone (TC) activity on the interannual timescale is well understood, with El Niño (La Niña) inhibiting (supporting) TCs through enhanced (reduced) vertical wind shear in the Atlantic main development region (MDR). The switch from relatively inactive to active Atlantic TC seasons in the mid-1990's has highlighted the influence of interannual to decadal modes of Atlantic climate variability, including the Atlantic Multidecadal Oscillation (AMO) and the Atlantic Meridional Mode (AMM). An important issue is the relative strengths of ENSO and AMM in modulating Atlantic TC activity on interannual timescales, and possible interactions between these two influences. We have carried out mechanistic simulations using a 27-km resolution regional climate model (the NCAR WRF model) to address this issue. The model simulates the observed 1980-2000 interannual variability of Atlantic accumulated cyclone energy (ACE; 104 kt2) with a correlation of 0.58 when observed Atlantic and eastern tropical Pacific sea surface temperature (SST) and lateral boundary conditions (LBCs) are prescribed. Mechanistic experiments are configured by forcing the model with a strong El Niño or La Niña by prescribing LBCs and eastern tropical Pacific SST of 1987 and 1999 respectively, in combination with strongly positive, neutral/weakly positive, and strongly negative phases of the AMM through prescribed Atlantic SST of 2005, 1987 or 1999, and 1984, respectively. Two-member ensembles of each experiment are run. During the strong El Niño, simulated Atlantic ACE is weaker than the simulated 1980-2000 mean regardless of AMM phase. The ACE changes relatively little between the negative and neutral AMM, but increases moderately between the neutral and positive AMM during El Niño. This, together with the response in MDR vertical wind shear suggests that the threshold MDR shear for TC suppression occurs between the neutral and

  1. El Niño Southern Oscillation (ENSO) enhances CO2 exchange rates in freshwater Marsh ecosystems in the Florida everglades.

    PubMed

    Malone, Sparkle L; Staudhammer, Christina L; Oberbauer, Steven F; Olivas, Paulo; Ryan, Michael G; Schedlbauer, Jessica L; Loescher, Henry W; Starr, Gregory

    2014-01-01

    This research examines the relationships between El Niño Southern Oscillation (ENSO), water level, precipitation patterns and carbon dioxide (CO2) exchange rates in the freshwater wetland ecosystems of the Florida Everglades. Data was obtained over a 5-year study period (2009-2013) from two freshwater marsh sites located in Everglades National Park that differ in hydrology. At the short-hydroperiod site (Taylor Slough; TS) and the long-hydroperiod site (Shark River Slough; SRS) fluctuations in precipitation patterns occurred with changes in ENSO phase, suggesting that extreme ENSO phases alter Everglades hydrology which is known to have a substantial influence on ecosystem carbon dynamics. Variations in both ENSO phase and annual net CO2 exchange rates co-occurred with changes in wet and dry season length and intensity. Combined with site-specific seasonality in CO2 exchanges rates, El Niño and La Niña phases magnified season intensity and CO2 exchange rates at both sites. At TS, net CO2 uptake rates were higher in the dry season, whereas SRS had greater rates of carbon sequestration during the wet season. As La Niña phases were concurrent with drought years and extended dry seasons, TS became a greater sink for CO2 on an annual basis (-11 to -110 g CO2 m-2 yr-1) compared to El Niño and neutral years (-5 to -43.5 g CO2 m-2 yr-1). SRS was a small source for CO2 annually (1.81 to 80 g CO2 m-2 yr-1) except in one exceptionally wet year that was associated with an El Niño phase (-16 g CO2 m-2 yr-1). Considering that future climate predictions suggest a higher frequency and intensity in El Niño and La Niña phases, these results indicate that changes in extreme ENSO phases will significantly alter CO2 dynamics in the Florida Everglades.

  2. El Niño Southern Oscillation (ENSO) Enhances CO2 Exchange Rates in Freshwater Marsh Ecosystems in the Florida Everglades

    PubMed Central

    Malone, Sparkle L.; Staudhammer, Christina L.; Oberbauer, Steven F.; Olivas, Paulo; Ryan, Michael G.; Schedlbauer, Jessica L.; Loescher, Henry W.; Starr, Gregory

    2014-01-01

    This research examines the relationships between El Niño Southern Oscillation (ENSO), water level, precipitation patterns and carbon dioxide (CO2) exchange rates in the freshwater wetland ecosystems of the Florida Everglades. Data was obtained over a 5-year study period (2009–2013) from two freshwater marsh sites located in Everglades National Park that differ in hydrology. At the short-hydroperiod site (Taylor Slough; TS) and the long-hydroperiod site (Shark River Slough; SRS) fluctuations in precipitation patterns occurred with changes in ENSO phase, suggesting that extreme ENSO phases alter Everglades hydrology which is known to have a substantial influence on ecosystem carbon dynamics. Variations in both ENSO phase and annual net CO2 exchange rates co-occurred with changes in wet and dry season length and intensity. Combined with site-specific seasonality in CO2 exchanges rates, El Niño and La Niña phases magnified season intensity and CO2 exchange rates at both sites. At TS, net CO2 uptake rates were higher in the dry season, whereas SRS had greater rates of carbon sequestration during the wet season. As La Niña phases were concurrent with drought years and extended dry seasons, TS became a greater sink for CO2 on an annual basis (−11 to −110 g CO2 m−2 yr−1) compared to El Niño and neutral years (−5 to −43.5 g CO2 m−2 yr−1). SRS was a small source for CO2 annually (1.81 to 80 g CO2 m−2 yr−1) except in one exceptionally wet year that was associated with an El Niño phase (−16 g CO2 m−2 yr−1). Considering that future climate predictions suggest a higher frequency and intensity in El Niño and La Niña phases, these results indicate that changes in extreme ENSO phases will significantly alter CO2 dynamics in the Florida Everglades. PMID:25521299

  3. The effects of an "El Niño" southern oscillation event on reproduction in male and female blue-footed boobies, Sula nebouxii.

    PubMed

    Wingfield, J C; Ramos-Fernandez, G; Nuñez-de la Mora, A; Drummond, H

    1999-05-01

    This study attempted to determine endocrine correlates of reproductive success in relation to major deleterious environmental conditions. In 1992, an El Niño southern oscillation event resulted in complete reproductive failure in a colony of blue-footed boobies, Sula nebouxi, on Isla Isabel in the Pacific Ocean off San Blas, Nayarit, Mexico (21.5 degrees N, 105.5 degrees W). In 1993, the El Niño event had waned and reproductive success was high. The mean sea surface temperature in 1992 was 26.69 degrees, the warmest year for 11 years of data (mean, 25.63 degrees ). In 1993, mean sea surface temperature was 25.75 degrees. Plasma levels of testosterone were highest during the egg-laying period in 1993 and declined markedly during incubation. There were no differences between males and females. Comparisons of testosterone levels between 1992 and 1993 (egg-laying time point removed for 1993) showed no significant differences. Thus reproductive failure during an El Niño year was not related to testosterone levels. Baseline plasma levels of corticosterone did not change over the nesting cycle in either sex. There was a trend for plasma levels of corticosterone to be higher in males and females during the earlier stages of breeding in 1992 compared with 1993, and if all levels were combined within years then females showed significantly higher plasma levels of corticosterone in the El Niño year. Plasma levels of corticosterone showed marked increases following capture and handling in both sexes and at every stage of the breeding cycle in each year. There was no variation in the adrenocortical responses to stress with year or stage of nesting in males. However, in females, maximum corticosterone levels were greatest during the parental phase of 1992, the El Niño year, when all nests ultimately failed. Comparisons of the dynamics of corticosterone changes during the capture stress protocol revealed no correlations with body mass in 1992 or 1993. These data suggest that

  4. Observed Influence of Amazon rainfall on the Atlantic ITCZ and Atlantic Nino

    NASA Astrophysics Data System (ADS)

    Fu, R.; Wang, H.

    2007-05-01

    Most of previous studies on climate variabilities of the tropical Atlantic Ocean have been focused on remote and internal oceanic processes or atmosphere-ocean interaction. In comparison, relatively few studies have examined the influences from adjacent continents, especially the influence of rainfall over the South American continent. Using the Tropical Rainfall Measuring Mission (TRMM) daily rain-rate dada, the QuikSCAT ocean surface wind and PIRATA buoy data, we have found that convection developed over the Amazonia appears to propagate eastward across the Atlantic and then into Africa. Such changes modulate the intensity and location of the convection within the Atlantic ITCZ and result in a zonal oscillation of the ITCZ between the west and east equatorial Atlantic Ocean. The eastward propagating disturbances appear to be an atmospheric Kelvin wave with a period of 6 to 7 days and a phase speed of around 12 m s-1. Such convectively coupled Kelvin wave is particularly strong during boreal spring and dominates the synoptic variations of the lower and upper troposphere winds. Our results further suggest that the interannual changes of these convective coupled Kelvin waves have an important influence on trigging the onset of Atlantic Ninos. In particular, anomalously late northward withdraw of the South American rainfall in boreal spring lead to stronger Kelvin wave activities and stronger westerly wind anomalies in the western equatorial Atlantic. The latter triggers a change of the slope of the thermocline in the equatorial Atlantic Ocean and induces sea surface temperature anomalies in the eastern Atlantic. These changes contribute to the onset of the Atlantic Nino in earlier boreal summer.

  5. Super El Nino - a synchrony of Indian Ocean Dipole and ENSO dynamics?

    NASA Astrophysics Data System (ADS)

    Hameed, Saji; Dachao, Jin; Thilakan, Vishnu; An, KyongHee

    2016-04-01

    El Ninos significantly affect societies, economies and ecosystems on a global scale. The strongest of these events, hereafter super El Ninos, have disproportionately larger impacts. It is unclear whether a particular combination of climate states, either internal or external to the equatorial Pacific, is associated with the unique spatial and temporal characteristics of these events. This became clear in the case of the much anticipated 2014 super El Nino - although several hypothesized precursor climate states were present, the Pacific warming of 2014 did not develop into a super El Nino. Past studies using statistical analysis and coupled model experiments have pointed to the possible role of the Indian Ocean Dipole (IOD) in affecting El Nino. However, no direct observational evidence for the role of IOD has yet been found. Here we present for the first time strong and direct observational evidence for the distinct role of IOD dynamics in modulating El Nino evolution during co-occurring events. Further, we identify the key process in this interaction as an atmospheric Kelvin wave dominated downstream circulation forced by equatorial Indian Ocean convection. We propose that the synchrony of this IOD forced process with the inherent coupled dynamics in the Pacific associated with El Nino explains the strong intensity as well as the rapid evolution and termination of super El Ninos, along with their disproportionate global impacts. We discuss the implication of our findings for the ongoing El Nino event which has been projected to rival the 1997 super El Nino in strength and impacts.

  6. Modulation of Atlantic Aerosols by the Madden-Julian Oscillation

    NASA Technical Reports Server (NTRS)

    Tian, B.; Waliser, D. E.; Kahn, Ralph A.; Wong, S.

    2010-01-01

    Much like the better-known EI Nino-Southern Oscillation, the Madden-Julian Oscillation (MJO) is a global-scale atmospheric phenomenon. The MJO involves periodic, systematic changes in the distribution of clouds and precipitation over the western Pacific and Indian oceans, along with differences in wind intensity over even more extensive areas, including the north and subtropical Atlantic Ocean. The lead authors of this paper developed a sophisticated mathematical technique for mapping the spatial and temporal behavior of changes in the atmosphere produced by the MJO. In a previous paper, we applied this technique to search for modulation of airborne particle amount in the eastern hemisphere associated with the "wet" (cloudy) vs. "dry" phases of the MJO. The study used primarily AVHRR, MODIS, and TOMS satellite-retrieved aerosol amount, but concluded that other factors, such as cloud contamination of the satellite signals, probably dominated the observed variations. The current paper looks at MJO modulation of desert dust transport eastward across the Atlantic from northern Africa, a region much less subject to systematic cloud contamination than the eastern hemisphere areas studied previously. In this case, a distinct aerosol signal appears, showing that dust is transported westward much more effectively during the MJO phase that favors westward-flowing wind, and such transport is suppressed when the MJO reduces these winds. Aside form the significant achievement in identifying such an effect, the result implies that an important component of global dust transport can be predicted based on the phase of the MJO. As a consequence, the impact of airborne dust on storm development in the Atlantic, and on dust deposition downwind of the desert sources, can also be predicted and more accurately modeled.

  7. On the roles of the northeast cold surge, the Borneo vortex, the Madden-Julian Oscillation, and the Indian Ocean Dipole during the extreme 2006/2007 flood in southern Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Tangang, Fredolin T.; Juneng, Liew; Salimun, Ester; Vinayachandran, P. N.; Seng, Yap Kok; Reason, C. J. C.; Behera, S. K.; Yasunari, T.

    2008-05-01

    The mid-December 2006 to late January 2007 flood in southern Peninsular Malaysia was the worst flood in a century and was caused by three extreme precipitation episodes. These extreme precipitation events were mainly associated with strong northeasterly winds over the South China Sea. In all cases, the northeasterlies penetrated anomalously far south and followed almost a straight trajectory. The elevated terrain over Sumatra and southern Peninsular Malaysia caused low-level convergence. The strong easterly winds near Java associated with the Rossby wave-type response to Madden-Julian Oscillation (MJO) inhibited the counter-clockwise turning of the northeasterlies and the formation of the Borneo vortex, which, in turn, enhanced the low-level convergence over the region. The abrupt termination of the Indian Ocean Dipole (IOD) in December 2006 played a secondary role as warmer equatorial Indian Ocean helped in the MJO formation.

  8. Microwave Limb Sounder/El Nino Watch - 1997 Research Data Reveal Clues about El Nino's Influence

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image displays wind measurements taken by the satellite-borne NASA Scatterometer (NSCAT) during the last 10 days of May 1997, showing the relationship between the ocean and the atmosphere at the onset of the 1997-98 El Nino condition. The data have helped scientists confirm that the event began as an unusual weakening of the trade winds that preceded an increase in sea surface temperatures. The arrows represent wind speed and direction while the colors indicate sea surface temperature. The sea surface temperatures were measured by the Advanced Very High Resolution Radiometer, a joint mission of NASA and the National Oceanographic and Atmospheric Administration (NOAA). The trade winds normally blow from east to west, but the small arrows in the center of the image show the winds have changed direction and are blowing in the opposite direction. The areas shown in red are above normal sea surface temperatures -- along the equator, off the west coast of the U.S., and along the west coast of Mexico. This image also shows an unusual low pressure system with cyclonic (counterclockwise) circulation near the western North American coast. NSCAT also observed that winds associated with this circulation pattern branched off from the equator, bypassed Hawaii, and brought heat and moisture from the tropical ocean towards San Francisco, in what is often called the 'pineapple express.'

  9. A successful forecast of an El Nino winter

    SciTech Connect

    Kerr, R.A.

    1992-01-24

    This year, for the first time, weather forecasters used signs of a warming in the tropical Pacific as the basis for a long-range prediction of winter weather patterns across the United States. Now forecasters are talking about the next step: stretching the lead time for such forecasts by a year or more. That seems feasible because although this Pacific warming was unmistakable by the time forecasters at the National Weather Service's Climate Analysis Center (CAC) in Camp Springs, Maryland, issued their winter forecast, the El Nino itself had been predicted almost 2 years in advance by a computer model. Next time around, the CAC may well be listening to the modelers and predicting El Nino-related patterns of warmth and flooding seasons in advance.

  10. The effects of the El Niño Southern Oscillation on skin and skin-related diseases: a message from the International Society of Dermatology Climate Change Task Force.

    PubMed

    Andersen, Louise K; Davis, Mark D P

    2015-12-01

    The El Niño Southern Oscillation (ENSO) is a complex climate phenomenon occurring in the Pacific Ocean at intervals of 2-7 years. The term refers to fluctuations in ocean temperatures in the tropical eastern Pacific Ocean (El Niño [the warm phase of ENSO] and La Niña [the cool phase of ENSO]) and in atmospheric pressure across the Pacific basin (Southern Oscillation). This weather pattern is attributed with causing climate change in certain parts of the world and is associated with disease outbreaks. The question of how ENSO affects skin and skin-related disease is relatively unanswered. We aimed to review the literature describing the effects of this complex weather pattern on skin. El Niño has been associated with increases in the occurrence of actinic keratosis, tinea, pityriasis versicolor, miliaria, folliculitis, rosacea, dermatitis by Paederus irritans and Paederus sabaeus, and certain vector-borne and waterborne diseases, such as dengue fever, leishmaniasis, Chagas' disease, Barmah Forest virus, and leptospirosis, and with decreases in the occurrence of dermatitis, scabies, psoriasis, and papular urticaria. La Niña has been associated with increases in the occurrence of varicella, hand, foot, and mouth disease, and Ross River virus (in certain areas), and decreases in viral warts and leishmaniasis. Reports on the effects of ENSO on skin and skin-related disease are limited, and more studies could be helpful in the future.

  11. The effects of the El Niño Southern Oscillation on skin and skin-related diseases: a message from the International Society of Dermatology Climate Change Task Force.

    PubMed

    Andersen, Louise K; Davis, Mark D P

    2015-12-01

    The El Niño Southern Oscillation (ENSO) is a complex climate phenomenon occurring in the Pacific Ocean at intervals of 2-7 years. The term refers to fluctuations in ocean temperatures in the tropical eastern Pacific Ocean (El Niño [the warm phase of ENSO] and La Niña [the cool phase of ENSO]) and in atmospheric pressure across the Pacific basin (Southern Oscillation). This weather pattern is attributed with causing climate change in certain parts of the world and is associated with disease outbreaks. The question of how ENSO affects skin and skin-related disease is relatively unanswered. We aimed to review the literature describing the effects of this complex weather pattern on skin. El Niño has been associated with increases in the occurrence of actinic keratosis, tinea, pityriasis versicolor, miliaria, folliculitis, rosacea, dermatitis by Paederus irritans and Paederus sabaeus, and certain vector-borne and waterborne diseases, such as dengue fever, leishmaniasis, Chagas' disease, Barmah Forest virus, and leptospirosis, and with decreases in the occurrence of dermatitis, scabies, psoriasis, and papular urticaria. La Niña has been associated with increases in the occurrence of varicella, hand, foot, and mouth disease, and Ross River virus (in certain areas), and decreases in viral warts and leishmaniasis. Reports on the effects of ENSO on skin and skin-related disease are limited, and more studies could be helpful in the future. PMID:26471012

  12. Modern California current system and radiolarian responses to normal (anti-El Nino) conditions

    SciTech Connect

    Casey, R.E.; Carson, T.L.; Weinheimer, A.L.

    1986-04-01

    The modern California Current is a relatively wide, slow, southward flow of cold, low-salinity water subject to considerable seasonal upwelling and other seasonal and supraseasonal perturbations. The radiolarian fauna contained within these waters reflects the parameters and perturbations common to eastern boundary currents. Radiolarian faunas characteristic of the California Current (subarctic and transitional waters), the offshore gyre (North Pacific anticyclonic subtropical gyre), the eastern tropical Pacific, and underlying intermediate and deep waters have been documented and characterized. During normal (anti-El Nino) conditions within the California Current system, the following physical oceanographic changes (and their characteristic radiolarian responses) occur. Spring and summer are dominated by the strongest southerly flow of the California Current - with high-standing crops of subarctic and transitional radiolarians in the core of that current - whose core is seaward of the southern California continental borderland. Spring and summer are also periods of strongest upwelling, with deeper radiolarians appearing at or near the surface. During fall and into winter, the California Current slows and a coastal countercurrent, the Davidson Current, develops. Radiolarians indicate that a much reduced core of the California Current swings in over the southern California continental borderland, and that faunas from the south are brought northward near the shore.

  13. Are population dynamics of shorebirds affected by El Niño/Southern Oscillation (ENSO) while on their non-breeding grounds in Ecuador?

    NASA Astrophysics Data System (ADS)

    O'Hara, Patrick D.; Haase, Ben J. M.; Elner, Robert W.; Smith, Barry D.; Kenyon, Jamie K.

    2007-08-01

    Declines in avian populations are a global concern, particularly for species that migrate between Arctic-temperate and tropical locations. Long-term population studies offer opportunities to detect and document ecological effects attributable to long-term climatic cycles such as the El Niño/Southern Oscillation (ENSO). In this study, we report possible population-level effects of such climatic cycles on shorebird species that use two non-breeding season sites in Ecuador (Santa Elena peninsula area, near La Libertad). During our 9-year study period (1991/1992-1999/2000), there was a particularly strong ENSO warm phase event during 1997/1998. Population trend data for three species of shorebird, Western Sandpipers ( Calidris mauri), Semipalmated Sandpipers ( C. pusilla), and Least Sandpipers ( C. minutilla), indicated abundances generally declined during the 1990s, but there was an increase in the proportion of first-year birds and their abundance in the years following the 1997/1998 ENSO warm phase. There was some support for variation in apparent survivorship associated with the onset of the ENSO warm phase event in our population models, based on capture-mark-recapture data. Following the 1997/1998 ENSO event onset, individuals for all three species were significantly lighter during the non-breeding season ( F1,3789 = 6.6, p = 0.01). Least-squares mean mass (controlling for size, sex and day of capture) for first-year birds dropped significantly more than for adults following ENSO (first-year mass loss = 0.69 ± 0.12 g; adult mass loss = 0.34 ± 0.11 g, F1,3789 = 5.31, p = 0.021), and least-squares mean mass dropped most during the period when sandpipers prepare for northward migration by gaining mass and moulting into breeding plumage. Least Sandpipers may have declined the most in mean mass following ENSO (0.76 ± 0.19 g), whereas Semipalmated Sandpipers were 0.52 ± 0.12 g lighter, and Western Sandpipers 0.40 ± 0.13 g lighter, but overall variation among

  14. Characteristics of extreme rainfall events in northwestern Peru during the 1982-1983 El Nino period

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Tisnado, G. M.; Scofield, R. A.

    1987-01-01

    Histograms and contour maps describing the daily rainfall characteristics of a northwestern Peru area most severely affected by the 1982-1983 El Nino event were prepared from daily rainfall data obtained from 66 stations in this area during the El Nino event, and during the same 8-month intervals for the two years preceding and following the event. These data were analyzed, in conjunction with the anlysis of visible and IR satellite images, for cloud characteristics and structure. The results present a comparison of the rainfall characteristics as a function of elevation, geographic location, and the time of year for the El Nino and non-El Nino periods.

  15. Signature of El Nino off Oregon, 1982-1983

    SciTech Connect

    Huyer, A.; Smith, R.L.

