Decadal and Century-Long Changes in Storminess at Long-Term Ecological Research Sites

2003 ◽  
Author(s):  
Bruce P. Hayden ◽  
Nils R. Hayden
Keyword(s):  
United States ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Jet Stream ◽  
Ecological Research ◽  
La Nina ◽  
Extratropical Storms ◽  
Long Term Ecological Research

Ecological disturbances at Long-Term Ecological Research (LTER) sites are often the result of extreme meteorological events. Among the events of significance are tropical storms, including hurricanes, and extratropical cyclones. Extratropical storms are low-pressure systems of the middle and high latitudes with their attendant cold and warm fronts. These fronts are associated with strong, horizontal thermal gradients in surface temperatures, strong winds, and a vigorous jet stream aloft. These storms and their attendant fronts generate most of the annual precipitation in the continental United States and provide the lifting mechanisms for thunderstorms that, on occasion, spawn tornadoes. Off the United States West and East Coasts, extratropical storms generate winds, wind waves, wind tides, and long-shore currents that rework coastal sediments, alter landscape morphology, and change the regional patterns of coastal erosion and accretion (Dolan et al. 1988). Although extratropical storms do not match hurricanes in either precipitation intensity or in the strength of the winds generated, they are much larger in size and have a more extensive geographic impact. On occasion, extratropical storms will intensify at an extraordinary rate of 1 millibar (mb) per hour for 24 hours or more. Such storms are classed as “bomb” and are comparable to hurricanes. Extratropical storms occur in all months of the year but are most frequent and more intense in winter when the north-south temperature contrast is large and dynamic support for storm intensification from the stronger jet stream aloft is great. In this chapter, we will explore the history of storminess for those LTER sites in the continental United States at which more than a century of data on storms and their storm tracks are readily available. Specifically, we will look at the record of changes in storminess at both the regional and national scales. During the 1990s, significant storms along the U.S. West Coast and droughts and fires in Florida in an El Niño year led to a hypothesis that El Niño and La Niña conditions were associated with a modulation in the frequency of storms. In addition, it has been suggested that the frequency of El Niño and La Niña events and, by inference, storminess, has increased during the past century.

Climate Assessment for 1998

1999 ◽  
Vol 80 (5s) ◽  
pp. S1-S48 ◽  
Author(s):  
Gerald D. Bell ◽  
Michael S. Halpert ◽  
Chester F. Ropelewski ◽  
Vernon E. Kousky ◽  
Arthur V. Douglas ◽  
...  
Keyword(s):  
United States ◽  
El Niño ◽  
El Nino ◽  
Historical Record ◽  
Tropical Pacific ◽  
La Niña ◽  
Extreme Drought ◽  
Northern Australia ◽  
Hurricane Mitch ◽  
La Nina

The global climate during 1998 was affected by opposite extremes of the ENSO cycle, with one of the strongest Pacific warm episodes (El Niño) in the historical record continuing during January–early May and Pacific cold episode (La Niña) conditions occurring from JulyñDecember. In both periods, regional temperature, rainfall, and atmospheric circulation patterns across the Pacific Ocean and the Americas were generally consistent with those observed during past warm and cold episodes. Some of the most dramatic impacts from both episodes were observed in the Tropics, where anomalous convection was evident across the entire tropical Pacific and in most major monsoon regions of the world. Over the Americas, many of the El Niño– (La Niña–) related rainfall anomalies in the subtropical and extratropical latitudes were linked to an extension (retraction) of the jet streams and their attendant circulation features typically located over the subtropical latitudes of both the North Pacific and South Pacific. The regions most affected by excessive El Niño–related rainfall included 1) the eastern half of the tropical Pacific, including western Ecuador and northwestern Peru, which experienced significant flooding and mudslides; 2) southeastern South America, where substantial flooding was also observed; and 3) California and much of the central and southern United States during January–March, and the central United States during April–June. El Niño–related rainfall deficits during 1998 included 1) Indonesia and portions of northern Australia; 2) the Amazon Basin, in association with a substantially weaker-than-normal South American monsoon circulation; 3) Mexico, which experienced extreme drought throughout the El Niño episode; and 4) the Gulf Coast states of the United States, which experienced extreme drought during April–June 1998. The El Niño also contributed to extreme warmth across North America during January–May. The primary La Niña–related precipitation anomalies included 1) increased rainfall across Indonesia, and a nearly complete disappearance of rainfall across the east-central equatorial Pacific; 2) above-normal rains across northwestern, eastern, and northern Australia; 3) increased monsoon rains across central America and Mexico during October–December; and 4) dryness across equatorial eastern Africa. The active 1998 North Atlantic hurricane season featured 14 named storms (9 of which became hurricanes) and the strongest October hurricane (Mitch) in the historical record. In Honduras and Nicaragua extreme flooding and mudslides associated with Hurricane Mitch claimed more than 11 000 lives. During the peak of activity in August–September, the vertical wind shear across the western Atlantic, along with both the structure and location of the African easterly jet, were typical of other active seasons. Other regional aspects of the short-term climate included 1) record rainfall and massive flooding in the Yangtze River Basin of central China during June–July; 2) a drier and shorter-than-normal 1997/98 rainy season in southern Africa; 3) above-normal rains across the northern section of the African Sahel during June–September 1998; and 4) a continuation of record warmth across Canada during June–November. Global annual mean surface temperatures during 1998 for land and marine areas were 0.56°C above the 1961–90 base period means. This record warmth surpasses the previous highest anomaly of +0.43°C set in 1997. Record warmth was also observed in the global Tropics and Northern Hemisphere extratropics during the year, and is partly linked to the strong El Nino conditions during January–early May.