    1985-07-20

    Current and conductivity, temperature, and depth (CTD) measurements were made over the Oregon shelf near 43/sup 0/N between February 1981 and April 1984 as part of a large-scale west coast shelf experiment (SuperCODE). The data set includes a nearly continuous record of current velocity and temperature over the continental shelf off Coos Bay from May 1981 through January 1984, CTD sections off Coos Bay in January or February of each year from 1981 to 1984, and CTD sections off Newport (44.6/sup 0/N) in April 1983, and April 1984. The latter are compared with sections off Newport made during the previous two decades. Sea level from the Newport tide gage, daily sea surface temperature at Charleston (43.3/sup 0/N), the alongshore component of the wind stress at 45/sup 0/N and the large-scale North Pacific atmospheric pressure pattern provide a climatological perspective. The initial manifestation of El Nino off Oregon was in October 1982: anomalously high sea level, high coastal sea surface temperature, and increased poleward flow. These effects occurred within 1 month of the onset of El Nino off Peru and preceded any local (North Pacific) atmospheric effect by 2 to 3 months. The anomalous local meteorological conditions, which became manifest in December and January, greatly enhanced the initial effects and inserted their own signal. The first signals of El Nino probably arrived by an oceanic path, but there is no doubt they were subsequently reinforced by anomalous atmospheric conditions.

  16. World Encircling Tectonic Vortex Street - Geostreams Revisited: The Southern Ring Current EM Plasma-Tectonic Coupling in the Western Pacific Rim

    NASA Astrophysics Data System (ADS)

    Leybourne, Bruce; Smoot, Christian; Longhinos, Biju

    2014-05-01

    Interplanetary Magnetic Field (IMF) coupling to south polar magnetic ring currents transfers induction energy to the Southern Geostream ringing Antarctica and underlying its encircling mid-ocean ridge structure. Magnetic reconnection between the southward interplanetary magnetic field and the magnetic field of the earth is the primary energy transfer mechanism between the solar wind and the magnetosphere. Induced telluric currents focused within joule spikes along Geostreams heat the southern Pacific. Alignment of the Australian Antarctic Discordance to other tectonic vortexes along the Western Pacific Rim, provide electrical connections to Earths core that modulate global telluric currents. The Banda Sea Triple Junction, a mantle vortex north of Australia, and the Lake Baikal Continental Rift vortex in the northern hemisphere modulate atmospheric Jetstream patterns gravitationally linked to internal density oscillations induced by these telluric currents. These telluric currents are driven by solar magnetic power, rotation and orbital dynamics. A solar rotation 40 day power spectrum in polarity controls north-south migration of earthquakes along the Western Pacific Rim and manifest as the Madden Julian Oscillation a well-documented climate cycle. Solar plasma turbulence cycles related to Hale flares trigger El Nino Southern Oscillations (ENSO's), while solar magnetic field strength frequencies dominate global warming and cooling trends indexed to the Pacific Decadal Oscillation. These Pacific climate anomalies are solar-electro-tectonically modulated via coupling to tropical geostream vortex streets. Particularly the section along the Central Pacific Megatrend connecting the Banda Sea Triple Junction (up welling mantle vortex) north of Australia with the Easter Island & Juan Fernandez twin rotating micro-plates (twin down welling mantle vortexes) along the East Pacific Rise modulating ENSO. Solar eruptions also enhance the equatorial ring current located

  17. The leading modes of decadal SST variability in the Southern Ocean in CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Dommenget, Dietmar

    2016-09-01

    The leading modes of Sea Surface Temperature variability in the Southern Ocean on decadal and even larger time scales are analysed using Coupled Model Intercomparison Project 5 (CMIP5) model simulations and observations. The analysis is based on Empirical Orthogonal Function modes of the CMIP5 model super ensemble. We compare the modes from the CMIP5 super ensemble against several simple null hypotheses, such as isotropic diffusion (red noise) and a Slab Ocean model, to investigate the sources of decadal variability and the physical processes affecting the characteristics of the modes. The results show three main modes in the Southern Ocean: the first and most dominant mode on interannual to decadal time scales is an annular mode with largest amplitudes in the Pacific, which is strongly related to atmospheric forcing by the Southern Annular Mode and El Nino Southern Oscillation. The second mode is an almost basin wide monopole pattern, which has pronounced multi-decadal and longer time scales variability. It is firstly inducted by the Wave-3 patterns in the atmosphere and further developed via ocean dynamics. The third mode is a dipole pattern in the southern Pacific that has a pronounced peak in the power spectrum at multi-decadal time scales. All three leading modes found in the CMIP5 super model have distinct patterns and time scale behaviour that can not be explained by simple stochastic null hypothesis, thus all three leading modes are ocean-atmosphere coupled modes and are likely to be substantially influenced or driven by ocean dynamical processes.

  18. TOPEX/El Nino Watch - El Nino Warm Water Pool Returns to Near Normal State, Mar, 14, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Mar. 14, 1998 and sea surface height is an indicator of the heat content of the ocean. The image shows that the sea surface height along the central equatorial Pacific has returned to a near normal state. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition. Remnants of the El Nino warm water pool, shown in red and white, are situated to the north and south of the equator. These sea surface height measurements have provided scientists with a detailed view of how the 1997-98 El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather

  19. TOPEX/El Nino Watch - Satellite shows El Nino-related Sea Surface Height, Mar, 14, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Mar. 14, 1998 and sea surface height is an indicator of the heat content of the ocean. The image shows that the sea surface height along the central equatorial Pacific has returned to a near normal state. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition. Remnants of the El Nino warm water pool, shown in red and white, are situated to the north and south of the equator. These sea surface height measurements have provided scientists with a detailed view of how the 1997-98 El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather

  20. Spatial Correlations of Anomalies of Tropospheric Temperature and Water Vapor, Cloud Cover, and OLR with the El Nino Index

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Iredell, Lena; Lee, Jae N.

    2014-01-01

    In this presentation, we will show AIRS Version-6 area weighted anomaly time series over the time period September 2002 through August 2014 of atmospheric temperature and water vapor profiles as a function of height. These anomaly time series show very different behaviors in the stratosphere and in the troposphere. Tropical mean stratospheric temperature anomaly time series are very strongly influenced by the Quasi-Biennial Oscillation (QBO) with large anomalies that propagate downward from 1 mb to 100 mb with a period of about two years. AIRS stratospheric temperature anomalies are in good agreement with those obtained by MLS over a common period. Tropical mean tropospheric temperature profile anomalies appear to be totally disconnected from those of the stratosphere and closely follow El Nino La Nina activity.

  1. A View From Space: Evolution of the 1997-1998 El Nino and La Nina

    NASA Technical Reports Server (NTRS)

    Busalacchi, Antonio

    1999-01-01

    After the last extreme El Nino in 1982-1983, an extensive in situ observing system was deployed in the tropical Pacific Ocean in support of monitoring and predicting El Nino. Within the past ten years a series of ocean and atmosphere remote sensing satellites have been launched that serve to supplement and enhance the observations being taken at the surface, and at depth, in the equatorial Pacific Ocean. The 1997-1998 "El Nino Event of the Century" has been the best monitored El Nino on record. The 1997-1998 El Nino will be the first time a major El Nino event and subsequent La Nina will have been observed from start to finish from a combination of remotely-sensed measurements of sea surface temperature, sea surface topography, sea surface wind, ocean color, and precipitation, Among some of the lessons learned to date from the 1997-1998 event have been the need for global observation in addition to just those in the equatorial Pacific Ocean. In this presentation the evolution of the 1997-1998 El Nino will be depicted from the unique vantage point provided by these space-based observations as analyzed separately, and together as a representation of the coupled system. Comparisons and contrasts with the evolution 1982-1983 El Nino and how the in situ and space-based observations complement each other will be discussed.

  2. A View from Space: Evolution of the 1997-98 El Nino and La Nina

    NASA Technical Reports Server (NTRS)

    Busalacchi, Antonio J.

    1999-01-01

    After the last extreme El Nino in 1982-1983, an extensive in situ observing system was deployed in the tropical Pacific Ocean in support of monitoring and predicting El Nino. Within the past ten years a series of ocean and atmosphere remote sensing satellites have been launched that serve to supplement and enhance the observations being taken at the surface, and at depth, in the equatorial Pacific Ocean. The 1997-1998 "El Nino Event of the Century" has been the best monitored El Nino on record. The 1997-1998 El Nino will be the first time a major El Nino event and subsequent La Nina will have been observed from start to finish from a combination of remotely-sensed measurements of sea surface temperature, sea surface topography, sea surface winds, ocean color, and precipitation. Among some of the lessons learned to date from the 1997-1998 event have been the need for global observations in addition to just those in the equatorial Pacific Ocean. In this presentation the evolution of the 1997-1998 El Nino will be depicted from the unique vantage point provided by these space-based observations as analyzed separately, and together as a representation of the coupled system. Comparisons and contrasts with the evolution 1982-1983 El Nino and how the in situ and space-based observations complement each other will be discussed.

  3. A View from Space: Evolution of the 1997-1998 El Nino and La Nina

    NASA Technical Reports Server (NTRS)

    Busalacchi, Antonio J.

    1997-01-01

    After the last extreme El Nino in 1982-1983, an extensive in situ observing system was deployed in the tropical Pacific Ocean in support of monitoring and predicting El Nino. Within the past ten years a series of ocean and atmosphere remote sensing satellites have been launched that serve to supplement and enhance the observations being taken at the surface, and at depth, in the equatorial Pacific Ocean. The 1997-1998 "El Nino Event of the Century" has been the best monitored El Nino on record. The 1997-1998 El Nino will be the first time a major El Nino event and subsequent La Nina will have been observed from start to finish from a combination of remotely-sensed measurements of sea surface temperature, sea surface topography, sea surface winds, ocean color, and precipitation. Among some of the lessons learned to date from the 1997-1998 event have been the need for global observations in addition to just those in the equatorial Pacific Ocean. In this presentation the evolution of the 1997-1998 El Nino will be depicted from the unique vantage point provided by these space-based observations as analyzed separately, and together as a representation of the coupled system. Comparisons and contrasts with the evolution 1982-1983 El Nino and how the in situ and space-based observations complement each other will be discussed.

  4. The spectral details of observed and simulated short-term water vapor feedbacks of El Niño-Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Pan, F.; Huang, X.; Chen, X.

    2015-12-01

    Radiative kernel method has been validated and widely used in the study of climate feedbacks. This study uses spectrally resolved longwave radiative kernels to examine the short-term water vapor feedbacks associated with the ENSO cycles. Using a 500-year GFDL CM3 and a 100-year NCAR CCSM4 pre-industry control simulation, we have constructed two sets of longwave spectral radiative kernels. We then composite El Niño, La Niña and ENSO-neutral states and estimate the water vapor feedbacks associated with the El Niño and La Niña phases of ENSO cycles in both simulations. Similar analysis is also applied to 35-year (1979-2014) ECMWF ERA-interim reanalysis data, which is deemed as observational results here. When modeled and observed broadband feedbacks are compared to each other, they show similar geographic patterns but with noticeable discrepancies in the contrast between the tropics and extra-tropics. Especially, in El Niño phase, the feedback estimated from reanalysis is much greater than those from the model simulations. Considering the observational data span, we carry out a sensitivity test to explore the variability of feedback-deriving using 35-year data. To do so, we calculate the water vapor feedback within every 35-year segment of the GFDL CM3 control run by two methods: one is to composite El Nino or La Nina phases as mentioned above and the other is to regressing the TOA flux perturbation caused by water vapor change (δR_H­2O) against the global-mean surface temperature a­­­­nomaly. We find that the short-term feedback strengths derived from composite method can change considerably from one segment to another segment, while the feedbacks by regression method are less sensitive to the choice of segment and their strengths are also much smaller than those from composite analysis. This study suggests that caution is warranted in order to infer long-term feedbacks from a few decades of observations. When spectral details of the global-mean feedbacks

  5. Braided oscillators

    NASA Astrophysics Data System (ADS)

    Yildiz, A.

    2002-03-01

    A generalized oscillator algebra is proposed and the braided Hopf algebra structure for this generalized oscillator is investigated. Using the solutions for the braided Hopf algebra structure, two types of braided Fibonacci oscillators are introduced. This leads to two types of braided Biedenharn-Macfarlane oscillators as special cases of the Fibonacci oscillators. We also find the braided Hopf algebra solutions for the three dimensional braided space. One of these, as a special case, gives the Hopf algebra given in the literature.

  6. The Impact of Warm Pool El Nino Events on Antarctic Ozone

    NASA Technical Reports Server (NTRS)

    Hurwitz, Margaret M.; Newman, P. A.; Song, In-Sun; Frith, Stacey M.

    2011-01-01

    Warm pool El Nino (WPEN) events are characterized by positive sea surface temperature (SST) anomalies in the central equatorial Pacific in austral spring and summer. Previous work found an enhancement in planetary wave activity in the South Pacific in austral spring, and a warming of 3-5 K in the Antarctic lower stratosphere during austral summer, in WPEN events as compared with ENSO neutral. In this presentation, we show that weakening of the Antarctic vortex during WPEN affects the structure and magnitude of high-latitude total ozone. We use total ozone data from TOMS and OMI, as well as station data from Argentina and Antarctica, to identify shifts in the longitudinal location of the springtime ozone minimum from its climatological position. In addition, we examine the sensitivity of the WPEN-related ozone response to the phase of the quasi-biennial oscillation (QBO). We then compare the observed response to WPEN events with Goddard Earth Observing System chemistry-climate model, version 2 (GEOS V2 CCM) simulations. Two, 50-year time-slice simulations are forced by annually repeating SST and sea ice climatologies, one set representing observed WPEN events and the second set representing neutral ENSO events, in a present-day climate. By comparing the two simulations, we isolate the impact of WPEN events on lower stratospheric ozone, and furthermore, examine the sensitivity of the WPEN ozone response to the phase of the QBO.

  7. Effects of the 2004 El Nino on Tropospheric Ozone and Water Vapor

    NASA Technical Reports Server (NTRS)

    Chandra, S.; Ziemke, J. R.; Schoeberl, M. R.; Froidevaux, L.; Read, W. G.; Levelt, P. F.; Bhartia, P. K.

    2007-01-01

    The global effects of the 2004 El Nino on tropospheric ozone and H2O based on Aura OM1 and MLS measurements are analyzed. Although it was a weak El Nino from a historical perspective, it produced significant changes in these parameters in tropical latitudes. Tropospheric ozone increased by 10-20% over most of the western Pacific region and decreased by about the same amount over the eastern Pacific region. H2O in the upper troposphere showed similar changes but with opposite sign. These zonal changes in tropospheric ozone and H2O are caused by the eastward shift in the Walker circulation in the tropical pacific region during El Nino. For the 2004 El Nino, biomass burning did not have a significant effect on the ozone budget in the troposphere unlike the 1997 El Nino. Zonally averaged tropospheric column ozone did not change significantly either globally or over the tropical and subtropical latitudes.

  8. TOPEX/El Nino Watch - October 23, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/POSEIDON satellite. The image shows sea surface height relative to normal ocean conditions on Oct. 23, 1997 as the warm water associated with El Nino (in white) spreads northward along the entire coast of North America from the equator all the way to Alaska. The warm water pool associated with the El Nino has returned to the volume it was in mid-September after dropping to a temporary low at the beginning of October. The sea surface elevation just north of the El Nino warm pool continues to drop (purple area), enhancing the eastward flowing North Equatorial Counter Current. The intensification of this current is another tell-tale sign of the El Nino phenomenon. This flow contributes to the rise in sea level along the western coasts of the Americas that will progress towards both the north and south poles over the next several months. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21-30 degrees Celsius (70- 85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of

  9. Coolness in the tropical Pacific during an El Nino episode

    SciTech Connect

    Chou, M.

    1994-11-01

    The response of radiation budgets to changes in water vapor and clouds in an El Nino episode is investigated using the analyzed sea surface temperature (SST) and satellite-derived clouds and the earth radiation budgets for the tropical Pacific (30 deg N-30 deg S, 100 deg E-100 deg W). Analyses are performed for April 1985 and April 1987. The former is a non-El Nino year and the latter is an El Nino year. Compared to April 1985, when the SST over the central and eastern equatorial Pacific is approximately 2 C lower, the high-level cloudiness in April 1987 increases in the central and eastern equatorial Pacific. Corresponding to the increase in cloudiness, the outgoing longwave radiation and the net downward solar radiation at the top of the atmosphere decrease. The patterns of these changes are reversed in the western tropical Pacific and the Northern Hemispheric (NH) subsidence region centered at approximately 20 deg N, indicating an eastward shift of the convection center from the maritime continents to the central equatorial Pacific and a strengthened NH Hadley circulation. The earth-atmosphere system in the region receives less radiative energy by 4 W/sq m in the warmer month of April 1987 than in the month of April 1985, which is primarily caused by a reduced atmospheric clear sky greenhouse effect in the NH tropical Pacific in April 1987. Clouds have strong effects on both the IR and solar radiation, but the net effect on the radiation budget at the top of the atmopshere changes only slightly between April 1985 and April 1987. The results are consistent with Lindzen`s hypothesis that reduced upper-tropospheric water vapor in the vicinity of the enhanced convection region produces cooling that counteracts warming in the Tropics.

  10. TOPEX/El Nino Watch - March thru June, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These four views of the Pacific Ocean were produced using sea surface height measurements taken by the U.S./French TOPEX/POSEIDON satellite. The images show sea surface height relative to normal ocean conditions from March 1997 through June 1997. This evolutionary view is providing oceanographers with more convincing information that the weather-disrupting phenomenon known as El Nino is back and getting stronger. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it s about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21-30 degrees Celsius (70-85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the presence of the early indications of El Nino conditions.

  11. TOPEX/El Nino Watch - June 25, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/POSEIDON satellite. The image shows sea surface height relative to normal ocean conditions on June 25, 1997 and provides more convincing information that the weather-disrupting phenomenon known as El Nino is back and getting stronger. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it s about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21-30 degrees Celsius (70-85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the presence of the early indications of El Nino conditions.

  12. TOPEX/El Nino Watch - October 3, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Oct. 3, 1997 as the warm water associated with El Nino (in white) spreads northward along the entire coast of North America from the equator all the way to Alaska. The warm water pool in tropical Pacific resulting from El Nino seems to have stabilized. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21 and 30 C (70 to 85 F), carries the amount of heat equal to 100 times the amount of fossil fuel energy consumed by the entire U.S. population during one year. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA) has issued an advisory

  13. El Nino and the Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Halpern, David

    1999-01-01

    Until a decade ago, an often-quoted expression in oceanography is that very few observations are recorded throughout the ocean. Now, the sentiment is no longer valid in the uppermost 10% of the tropical Pacific Ocean nor at the surface of the global ocean. One of the remarkable legacies of the 1985-1994 Tropical Oceans Global Atmosphere (TOGA) Program is an in situ marine meteorological and upper oceanographic measurement array throughout the equatorial Pacific to monitor the development and maintenance of El Nino episodes. The TOGA Observing System, which initially consisted of moored- and drifting-buoy arrays, a network of commercial ships, and coastal and island stations, now includes a constellation of satellites and data-assimilating models to simulate subsurface oceanographic conditions. The El Nino and La Nina tropical Pacific Ocean observing system represents the initial phase of an integrated global ocean observing system. Remarkable improvements have been made in ocean model simulation of subsurface currents, but some problems persist. For example, the simulation of the South Equatorial Current (SEC) remains an important challenge in the 2S-2N Pacific equatorial wave guide. During El Nino the SEC at the equator is reduced and sometimes the direction is reversed, becoming eastward. Both conditions allow warm water stored in the western Pacific to invade the eastern region, creating an El Nino episode. Assimilation of data is a tenet of faith to correct simulation errors caused by deficiencies in surface fluxes (especially wind stress) and parameterizations of subgrid-scale physical processes. In the first of two numerical experiments, the Pacific SEC was simulated with and without assimilation of subsurface temperature data. Along the equator, a very weak SEC occurred throughout the eastern Pacific, independent of assimilation of data. However, as displayed in the diagram, in the western Pacific there was no satisfactory agreement between the two

  14. Granger causality from changes in level of atmospheric CO2 to global surface temperature and the El Niño-Southern Oscillation, and a candidate mechanism in global photosynthesis

    NASA Astrophysics Data System (ADS)

    Leggett, L. M. W.; Ball, D. A.

    2015-10-01

    A significant difference, now of some 16 years' duration, has been shown to exist between the observed global surface temperature trend and that expected from the majority of climate simulations. For its own sake, and to enable better climate prediction for policy use, the reasons behind this mismatch need to be better understood. While an increasing number of possible causes have been proposed, the candidate causes have not yet converged. With this background, this paper reinvestigates the relationship between change in the level of CO2 and two of the major climate variables, atmospheric temperature and the El Niño-Southern Oscillation (ENSO). Using time-series analysis in the form of dynamic regression modelling with autocorrelation correction, it is shown that first-difference CO2 leads temperature and that there is a highly statistically significant correlation between first-difference CO2 and temperature. Further, a correlation is found for second-difference CO2 with the Southern Oscillation Index, the atmospheric-pressure component of ENSO. This paper also shows that both these correlations display Granger causality. It is shown that the first-difference CO2 and temperature model shows no trend mismatch in recent years. These results may contribute to the prediction of future trends for global temperature and ENSO. Interannual variability in the growth rate of atmospheric CO2 is standardly attributed to variability in the carbon sink capacity of the terrestrial biosphere. The terrestrial biosphere carbon sink is created by the difference between photosynthesis and respiration (net primary productivity): a major way of measuring global terrestrial photosynthesis is by means of satellite measurements of vegetation reflectance, such as the Normalized Difference Vegetation Index (NDVI). In a preliminary analysis, this study finds a close correlation between an increasing NDVI and the increasing climate model/temperature mismatch (as quantified by the difference

  15. Importance of salinity stratification in the build up of El Nino

    NASA Astrophysics Data System (ADS)

    Maes, C.; Picaut, J.; Belamari, S.

    2003-04-01

    An increase of mass and heat content in the equatorial band of the Pacific Ocean, and in particular in the western part of the basin, appears necessary for the initiation of El Nino. This build up has led to the recharge theory of El Nino. The western Pacific warm pool is also characterized by the presence of specific salinity stratification known as the barrier layer. This barrier isolates the warm surface water from entrainment cooling and potentially preserves the heat content prior to El Nino. The importance of salinity stratification in the build up of El Nino is investigated using a general circulation coupled model of the tropical Pacific. The Meteo-France/ARPEGE global atmospheric model coupled to the LODYC/OPA ocean model is able to reproduce self-sustained El Nino events. In particular, this coupled model displays an increase of heat content in the western equatorial Pacific the year prior to each El Nino event. The methodology consists of removing the stratification effect of salinity in the vertical mixing parameterization the year prior to El Nino, and then plugs it back. The cutoff is restricted to the western side of the equatorial band where sea surface temperature (SST) is greater than 28C. By removing the barrier layer the year prior to El Nino, the main effect is to reduce the ocean heat content in the western part of the equatorial band and increase it in the east. When the stratification effect of salinity is plug back, El Nino is greatly reduced or even aborted. This has tested over three El Nino events of different intensities and through 5 additional member ensemble. The failure for El Nino to start is statistically significant and proves that salinity stratification plays a crucial role in the build up of El Nino. Detailed analyses indicate that vertical diffusion in the warm pool and SST-wind coupling in the central Pacific are essential to set up the favorable condition for the initiation of El Nino.

  16. Assessing the impact of the 2015/2016 El Niño event on multi-satellite soil moisture over the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Dorigo, Wouter; Bauer-Marschallinger, Bernhard; Depoorter, Mathieu; Miralles, Diego

    2016-04-01

    In the past, El Niño has severely invigorated drought conditions over large parts of the Southern Hemisphere causing enormous ecological and socio-economic damage (e.g., agricultural loss, water scarcity, bush fires). Accurate assessments of its impacts are therefore crucial for improving seasonal predictions that can help to prevent and mitigate these consequences. However, the impact of El Niño Southern Oscillation (ENSO) on drought conditions over land are not yet well understood, partly because of the difficulty of linking sea surface temperature anomalies to regional precipitation anomalies over land, partly because it is not straightforward to disentangle the ENSO signal from other seasonal and climate variability in the data. Here, we present a new statistical method for assessing the impact of ENSO on drought conditions over land, based on the relationship between the NINO3.4 ENSO index and ESA CCI long-term satellite observations of soil moisture. The new method is able to clearly separate the ENSO signal from other short-term and long-term variability in the soil moisture data, both in time and space. In the presentation we will show how the recent 2015/2016 El Niño has affected soil moisture in the Southern Hemisphere. In addition, we will show how the statistical method can be coupled to ENSO forecasts to predict the impact of future El Niño events on drought conditions up to 9 months ahead.

  17. A simulation of the 1982-1983 El Nino

    SciTech Connect

    Jia, Y.L.; Wells, N.C. ); Rowe, M.A. )

    1990-04-15

    A general circulation model of the equatorial Pacific Ocean was used to simulate the 1982-1983 El Nino event. The wind data set used to force the model is that of Florida State University (FSU). The results are presented here and compared with those from other simulations. The model results show that the simulation is successful in reproducing the major features of the 1982-1983 El Nino such as the disappearance of the Equatorial Undercurrent, the pattern and magnitude of the sea surface temperature anomaly, and the variations of the thermocline. However, there is a delay of about 2-3 months in these events in the model compared with those observed. This is attributed to the wind stress forcing during 1982 in the eastern equatorial Pacific, which is more intense in the FSU wind data set than in the National Meteorological Center data set. Along the South American coast the model results show a persistent cooling before a slight warming in April 1983 during the event, which is not understood.

  18. Microwave Limb Sounder/El Nino Watch - December, 1997

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image shows differences in atmospheric water vapor relative to a normal (average) year in the Earth's upper troposphere about 10 kilometers (6 miles) above the surface. The measurements were taken by the Microwave Limb Sounder (MLS) instrument aboard NASA's Upper Atmosphere Research Satellite (UARS). These data, collected in late December 1997, show higher than normal levels of water vapor (red) over the central and eastern Pacific which indicates the presence of an El Nino condition. At the same time, the western Pacific (blue) is much drier than normal. The unusually moist air above the central and eastern Pacific is a consequence of the much warmer-than-normal ocean waters which occur during El Nino. Warmer water evaporates at a higher rate and the resulting warm moist air rises and forms tall cloud towers. In the tropics, the warm water and the resulting tall cloud towers typically produce large amounts of rain. These data show significant increases in the amount of atmospheric moisture off the coast of Peru and Ecuador since measurements were made in November 1997. The maximum water temperature in the eastern tropical Pacific, as measured by the National Oceanic and Atmospheric Administration (NOAA), is still higher than normal and these high ocean temperatures are likely responsible for an increase in evaporation and the subsequent rise in humidity.

  19. Mechanisms Controlling the Interannual Variation of Mixed Layer Temperature Averaged over the Nino-3 Region

    NASA Technical Reports Server (NTRS)

    Kim, Seung-Bum; Lee, Tong; Fukumori, Ichiro

    2007-01-01

    The present study examines processes governing the interannual variation of MLT in the eastern equatorial Pacific.Processes controlling the interannual variation of mixed layer temperature (MLT) averaged over the Nino-3 domain (5 deg N-5 deg S, 150 deg-90 deg W) are studied using an ocean data assimilation product that covers the period of 1993-2003. The overall balance is such that surface heat flux opposes the MLT change but horizontal advection and subsurface processes assist the change. Advective tendencies are estimated here as the temperature fluxes through the domain's boundaries, with the boundary temperature referenced to the domain-averaged temperature to remove the dependence on temperature scale. This allows the authors to characterize external advective processes that warm or cool the water within the domain as a whole. The zonal advective tendency is caused primarily by large-scale advection of warm-pool water through the western boundary of the domain. The meridional advective tendency is contributed to mostly by Ekman current advecting large-scale temperature anomalies through the southern boundary of the domain. Unlike many previous studies, the subsurface processes that consist of vertical mixing and entrainment are explicitly evaluated. In particular, a rigorous method to estimate entrainment allows an exact budget closure. The vertical mixing across the mixed layer (ML) base has a contribution in phase with the MLT change. The entrainment tendency due to the temporal change in ML depth is negligible compared to other subsurface processes. The entrainment tendency by vertical advection across the ML base is dominated by large-scale changes in upwelling and the temperature of upwelling water. Tropical instability waves (TIWs) result in smaller-scale vertical advection that warms the domain during La Nina cooling events. However, such a warming tendency is overwhelmed by the cooling tendency associated with the large-scale upwelling by a factor of

  20. TOPEX El Nino/La Nina - Entire Pacific is out of Whack, April 7, 1999

    NASA Technical Reports Server (NTRS)

    1999-01-01

    New sea surface height measurements from the TOPEX/Poseidon satellite show that the sea level and temperature of the entire Pacific is 'out of balance,' including a large area of abnormally cool water along the west coast of North America that scientists say will influence regional weather patterns along the west coast of the Americas this summer. Southern California's seasonal 'June gloom' weather, caused by a marine layer that traps smog over the Los Angeles basin, may linger throughout the summer as a result, according to oceanographer Dr. William Patzert of JPL. 'Our data certainly show that the unusual oceanic climatic conditions that gave rise to El Nino and La Nina are not returning to a normal state.' he said. 'Our planet's climate system continues to exhibit rather wild behavior. These large warm and cold, high and low sea levels are slow-developing and long-lasting, and will certainly influence global climate and weather for the coming summer and into next fall.' The unusually cool water (areas of lower sea level shown in blue and purple) extends from the Gulf of Alaska along the North American coast, sweeping south-westward from Baja California, where it merges with the remnants of La Nina. The La Nina phenomenon's cool, lower sea levels across the equator continue to weaken and break into (purple) patches. The northwest Pacific continues to be warmer than normal, though the variations from normal are not as great as in recent months. Areas where the Pacific Ocean is normal appear in green. The data represented in the image were collected from May 12-22.

    TOPEX/Poseidon's sea-surface height measurements have provided scientists with a detailed view of the 1998-99 La Nina and the 1997-98 El Nino because the satellite's altimeter measures the changing sea-surface height with unprecedented precision. In this image, the purple areas are about 18 centimeters (7 inches) below normal, creating a deficit in the heat supply to the surface waters. The white

  1. Water displacements in the Pacific and the genesis of El Nino cycles

    SciTech Connect

    Wyrtki, K.

    1985-07-20

    Sea level observations are used to estimate the amounts of warm water exchanged during the 1982 to 1983 El Nino event, indicating an eastward flux of about 40 x 10/sup 6/ m/sup 3/ s/sup -1/. At the end of El Nino the equatorial Pacific is depleted of warm water which is lost toward higher latitudes. The duration of a complete El Nino cycle is determined by the time required for the slow accumulation of warm water in the western Pacific. The cycle constitutes an energy relaxation of the ocean-atmosphere system.

  2. Comparison of 1997 and 2015 El-Nino on Meteorological and Atmospheric Parameters

    NASA Astrophysics Data System (ADS)

    Wolfe, Lindsey; Singh, Ramesh

    2016-07-01

    This paper investigates the impact of dramatic 1997-1998 and 2015-2016 El-Nino on meteorological and atmospheric parameters globally using satellite and ground observations. We have considered meteorological parameters (rainfall, air temperature, surface pressure, winds, water vapor) and atmospheric parameters (air temperature, total ozone column). Our detailed analysis shows pronounced changes in some of meteorological and atmospheric parameters in different parts of the world at different time. Further, we have carried out comparison of some of the various meteorological and atmospheric parameters associated with El-Nino of 1997-1998 and 20015-2016, detrimental impact of 2015-2016 El-Nino is observed.

  3. TOPEX/El Nino Watch- September 20, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/POSEIDON satellite. The image shows sea surface height relative to normal ocean conditions on September 20, 1997 and provides more convincing information that the weather-disrupting phenomenon known as El Nino is back and getting stronger. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters ( 6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21-30 degrees Celsius (70-85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the presence of the early indications of El Nino conditions.

    For more information, please visit the TOPEX/Poseidon project web page

  4. On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes - Part 2: The effects of the El Niño/Southern Oscillation, volcanic eruptions and contributions of atmospheric dynamics and chemistry to long-term total ozone changes

    NASA Astrophysics Data System (ADS)

    Rieder, H. E.; Frossard, L.; Ribatet, M.; Staehelin, J.; Maeder, J. A.; Di Rocco, S.; Davison, A. C.; Peter, T.; Weihs, P.; Holawe, F.

    2013-01-01

    We present the first spatial analysis of "fingerprints" of the El Niño/Southern Oscillation (ENSO) and atmospheric aerosol load after major volcanic eruptions (El Chichón and Mt. Pinatubo) in extreme low and high (termed ELOs and EHOs, respectively) and mean values of total ozone for the northern and southern mid-latitudes (defined as the region between 30° and 60° north and south, respectively). Significant influence on ozone extremes was found for the warm ENSO phase in both hemispheres during spring, especially towards low latitudes, indicating the enhanced ozone transport from the tropics to the extra-tropics. Further, the results confirm findings of recent work on the connection between the ENSO phase and the strength and extent of the southern ozone "collar". For the volcanic eruptions the analysis confirms findings of earlier studies for the northern mid-latitudes and gives new insights for the Southern Hemisphere. The results provide evidence that the negative effect of the eruption of El Chichón might be partly compensated by a strong warm ENSO phase in 1982-1983 at southern mid-latitudes. The strong west-east gradient in the coefficient estimates for the Mt. Pinatubo eruption and the analysis of the relationship between the AAO and ENSO phase, the extent and the position of the southern ozone "collar" and the polar vortex structure provide clear evidence for a dynamical "masking" of the volcanic signal at southern mid-latitudes. The paper also analyses the contribution of atmospheric dynamics and chemistry to long-term total ozone changes. Here, quite heterogeneous results have been found on spatial scales. In general the results show that EESC and the 11-yr solar cycle can be identified as major contributors to long-term ozone changes. However, a strong contribution of dynamical features (El Niño/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Antarctic Oscillation (AAO), Quasi-Biennial Oscillation (QBO)) to ozone variability and

  5. On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes - Part 2: The effects of the El Niño/Southern Oscillation, volcanic eruptions and contributions of atmospheric dynamics and chemistry to long-term total ozone changes

    NASA Astrophysics Data System (ADS)

    Rieder, H. E.; Frossard, L.; Ribatet, M.; Staehelin, J.; Maeder, J. A.; Di Rocco, S.; Davison, A. C.; Peter, T.; Weihs, P.; Holawe, F.

    2012-05-01

    We present the first spatial analysis of "fingerprints" of the El Niño/Southern Oscillation (ENSO) and atmospheric aerosol load after major volcanic eruptions (El Chichón and Mt. Pinatubo) in extreme low and high (termed ELOs and EHOs, respectively) and mean values of total ozone for the northern and southern mid-latitudes (defined as the region between 30° and 60° north and south, respectively). Significant influence on ozone extremes was found for the warm ENSO phase in both hemispheres during spring, especially towards low latitudes, indicating the enhanced ozone transport from the tropics to the extra-tropics. Further, the results confirm findings of recent work on the connection between the ENSO phase and the strength and extent of the southern ozone "collar". For the volcanic eruptions the analysis confirms findings of earlier studies for the northern mid-latitudes and gives new insights for the Southern Hemisphere. The results provide evidence that the negative effect of the eruption of El Chichón might be partly compensated by a strong warm ENSO phase in 1982-83 at southern mid-latitudes. The strong west-east gradient in the coefficient estimates for the Mt. Pinatubo eruption and the analysis of the relationship between the AAO and ENSO phase, the extent and the position of the southern ozone "collar" and the polar vortex structure provide clear evidence for a dynamical "masking" of the volcanic signal at southern mid-latitudes. The paper also analyses the contribution of atmospheric dynamics and chemistry to long-term total ozone changes. Here, quite heterogeneous results have been found on spatial scales. In general the results show that EESC and the 11-yr solar cycle can be identified as major contributors to long-term ozone changes. However, a strong contribution of dynamical features (El Niño/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Antarctic Oscillation (AAO), Quasi-Biennial Oscillation (QBO)) to ozone variability and

  6. El Nino/la Nina Transition In The Equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Lewis, M.; Turk, D.; McPhadden, Mike; Lagerloef, G.; Asanuma, I.

    A massive bloom of phytoplankton in the normally oligotrophic Western Pacific was the first manifestation of the termination of the 1997-1998 El Nino, by most measures, the strongest on record. This bloom represented a 4-fold increase in the background chlorophyll distribution, as viewed by the Sea-Viewing, Wide Field of View Sensor (SeaWiFS). A combination of physical and bio-optical observations from satellites, moored buoys, and ships lead to the conclusion that this bloom was a direct result of the interaction of surface currents with a series of island atolls (Kiribati) that induced strong vertical mixing and subsequent downstream advection of waters rich in nutrients. The increase in phytoplankton concentration represents a lower limit to a dramatically increased level of exported carbon from the normally biologically poor western Pacific region, and is a novel observation of topographic influences which are not normally resolved by most models of equatorial ocean dynamics.

  7. Neurodynamic oscillators

    NASA Technical Reports Server (NTRS)

    Espinosa, Ismael; Gonzalez, Hortensia; Quiza, Jorge; Gonazalez, J. Jesus; Arroyo, Ruben; Lara, Ritaluz

    1995-01-01

    Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.

  8. Contrasting Effects of Central Pacific and Eastern Pacific El Nino on Stratospheric Water Vapor

    NASA Technical Reports Server (NTRS)

    Garfinkel, Chaim I.; Hurwitz, Margaret M.; Oman, Luke D.; Waugh, Darryn W.

    2013-01-01

    Targeted experiments with a comprehensive chemistry-climate model are used to demonstrate that seasonality and the location of the peak warming of sea surface temperatures dictate the response of stratospheric water vapor to El Nino. In spring, El Nino events in which sea surface temperature anomalies peak in the eastern Pacific lead to a warming at the tropopause above the warm pool region, and subsequently to more stratospheric water vapor (consistent with previous work). However, in fall and in early winter, and also during El Nino events in which the sea surface temperature anomaly is found mainly in the central Pacific, the response is qualitatively different: temperature changes in the warm pool region are nonuniform and less water vapor enters the stratosphere. The difference in water vapor in the lower stratosphere between the two variants of El Nino approaches 0.3 ppmv, while the difference between the winter and spring responses exceeds 0.5 ppmv.

  9. El Nino, La Nina and VLBI Measured LOD

    NASA Technical Reports Server (NTRS)

    Clark, Thomas A.; Gipson, J. M.; Ma, C.

    1998-01-01

    VLBI is one of the most important techniques for measuring Earth orientation parameters (EOP), and is unique in its ability to make high accuracy measurements of UT1, and its time derivative, which is related to changes in the length of day, conventionally called LOD. These measurements of EOP give constraints on geophysical models of the solid-Earth, atmosphere and oceans. Changes in EOP are due either to external torques from gravitational forces, or to the exchange of angular momentum between the Earth, atmosphere and oceans. The effect of the external torques is strictly harmonic and nature, and is therefore easy to remove. We analyze an LOD time series derived from VLBI measurements with the goal of comparing this to predictions from AAM, and various ENSO indices. Previous work by ourselves and other investigators demonstrated a high degree of coherence between atmospheric angular momentum (AAM) and EOP. We continue to see this. As the angular momentum of the atmosphere increases, the rate of rotation of the Earth decreases, and vice versa. The signature of the ENSO is particularly strong. At the peak of the 1982-83 El Nino increased LOD by almost 1 ms. This was subsequently followed by a reduction in LOD of 0.75 ms. At its peak, in February of 1998, the 1997-98 El Nino increased LOD by 0.8 msec. As predicted at the 1998 Spring AGU, this has been followed by an abrupt decrease in LOD which is currently -0.4 ms. At this time (August, 1998) the current ENSO continues to develop in new and unexpected ways. We plan to update our analysis with all data available prior to the Fall AGU.

  10. El Nino - La Nina events simulated with Cane and Zebiak`s model and observed with satellite or in situ data. Part I: Model data comparison

    SciTech Connect

    Perigaud C.; Dewitte, B.

    1996-01-01

    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 is 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.

  11. Southern Hemisphere Carbon Monoxide Inferannual Variability Observed by Terra/Measurement of Pollution in the Troposphere (MOPITT)

    NASA Technical Reports Server (NTRS)

    Edwards, D. P.; Petron, G.; Novelli, P. C.; Emmons, L. K.; Gille, J. C.; Drummond, J. R.

    2010-01-01

    Biomass burning is an annual occurrence in the tropical southern hemisphere (SH) and represents a major source of regional pollution. Vegetation fires emit carbon monoxide (CO), which due to its medium lifetime is an excellent tracer of tropospheric transport. CO is also one of the few tropospheric trace gases currently observed from satellite and this provides long-term global measurements. In this paper, we use the 5 year CO data record from the Measurement Of Pollution In The Troposphere (MOPITT) instrument to examine the inter-annual variability of the SH CO loading and show how this relates to climate conditions which determine the intensity of fire sources. The MOPITT observations show an annual austral springtime peak in the SH zonal CO loading each year with dry-season biomass burning emissions in S. America, southern Africa, the Maritime Continent, and northwestern Australia. Although fires in southern Africa and S. America typically produce the greatest amount of CO, the most significant inter-annual variation is due to varying fire activity and emissions from the Maritime Continent and northern Australia. We find that this variation in turn correlates well with the El Nino Southern Oscillation precipitation index. Between 2000 and 2005, emissions were greatest in late 2002 and an inverse modeling of the MOPITT data using the MOZART chemical transport model estimates the southeast Asia regional fire source for the year August 2002 to September 2003 to be 52 Tg CO. Comparison of the MOPITT retrievals and NOAA surface network measurements indicate that the latter do not fully capture the inter-annual variability or the seasonal range of the CO zonal average concentration due to biases associated with atmospheric and geographic sampling.

  12. Modelled rainfall skill assessment against a 1000-year time/space isotope dendro-climatology for southern Africa

    NASA Astrophysics Data System (ADS)

    Woodborne, Stephan; Hall, Grant; Zhang, Qiong

    2016-04-01

    Palaeoclimate reconstruction using isotopic analysis of tree growth increments has yielded a 1000-year record of rainfall variability in southern Africa. Isotope dendro-climatology reconstructions from baobab trees (Adansonia digitata) provide evidence for rainfall variability from the arid Namib Desert and the Limpopo River Valley. Isotopic analysis of a museum specimen of a yellowwood tree (Podocarps falcatus) yields another record from the southwestern part of the subcontinent. Combined with the limited classic denro-climatologies available in the region these records yield palaeo-rainfall variability in the summer and winter rainfall zones as well as the hyper-arid zone over the last 1000 years. Coherent shifts in all of the records indicate synoptic changes in the westerlies, the inter-tropical convergence zone, and the Congo air boundary. The most substantial rainfall shift takes place at about 1600 CE at the onset of the Little Ice Age. Another distinctive feature of the record is a widespread phenomenon that occurs shortly after 1810 CE that in southern Africa corresponds with a widespread social upheaval known as the Difequane or Mfekane. Large scale forcing of the system includes sea-surface temperatures in the Agulhas Current, the El Nino Southern Oscillation and the Southern Annular Mode. The Little Ice Age and Mfekane climate shifts result from different forcing mechanisms, and the rainfall response in the different regions at these times do not have a fixed phase relationship. This complexity provides a good scenario to test climate models. A first order (wetter versus drier) comparison between each of the tree records and a 1000-year palaeoclimate model simulation for the Little Ice Age and Mfekane transitions demonstrates a generally good correspondence.

  13. The Role of Solar Eclipses in El Nino/La Nina Events

    NASA Astrophysics Data System (ADS)

    Chiu, B. C.

    2005-08-01

    The first hint of the fact that solar eclipses mark the enhanced storms called El Nino or La Nina, came from the article by Robert Allan on analysis of frequencies of these events (2001, perhaps Fourier analysis). One mystery was the cause of a cycle with period 15 to 20 years. But the Saros Series of solar eclipses has a period of 18+ years. Then we had the data from Galapagos Islands for the whole 20th century (Philander 2004). The graph of high and low temperatures indicates El Ninos and La Ninas. A search through charts of solar eclipses for those with good locations for bringing high tides at the Tropics, gave a good picture: those at the eastern coast of the pacific Ocean gave El Ninos, and those at the west gave La Ninas. More than half of the peaks and troughs on the temperature graph can be identified with solar eclipses. We looked more closely at a few events that caused great storms. They are described in J. M. Nash's book, ``El Nino" (2002). The most striking case is that of the 1998 Feb. 22 solar eclipse, which corresponds to the so-called El Nino of 1997-98. In conclusion, I would say that the annual El nino effect is due to the sun's travel between the Tropic of Cancer and Tropic of Capricorn. But the enhanced El Niino/La Nina is due to the coming together of sun and moon in the solar eclipses, which seem to come irregularly.