Impact of Rossby Wave Breaking on U.S. West Coast Winter Precipitation during ENSO Events

2013 ◽  
Vol 26 (17) ◽  
pp. 6360-6382 ◽  
Author(s):  
Ju-Mee Ryoo ◽  
Yohai Kaspi ◽  
Darryn W. Waugh ◽  
George N. Kiladis ◽  
Duane E. Waliser ◽  
...  
Keyword(s):  
United States ◽  
West Coast ◽  
El Niño ◽  
Wave Breaking ◽  
El Nino ◽  
The United States ◽  
La Niña ◽  
The West ◽  
La Nina ◽  
Subtropical Jet

Abstract This study demonstrates that water vapor transport and precipitation are largely modulated by the intensity of the subtropical jet, transient eddies, and the location of wave breaking events during the different phases of ENSO. Clear differences are found in the potential vorticity (PV), meteorological fields, and trajectory pathways between the two different phases. Rossby wave breaking events have cyclonic and anticyclonic regimes, with associated differences in the frequency of occurrence and the dynamic response. During La Niña, there is a relatively weak subtropical jet allowing PV to intrude into lower latitudes over the western United States. This induces a large amount of moisture transport inland ahead of the PV intrusions, as well as northward transport to the west of a surface anticyclone. During El Niño, the subtropical jet is relatively strong and is associated with an enhanced cyclonic wave breaking. This is accompanied by a time-mean surface cyclone, which brings zonal moisture transport to the western United States. In both (El Niño and La Niña) phases, there is a high correlation (>0.3–0.7) between upper-level PV at 250 hPa and precipitation over the west coast of the United States with a time lag of 0–1 days. Vertically integrated water vapor fluxes during El Niño are up to 70 kg m−1 s−1 larger than those during La Niña along the west coast of the United States. The zonal and meridional moist static energy flux resembles wave vapor transport patterns, suggesting that they are closely controlled by the large-scale flows and location of wave breaking events during the different phase of ENSO.

scholarly journals Can small pelagic fish landings be used as predictors of high-frequency oceanographic fluctuations in the 1–2 El Niño region?

2016 ◽  
Vol 42 ◽  
pp. 61-72 ◽  
Author(s):  
Franklin Isaac Ormaza-González ◽  
Alejandra Mora-Cervetto ◽  
Raquel María Bermúdez-Martínez ◽  
Mario Armando Hurtado-Domínguez ◽  
Manuel Raúl Peralta-Bravo ◽  
...  
Keyword(s):  
Linear Correlation ◽  
El Niño ◽  
El Nino ◽  
Pelagic Fish ◽  
La Niña ◽  
Negative Slope ◽  
South American ◽  
Small Pelagic Fish ◽  
La Nina

Abstract. A group of small pelagic fish captured between 1981 and 2012 within El Niño area 1–2 by the Ecuadorian fleet was correlated with the oceanographic Multivariate ENSO Index (MEI), and the Oceanographic El Niño Index (ONI) referred to El Niño region 3–4. For the period 1981–2012, total landings correlated poorly with the indexes, but during 2000–2012 (cold PDO) they proved to have a 14–29 % association with both indexes; the negative slope of the curves suggested higher landing during cold events (La Niña) and also indicated a tendency to decrease at extreme values ( >  0.5 and  < −1.0). Round herring (Etrumeus teres) fourth-quarter (Q4) landings were related to the MEI in a nonlinear analysis by up to 80 %. During moderate or strong La Niña events landings noticeably increased. Bullet tuna (Auxis spp.) catches showed a negative gradient from cold to warm episodes with an R2 of 0.149. For Chilean jack mackerel (Trachurus murphyi) irregular landings between 2003 and 2007 were observed and were poorly correlated (R2 < 0.1) with ONI or MEI. Anchovy (Engraulis ringens) captured in Ecuadorian waters since 2000 had an R2 of 0.302 and 0.156 for MEI and ONI, respectively, but showed a higher correlation with the cold Pacific Decadal Oscillation (PDO). South American pilchard (Sardinops sagax) was higher than −0.5 for the ONI and MEI, and landings dramatically decreased; however, Q4 landings correlated with ONI and MEI, with R2 of 0.109 and 0.225, respectively (n = 3). Linear correlation of Q4 indexes against the following year's Q1 landings had a linkage of up to 22 %; this species could therefore be considered a predictor of El Niño. Chub mackerel (Scomber japonicus) landings did not have a significant linear correlation with the indexes for 1981–2012 and therefore could not be considered a valid predictor. Chuhueco (Cetengraulis mysticetus) is a local species with high landings during El Niño years and, conversely, remarkably low landings during La Niña years. Additionally, chuhueco availability and landings were negatively affected by cold PDOs. Pacific thread herring (Opisthonema spp.) showed a 24 and 36 % relationship between landings (Q1) and the MEI and ONI (Q4). Therefore, results suggest that the South American pilchard and Pacific thread herring could be considered good species to use as predictors of El Niño in region 1–2 (Ecuador), especially when average Q4 MEI ∕ ONI is used against the next trimester Q1 landing. All species were prone to lower landings and/or fishing availability during strong–extreme events (ONI/MEI,  >  1.0 and  <  −1.0), and were also shown to be affected by the PDO. In the long term, landings decreased under warm PDO and vice versa, and therefore PDO fluctuations could be used to help manage these fisheries and to help the industry in long-term planning.