  14. Westerly Wind Events in the Eastern Indian Ocean as a Precursor to El Nino: A Case Study for the 2002-03 El Nino

    NASA Technical Reports Server (NTRS)

    Curtis, Scott; Adler, Robert F.; Huffman, George J.; Gu, Guojun

    2003-01-01

    This paper extends the work of our previous study, which showed the potential of using precipitation in the eastern Indian Ocean to predict when an El Nino would begin. The paper begins by showing the successful prediction of the 2002-03 El Nino. However, precipitation is really used as a substitute for wind (storms are usually accompanied by heavy wind), because a popular hypothesis is that winds (especially % winds out of the West) stir up the ocean surface in the western Pacific sending currents of warm waters to the east Pacific where El Ninos form. This paper shows that it is typical for storms that produce strong winds in the western Pacific to have traveled from the Indian Ocean. We begin in the Indian Ocean looking at strong bursts of wind over several days. The number of windy days seems to increase in the months prior to El Nino. We examined these relationships in detail for November 2001 to April 2002, before the recent El Nino, using NASA's TRMM and QuikSCAT data. We found in one case that a warming of the eastern Indian Ocean occurred about 25 days before heavy rainfall formed. As the stormed moved eastward it was followed (6 days later) by strong winds out of the West. The entire storm system (and warming of the sea) moved eastward through a small strip of water between Indonesia and Australia, before reaching the western Pacific. Thus, this paper increases our understanding of the physical processes leading to the formation of El Nino.

  15. Patterns and sources of multidecadal oscillations in drought-sensitive tree-ring records from the central and southern Rocky Mountains

    USGS Publications Warehouse

    Gray, S.J.; Betancourt, J.L.; Fastie, C.L.; Jackson, S.T.

    2003-01-01

    Tree-ring records spanning the past seven centuries from the central and southern Rocky Mountains were studied using wavelet analysis to examine multidecadal (>30-70 yr) patterns of drought variation. Fifteen tree-ring series were grouped into five regional composite chronologies based on shared low-frequency behavior. Strong multidecadal phasing of moisture variation was present in all regions during the late 16th century megadrought. Oscillatory modes in the 30-70 yr domain persisted until the mid-19th century in two regions, and wet-dry cycles were apparently synchronous at some sites until the 1950s drought. The 16th/17th century pattern of severe multidecadal drought followed by decades of wet conditions resembles the 1950s drought and post-1976 wet period. The 16th century megadrought, which may have resulted from coupling of a decadal (???20-30 yr) Pacific cool phase with a multidecadal warm phase in the North Atlantic, marked a substantial reorganization of climate in the Rocky Mountain region.

  16. Climatic change and quasi-oscillations in central-west Argentina summer precipitation: main features and coherent behaviour with southern African region

    NASA Astrophysics Data System (ADS)

    Compagnucci, R. H.; Agosta, E. A.; Vargas, W. M.

    Summer rainfall variability (October to March) shows inter-annual to multi-decadal fluctuations over a vast area of subtropical Argentina between 28°S-38°S and 65°W-70°W. Statistically significant oscillations of quasi-period in the bands of 18-21, 6, 4 and 2 years can be found throughout the region and intra-regionally, though the latter are variable. The lower frequency variation produces alternating episodes of above and below normal rainfall each lasting roughly 9 years. This quasi-fluctuation appears to be shared with the summer rainfall region of South Africa and were in-phase related one another until mid-1970s. The teleconnection between both subtropical regions could be generated by an atmospheric-oceanic bridge through the global sea surface temperatures (SSTs), particularly those of the equatorial-tropical South Atlantic. From mid-1970s, the alternating wet and dry pattern has been interrupted in the Argentine region producing the longest, as yet unfinished, wet spell of the century. Thus, a significant change of the long-term variation was observed around 1977 toward lower frequencies. Since then the statistical model that explains more than 89% of the variance of the series until 1977, diverges from the observed values in the 1980s and 1990s. In addition the Yamamoto statistical index, employed to detect a climatic jump, reaches its major value in 1973 at the beginning of the current long wet spell. Therefore the change could be located between 1973 and 1977. Application of the t-student's test gives significant differences of mean values for pre-1977 and post-1977 sub-samples from both individual time series and the regional index series. The spectral analysis also shows changes in energy bands in concordance with the features of the change that occurred from mid-1970s. The change gives rise to a significant increment of more than 20% in average of normal rainfall over the region. Conversely, a drought between mid-1980s and the 1990s has been

  17. Lightning activity with rainfall during El Nino and La Nina events over India

    NASA Astrophysics Data System (ADS)

    Tinmaker, M. I. R.; Aslam, M. Y.; Ghude, Sachin D.; Chate, D. M.

    2016-08-01

    This paper appraises the association of lightning flash count (FC) with rainfall using the satellite-borne Lightning Imaging Sensor's (LIS) data along with gridded rainfall data (0.5o × 0.5o) for Indian summer monsoon seasons over 10 years (2001-2010). During strong El Nino years, 2002 and 2009, FCs were greater in magnitude by about 26.5 % and 37 %, than the long-term average, respectively, while during weak El Nino year (2004), it was more by 8 %. During the same years, the rainfall was deficient by about 10 % than the long-term average. Similarly, a rise in aerosol optical depth (AOD) over its average value (by about 15 % and 20 %) reduces the ratio of rainfall to FC (RLR) by 41 % and 44 % for strong El Nino years 2002 and 2009, respectively, and for weak El Nino year (2004), a 6.5 % rise in AOD lowers the RLR by 20 %. Bowen ratio more by 11 % and 17 % of its average value reduces the RLR by 41 % and 44 % for strong El Nino years 2002 and 2009, respectively, and, also, Bowen ratio higher by 8 % for 2004 declines RLR by 20 %. On the other hand, Bowen ratio less by 9 % and 6 % raises the RLR by 19 % and 56 % for moderate La Nina year (2007) and strong La Nina year (2010), respectively. Results for the daily rainfall, AOD and Bowen ratio over Indian regions, are discussed for strong El Nino and La Nina years. Correlations of FC with AOD and Bowen ratio of 0.66 and 0.71, respectively, while, that of FC with ONI of 0.56 indicates numerous (fewer) break days during El Nino (La Nina) years.

  18. Impact of Indonesian forest fires during the 1997 El Nino on aerosol distribution and clear sky aerosol aradiatikve forcing over the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Parameswaran, K.; Nair, S.; Rejeev, K.

    The El Nino event of 1997-1998 followed by the La Nina in 1998-1999 was the strongest of its kind encountered in the 20t h century. Associated with this event Indonesia experienced severe drought leading to large forest fires. Large aerosol plume from these fires has advected over the Equatorial Indian Ocean region. Development and decay of this plume and its regional transport are studied using aerosol optical depth (AOD) derived from NOAA-14 AVHRR data using the Discrete Ordinate Method along with the tropospheric circulation derived from NCEP/NCAR reanalysis. In the second half of 1997 extensive smoke and haze episodes are observed over the tropical Indian Ocean in the latitude range of 5° N to 10° S. The AOD values at 630nm often exceeded 1.0 near Indonesia and in the southeastern parts of Bay of Bengal. Development of this plume started from September and continued up to the first half of November. During first half of September, the plume was conf ined to the coastal regions of Indonesia and then started developing towards west to reach up to 60°E. Decay of the plume started by the middle of November and subsided almost completely by December. During the development phase this plume showed a consistent increase in AOD from western Indian Ocean to Eastern part of tropical Indian Ocean. This westward transport of aerosols from the Indonesian region was confined to the equatorial latitudes. This was due to the reversal of zonal circulation during the El Nino period leading to large westward wind anomaly in the equatorial Indian Ocean region. Westward propagation of the aerosol plume is arrested near ~60°E because of the large convection and rainfall caused by El Nino in this longitude region. The El Nino related weather and atmospheric dynamics is found to have significantly influenced the regional aerosol distribution over the Indian Ocean. On an average, the diurnal mean clear sky aerosol radiative forcing at top of atmosphere (TOA) is estimated to be

  19. Power oscillator

    DOEpatents

    Gitsevich, Aleksandr

    2001-01-01

    An oscillator includes an amplifier having an input and an output, and an impedance transformation network connected between the input of the amplifier and the output of the amplifier, wherein the impedance transformation network is configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and wherein the impedance transformation network is configured to protect the input of the amplifier from a destructive feedback signal. One example of the oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  20. Raindrop oscillations

    NASA Technical Reports Server (NTRS)

    Beard, K. V.

    1982-01-01

    A model of the change in shape of a raindrop is presented. Raindrops measured by two orthogonal cameras were classified by shape and orientation to determine the nature of the oscillation. A physical model based on potential energy was then developed to study the amplitude variation of oscillating drops. The model results show that oscillations occur about the equilibrium axis ratio, but the time average axis ratio if significantly more spherical for large amplitudes because of asymmetry in the surface potential energy. A generalization of the model to oscillations produced by turbulence yields average axis ratios that are consistent with the camera measurements. The model results for average axis ratios were applied to rainfall studies with a dual polarized radar.

  1. Impact of the 1997-1998 El-Nino of Regional Hydrology

    NASA Technical Reports Server (NTRS)

    Lakshmi, Venkataraman; Susskind, Joel

    1998-01-01

    The 1997-1998 El-Nino brought with it a range of severe local-regional hydrological phenomena. Record high temperatures and extremely dry soil conditions in Texas is an example of this regional effect. The El-Nino and La-Nina change the continental weather patterns considerably. However, connections between continental weather anomalies and regional or local anomalies have not been established to a high degree of confidence. There are several unique features of the recent El-Nino and La-Nina. Due to the recognition of the present El-Nino well in advance, there have been several coupled model studies on global and regional scales. Secondly, there is a near real-time monitoring of the situation using data from satellite sensors, namely, SeaWIFS, TOVS, AVHRR and GOES. Both observations and modeling characterize the large scale features of this El-Nino fairly well. However the connection to the local and regional hydrological phenomenon still needs to be made. This paper will use satellite observations and analysis data to establish a relation between local hydrology and large scale weather patterns. This will be the first step in using satellite data to perform regional hydrological simulations of surface temperature and soil moisture.

  2. The 1997/98 El Nino: A Test for Climate Models

    SciTech Connect

    Lu, R; Dong, B; Cess, R D; Potter, G L

    2004-03-05

    Version 3 of the Hadley Centre Atmospheric Model (HadAM3) has been used to demonstrate one means of comparing a general circulation model with observations for a specific climate perturbation, namely the strong 1997/98 El Nino. This event was characterized by the collapse of the tropical Pacific's Walker circulation, caused by the lack of a zonal sea surface temperature gradient during the El Nino. Relative to normal years, cloud altitudes were lower in the western portion of the Pacific and higher in the eastern portion. HadAM3 likewise produced the observed collapse of the Walker circulation, and it did a reasonable job of reproducing the west/east cloud structure changes. This illustrates that the 1997/98 El Nino serves as a useful means of testing cloud-climate interactions in climate models.

  3. The impact of El Nino on island ecosystems in the gulf of California

    SciTech Connect

    Polis, G.A.; Hurd, S.D.

    1995-09-01

    The El Nino event of 1992-1993 had significant effects on all functional levels of the terrestrial food web of islands in the Gulf of California. These islands are normally very dry; however, during this El Nino event, annual precipitation was nearly five times the median annual precipitation. This caused tremendous increases in plant cover and a significant rise in aerial arthropod abundance. At first, spiders benefited from increased productivity: in 1992, spiders increased to their highest densities in the three years of the study. However, in 1993, despite continued high plant cover and insect prey abundance, spider densities dropped precipitously. This decrease appears to be due to the emergence of numerous parasitoid wasps that formed a hidden trophic influence. Wasps were ineffective at controlling spider densities during dry years due to the absence of their adult food, nectar and pollen from flowering land plants. Abundant flowers during El Nino allowed the wasp population to increase and reproduce successfully.

  4. Holocene history of the El Nino phenomenon as recorded in flood sediments of northern coastal Peru

    SciTech Connect

    Wells, L.E. )

    1990-11-01

    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.

  5. The Leading Modes of Decadal SST Variability in the Southern Ocean in CMIP5 Simulations

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Dommenget, Dietmar

    2016-04-01

    The leading modes of Sea Surface Temperature (SST) variability in the Southern Ocean on decadal and even larger time scales are analysed using Coupled Model Intercomparison Project 5 (CMIP5) model simulations and observations. We compare the modes from the CMIP5 super ensemble against several simple null hypotheses, such as isotropic diffusion (red noise) and a Slab Ocean model, to investigate the sources of decadal variability and the physical processes affecting the characteristics of the modes. The results show three main modes in the Southern Ocean: the first and most dominant mode on interannual to decadal time scales is an annular mode with largest amplitudes in the Pacific, which is strongly related to atmospheric forcing by the Southern Annular Mode (SAM) and El Nino Southern Oscillation (ENSO). The second mode is an almost basin wide monopole pattern, which has pronounced multi-decadal and longer time scales variability. It is firstly inducted by the Wave-3 patterns in the atmosphere and further developed via ocean dynamics. The third mode is a dipole pattern in the southern Pacific that has a pronounced peak in the power spectrum at multi-decadal time scales. All three leading modes found in the CMIP5 super model have distinct patterns and time scale behaviour that can not be explained by simple stochastic null hypothesis, thus all three leading modes are ocean-atmospheric coupled modes and are likely to be substantially influenced or driven by ocean dynamical processes. The mechanism of the basin-wide mode is further analysed based on a series of idealized experiments. The results show that the monopole mode has a two-step power spectrum, with a first spectral increase on interannual time scale and a second higher up level on the multi-decadal to centennial time scales. Ocean dynamics, especially the ocean advection, transport the anomalous signals, connect the entire ocean and lead to the homogeneous-like spatial pattern even under stochastic

  6. Early maritime economy and El Nino events at Quebrada Tacahuay, Peru

    USGS Publications Warehouse

    Keefer, D.K.; DeFrance, Susan D.; Moseley, M.E.; Richardson, J. B.; Satterlee, D.R.; Day-Lewis, A.

    1998-01-01

    The archaeological site of Quebrada Tacahuay, Peru, dates to 12,700 to 12,500 calibrated years before the present (10,770 to 10,530 carbon-14 years before the present). It contains some of the oldest evidence of maritime- based economic activity in the New World. Recovered materials include a hearth, lithic cutting tools and flakes, and abundant processed marine fauna, primarily seabirds and fish. Sediments below and above the occupation layer were probably generated by El Nino events, indicating that El Nino was active during the Pleistocene as well as during the early and middle Holocene.

  7. El Nino impacts on seasonal high ozone levels in the lower troposphere

    SciTech Connect

    Linse, E.W. Jr.

    1996-12-31

    The purpose of this paper is to clarify one difficulty in evaluating the control strategies for ozone concentrations. El Nino years may be mistakenly interpreted as periods having improved air quality because of those control programs. In fact, the differences in atmospheric stability and mixing have made some years especially benign for air quality. Improvements or the effectiveness of control programs can only be effectively reviewed if the meteorological signature is removed. It may not be generally known how large the impacts of the El Nino conditions can be.

  8. Programmable Oscillator

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Lee, Clement G.; Nguyen, Huy

    2011-01-01

    A programmable oscillator is a frequency synthesizer with an output phase that tracks an arbitrary function. An offset, phase-locked loop circuit is used in combination with an error control feedback loop to precisely control the output phase of the oscillator. To down-convert the received signal, several stages of mixing may be employed with the compensation for the time-base distortion of the carrier occurring at any one of those stages. In the Goldstone Solar System Radar (GSSR), the compensation occurs in the mixing from an intermediate frequency (IF), whose value is dependent on the station and band, to a common IF used in the final stage of down-conversion to baseband. The programmable oscillator (PO) is used in the final stage of down-conversion to generate the IF, along with a time-varying phase component that matches the time-base distortion of the carrier, thus removing it from the final down-converted signal.

  9. East Asian Monsoon and EL NIÑO-SOUTHERN Oscillation Activities Since the Mid-Holocene Evidences from Massive Corals in the the Central Vietnamese Coast, Western South China Sea

    NASA Astrophysics Data System (ADS)

    Nguyen, A. D.; Zhao, J.; Feng, Y.; Yu, K.; Gasparon, M.; U-Series Dating Technique Team

    2011-12-01

    The climate of the Vietnamese coast, western South China Sea (SCS), is driven by the annually reversing East Asian Monsoon (EAM) system which is also related to the El Niño-Southern Oscillation (ENSO) through teleconnection. Our understanding of EAM activity and its connection with global climate is not fully established. In this study high resolution Sr/Ca and δ18O records derived from four fossil Porites sp. corals with U-series ages ranging from ~7000 to 1800 years (yrs) were used to characterise the EAM-ENSO activities since the mid-Holocene. The results show that both the summer and winter monsoons were stronger than present ~ 7000 yrs ago, as evidenced by the higher-than-present amplitudes of annual cycles in SST (9.1 °C) and seawater δ18O (1.4%). The strengthened summer monsoon is considered to result from higher Northern Hemispheric insolation during the mid-Holocene, while the enhanced winter monsoon could be attributed to a reduction/shutdown of North Atlantic Meridional Overturning (NAMOC), leading to a prevailing "cold tongue" off the Vietnamese coast, and an amplified east-west SST gradient in the northern SCS. The EAM was weakened ca. 4200 yrs ago, as reflected by the lower amplitude of SST (4.3 °C) and seawater δ18O (0.57%) annual cycles. The downturn of the EAM is correlated in timing with the cold phase or the Bond event of the high-latitude climate, the Neolithic cultural collapse in China, and the strengthened ENSO in the Pacific. After this downturn, the EAM was slightly strengthened ~3600 and 1800 yrs ago as shown by larger amplitudes of SST (~ 5 °C) and seawater δ18O (1.0-1.2%) annual cycles. The enhanced EAM at these times are out of phase with the high-latitude climate, but are consistent with evidence from historical documents in Vietnam and China. The waxing/waning of the EAM appear to match with the waning/waxing of the ENSO intensity throughout the records since the mid-Holocene. The changes in EAM activity were accompanied by

  10. Late Quaternary hydroclimatology of a hyper-arid Andean watershed: Climate change, floods, and hydrologic responses to the El Niño-Southern Oscillation in the Atacama Desert

    NASA Astrophysics Data System (ADS)

    Magilligan, F. J.; Goldstein, P. S.; Fisher, G. B.; Bostick, B. C.; Manners, R. B.

    2008-10-01

    Although certain characteristics of the El Niño-Southern Oscillation (ENSO) are well known on contemporary timescales, less is known about the magnitude-frequency relationships of this atmospheric phenomenon on longer timescales or its relationship to widespread flooding, especially in its core zone along the sub-tropical Andes where La Niña or El Niño episodes control regional hydroclimatology. Using a combination of stratigraphic evidence, geochronologic dating ( 14C and OSL), stable isotope analyses, and water geochemistry along the Rio Moquegua in the northern fringes of the Atacama Desert, we assemble a paleoflood chronology for mainstem and tributary sections for the past ca. 20 ka and ascertain the variation in ENSO frequency and magnitude. Because of the inherent watershed structure and regional hydroclimatology, mid-valley tributaries of the Rio Moquegua only flood during El Niño episodes and thus provide an important proxy of extreme El Niños while mainstem stratigraphy records both La Niña and El Niño episodes. El Niño floods appear to have been pronounced during the Late Pleistocene and up to at least the Younger Dryas (~ 12,000 cal yr BP) while stratigraphic evidence of large El Niño floods is lacking in tributary systems during the Mid-Holocene. Flood stratigraphy in a ~ 2 ka 7 m high terrace along the mainstem indicates an increased frequency and magnitude of large floods between ca. 700 and 1610 AD as compared to the period from ca. 160 BCE to 700 AD with "mega-Niños" occurring ca. 1330 AD and ca. 1650 AD. Water geochemistry and radiocarbon dating indicate that at least two major aquifers exist, with wells and springs in the mid-valley dating to 710 and 3100 14C yr BP, respectively, while water from a spring in the headwaters dates to 10,320 14C yr BP. This range in dates suggests that groundwater flow in the mid-valley is neither fossil water nor exclusively recharged from local precipitation while the older date for headwater sections

  11. How El-Nino affects Ethiopian summer rainfall

    NASA Astrophysics Data System (ADS)

    Gleixner, Stephanie; Keenlyside, Noel; Viste, Ellen

    2016-04-01

    Ethiopian economy and society are strongly dependent on agriculture and therefore rainfall. Reliable forecasts for the rainy seasons are important to allow for agricultural planning and drought preparations. The operational seasonal forecasts for Ethiopia are based on analogue methods relying mainly on sea surface temperature (SST) indices. A better understanding of the physical links between Ethiopian rainfall and SST may help to improve forecasts. The highest rainfall rates are observed in the Kiremt season (defined as JJAS), which is the rainy season in Central and Northwestern Ethiopia. Kiremt rainfall shows clear negative correlation with Central Pacific SST, linking dry Ethiopian summers with ENSO-like warm SST anomalies. We use the atmosphere general circulation model Echam5.3 to investigate the physical link between Pacific SST anomalies and Kiremt rainfall. We compare a historical simulation with a T106 horizontal resolution (~ 1.125°), forced with reconstructed SST data, to gauge-based rainfall observations for the time period of 1961 to 2009. Composite analysis for model and observations show warm SST anomalies in the Central Pacific and a corresponding large-scale circulation anomaly with subsidence over Ethiopia in dry Kiremt seasons. Horizontal wind fields show a slow-down of the whole Indian monsoon system with a weaker Tropical Easterly Jet (TEJ) and a weaker East African Low-Level Jet (EALLJ) in these summers. We conducted a sensitivity experiment with El Nino like SST anomalies in the Central Pacific with the same Echam version. Its results show that warm Pacific SST anomalies cause dry summer conditions over Ethiopia. While the large-scale subsidence over East Africa is present in the experiment, there is no significant weakening of the Indian monsoon system. We rather find an anomalous circulation cell over Northern Africa with westerlies at 100-200 hPa and easterlies below 500 hPa. The anomalous easterly flow in the lower and middle

  12. Climate network reveals the effect of deep equatorial Pacific ridge on El-Nino

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Gozolchiani, Avi; Ashkenazy, Yosef; Havlin, Shlomo

    2015-04-01

    In spite of the intensive research of El-Nino, one of the most influential climate phenomenon on annual time scales, the origin of the emergence and dissipation locations of waves associated with El-Nino are still not settled. Here we develop a novel method that relies on network theory to quantify the properties of tropical El-Nino related Kelvin and Rossby oceanic waves, based on sea-surface height altimetry data. The climate network exhibits well-defined locations of the waves' initiation and termination and is used to quantify successfully the waves' characteristics. It is found that the location of the hubs of the out-going and in-coming links in this climate network are in concert with the locations of the westerly wind bursts (WWBs) and the deep Pacific (Kiribati) ridge respectively. This suggests that El-Nino dynamics is influenced by the very deep (~2 km) Kiribati ridge; this idea is supported by simulations of an oceanic general circulation model.

  13. Tropical Cyclone Activities in the WNP Regions associated with CT/WP El Nino

    NASA Astrophysics Data System (ADS)

    Kim, J. S.; Moon, Y. I.; Choi, J. H.

    2015-12-01

    Tropical cyclones (TCs) occurring in the Western North Pacific (WNP) serve as a hydrometeorological factor that affects change in the precipitation pattern during the summer in East Asia. While the influence of El Niño on WNP TCs has been investigated extensively, relatively little research has been conducted to quantify the impacts of CT/WP El Niño on Korea-affected TC activities and regional variability in TC-induced precipitation over the Korean peninsula. The result of analyzing the large-scale environments associated with CT/WP El Nino was revealed that atmosphere-ocean environment of large-scale in WP El Nino years offers better conditions for typhoon development more than that in CT El Nino years. In particular, comparison of the SST, a direct heat source of typhoon, with the atmosphere environment showed a remarkable difference. The result of this study relies on short observations and samples relatively, but it was found that KP-affected TC activities and changes in rainfalls of TCs through CT/WP El Nino was sensitively occurred, and it is expected to reduce the damages caused by TCs and response properly to each basin and be used to establish the ways of adjustment in a changing climate.

  14. An application of LIDAR to analyses of El Nino erosion in the Netarts littoral cell, Oregon

    USGS Publications Warehouse

    Revell, D.L.; Komar, P.D.; Sallenger, A.H.

    2002-01-01

    El Nin??o produces coastal and beach erosion along the West Coast of the USA by elevating mean water levels so that tides are significantly higher than predicted, and by altering the paths of storms that generate large waves. In the past it has been difficult to adequately document the erosion impacts since they are so widespread. This difficulty has been solved through the application of LIDAR, which uses a scanning laser mounted in a small aircraft to rapidly and accurately survey beach elevations. This study uses LIDAR to document the beach changes and shoreline erosion that occurred during the 1997-98 El Nin??o within the Netarts Littoral Cell on the Oregon coast, a 14-km long "pocket beach" between large rocky headlands. The LIDAR surveys demonstrate that sand generally migrated northward within the cell due to the southwest approach of the El Nin??o storm waves, but there was a complex pattern of beach-elevation change due to the superposition of eroded rip-current embayments. The greatest beach erosion occurred near the south end of the cell, where it impacted Cape Lookout State Park, and to the north of the inlet to Netarts Bay where it threatened The Capes, a development of condominiums located on a high bluff. In both cases the LIDAR data proved to be extremely useful in quantifying the erosion, and in providing a better understanding of the erosion processes that occur during an El Nin??o.

  15. Effect of the 1982-1983 El Nino on bivalve mollusks. [Chione subrugosa; Trachycardium procerum

    SciTech Connect

    Rollins, H.B.

    1986-01-01

    Mollusks from the peruvian coast were studied in 1984 for shell patterns indicative of stress caused by the 1982-1983 El Nino. Analysis of growth increments showed physiological stress, and there was evidence (from interviews with fishermen) of sever mortality for some species.

  16. Eastern equatorial Pacific Ocean T-S variations with El Nino

    NASA Technical Reports Server (NTRS)

    Wang, O.; Fukumori, I.; Lee, T.; Johnson, G. C.

    2004-01-01

    Temperature-Salinity (T-S) relationship variability in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5 degrees S ??degrees N, 150 degrees W ?? degrees W) over the last two decades is investigated using observational data and model simulation.

  17. Project Profile: Ninos Especiales Special Children Program. A Culturally Sensitive Early Intervention Model.

    ERIC Educational Resources Information Center

    Bruder, Mary Beth; And Others

    1991-01-01

    Described is the Ninos Especiales Program, a 3-year demonstration project in Hartford, Connecticut, which provided culturally sensitive early intervention services to 34 infants with severe disabilities and their families of Puerto Rican heritage. Included is information on program philosophy, services, evaluation, and participating families.…

  18. The Rise and Fall of Andean Empires: El Nino History Lessons.

    ERIC Educational Resources Information Center

    Wright, Kenneth R.

    2000-01-01

    Provides information on El Nino and the methods for investigating ancient climate record. Traces the rise and fall of the Andean empires focusing on the climatic forces that each empire (Tiwanaku, Wari, Moche, and Inca) endured. States that modern societies should learn from the experiences of these ancient civilizations. (CMK)

  19. A Remote Sensing Class Exercise To Study the Effects of "El Nino" in South America.

    ERIC Educational Resources Information Center

    Moxey, Lucas Eduardo

    2002-01-01

    Describes an undergraduate physical science laboratory course exercising the utilization of satellite imagery for studying the floods that resulted in the Parana River region in South America during El Nino (1997-1998), and examines vegetation cover and spectral profiles from the study area in order to further understand and assess the changes…

  20. Statistical Aspects of ENSO Events (1950-1997) and the El Nino-Atlantic Intense Hurricane Activity Relationship

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1998-01-01

    On the basis of Trenberth's quantitative definition for marking the occurrence of an El Nino (or La Nina), one can precisely identify by month and year the starts and ends of some 15 El Nino and 10 La Nina events during the interval of 1950-1997, an interval corresponding to the most reliable for cataloging intense hurricane activity in the Atlantic basin (i.e., those of category 3-5 on the Saffir-Simpson hurricane scale). The main purpose of this investigation is primarily two-fold: First, the statistical aspects of these identified extremes and the intervening periods between them (called "interludes") are examined and, second, the statistics of the seasonal frequency of intense hurricanes in comparison to the extremes and interludes are determined. This study clearly demonstrates that of the last 48 hurricane seasons, 20 (42 percent) can be described as being "El Nino-related" (i.e., an El Nino was in progress during all, or part, of the yearly hurricane season--June-November), 13 (27 percent) as "La Nina-related" (i.e., a La Nina was in progress during all, or part, of the yearly hurricane season), and 15 (31 percent) as "interlude-related" (i.e., neither an El Nino nor a La Nina was in progress during any portion of the yearly hurricane season). Combining the latter two subgroups into a single grouping called "non-El Nino-related" seasons, one finds that they have had a mean frequency of intense hurricanes measuring 2.8 events per season, while the El Nino-related seasons have had a mean frequency of intense hurricanes measuring 1.3 events per season, where the observed difference in the means is inferred to be statistically important at the 99.8-percent level of confidence. Therefore, as previously shown more than a decade ago using a different data set, there undeniably exists an El Nino-Atlantic hurricane activity relationship, one which also extends to the class of intense hurricanes. During the interval of 1950-1997, fewer intense hurricanes occurred

  1. Midlatitude atmosphere-ocean interaction during El Nino. Part II. The northern hemisphere atmosphere

    SciTech Connect

    Alexander, M.A. )

    1992-09-01

    The influence of midlatitude air-sea interaction on the atmospheric anomalies associated with El Nino is investigated by coupling the Community Climate Model to a mixed-layer ocean model in the North Pacific. Prescribed El Nino conditions, warm sea surface temperatures (SST) in the tropical Pacific, cause a southward displacement and strengthening of the Aleutian Low. This results in enhanced (reduced) advection of cold Asian air over the west-central (northwest) Pacific and northward advection of warm air over the eastern Pacific. Allowing air-sea feedback in the North Pacific slightly modified the El Nino-induced near-surface wind, air temperature, and precipitation anomalies. The anomalous cyclonic circulation over the North Pacific is more concentric and shifted slightly to the east in the coupled simulations. Air-sea feedback also damped the air temperature anomalies over most of the North Pacific and reduced the precipitation rate above the cold SST anomaly that develops in the central Pacific. The simulated North Pacific SST anomalies and the resulting Northern Hemisphere atmospheric anomalies are roughly one-third as large as those related to the prescribed El Nino conditions in a composite of five cases. The composite geopotential height anomalies associated with changes in the North Pacific SSTs have an equivalent barotropic structure and range from -65 m to 50 m at the 200-mb level. Including air-sea feedback in the North Pacific tended to damp the atmospheric anomalies caused by the prescribed El Nino conditions in the tropical Pacific. As a result, the zonally elongated geopotential height anomalies over the West Pacific are reduced and shifted to the east. However, the atmospheric changes associated with the North Pacific SST anomalies vary widely among the five cases.

  2. STABILIZED OSCILLATOR

    DOEpatents

    Jessen, P.L.; Price, H.J.

    1958-03-18

    This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

  3. Antiperiodic oscillations

    PubMed Central

    Freire, Joana G.; Cabeza, Cecilia; Marti, Arturo; Pöschel, Thorsten; Gallas, Jason A. C.

    2013-01-01

    The investigation of regular and irregular patterns in nonlinear oscillators is an outstanding problem in physics and in all natural sciences. In general, regularity is understood as tantamount to periodicity. However, there is now a flurry of works proving the existence of “antiperiodicity”, an unfamiliar type of regularity. Here we report the experimental observation and numerical corroboration of antiperiodic oscillations. In contrast to the isolated solutions presently known, we report infinite hierarchies of antiperiodic waveforms that can be tuned continuously and that form wide spiral-shaped stability phases in the control parameter plane. The waveform complexity increases towards the focal point common to all spirals, a key hub interconnecting them all. PMID:23739041

  4. FEL Oscillators

    SciTech Connect

    George Neil

    2003-05-12

    FEL Oscillators have been around since 1977 providing not only a test bed for the physics of Free Electron Lasers and electron/photon interactions but as a workhorse of scientific research. More than 30 FEL oscillators are presently operating around the world spanning a wavelength range from the mm region to the ultraviolet using DC and rf linear accelerators and storage rings as electron sources. The characteristics that have driven the development of these sources are the desire for high peak and average power, high micropulse energies, wavelength tunability, timing flexibility, and wavelengths that are unavailable from more conventional laser sources. Substantial user programs have been performed using such sources encompassing medicine, biology, solid state research, atomic and molecular physics, effects of non-linear fields, surface science, polymer science, pulsed laser vapor deposition, to name just a few.

  5. Neutrino oscillations.

    PubMed

    Thomson, Mark

    2002-05-15

    The wave theory of light, and in particular the principle of interference, was formulated by Thomas Young in 1801. In the 20th century, the principle of interference was extended to the quantum mechanical wave functions describing matter. The phenomenon of quantum mechanical interference of different neutrino states, neutrino oscillations, has provided one of the most exciting developments in high energy particle physics of the last decade. Observations of the flavour oscillations of neutrinos produced by distant sources, such as from the core of the Sun, provide compelling evidence that neutrinos have mass. This article describes the main features and the most significant experimental observations of this unusual application of the principle of interference.

  6. Spike oscillations

    NASA Astrophysics Data System (ADS)

    Heinzle, J. Mark; Uggla, Claes; Lim, Woei Chet

    2012-11-01

    According to Belinskiǐ, Khalatnikov and Lifshitz (BKL), a generic spacelike singularity is characterized by asymptotic locality: Asymptotically, toward the singularity, each spatial point evolves independently from its neighbors, in an oscillatory manner that is represented by a sequence of Bianchi type I and II vacuum models. Recent investigations support this conjecture but with a modification: Apart from local BKL behavior there also exists formation of spatial structures (“spikes”) at, and in the neighborhood of, certain spatial surfaces that break asymptotic locality; the complete description of a generic spacelike singularity involves spike oscillations, which are described by sequences of Bianchi type I and certain inhomogeneous vacuum models. In this paper we describe how BKL and spike oscillations arise from concatenations of exact solutions in a Hubble-normalized state space setting, suggesting the existence of hidden symmetries and showing that the results of BKL are part of a greater picture.

  7. Solar Oscillations

    NASA Technical Reports Server (NTRS)

    Duvall, Thomas

    2004-01-01

    Oscillations were first detected in the solar photosphere in 1962 by Leighton and students. In 1970 it was calculated that these oscillations, with a period near five minutes, were the manifestations of acoustic waves trapped in the interior. The subsequent measurements of the frequencies of global oscillation modes from the spatio-temporal power spectrum of the waves made possible the refinement of solar interior models. Over the years, increased understanding of the nuclear reaction rates, the opacity, the equation of state, convection, and gravitational settling have resulted. Mass flows shift the frequencies of modes leading to very accurate measurements of the interior rotation as a function of radius and latitude. In recent years, analogues of terrestrial seismology have led to a tomography of the interior, including measurements of global north-south flows and flow and wave speed measurements below features such as sunspots. The future of helioseismology seems bright with the approval of NASA's Solar Dynamics Observatory mission, to be launched in 2008.

  8. ENSO diversity as a result of the equatorial recharge oscillator interacting with noise

    NASA Astrophysics Data System (ADS)

    Yu, Yanshan; Dommenget, Dietmar; Frauen, Claudia; Wales, Scott; Wang, Gang; Tyrrell, Nicholas

    2014-05-01

    In this study we address the cause of the diversity in the spatial structure of ENSO variability. We explore the idea that ENSO is a fixed pattern of variability following the recharge oscillator mechanism, which interacts with the atmospheric weather noise. We present a simulation in which a fixed pattern recharge oscillator model is coupled to an AGCM with a slab ocean model. The model is capable in simulating the leading modes of SST variability in the tropical Pacific with better agreement to the observations than most coupled GCMs in the CMIP database. The ENSO amplitude, seasonality, period, the structure of the leading pattern and its variations in an eastern and central Pacific pattern, i.e. EP El Nino and CP El Nino, are simulated very well by including the interaction of recharge oscillator and slab noise in our model. Furthermore, we find that the observed 1st EOF mode might result from the interaction between slab ocean noise and recharge oscillator which is believed to be only activated in a narrow band along the equator.

  9. Sea-cliff erosion as a function of beach changes and extreme wave runup during the 1997-1998 El Nino

    USGS Publications Warehouse

    Sallenger, A.H.; Krabill, W.; Brock, J.; Swift, R.; Manizade, S.; Stockdon, H.

    2002-01-01

    Over time scales of hundreds to thousands of years, the net longshore sand transport direction along the central California coast has been driven to the south by North Pacific winter swell. In contrast, during the El Nin??o winter of 1997-1998, comparisons of before and after airborne lidar surveys showed sand was transported from south to north and accumulated on the south sides of resistant headlands bordering pocket beaches. This resulted in significant beach erosion at the south ends of pocket beaches and deposition in the north ends. Coincident with the south-to-north redistribution of sand, shoreline morphology became prominently cuspate with longshore wavelengths of 400-700 m. The width and elevation of beaches were least where maximum shoreline erosion occurred, preferentially exposing cliffs to wave attack. The resulting erosional hotspots typically were located in the embayments of giant cusps in the southern end of the pocket beaches. The observed magnitude of sea cliff retreat, which reached 14 m, varied with the number of hours that extreme wave runup exceeded certain thresholds representing the protective capacity of the beach during the El Nin??o winter. A threshold representing the width of the beach performed better than a threshold representing the elevation of the beach. The magnitude of cliff erosion can be scaled using a simple model based on the cross-shore distance that extreme wave runup exceeded the pre-winter cliff position. Cliff erosion appears to be a balance between terrestrial mass wasting processes, which tend to decrease the cliff slope, and wave attack, which removes debris and erodes the cliff base increasing the cliff slope. ?? 2002 Elsevier Science B.V. All rights reserved.

  10. Cloud Structure Anomalies Over the Tropical Pacific During the 1997/98 El Nino

    NASA Technical Reports Server (NTRS)

    Cess, Robert D.; Zhang, Minghua; Wang, Pi-Huan; Wielicki, Bruce A.

    2001-01-01

    Satellite measurements of both cloud vertical structure and cloud-radiative forcing have been used to show that during the strong 1997/98 El Nino there was a substantial change in cloud vertical structure over the tropical Pacific Ocean. Relative to normal years, cloud altitudes were lower in the western portion of the Pacific and higher in the eastern portion. The reason for these redistributions was a collapse of the Walker circulation and enhanced large-scale upward motion over the eastern Pacific, both caused by the lack of a zonal sea surface temperature gradient during El Nino. It is proposed that these cloud structure changes, which significantly impact satellite measurements of the tropical Pacific's radiation budget, would serve as one useful means of testing cloud-climate interactions in climate models.

  11. Sea-cliff erosion at Pacifica, California caused by 1997/98 El Nino storms

    USGS Publications Warehouse

    Snell, Charles B.; Lajoie, K.R.; Medley, Edward W.

    2000-01-01

    Twelve homes were constructed in 1949 at the top of a sea cliff along Esplanade Drive in the City of Pacifica, located on the northern coast of San Mateo County, California. During the heavy storms of the 1997/98 El Nino winter, a severe episode of cliff retreat undermined seven homes and threatened three others. The geologic, tide, wave, rainfall and wind data were analyzed to determine the causes of this erosion events.

  12. On the dynamical basis for the Asian summer monsoon rainfall-El Nino relationship

    SciTech Connect

    Nigam, S.

    1994-11-01

    The dynamical basis for the Asian summer monsoon rainfall-El Nino linkage is explored through diagnostic calculations with a linear steady-state multilayer primitive equation model. The contrasting monsoon circulation during recent El Nino (1987) and La Nina (1988) years is first simulated using orography and the residually diagnosed heating (from the thermodynamic equation and the uninitialized, but mass-balanced, ECMWF analysis) as forcings, and then analyzed to provide insight into the importance of various regional forcings, such as the El Nino-related heating anomalies over the tropical Indian and Pacific Oceans. The striking simulation of the June-August (1987-1988) near-surface and upper-air tropical circulation anomalies indicates that tropical anomaly dynamics during northern summer is essentially linear even at the 150-mb level. The vertical structure of the residually diagnosed heating anomaly that contributes to this striking simulation differs significantly from the specified canonical vertical structure (used in generating 3D heating from OLR/precipitation distributions) near the tropical tropopause. The dynamical diagnostic analysis of the anomalous circulation during 1987 and 1988 March-May and June-August periods shows the orographically forced circulation anomaly (due to changes in the zonally averaged basic-state flow) to be quite dominant in modulating the low-level moisture-flux convergence and hence monsoon rainfall over Indochina. The El Nino-related persistent (spring-to-summer) heating anomalies over the tropical Pacific and Indian Ocean basins, on the other hand, mostly regulate the low-level westerly monsoon flow intensity over equatorial Africa and the northern Indian Ocean and, thereby, the large-scale moisture flux into Sahel and Indochina. 38 refs., 12 figs.

  13. The nonlinear equatorial Kelvin wave. [in coastal currents of El Nino and Gulf of Guinea

    NASA Technical Reports Server (NTRS)

    Boyd, J. P.

    1980-01-01

    Using the method of strained coordinates, a uniformly valid approximation to the nonlinear equatorial Kelvin wave is derived. It is shown that nonlinear effects are negligible for the Kelvin waves associated with the Gulf of Guinea upwelling. The Kelvin waves involved in El Nino, however, are significantly distorted both in shape and speed. The leading edge is smoothed and expanded rather than steepened, but the trailing edge will form sharp fronts and eventually break.

  14. Soil CO2 Flux in the Amargosa Desert, Nevada, during El Nino 1998 and La Nina 1999

    USGS Publications Warehouse

    Riggs, Alan C.; Stannard, David I.; Maestas, Florentino B.; Karlinger, Michael R.; Striegl, Robert G.

    2009-01-01

    Mean annual soil CO2 fluxes from normally bare mineral soil in the Amargosa Desert in southern Nevada, United States, measured with clear and opaque soil CO2-flux chambers (autochambers) were small - <5 millimoles per square meter per day - during both El Nino 1998 and La Nina 1999. The 1998 opaque-chamber flux exceeded 1999 opaque-chamber flux by an order of magnitude, whereas the 1998 clear-chamber flux exceeded 1999 clear-chamber flux by less than a factor of two. These data suggest that above-normal soil moisture stimulated increased metabolic activity, but that much of the extra CO2 produced was recaptured by plants. Fluxes from warm moist soil were the largest sustained fluxes measured, and their hourly pattern is consistent with enhanced soil metabolic activity at some depth in the soil and photosynthetic uptake of a substantial portion of the CO2 released. Flux from cool moist soil was smaller than flux from warm moist soil. Flux from hot dry soil was intermediate between warm-moist and cool-moist fluxes, and clear-chamber flux was more than double the opaque-chamber flux, apparently due to a chamber artifact stemming from a thermally controlled CO2 reservoir near the soil surface. There was no demonstrable metabolic contribution to the very small flux from cool dry soil, which was dominated by diffusive up-flux of CO2 from the water table and temperature-controlled CO2-reservoir up- and down-fluxes. These flux patterns suggest that transfer of CO2 across the land surface is a complex process that is difficult to accurately measure.

  15. Oscillator detector

    SciTech Connect

    Potter, B.M.

    1980-05-13

    An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.

  16. Analysis of rainfall over northern Peru during El Nino: A PCDS application

    NASA Technical Reports Server (NTRS)

    Goldberg, R.; Tisnado, G.

    1986-01-01

    In an examination of GOES satellite data during the 1982 through 1983 El Nino period, the appearance of lee wave cloud patterns was revealed. A correlation was hypothesized relating an anomalous easterly flow across the Andes with the appearance of these wave patterns and with the subsequent onset of intense rainfall. The cloud patterns are belived to be associated with the El Nino period and could be viewed as precursors to significant changes in weather patterns. The ultimate goal of the researchers will be the ability to predict occurrences of rainstorms associated with the appearance of lee waves and related cloud patterns as harbingers of destruction caused by flooding, huaycos, and other catastrophic consequences of heavy and abnormal rainfall. Rainfall data from about 70 stations in northern Peru from 1980 through 1984 were formatted to be utilized within the Pilot Climate Data System (PCDS). This time period includes the 1982 through 1983 El Nino period. As an example of the approach, a well-pronounced lee wave pattern was shown from a GOES satellite image of April 4, 1983. The ground truth data were then displayed via the PCDS to graphically demonstrate the increase in intensity and areal distribution of rainfall in the northern Peruvian area in the next 4 to 5 days.

  17. Midlatitude atmosphere-ocean interaction during El Nino. Part I. The north Pacific ocean

    SciTech Connect

    Alexander, M.A. )

    1992-09-01

    Atmosphere-ocean modeling experiments are used to investigate the formation of sea surface temperature (SST) anomalies in the North Pacific Ocean during fall and winter of the El Nino year. Experiments in which the NCAR Community Climate Model (CCM) surface fields are used to force a mixed-layer ocean model in the North Pacific (no air-sea feedback) are compared to simulations in which the CCM and North Pacific Ocean model are coupled. Anomalies in the atmosphere and the North Pacific Ocean during El Nino are obtained from the difference between simulations with and without prescribed warm SST anomalies in the tropical Pacific. In both the forced and coupled experiments, the anomaly pattern resembles a composite of the actual SST anomaly field during El Nino: warm SSTs develop along the coast of North America and cold SSTs form in the central Pacific. In the coupled simulations, air-sea interaction results in a 25% to 50% reduction in the magnitude of the SST and mixed-layer depth anomalies, resulting in more realistic SST fields. Coupling also decreases the SST anomaly variance; as a result, the anomaly centers remain statistically significant even though the magnitude of the anomalies is reduced. Three additional sensitivity studies indicate that air-sea feedback and entrainment act to damp SST anomalies while Ekman pumping has a negligible effect on mixed-layer depth and SST anomalies in midatitudes.

  18. Impact of El Nino and La Nina on the meteorological elements

    NASA Astrophysics Data System (ADS)

    Jaiswal, Rajasri Sen; Subitha, T.; Samuthra, G.; Punitha, M.; Vinotha, R.

    2016-05-01

    The El Nino and La Nina have been found to influence the weather at a remote place. In this paper, the authors investigate the impact of El Nino & La Nina on the surface temperature and rainfall over few selected locations in India and abroad. The study shows that the ENSO affects the surface rainfall; however, the impact is not the same over all the locations. In order to find out whether such influence is latitude sensitive, the study has been performed over locations located at different latitudes and at a fixed longitude. To check if the El Nino/La Nina leaves any impressions on the upper air meteorological elements, the cloud liquid water (CLW), precipitation water (PW), latent heat (LH), freezing level height (HFL) and the bright band height (BBH) over a few locations have been studied from the Earth's surface up to a height of 18 km above. The CLW, PW and LH values have been obtained from the data product 2A12 of the Tropical Microwave Imager (TMI) onboard the Tropical Rainfall Measuring Satellite (TRMM), while that of the BBH and the HFL are obtained from the data product 2A23 of the precipitation radar (PR) onboard the TRMM.

  19. Microwave Limb Sounder/El Nino Watch - Water Vapor Measurement, October, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image shows atmospheric water vapor in Earth's upper troposphere, about 10 kilometers (6 miles) above the surface, as measured by the Microwave Limb Sounder (MLS) instrument flying aboard the Upper Atmosphere Research Satellite. These data collected in early October 1997 indicate the presence of El Nino by showing a shift of humidity from west to east (blue and red areas) along the equatorial Pacific Ocean. El Nino is the term used when the warmest equatorial Pacific Ocean water is displaced toward the east. The areas of high atmospheric moisture correspond to areas of very warm ocean water. Warmer water evaporates at a higher rate and the resulting warm moist air then rises, forming tall cloud towers. In the tropics, the warm water and the resulting tall cloud towers typically produce large amounts of rain. The MLS instrument, developed at NASA's Jet Propulsion Laboratory, measures humidity at the top of these clouds, which are very moist. This rain is now occurring in the eastern Pacific Ocean and has left Indonesia (deep blue region) unusually dry, resulting in the current drought in that region. This image also shows moisture moving north into Mexico, an effect of several hurricanes spawned by the warm waters of El Nino.

  20. TOPEX/El Nino Watch - La Nina Conditions Likely to Prevail, October 10, 1999

    NASA Technical Reports Server (NTRS)

    1999-01-01

    A repeat of last year's mild La Nina conditions -- with a stormy winter in the Pacific Northwest and a dry winter in the southwestern United States -- will be the likely outcome of sea-surface heights observed by NASA's TOPEX/Poseidon satellite, scientists say.

    TOPEX/Poseidon has detected lower than normal sea-surface heights in the eastern North Pacific and unusually high sea-surface heights in the western and mid-latitude Pacific. The height of the sea surface over a given area is an indicator of ocean temperature and other factors that influence climate.

    The latest measurements, taken during a 10-day data cycle October 5-15, are available at http://www.jpl.nasa.gov/elnino . Sea-surface height is shown relative to normal (green) and reveals cooler water (blue and purple) measuring about 14 centimeters (6 inches) lower in the eastern North Pacific, from the Gulf of Alaska to central Alaska, and along the equator. The cooling trend sets the stage for another La Nina this winter.

    'A mirror image of that oceanic profile prevails in the western and mid-latitude Pacific Ocean, where higher than normal sea-surface heights (red and white) are currently about 20 centimeters or 8 inches. Unusually warm temperatures (shown in red and white) have persisted and topped last year's temperatures,' said Dr. William Patzert, an oceanographer at NASA's Jet Propulsion Laboratory, Pasadena, CA.

    'These unbalanced conditions will undoubtedly exert a very strong influence on climate over North America this fall and winter,' Patzert said. 'Our profile of high sea-surface heights and warm temperatures in the western Pacific Ocean contrasts with low sea-surface heights and cool conditions in the eastern and equatorial Pacific. Those conditions will have a powerful impact on the weather system delivering jet streams out of the North Pacific.'

    Conditions are ripe for a stormy, wet winter in the Pacific Northwest and a dry, relatively rainless winter in Southern California and

  1. TOPEX/El Nino Watch - 'Double Peak' Pattern Complete, Dec, 1, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Dec. 1, 1997. The volume of the warm water related to El Nino has receded to about the level it was in early September. Oceanographers note that this El Nino has just completed a classic 'double peak' pattern in the eastern Pacific with the first peak in sea level occurring in July and the second peak in October. This pattern is very similar to what was observed during the 1982-83 El Nino, although at that time the double peaks occurred in January and April 1983. After the appearance of the double peaks in 1982-83, the sea level then began falling back to normal levels within a few months. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the

  2. North Atlantic Basin Tropical Cyclone Activity in Relation to Temperature and Decadal- Length Oscillation Patterns

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2009-01-01

    Yearly frequencies of North Atlantic basin tropical cyclones, their locations of origin, peak wind speeds, average peak wind speeds, lowest pressures, and average lowest pressures for the interval 1950-2008 are examined. The effects of El Nino and La Nina on the tropical cyclone parametric values are investigated. Yearly and 10-year moving average (10-yma) values of tropical cyclone parameters are compared against those of temperature and decadal-length oscillation, employing both linear and bi-variate analysis, and first differences in the 10-yma are determined. Discussion of the 2009 North Atlantic basin hurricane season, updating earlier results, is given.

  3. The difference of tropical Indian Ocean warming, PJ-pattern, oceanic and atmospheric changes around Philippines Sea and East Asia after two types of El Nino

    NASA Astrophysics Data System (ADS)

    Hasegawa, T.; Kubota, H.; Kosaka, Y.; Xie, S.

    2012-12-01

    At the termination year of El Nino event, the tropical Indian Ocean (TIO) SST warming appears in boreal summer accompanying with anomalous anticyclone over the Philippine Sea with negative phase of Pacific-Japan (PJ) teleconnection pattern (i.e., low pressure centered east of Japan) and is related to the increase of mei-yu-baiu rainfall over East Asia. Previous studies showed that above oceanic and atmospheric process becomes dominant after the climate regime shift of 1977. It was reported that there are two types of El Nino: one is strong El Nino type having large positive SST anomalies in the central-to-eastern Pacific (e.g., 1997/98 El Nino), and the other is weak El Nino type that shows weak/medium positive SST anomalies centered at the International Date Line (or El Nino Modoki). At present it is unclear whether or not TIO SST warming and following atmospheric and oceanic variations show different feature between the two El Nino types. The purpose of this study is to explore the differences in TIO SST warming and also related climate variations in the boreal summer of the El Nino termination year between the two El Nino types after the 1977 regime shift. The composite analysis of SST shows that strong El Nino type (occurring in 1982, 1986, and 1998) shows TIO SST warming in boreal summer of El Nino termination year. On the other hand, weak type (occurring in 1991, 1994, 2002, 2004, and 2006) shows other SST anomaly pattern in IO: weak positive SST anomalies and negative SST anomalies appear in the north IO and the south IO respectively. Also, strong type shows clear negative PJ pattern and negative air temperature anomalies especially in the north Japan. Weak type does not show such tendency. In summer of the termination year of weak type El Nino events except for 2002/03 El Nino, anomalies of air-temperature in north Japan are positive or almost zero, in contrast to strong type. The present study indicates that strong type shows clear signals of TIO SST

  4. Gravity and Rossby Wave Signatures in the Tropical Troposphere and Lower Stratosphere Based on Southern Hemisphere Additional Ozonesondes (SHADOZ), 1998-2007

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Allen, Amber L.; Lee, Sukyoung; Miller, Sonya K.; Witte, Jacquelyn C.

    2011-01-01

    Prior investigations attempted to determine the relative influence of advection and convective processes on ozone and water vapor distributions in the tropical tropopause layer (TTL) through analyses of tracers, related physical parameters (e.g., outgoing long-wave radiation, precipitable water, and temperature), or with models. In this study, stable laminae in Southern Hemisphere Additional Ozonesonde Network (SHADOZ) ozone profIles from 1998 to 2007 are interpreted in terms of gravity waves (GW) or Rossby waves (RW) that are identified with vertical and quasi-horizontal displacements, respectively. Using the method of Pierce and Grant (1998) as applied by Thompson et al. (2007a, 2007b, 2010, 2011), amplitudes and frequencies in ozone laminae are compared among representative SHADOZ sites over Africa and the Pacific, Indian, and Atlantic oceans. GW signals maximize in the TTL and lower stratosphere. Depending on site and season, GW are identified in up to 90% of the soundings. GW are most prevalent over the Pacific and eastern Indian oceans, a distribution consistent with vertically propagating equatorial Kelvin waves. Ozone laminae from RW occur more often below the tropical tropopause and with lower frequency 20%). Gravity wave and Rossby wave indices (GWI, RWI) are formulated to facilitate analysis of interannual variability of wave signatures among sites. GWI is positively correlated with a standard ENSO (El Nino-Southern Oscillation) index over American Samoa (14degS, 171degW) and negatively correlated at Watukosek, Java (7.5degS, 114degE), Kuala Lumpur (3degN, 102degE), and Ascension Island (80degS, 15degW). Generally, the responses of GW and RW to ENSO are consistent with prior studies.

  5. Texas floods, El Nino and climate change - 2015

    NASA Astrophysics Data System (ADS)

    Wang, S. Y.; Huang, W. R.; Hsu, H. H.; Gillies, R. R.

    2015-12-01

    The climate anomalies leading to the May 2015 floods in Texas and Oklahoma were analyzed in the context of El Niño teleconnection in a warmer climate. El Niño tends to increase late-spring precipitation in the southern Great Plains and this effect has intensified since 1980. There was a detectable effect of anthropogenic global warming in the physical processes that caused the persistent precipitation in May of 2015: Warming in the tropical Pacific acted to strengthen the teleconnection towards North America, modification of zonal wave-5 circulation that deepened the anomalous trough to the west of Texas, and an enhanced Great Plains low-level southerlies increasing moisture supply from the Gulf of Mexico. Attribution analysis using the CMIP5 single-forcing experiments and the CESM Large Ensemble Project indicated a significant increase in the El Niño- induced precipitation anomalies over Texas and Oklahoma when increases in the anthropogenic greenhouse gases were taken into account.

  6. Variation of Surface Air Temperature in Relation to El Nino and Cataclysmic Volcanic Eruptions, 1796-1882

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1999-01-01

    During the contemporaneous interval of 1796-1882 a number of significant decreases in temperature are found in the records of Central England and Northern Ireland. These decreases appear to be related to the occurrences of El Nino and/or cataclysmic volcanic eruptions. For example, a composite of residual temperatures of the Central England dataset, centering temperatures on the yearly onsets of 20 El Nino of moderate to stronger strength, shows that, on average, the change in temperature varied by about +/- 0.3 C from normal being warmer during the boreal fall-winter leading up to the El Nino year and cooler during the spring-summer of the El Nino year. Also, the influence of El Nino on Central England temperatures appears to last about 1-2 years. Similarly, a composite of residual temperatures of the Central England dataset, centering temperatures on the month of eruption for 26 cataclysmic volcanic eruptions, shows that, on average, the change in temperature decreased by about 0.1 - 0.2 C, typically, 1-2 years after the eruption, although for specific events, like Tambora, the decrease was considerably greater. Additionally, tropical eruptions appear to produce greater changes in temperature than extratropical eruptions, and eruptions occurring in boreal spring-summer appear to produce greater changes in temperature than those occurring in fall-winter.

  7. Southern Africa

    Atmospheric Science Data Center

    2013-04-16

    article title:  Southern Africa     View larger JPEG image ... visibility of smoke plumes and haze. The southern tip of South Africa is at the bottom of the image, and Zambia is at the top. ... MISR Team. Aug 25, 2000 - South Africa to Zambia including the Okavango Delta. project:  ...

  8. Interdecadal changes in El Nino onset in the last four decades

    SciTech Connect

    Wang, B.

    1995-02-01

    The characteristics of the onset of the Pacific basin-wide warming have experienced notable changes since the late 1970s. The changes are caused by a concurrent change in the background state on which El Nino evolves. For the most significant warm episodes before the late 1970s (1957, 1965, and 1972), the atmospheric anomalies in the onset phase (November to December of the year preceding the El Nino) were characterized by a giant anomalous cyclone over east Australia whose eastward movement brought anomalous westerlies into the western equatorial Pacific, causing development of the basin-wide warming. Meanwhile, the trades in the southeastern Pacific relaxed back to their weakest stage, resulting in a South American coastal warming, which led the central Pacific warming about three seasons. Conversely, in the warm episodes after the late 1970s (1982, 1986-87, and 1991), the onset phase was characterized by an anomalous cyclone over the Philippine Sea whose intensification established anomalous westerlies in the western equatorial Pacific. Concurrently, the trades were enhanced in the southeastern Pacific, so that the coastal warming off Ecuado occurred after the central Pacific warming. It is found that the atmospheric anomalies occurring in the onset phase are controlled by background SSTs that exhibit a significant secular variation. In the late 1970s, the tropical Pacific between 20{degrees}S and 20{degrees}N experienced an abrupt interdecadal warming, concurrent with a cooling in the extratropical North Pacific and South Pacific and a deepening of the Aleutian Low. The interdecadal change of the background state affected El Nino onset by altering the formation of the onset cyclone and equatorial westerly anomalies and through changing the trades in the southeast Pacific, which determine whether a South American coastal warming leads or follows the warming at the central equatorial Pacific. 49 refs., 13 figs.

  9. TOPEX/El Nino Watch - Warm Water Pool is Thinning, Feb, 5, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Feb. 5, 1998 and sea surface height is an indicator of the heat content of the ocean. The area and volume of the El Nino warm water pool that is affecting global weather patterns remains extremely large, but the pool has thinned along the equator and near the coast of South America. This 'thinning' means that the warm water is not as deep as it was a few months ago. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition that they would expect to see during the ocean's gradual transition back to normal sea level. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather conditions that have impacted much of the United States and the world are expected to remain through

  10. a General Circulation Model Investigation of the Atmospheric Response to EL Nino

    NASA Astrophysics Data System (ADS)

    de Aragao, Jose Oribe Rocha

    The observed atmospheric response to sea surface temperature (SST) anomalies associated with El Nino episodes is simulated with the use of a general circulation model (GCM) of the atmosphere. A series of experiments has been performed with the Rasmusson and Carpenter six-episode (El Nino) composite SST anomaly (SSTA) in the tropical Pacific superimposed upon the prescribed climatological SST (CSST). Five independent 400-day runs were made beginning in April of the El Nino year (Year 0) and ending in May of the year after the maximum SSTA in the tropical Pacific (Year +1). Each of the integrations started from different initial conditions selected from different years in a 20 -year control run. The five-year El Nino integration was compared with the control run by analyzing the ensemble monthly, seasonal and annual mean statistics. The model's tropical response resembles the anomalous features found in previous studies. Some features are expected from the constraint imposed by the vorticity balance in the linear theory. For example, the upper level anticyclone pair and the lower level cyclonic circulation centers in the central Pacific are present for almost all months. These responses are significant and seem to be related to the location of both the maximum in CSST and the maximum in SSTA. An anomalous Walker Circulation is found in the vertical plane along the equatorial region. Rainfall departures from the long-term mean are associated with the anomalous Walker Circulation. An analysis of rainfall data over Northeast Brazil reveals sup- pressed rainfall in this area during the rainy season of Year(+1). Significant lower-than-normal rainfall is also found in the model's response during that period. This reduction in precipitation is associated with the downward branch of the anomalous Walker Circulation. The model's extratropical response is weaker than the tropical response and is not well organized. A Pacific/North American (PNA) pattern is present during the

  11. Microplankton species assemblages at the Scripps Pier from March to November 1983 during the 1982-1984 El Nino event

    NASA Technical Reports Server (NTRS)

    Reid, F. M. H.; Lange, C. B.; White, M. M.

    1985-01-01

    A semiweekly sampling program at the Scripps Institution of Oceanography Pier was begun in 1983 during an El Nino event. Microplankton data for March to November 1983 show a temporal sequence of species assemblages of the 24 important taxa, with a residence time of 1 to 4 weeks. From March to early September, the assemblages consisted of typial neritic taxa. From mid-September to mid-November, the presence of oceanic warm-wave species was associated with positive temperature anomalies characteristic of the El Nino condition. During the period studied numerical abundances were low.

  12. Microplankton species assemblages at the Scripps Pier from March to November 1983 during the 1982-1984 El Nino event

    NASA Technical Reports Server (NTRS)

    Reid, F. M. H.; Lange, C. B.; White, M. M.

    1984-01-01

    A semiweekly sampling program at the Scripps Institution of Oceanography pier was begun in 1983 during an El Nino event. Microplankton data for March to November 1983 show a temporal sequence of species assemblages of the 24 important taxa, with a residence time of 1 to 4 weeks. From March to early September, the assemblages consisted of typical neritic taxa. From mid-September to mid-November, the presence of oceanic warm-wave species was associated with positive temperature anomalies characteristic of the El Nino condition. During the period studied numerical abundances were low.

  13. ENSO and winter storms in California

    USGS Publications Warehouse

    Cayan, D.R.; Bromirski, Peter

    2003-01-01

    The frequency and intensity of North Pacific winter storms that penetrate the California coast drives the winds, sea level, precipitation and streamflow that are crucial influences on coastal processes. There is considerable variability of these storm characteristics, in large part owing to the El Nino/Southern Oscillation (ENSO} phenomenon. There is a great contrast of the storm characteristics during the El Nino phase vs. the La Nina phase, with the largest scale, southerly extensive winter storms generated during El Nino.

  14. Climate variability and spatiotemporal dynamics of five Southern Ocean krill species

    NASA Astrophysics Data System (ADS)

    Loeb, Valerie J.; Santora, Jarrod A.

    2015-05-01

    Understanding the ecological response of marine organisms to future climate change will benefit from quantifying spatiotemporal aspects of their distribution and abundance as well as the influence of ocean-atmospheric climate modes on their population cycles. Our study provides a synthesis of 18 years of data (1992-2009) for 5 krill (euphausiid) species monitored near the North Antarctic Peninsula (NAP) during austral summer. Distribution and abundance data are presented for postlarval stages of Euphausia crystallorophias, E. frigida, E. superba, E. triacantha and Thysanoessa macrura and larval E. superba and T. macrura. Intraseasonal, interannual and longer-term distribution and abundance patterns are quantified relative to climate modes driving ecosystem variability off the Antarctic Peninsula: El Niño-Southern Oscillation (ENSO), Southern Annual Mode (SAM) and associated zonal and meridional winds. Interannual abundance variations of all 5 species are significantly correlated with seasonally averaged ENSO indices and, with the exception of E. triacantha, elevated population sizes are associated with the higher productivity La Niña phase. Time-lagged responses of each species to ENSO indices approximate their generation times and suggest evolution of their life histories and reproductive efforts in accordance with the ENSO cycle. Postlarval E. crystallorophias and E. frigida and larval T. macrura demonstrate significant abundance increases after 1998 associated with a shift from an El Niño dominated period to predominantly La Niña and "Nino-neutral" conditions. Seasonal changes in species distributions and co-occurrence indicate portions of the southernmost E. frigida, E. triacantha and T. macrura populations move poleward with E. superba during late-summer, suggesting that environmental conditions associated with sea ice development (e.g., food, retention) may be more favorable than within the Antarctic Circumpolar Current during low productivity seasons

  15. Impact of the 2015 El Nino event on winter air quality in China

    NASA Astrophysics Data System (ADS)

    Chang, Luyu; Xu, Jianming; Tie, Xuexi; Wu, Jianbin

    2016-09-01

    During the winter of 2015, there was a strong El Nino (ENSO) event, resulting in significant anomalies for meteorological conditions in China. Analysis shows that the meteorological conditions in December 2015 (compared to December 2014) had several important anomalies, including the following: (1) the surface southeasterly winds were significantly enhanced in the North China Plain (NCP); (2) the precipitation was increased in the south of eastern China; and (3) the wind speeds were decreased in the middle-north of eastern China, while slightly increased in the south of eastern China. These meteorological anomalies produced important impacts on the aerosol pollution in eastern China. In the NCP region, the PM2.5 concentrations were significantly increased, with a maximum increase of 80–100 μg m‑3. A global chemical/transport model (MOZART-4) was applied to study the individual contribution of the changes in winds and precipitation to PM2.5 concentrations. This study suggests that the 2015El Nino event had significant effects on air pollution in eastern China, especially in the NCP region, including the capital city of Beijing, in which aerosol pollution was significantly enhanced in the already heavily polluted capital city of China.

  16. El Nino and Health Risks from Landscape Fire Emissions in Southeast Asia

    NASA Technical Reports Server (NTRS)

    Marlier, Miriam E.; Defries, Ruth S.; Voulgarakis, Apostolos; Kinney, Patrick L.; Randerson, James T.; Shindell, Drew T.; Chen, Yang; Faluvegi, Greg

    2013-01-01

    Emissions from landscape fires affect both climate and air quality. Here, we combine satellite-derived fire estimates and atmospheric modelling to quantify health effects from fire emissions in southeast Asia from 1997 to 2006. This region has large interannual variability in fire activity owing to coupling between El Nino-induced droughts and anthropogenic land-use change. We show that during strong El Nino years, fires contribute up to 200 micrograms per cubic meter and 50 ppb in annual average fine particulate matter (PM2.5) and ozone surface concentrations near fire sources, respectively. This corresponds to a fire contribution of 200 additional days per year that exceed the World Health Organization 50 micrograms per cubic metre 24-hr PM(sub 2.5) interim target and an estimated 10,800 (6,800-14,300)-person (approximately 2 percent) annual increase in regional adult cardiovascular mortality. Our results indicate that reducing regional deforestation and degradation fires would improve public health along with widely established benefits from reducing carbon emissions, preserving biodiversity and maintaining ecosystem services.

  17. Influence of SSTs over Nino-3.4 Region on the Indian Summer Monsoon Rainfall

    NASA Astrophysics Data System (ADS)

    Wilson, S. S.; Gleixner, S.; K, M.

    2014-12-01

    Indian Summer Monsoon Rainfall (ISMR) is sensitive to SST variations in the Pacific Ocean. In this study, the correlation coefficients between the SST in the Nino-3.4 region of season (June-August) and ISMR are evaluated using the datasets ERSST v3b and ISMR data (www.tropmet.res.in). An analysis of the mean monthly data of 64 years (1955-2013) reveals that the relationship between the SST in the Nino-3.4 region in June-August and the ISMR is changed after 1983. Seven drought years were reported between 1955 and 1983 and the warmest SST is in the equatorial eastern Pacific. After 1983, the warmest SST is shifted towards the central Pacific region during drought years. The coldest region in the central Pacific during wet years is shifted towards the eastern Pacific after 1983. The position of the sensitive area in the Pacific Ocean thus influences the drought/wet which is found to be changed in the recent epoch.

  18. Impact of the 2015 El Nino event on winter air quality in China

    PubMed Central

    Chang, Luyu; Xu, Jianming; Tie, Xuexi; Wu, Jianbin

    2016-01-01

    During the winter of 2015, there was a strong El Nino (ENSO) event, resulting in significant anomalies for meteorological conditions in China. Analysis shows that the meteorological conditions in December 2015 (compared to December 2014) had several important anomalies, including the following: (1) the surface southeasterly winds were significantly enhanced in the North China Plain (NCP); (2) the precipitation was increased in the south of eastern China; and (3) the wind speeds were decreased in the middle-north of eastern China, while slightly increased in the south of eastern China. These meteorological anomalies produced important impacts on the aerosol pollution in eastern China. In the NCP region, the PM2.5 concentrations were significantly increased, with a maximum increase of 80–100 μg m−3. A global chemical/transport model (MOZART-4) was applied to study the individual contribution of the changes in winds and precipitation to PM2.5 concentrations. This study suggests that the 2015El Nino event had significant effects on air pollution in eastern China, especially in the NCP region, including the capital city of Beijing, in which aerosol pollution was significantly enhanced in the already heavily polluted capital city of China. PMID:27671839

  19. Simulating the atmospheric response to the 1985-1987 El Nino cycle

    SciTech Connect

    Hoerling, M.P.; Ting, Mingfang ); Blackmon, M.L. )

    1992-07-01

    The atmospheric response to the evolution of global sea surface temperatures (SSTS) from 1985 to 1987 is studied using the NCAR Community Climate Model (CCM I). Five separate 2-year integrations are performed, and results are presented for the ensemble-averaged response during the pre-El Nino 1985/86 winter and the mature El Nino 1986/87 winter. No skill is found in CCM I's simulation for 1985/86. The simulation for the following winter, when tropical Pacific SST anomalies approached 2[degrees]C is more successful. A large-amplitude wave train extends poleward and eastward from the location of anomalous central Pacific convection in CCM 1, although the model's wave train is shifted 30[degrees] too far east compared to observations. A linear barotropic stationary wave model is used to diagnose CCM I's response during 1986/87. The eastward-shifted PNA response is easily excited by a dipole pattern of upper-level forcing with convergence over the western tropical Pacific and divergence over the central tropical Pacific. In contrast, the observed anomaly pattern during 1986/87 is most effectively forced by anomalous subtropical convergence over the central Pacific. Zonally asymmetric features of CCM I's climate drift, in particular the pattern of zonal wind biases over the tropical and midlatitude North Pacific, are shown to account for these different sensitivities.

  20. Satellite Observation of El Nino Effects on Amazon Forest Phenology and Productivity

    NASA Technical Reports Server (NTRS)

    Asner, Gregory P.; Townsend, Alan R.; Braswell, Bobby H.

    2000-01-01

    Climate variability may affect the functioning of Amazon moist tropical forests, and recent modeling analyses suggest that the carbon dynamics of the region vary interannually in response to precipitation and temperature anomalies. However, due to persistent orbital and atmospheric artifacts in the satellite record, remote sensing observations have not provided quantitative evidence that climate variation affects Amazon forest phenology or productivity, We developed a method to minimize and quantify non-biological artifacts in NOAA AVHRR satellite data, providing a record of estimated forest phenological variation from 1982-1993. The seasonal Normalized Difference Vegetation Index (NDVI) amplitude (a proxy for phenology) increased throughout much of the basin during El Nino periods when rainfall was anomalously low. Wetter La Nina episodes brought consistently smaller NDVI amplitudes. Using radiative transfer and terrestrial biogeochemical models driven by these satellite data, we estimate that canopy-energy absorption and net primary production of Amazon forests varied interannually by as much as 21% and 18%, respectively. These results provide large-scale observational evidence for interannual sensitivity to El Nino of plant phenology and carbon flux in Amazon forests.

  1. TOPEX/El Nino Watch - Little Change in Pacific, August 13, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea-surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on August 13, 1998; sea surface height is an indicator of the heat content of the ocean. The purple area in the center of the image is a pool of cold water that the satellite measures as a region of lower than normal sea level. This image shows that the rapid cooling of the central tropical Pacific has stalled and this area of low sea level has stayed in about the same place for the last two months. The purple areas are about 18 centimeters (7 inches) below normal, creating a deficit in the heat supply to the surface waters. It is not certain yet, if this current cooling trend (shown in purple) will eventually evolve into a long-lasting La Nina situation. Remnants of the El Nino warm water pool, shown here in red and white, are still lingering to the north and south of the equator. The effects of El Nino can remain in the climate system for a long time and could still impact weather conditions around the world. The satellite's sea-surface height measurements have provided scientists with a detailed view of the 1997-98 El Nino because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision. In this image, the white areas show the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The purple areas are 14 to 18 centimeters (6 to 7 inches) below normal and the blue areas are 5 to 13 centimeters (2 to 5 inches) below normal. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward

  2. TOPEX/El Nino Watch - Satellite shows Pacific Stabilizing, July 11, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on July 11, 1998; sea surface height is an indicator of the heat content of the ocean. The purple area in the center of the image is a pulse of cold water moving across the equator which the satellite measures as a region of lower than normal sea level. This image shows that the rapid cooling of the central tropical Pacific has stabilized and this area of low sea level has stayed in about the same place since mid-June. The purple areas are about 18 centimeters (7 inches) below normal, creating a deficit in the heat supply to the surface waters. It is not certain yet, if this current cooling trend (shown in purple) will eventually evolve into a long-lasting La Nina situation. Remnants of the El Nino warm water pool, shown here in red and white, are still lingering to the north and south of the equator in the center of this image. The effects of El Nino can remain in the climate system for a long time and could still impact weather conditions around the world. The satellite's sea-surface height measurements have provided scientists with a detailed view of the 1997-98 El Nino because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision. In this image, the white areas show the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The purple areas are 14 to 18 centimeters (6 to 7 inches) below normal and the blue areas are 5 to 13 centimeters (2 to 5 inches) below normal. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the

  3. TOPEX/El Nino Watch - Satellite Shows Pacific Running Hot and Cold, September 12, 1998

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image of the Pacific Ocean was produced using sea-surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on September 12, 1998; these sea surface heights are an indicator of the changing amount of heat stored in the ocean. The tropical Pacific Ocean continues to exhibit the complicated characteristics of both a lingering El Nino, and a possibly waning La Nina situation. This image shows that the rapid cooling of the central tropical Pacific has slowed and this area of low sea level (shown in purple) has decreased slightly since last month. It is still uncertain, scientists say, that this cold pool will evolve into a long-lasting La Nina situation. Remnants of the El Nino warm water pool, shown here in red and white, are still lingering to the north and south of the equator. The coexistence of these two contrasting conditions indicates that the ocean and the climate system remain in transition. These strong patterns have remained in the climate system for many months and will continue to influence weather conditions around the world in the coming fall and winter. The satellite's sea-surface height measurements have provided scientists with a detailed view of the 1997-98 El Nino because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision. The purple areas are about 18 centimeters (7 inches) below normal, creating a deficit in the heat supply to the surface waters. The white areas show the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The purple areas are 14 to 18 centimeters (6 to 7 inches) below normal and the blue areas are 5 to 13 centimeters (2 to 5 inches) below normal. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and

  4. Voltage-controlled oscillator

    NASA Technical Reports Server (NTRS)

    Durand, J. L.

    1971-01-01

    Oscillator generates symmetrical triangular waveform when inverting and noninverting inputs are equal. Oscillator portion of circuit has integrated circuit, high-performance operational amplifier wired as differential integrator, and two silicon controlled rectifiers.

  5. Saturation in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Roman, Ahmed; Hanna, James

    2015-03-01

    We consider a weakly nonlinear system consisting of a resonantly forced oscillator coupled to an unforced oscillator. It has long been known that, for quadratic nonlinearities and a 2:1 resonance between the oscillators, a perturbative solution of the dynamics exhibits a phenomenon known as saturation. At low forcing, the forced oscillator responds, while the unforced oscillator is quiescent. Above a critical value of the forcing, the forced oscillator's steady-state amplitude reaches a plateau, while that of the unforced oscillator increases without bound. We show that, contrary to established folklore, saturation is not unique to quadratically nonlinear systems. We present conditions on the form of the nonlinear couplings and resonance that lead to saturation. Our results elucidate a mechanism for localization or diversion of energy in systems of coupled oscillators, and suggest new approaches for the control or suppression of vibrations in engineered systems.

  6. El Nino Election. Grade 12 Lesson. Schools of California Online Resources for Education (SCORE): Connecting California's Classrooms to the World.

    ERIC Educational Resources Information Center

    Mac Donald, David R.; Karayan, Michael S.

    In this lesson plan, the city of Malibu (CA) is at the mercy of the weather phenomenon El Nino. The press secretary for the Mayor of Malibu recognizes an opportunity to turn this potential natural disaster into a re-election campaign. A task force will be assembled to protect the lives and property of the community. Students role play members of…

  7. Map showing locations of damaging landslides in Santa Cruz County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Baum, Rex L.; Schuster, Robert L.; Godt, Jonathan W.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. About $14.5 million in damages were assessed in Santa Cruz County.

  8. Map showing locations of damaging landslides in Sonoma County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Ramsey, David W.; Godt, Jonathan W.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. About $21 million in damages were assessed in Sonoma County.

  9. Map showing locations of damaging landslides in Marin County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Morrissey, Meghan M.; Wieczorek, Gerald F.; Godt, Jonathan W.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. About $2.5 million in damages were assessed in Marin County.

  10. Map showing locations of damaging landslides in Contra Costa County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Graymer, Russell W.; Godt, Jonathan W.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. About $27 million in damages were assessed in Contra Costa County.

  11. Map showing locations of damaging landslides in Santa Clara County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Ellis, William L.; Harp, Edwin L.; Arnal, Caroline H.; Godt, Jonathan W.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. About $7.6 million in damages were assessed in Santa Clara County.

  12. Map showing locations of damaging landslides in Solano County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Howell, David G.; Godt, Jonathan W.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. About $13.5 million in damages were assessed in Solano County.

  13. Comparison of shelf currents off central California prior to and during the 1997-1998 El Nino

    USGS Publications Warehouse

    Ryan, H.F.; Noble, M.A.

    2005-01-01

    Moored current, temperature, salinity, and pressure data were collected at three sites that transect the narrow continental shelf offshore of Davenport, CA, starting in August 1996 and continuing to the spring of 1998. This data set allowed a comparison of oceanographic conditions prior to (8/96-3/97) and during (8/97-3/98) the last major El Nin??o. During this El Nin??o, mean temperatures over the 8-month time period were about 3??C warmer than during the prior year at all of the sites. Correlations between near-surface and near-bottom temperatures, and between near-surface temperature and wind stress decreased during the El Nin??o compared to conditions the year before. The mean alongshore currents were more strongly poleward during El Nin??o at sites over the mid-shelf and near the shelf break. There was a general tendency for the energy in alongshore currents to move toward lower frequencies during the El Nin??o, particularly at the sites farther offshore. The processes that forced the shelf flows changed in relative importance throughout the study. The local alongshore wind stress was less important in driving shelf currents during the El Nin??o when much of the wind-induced upwelling was confined to less than 5 km of the coast. The observed strong poleward shelf currents on the mid- to outer-shelf were not clearly tied to local forcing, but were remotely driven, most likely by slope currents. The response of the Davenport shelf to an El Nin??o event may differ from other areas since the shelf is narrow, the wind forcing is weaker than areas to the north and south, and the shelf may be at times isolated by fronts that form at strong upwelling centers. In the winter, strong storm-related winds are important in driving currents at periods not only in the synoptic wind band, but also for periods on the order of 20 d and longer.

  14. An Assessment of the Impact of the 1997-98 El Nino on the Asian-Australian Monsoon

    NASA Technical Reports Server (NTRS)

    Lau, K.-M.; Wu, H.-T.

    1999-01-01

    Using state-of-the-art satellite-gauge monthly rainfall estimate and optimally interpolated sea surface temperature (SST) data, we have assessed the 1997-98 AA-monsoon anomalies in terms of three basic causal factors: basin-scale SST, regional coupling, and internal variability. Singular Value Decomposition analyses of rainfall and SST are carried out globally over the entire tropics and regionally over the AA-monsoon domain. Contributions to monsoon rainfall predictability by various factors are evaluated from cumulative anomaly correlation with dominant regional SVD modes. Results reveal a dominant, large-scale monsoon-El Nino coupled mode with well-defined centers of action in the near-equatorial monsoon regions during the boreal summer and winter respectively. The observed 1997-98 AA-monsoon anomalies are found to be very complex with approximately 34% of the anomalies of the Asian (boreal) summer monsoon and 74% of the Australia (austral) monsoon attributable to basin-scale SST influence associated with El Nino. Regional coupled processes contribute an additional 19% and 10%, leaving about 47% and 16% due to internal dynamics for the boreal and austral monsoon respectively. For the boreal summer monsoon, it is noted that the highest monsoon predictability is not necessary associated with major El Nino events (e.g. 1997, 1982) but rather in non-El Nino years (e.g. 1980, 1988) when contributions from the regional coupled modes far exceed those from the basin-scale SST. The results suggest that in order to improve monsoon seasonal-to-interannual predictability, there is a need to exploit not only monsoon-El Nino relationship, but also intrinsic monsoon regional coupled processes.

  15. Covariant harmonic oscillators and coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo; Kim, Young S.; Noz, Marilyn E.

    1995-01-01

    It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.

  16. TOPEX/El Nino Watch - La Nina Still a 'cool' Problem Child, March 23, 2000

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These TOPEX/Poseidon data, collected over the latest 10-day sampling cycle, March 1 to 11, 2000, show the La Nina condition still exists. The image of sea surface heights reflects unusual patterns of heat storage in the ocean. Sea-surface height is shown relative to normal height (green). The cooler water (blue and purple) measures between 8 and 24 centimeters (3 and 9 inches) lower than normal. The giant horseshoe of warmer water (red and white) continues to dominate the western Pacific with higher than normal sea-surface heights between 8 and 24 centimeters (3 and 9 inches).

    This view of the oceans from TOPEX/Poseidon is an input to the National Oceanic and Atmospheric Administration (NOAA) seasonal forecasts. The impacts of current ocean conditions in the Pacific for spring in the U.S., according to Dr. Ants Leetmaa, director of NOAA's Climate Prediction Center, imply drier than normal conditions for much of the southern half of the U.S. Leetmaa says the conditions also indicate above-normal rainfall in the Pacific northwest, and a warmer than normal U.S., except for the west coast where spring conditions will be near normal.

    Scientists continue to debate whether this image hints at the presence of a large, longer lasting climate pattern, the Pacific Decadal Oscillation. This long-term pattern that covers most of the Pacific Ocean has significant implications for global climate, especially over North America.

    The U.S.-French TOPEX/Poseidon mission is managed JPL for the NASA's Earth Science Enterprise, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.

  17. SHOCK-EXCITED OSCILLATOR

    DOEpatents

    Creveling, R.

    1957-12-17

    S> A shock-excited quartz crystal oscillator is described. The circuit was specifically designed for application in micro-time measuring work to provide an oscillator which immediately goes into oscillation upon receipt of a trigger pulse and abruptly ceases oscillation when a second pulse is received. To achieve the instant action, the crystal has a prestressing voltage applied across it. A monostable multivibrator receives the on and off trigger pulses and discharges a pulse through the crystal to initiate or terminate oscillation instantly.

  18. Discrete monotron oscillator

    SciTech Connect

    Carlsten, B.E.; Haynes, W.B.

    1996-08-01

    The authors theoretically and numerically investigate the operation and behavior of the discrete monotron oscillator, a novel high-power microwave source. The discrete monotron differs from conventional monotrons and transit time oscillators by shielding the electron beam from the monotron cavity`s RF fields except at two distinct locations. This makes the discrete monotron act more like a klystron than a distributed traveling wave device. As a result, the oscillator has higher efficiency and can operate with higher beam powers than other single cavity oscillators and has more stable operation without requiring a seed input signal than mildly relativistic, intense-beam klystron oscillators.

  19. Shorebird use of an exposed sandy beach in southern California

    NASA Astrophysics Data System (ADS)

    Hubbard, David M.; Dugan, Jenifer E.

    2003-10-01

    to minima of 0.8-2.1 and 2-8 species km -1, respectively, during June. In contrast, species turnover was lowest (1.1-1.7) in October and November, and generally highest (2-4) during early summer (June). The amount of sandy intertidal habitat available to shorebirds on the transect was estimated using sand elevations and predicted tide heights. In the fall and winter, the abundance of shorebirds was significantly and positively correlated with tide height, possibly reflecting feeding opportunities and high tide refuge effects during the highest tides. In the spring when sand levels were low, the abundance of shorebirds was negatively correlated with tide height. Prey availability, beach condition and the local availability, and condition of alternative foraging habitats may influence those relationships. Interannual variations in shorebird use and beach condition were observed in the course of the study. During an El Nino Southern Oscillation (ENSO) event (1997-1998), the extent of sandy habitat was greatly reduced and intertidal habitat was mostly converted to rocky substrate. The overall abundance of shorebirds and the mean abundance of some common species (e.g. sanderling) were depressed, and an uncommon species (surfbird, A. virgata) was unusually abundant during the ENSO event. In summary, the results suggest that sandy beaches are important habitat for many species of shorebirds, particularly in areas where alternative coastal foraging habitats, such as coastal wetlands, have become scarce. Understanding the dynamics of and threats to exposed sandy beaches may be increasingly important for shorebird conservation in many coastal regions.

  20. Nature's Autonomous Oscillators

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.

    2012-01-01

    Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.

  1. TOPEX/El Nino Watch - Warm Water Pool is Increasing, Nov. 10, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Nov. 10, 1997. The volume of extra warm surface water (shown in white) in the core of the El Nino continues to increase, especially in the area between 15 degrees south latitude and 15 degrees north latitude in the eastern Pacific Ocean. The area of low sea level (shown in purple) has decreased somewhat from late October. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 centimeters and 32 cm (6 inches to 13 inches) above normal; in the red areas, it is about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one-and-one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21 to 30 degrees Celsius (70 to 85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

    The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white areas) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmospheric system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and

  2. TOPEX/El Nino Watch - Indonesia Area, December, 1996 and August, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These images of the Pacific Ocean near Indonesia were produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The images show sea surface height relative to normal ocean conditions during December 1996 and August 1997. The difference in sea level between these months is tied to the movement of warm water away from Indonesia.

    In December (left image), red and white areas indicate the presence of warm, higher than average sea level around Indonesia. At this time, massive amounts of warm water were detected around Indonesia by the TOPEX/Poseidon satellite. The warm, wet air from this water fed the normally heavy rainfall in this region.

    By August 1997 (right image), sea level had dropped well below average as shown by purple areas (sea level at least 18 centimeters (7 inches) below normal). The warm water had shifted east towards the west coast of North and South America, taking the rains with it.

    The white and red areas indicate patterns of unusually high heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal.

    The movement of warm water away from the western Pacific is tied to the weather-disrupting phenomenon known as El Nino. The departure of the large mass of warm water that is normally located near Indonesia has affected where rain clouds form, altered the typical atmospheric patterns and brought devastating drought to Indonesia. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction.

    Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA) has issued an advisory indicating the presence of the early indications of El

  3. The Feasibility of Predicting Nino 3.4 Index Using a Sparse Approximation Algorithm

    NASA Astrophysics Data System (ADS)

    Peng, X.; Li, T.; Gu, Y.; Zhang, A.

    2015-12-01

    It is well established that sea surface temperature anomaly (SSTA) is one of the principle factors that have significant influence on global climate variability. Due to large mass and great thermal capacity of the oceans, oceanic conditions change relatively slowly and dominant patterns are thus easy to detect. Most of the current research on SSTA make use of PCA methods like EOF or SVD. Though such methods are effective in reducing dimensions, it is always hard to give a physical interpretation of the results and difficult to distinguish the minor eigenvectors from noises. Instead of finding patterns, we put forward a framework for the direct prediction of SSTAs, using a sparse approximation method, the least absolute shrinkage and selection operator (lasso), to reduce the noises in global SST observation. Global SSTA time series in 5°×5° resolution were used to fit each target SSTA vector and the lasso method was utilized to avoid over-fitting. Taking the Nino 3.4 Index as an example, the predictability of the lasso model was studied and the results showed a relatively satisfying prediction skill in terms of correlation coefficient and root-mean-square error compared with the results obtained from LDEO 5. Moreover, by taking other climate variables into consideration, we discovered a stable relation between the Nino 3.4 Index and the sea-ice extent anomaly in South Pole at a lead time of around 2 years. In addition, the bootstrapping method was used to resample the coefficients in the sparse regression model so that we could study their statistical property. 14 regressors were reserved suggesting 10 potential indices which have relatively strong relations with the Nino 3.4 Index. Some of the potential indices corresponded well to known climate indices while the rest indicated an undiscovered index in tropical oceans of eastern South America. In conclusion, the lasso method approved its feasibility in climate prediction at a relatively low computation cost, and

  4. Size of the California Brown Pelican Metapopulation During a Non-El Nino Year

    USGS Publications Warehouse

    Anderson, Daniel W.; Henny, Charles J.; Godinez-Reyes, Carlos; Gress, Franklin; Palacios, Eduardo L.; Santos del Prado, Karina; Bredy, James

    2007-01-01

    related to the natural cycles of El Ni?o/Southern Oscillation (ENSO) phenomena where very low breeding populations (as low as no nesting in many areas) might be expected to occur in these same areas censused in 2006 at least 40% of the time. From the 2006 aerial survey, extensive commercial and sport-fishing activity, resort/tourist developments and associated human activities along the coastal areas and at offshore islands, and extensive aquacultural (and to a lesser degree, agricultural) developments seen from the Rio Colorado Delta region, Sonora, south at least through San Blas, Nayarit (the southern terminus of our 2006 aerial survey) may result in substantial loss of breeding habitat. Juvenile (young of the 2005 breeding season) plus subadult brown pelicans comprised 28.1% ? 0.33% (mean ? 95% CI) of the total numbers in age-ratio samples. Thus, our overall metapopulation estimate for P. o. californicus in 2006 was 195,900 ? 7,225 individuals.

  5. Microwave Limb Sounder/El Nino Watch - February thru December, 1997

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This series of six images shows the movement of atmospheric water vapor over the Pacific Ocean during the formation of the 1997 El Nino condition. Higher than normal ocean water temperatures increase the rate of evaporation and the resulting warm moist air rises into the atmosphere altering global weather patterns. Data obtained by the Microwave Limb Sounder (MLS) on NASA's Upper Atmosphere Research Satellite (UARS), from late February 1997 to late December 1997, show the movement from the western Pacific to the eastern Pacific of high levels of water vapor (red) at 10 kilometers (6 miles) above the surface. Areas of unusually drier air (blue) appear over Indonesia. December 1997 data also show a rapid increase of water vapor off the coast of South America, the result of very high water temperatures in that region.

  6. Oceanic heat content variability in the Tropical Pacific during the 1982-1983 El Nino

    NASA Technical Reports Server (NTRS)

    Springer, Scott R.; Mcphaden, Michael J.; Busalacchi, Antonio J.

    1990-01-01

    A linear, multimode model forced by observed winds is used to investigate anomolous heat transport and storage during the 1982-1983 El Nino. The study compliments the work of Wyrtki (1985) and of Zebiak and Cane (1987) and contains the ocean dynamics invoked by both these studies to explain heat content anomalies. Model hindcasts are compared with observational evidence derived from the island sea level network. The meridional distribution of heat storage and the components of heat transport are considered. It is found that the mechanisms contributing to heat transport out of bands of latitude symmetric about the equator are isolated and related to the wind anomalies and wave dynamics usually associated with ENSO events. It is noted that although the spatial and temporal distribution of oceanic heat anomalies necessary to initiate an ENSO event can be determined only by studying coupled ocean-atmosphere models, an examination of the oceanic component alone is useful in determining constraints imposed by ocean dynamics.

  7. Observations of annual and El Nino thermal and flow variations at 0 deg, 110 deg W and 0 deg, 95 deg W during 1980-1985

    NASA Technical Reports Server (NTRS)

    Halpern, David

    1987-01-01

    The paper describes the low-frequency (i.e., time scales longer than a month) upper ocean (above 250 m) current and temperature moored measurements conducted from March 1980 to September 1985 at 0, 110 deg W and from July 1981 to November 1983 (i.e., including the period of the 1982-1983 El Nino) at 0, 95 deg W. Estimates of the annual cycle were removed from the observations to determine the current and temperature fluctuations due to the 1982-1983 El Nino. The circulation of the upper ocean was found to be dramatically altered during the El Nino: the normally westward flowing surface current in autumn months reversed direction, and the equatorial undercurrent, normally considered to be a permanent feature, disappeared. Associated with the El Nino was a massive redistribution of heat throughout the mixed layer and the thermocline.

  8. Systematic study of new types of Hamamatsu MPPCs read out with the NINO ASIC

    NASA Astrophysics Data System (ADS)

    Doroud, K.; Rodriguez, A.; Williams, M. C. S.; Yamamoto, K.; Zichichi, A.; Zuyeuski, R.

    2014-07-01

    Over the last decade there have been commercial TOF-PET scanners constructed using Photo-Multiplier Tubes (PMT) that have achieved ~ 500 ps FWHM Coincidence Time Resolution (CTR). A new device known as the Silicon PhotoMultiplier (SiPM) has the potential to overcome some of the limitations of the PMT. Therefore implementing a SiPM based TOF-PET scanner is of high interest. Recently Philips has introduced a TOF-PET scanner that uses digital Silicon PhotoMultipliers (d-SiPMs) which has a CTR of 350 ps. Here we will report on the timing performance of two Hamamatsu 3×3 mm2 analogue-SiPMs read out with the NINO ASIC: this is an ultra-fast amplifier/discriminator with a differential architecture. The differential architecture is very important since the single-ended readout uses the ground as the signal return; as the ground is also the reference level for the discriminators, the result is high crosstalk and degraded time resolution. However differential readout allows the scaling up from a single cell to a multi-cell device with no loss of time resolution; this becomes increasingly important for the highly segmented detectors that are being built today, both for particle and for medical instrumentation. We obtained excellent results for both the Single Photon Time Resolution (SPTR) and for the CTR using a LYSO crystal of 15 mm length. Such a crystal length has sufficient detection efficiency for 511 keV gammas to make an excellent PET device. The results presented here are proof that a TOF-PET detector with a CTR of 175 ps is indeed possible. This is the first step that defines the starting point of our SuperNINO project.

  9. Paradoxes of neutrino oscillations

    SciTech Connect

    Akhmedov, E. Kh.; Smirnov, A. Yu.

    2009-08-15

    Despite the theory of neutrino oscillations being rather old, some of its basic issues are still being debated in the literature. We discuss a number of such issues, including the relevance of the 'same energy' and 'same momentum' assumptions, the role of quantum-mechanical uncertainty relations in neutrino oscillations, the dependence of the coherence and localization conditions that ensure the observability of neutrino oscillations on neutrino energy and momentum uncertainties, the question of (in)dependence of the oscillation probabilities on the neutrino production and detection processes, and the applicability limits of the stationary-source approximation. We also develop a novel approach to calculation of the oscillation probability in the wave-packet approach, based on the summation/integration conventions different from the standard one, which allows a new insight into the 'same energy' vs. 'same momentum' problem. We also discuss a number of apparently paradoxical features of the theory of neutrino oscillations.

  10. Oscillations in stellar atmospheres

    NASA Technical Reports Server (NTRS)

    Costa, A.; Ringuelet, A. E.; Fontenla, J. M.

    1989-01-01

    Atmospheric excitation and propagation of oscillations are analyzed for typical pulsating stars. The linear, plane-parallel approach for the pulsating atmosphere gives a local description of the phenomenon. From the local analysis of oscillations, the minimum frequencies are obtained for radially propagating waves. The comparison of the minimum frequencies obtained for a variety of stellar types is in good agreement with the observed periods of the oscillations. The role of the atmosphere in the globar stellar pulsations is thus emphasized.

  11. Self-oscillation

    NASA Astrophysics Data System (ADS)

    Jenkins, Alejandro

    2013-04-01

    Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain dynamical systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy into the vibration: no external rate needs to be adjusted to the resonant frequency. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the swaying of the London Millennium Footbridge in 2000. Clocks are self-oscillators, as are bowed and wind musical instruments. The heart is a “relaxation oscillator”, i.e., a non-sinusoidal self-oscillator whose period is determined by sudden, nonlinear switching at thresholds. We review the general criterion that determines whether a linear system can self-oscillate. We then describe the limiting cycles of the simplest nonlinear self-oscillators, as well as the ability of two or more coupled self-oscillators to become spontaneously synchronized (“entrained”). We characterize the operation of motors as self-oscillation and prove a theorem about their limit efficiency, of which Carnot’s theorem for heat engines appears as a special case. We briefly discuss how self-oscillation applies to servomechanisms, Cepheid variable stars, lasers, and the macroeconomic business cycle, among other applications. Our emphasis throughout is on the energetics of self-oscillation, often neglected by the literature on nonlinear dynamical systems.

  12. Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, D. (Editor); Kim, Y. S. (Editor); Zachary, W. W. (Editor)

    1993-01-01

    Proceedings of a workshop on Harmonic Oscillators held at the College Park Campus of the University of Maryland on March 25 - 28, 1992 are presented. The harmonic oscillator formalism is playing an important role in many branches of physics. This is the simplest mathematical device which can connect the basic principle of physics with what is observed in the real world. The harmonic oscillator is the bridge between pure and applied physics.

  13. EXAFS studies on the structure of photoexcited cyclopentadienylnickelnitrosyl(C[sub 5]H[sub 5]NiNO)

    SciTech Connect

    Chen, L.X.; Bowman, M.K.; Montano, A. ); Norris, J.R. Chicago Univ., IL . Dept. of Chemistry)

    1993-01-01

    The structures of C[sub 5]H[sub 5]NiNO in a reversible photochemical reaction were studied via EXAFS, FTIR, and optical absorption spectroscopies. A photoexcited intermediate with distinctively different EXAFS, IR, and optical absorption spectra from those of the ground state molecules was generated upon irradiation using 365 mn light at 20K in a 3-methylpentane solution. The reverse reaction was induced by irradiation with 310 mn light. The EXAFS data analysis has shown a 0.12 [Angstrom] elongation of the Ni-N bond and the bending, of Ni-N-0 in the photoexcited intermediate. Several ZINDO calculations were conducted based on the structures obtained from the EXAFS spectroscopy. These calculations reproduced the changes in the optical spectra and the intramolecular electron transfer in C[sub 5]H[sub 5]NiNO.

  14. EXAFS studies on the structure of photoexcited cyclopentadienylnickelnitrosyl(C{sub 5}H{sub 5}NiNO)

    SciTech Connect

    Chen, L.X.; Bowman, M.K.; Montano, A.; Norris, J.R. |

    1993-05-01

    The structures of C{sub 5}H{sub 5}NiNO in a reversible photochemical reaction were studied via EXAFS, FTIR, and optical absorption spectroscopies. A photoexcited intermediate with distinctively different EXAFS, IR, and optical absorption spectra from those of the ground state molecules was generated upon irradiation using 365 mn light at 20K in a 3-methylpentane solution. The reverse reaction was induced by irradiation with 310 mn light. The EXAFS data analysis has shown a 0.12 {Angstrom} elongation of the Ni-N bond and the bending, of Ni-N-0 in the photoexcited intermediate. Several ZINDO calculations were conducted based on the structures obtained from the EXAFS spectroscopy. These calculations reproduced the changes in the optical spectra and the intramolecular electron transfer in C{sub 5}H{sub 5}NiNO.

  15. Map showing locations of damaging landslides in Napa County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Godt, Jonathan W.; Savage, William Z.; Wilson, Raymond C.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. Napa County was relatively unaffected in comparison to other counties in the region with approximately $1.1 million in damages assessed.

  16. Map showing locations of damaging landslides in San Mateo County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Jayko, Angela S.; De Mouthe, Jean; Lajoie, Kenneth R.; Ramsey, David W.; Godt, Jonathan W.

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. About $55 million in damages were assessed in San Mateo County. The only fatality attributed to landsliding in the region during the period occurred in San Mateo County near Loma Mar.

  17. Map showing locations of damaging landslides in Alameda County, California, resulting from 1997-98 El Nino rainstorms

    USGS Publications Warehouse

    Coe, J.A.; Godt, J.W.; Brian, Dianne; Houdre, Nicolas

    1999-01-01

    Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. In Alameda County more than $20 million in damages were assessed. Debris flows occurred in rural portions of the county, but were only responsible for $400 thousand in damages.

  18. Active-bridge oscillator

    DOEpatents

    Wessendorf, Kurt O.

    2001-01-01

    An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.

  19. Investigating Magnetic Oscillations.

    ERIC Educational Resources Information Center

    Brueningsen, Christopher A.

    1993-01-01

    Studies magnetic oscillation using an air track. Ceramic magnets are attached to the cart and also are used as dampeners in place of the springs. The resulting oscillations are fairly sinusoidal and is a good example of simple harmonic motion. (MVL)

  20. Oscillating Chemical Reactions

    ERIC Educational Resources Information Center

    Hawkins, M. D.; And Others

    1975-01-01

    Describes several oscillating chemical reactions which can be used in undergraduate chemistry laboratories. In one such reaction, ferroin oscillates from red (reducing solution) to blue (oxidizing solution) for about an hour at a frequency which can readily be shown to depend on such factors as the temperature, type of solvent, and concentration…

  1. Effects of productivity, consumers, competitors, and El Nino events on food chain patterns in a rocky intertidal community

    SciTech Connect

    Wootton, J.T.; Pfister, C.A.; Paine, R.T.

    1996-11-06

    We experimentally manipulated nutrient input to a rocky intertidal community, using nutrient-diffusing flowerpots, to determine (i) whether nutrients limited intertidal productivity, (ii) how a large-scale oceanographic disturbance (an El Nino event) affected patterns of nutrient limitation, (iii) the relative impacts of molluscan grazers and nutrient limitation, and (iv) if responses to experimental nutrient addition among trophic levels were more consistent with prey-dependent or ratio-dependent food chain models. Nutrients measurably increased the abundance of micrograzers (amphipods and chironomid larvae), but not algal biomass, during the summer of an El Nino years and during the autumn of an El Nino year. Adding nutrients did not affect food chain stability as assessed by temporal variation in algal biomass and micrograzer abundance. Large molluscan grazers caused large reductions in micrograzers and smaller reductions in algae, indicating consistent consumer effects. The results demonstrate that in this intertidal community, nutrient limitation can occur under conditions of nutrient stress, that top-down grazing effects are typically stronger than bottom-up nutrient effects, and that prey-dependent models are more appropriate than ratio-dependent models. 40 refs., 1 fig., 1 tab.

  2. Angular momentum and torques in a simulation of the atmosphere's response to the 1982-83 El Nino

    SciTech Connect

    Ponte, R.M.; Rosen, R.D. ); Boer, G.J. )

    1994-04-01

    Anomalies in the angular momentum of the atmosphere (M) during the 1982-83 El Nino event and the torques responsible for these anomalies are investigated using output from the Canadian Climate Centre general circulation model. Model values of M during the year of the event are generally larger than those for the model climatology, thereby capturing the observed tendency toward higher values of M during El Nino. Differences exist between the model and observations in the timing and amplitude of the largest anomalies, but these differences may be due to natural variability and not necessarily directly associated with the 1982-83 El Nino conditions. In late September and October 1982, the model atmosphere acquires momentum more rapidly than usual, leading to the development of the largest deviations from mean conditions at the end of October. A secondary maximum in the departure from mean M values occurs in January 1983 and is related to a general strengthening of westerly momentum anomalies over the model's tropical and midlatitude regions. Both mountain and tangential stress torques are involved in this episode, but no particular mechanism or region dominates the anomalous exchange of momentum. 24 refs., 10 figs., 1 tab.

  3. HIGH POWER PULSED OSCILLATOR

    DOEpatents

    Singer, S.; Neher, L.K.

    1957-09-24

    A high powered, radio frequency pulse oscillator is described for generating trains of oscillations at the instant an input direct voltage is impressed, or immediately upon application of a light pulse. In one embodiment, the pulse oscillator comprises a photo-multiplier tube with the cathode connected to the first dynode by means of a resistor, and adjacent dynodes are connected to each other through adjustable resistors. The ohmage of the resistors progressively increases from a very low value for resistors adjacent the cathode to a high value adjacent the plate, the last dynode. Oscillation occurs with this circuit when a high negative voltage pulse is applied to the cathode and the photo cathode is bombarded. Another embodiment adds capacitors at the resistor connection points of the above circuit to increase the duration of the oscillator train.

  4. Ultrastable Cryogenic Microwave Oscillators

    NASA Astrophysics Data System (ADS)

    Mann, Anthony G.

    Ultrastable cryogenic microwave oscillators are secondary frequency standards in the microwave domain. The best of these oscillators have demonstrated a short term frequency stability in the range 10-14 to a few times 10-16. The main application for these oscillators is as flywheel oscillators for the next generation of passive atomic frequency standards, and as local oscillators in space telemetry ground stations to clean up the transmitter close in phase noise. Fractional frequency stabilities of passive atomic frequency standards are now approaching 3 x10^-14 /τ where τ is the measurement time, limited only by the number of atoms that are being interrogated. This requires an interrogation oscillator whose short-term stability is of the order of 10-14 or better, which cannot be provided by present-day quartz technology. Ultrastable cryogenic microwave oscillators are based on resonators which have very high electrical Q-factors. The resolution of the resonator's linewidth is typically limited by electronics noise to about 1ppm and hence Q-factors in excess of 108 are required. As these are only attained in superconducting cavities or sapphire resonators at low temperatures, use of liquid helium cooling is mandatory, which has so far restricted these oscillators to the research or metrology laboratory. Recently, there has been an effort to dispense with the need for liquid helium and make compact flywheel oscillators for the new generation of primary frequency standards. Work is under way to achieve this goal in space-borne and mobile liquid-nitrogen-cooled systems. The best cryogenic oscillators developed to date are the ``whispering gallery'' (WG) mode sapphire resonator-oscillators of NASA's Jet Propulsion Laboratory (JPL) and the University of Western Australia (UWA), as well as Stanford University's superconducting cavity stabilized oscillator (SCSO). All of these oscillators have demonstrated frequency

  5. Southern blotting.

    PubMed

    Brown, T

    2001-05-01

    Southern blotting is the transfer of DNA fragments from an electrophoresis gel to a membrane support, resulting in immobilization of the DNA fragments, so the membrane carries a semipermanent reproduction of the banding pattern of the gel. After immobilization, the DNA can be subjected to hybridization analysis, enabling bands with sequence similarity to a labeled probe to be identified. This unit describes Southern blotting via upward capillary transfer of DNA from an agarose gel onto a nylon or nitrocellulose membrane, and subsequent immobilization by UV irradiation (for nylon) or baking (for nitrocellulose). A Support Protocol describes how to calibrate a UV transilluminator for optimal UV irradiation of a nylon membrane. An alternate protocol details transfer using nylon membranes and an alkaline buffer, and is primarily used with positively charged nylon membranes. A second alternate protocol describes a transfer method based on a different transfer-stack setup. The traditional method of upward capillary transfer of DNA from gel to membrane has certain disadvantages, notably the fact that the gel can become crushed by the weighted filter papers and paper towels that are laid on top of it. This slows down the blotting process and may reduce the amount of DNA that can be transferred. The downward capillary method described in the second alternate protocol is therefore more rapid and can result in more complete transfer. PMID:18432697

  6. Geology and mineralogy of the Santo Nino Ag-Pb-Zn vein, Fresnillo District, Mexico

    SciTech Connect

    Gemmell, J.B.; Zantop, H.; Birnie, R.W.

    1985-01-01

    The Santo Nino Ag-Pb-Zn vein is the major producer of the Fresnillo District, located 750 km NW of Mexico City. It is over 2.4 km long, more than 480 m in vertical extent, more than 2.5 m wide overall, and has average grades of >600 gm/t Ag and <2% combined Pb and Zn. The vein is hosted by a tilted sequence of Cretaceous graywackes, shales and andesitic volcanics and extends upward into a Lower Tertiary conglomerate. Up to 5 separate opening events occurred along the vein, resulting in discontinuous stages of brecciation and crustiform banding. Ore mineral zonation is well developed both vertically and laterally and closely reflects metal and metal ratio distributions. Ore minerals are sphalerite, galena, pyrite, chalcopyrite, arsenopyrite, marcasite, pyrrhotite, acanthite, native silver, and three coexisting solid solution series, pyrargyrite-proustite, polybasite-arsenopolybasite, and tetrahedrite-tennantite in a gangue of quartz, calcite, clay, sericite,and chlorite. A 5-stage paragenetic sequence can be established: 1) pyrite, arsenopyrite, quartz, 2) sphalerite, galena, chalcopyrite, quartz, 3) tetrahedrite, pyrargyrite, polybasite, quartz, 4) acanthite, native silver, calcite, quartz, and 5) calcite. Preliminary microprobe analyses indicate that the Ag-rich solid solution series are Sb-rich in the central and upper portions of the vein and As-rich at deeper levels.

  7. Southern blotting.

    PubMed

    Brown, T

    2001-05-01

    Southern blotting is the transfer of DNA fragments from an electrophoresis gel to a membrane support (the properties and advantages of the different types of membrane, transfer buffer, and transfer method are discussed in detail), resulting in immobilization of the DNA fragments, so the membrane carries a semipermanent reproduction of the banding pattern of the gel. After immobilization, the DNA can be subjected to hybridization analysis, enabling bands with sequence similarity to a labeled probe to be identified. This appendix describes Southern blotting via upward capillary transfer of DNA from an agarose gel onto a nylon or nitrocellulose membrane, using a high-salt transfer buffer to promote binding of DNA to the membrane. With the high-salt buffer, the DNA becomes bound to the membrane during transfer but not permanently immobilized. Immobilization is achieved by UV irradiation (for nylon) or baking (for nitrocellulose). A Support Protocol describes how to calibrate a UV transilluminator for optimal UV irradiation of a nylon membrane. An alternate protocol details transfer using nylon membranes and an alkaline buffer, and is primarily used with positively charged nylon membranes. The advantage of this combination is that no post-transfer immobilization step is required, as the positively charged membrane binds DNA irreversibly under alkaline transfer conditions. The method can also be used with neutral nylon membranes but less DNA will be retained. A second alternate protocol describes a transfer method based on a different transfer-stack setup. The traditional method of upward capillary transfer of DNA from gel to membrane described in the first basic and alternate protocols has certain disadvantages, notably the fact that the gel can become crushed by the weighted filter papers and paper towels that are laid on top of it. This slows down the blotting process and may reduce the amount of DNA that can b