scholarly journals Trends in Twentieth-Century U.S. Extreme Snowfall Seasons

2009 ◽  
Vol 22 (23) ◽  
pp. 6204-6216 ◽  
Author(s):  
Kenneth E. Kunkel ◽  
Michael A. Palecki ◽  
Leslie Ensor ◽  
David Easterling ◽  
Kenneth G. Hubbard ◽  
...  
Keyword(s):  
United States ◽  
El Niño ◽  
El Nino ◽  
The United States ◽  
La Niña ◽  
The South ◽  
North Central ◽  
La Nina ◽  
Central United States ◽  
Highly Correlated

Abstract Temporal variability in the occurrence of the most extreme snowfall years, both those with abundant snowfall amounts and those lacking snowfall, was examined using a set of 440 quality-controlled, homogenous U.S. snowfall records. The frequencies with which winter-centered annual snowfall totals exceeded the 90th and 10th percentile thresholds at individual stations were calculated from 1900–01 to 2006–07 for the conterminous United States, and for 9 standard climate regions. The area-weighted conterminous U.S. results do not show a statistically significant trend in the occurrence of either high or low snowfall years for the 107-yr period, but there are regional trends. Large decreases in the frequency of low-extreme snowfall years in the west north-central and east north-central United States are balanced by large increases in the frequency of low-extreme snowfall years in the Northeast, Southeast, and Northwest. During the latter portion of the period, from 1950–51 to 2006–07, trends are much more consistent, with the United States as a whole and the central and northwest U.S. regions in particular showing significant declines in high-extreme snowfall years, and four regions showing significant increases in the frequency of low-extreme snowfall years (i.e., Northeast, Southeast, south, and Northwest). In almost all regions of the United States, temperature during November–March is more highly correlated than precipitation to the occurrence of extreme snowfall years. El Niño events are strongly associated with an increase in low-extreme snowfall years over the United States as a whole, and in the northwest, northeast, and central regions. A reduction in low-extreme snowfall years in the Southwest is also associated with El Niño. The impacts of La Niña events are strongest in the south and Southeast, favoring fewer high-extreme snowfall years, and, in the case of the south, more low-extreme snowfall years occur. The Northwest also has a significant reduction in the chance of a low-extreme snowfall year during La Niña. A combination of trends in temperature in the United States and changes in the frequency of ENSO modes influences the frequency of extreme snowfall years in the United States.

scholarly journals An Investigation of the Southern Ocean Surface Temperature Variability Using Long-Term Optimum Interpolation SST Data

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Megha Maheshwari ◽  
Rajkumar Kamaljit Singh ◽  
Sandip Rashmikant Oza ◽  
Raj Kumar
Keyword(s):  
Southern Ocean ◽  
El Niño ◽  
El Nino ◽  
Linear Trend ◽  
Critical Role ◽  
La Niña ◽  
Optimum Interpolation ◽  
La Nina ◽  
Sst Anomaly

An attempt is made to understand the long-term variability of SST using NOAA optimum interpolation SST data for the period (1982–2011) in the Southern Ocean. This dataset has been used (i) to study the interannual variability in SST anomaly and (ii) to carry out regression analysis to compute linear trend in the annual averaged Southern Ocean SST. It is observed that summer season exhibits more variability than winter. Moreover, El Nino/La Nina events apparently play a critical role in the variability of Southern Ocean SST. Thus, higher SST anomalies were observed in El Nino years (e.g., 1983), while cooler anomalies were seen during La Nina years (e.g., 1985). In addition, the eastern and western sides of Antarctica experience episodes of warm and cold SST. Western parts of the Southern Ocean experienced higher anomalies during 1992, 1993, and 1994, while the eastern part experienced positive anomalies in 1997, 1998, 2002, and 2003. The paper also highlights the different regions of the Southern Ocean showing statistically significant positive/negative trends in the variability of interannual average SST. However, in general, the Southern Ocean as a whole is showing a weak interannual cooling trend in SST.

scholarly journals ENSO Teleconnections and Impacts on U.S. Summertime Temperature during a Multiyear La Niña Life Cycle

2020 ◽  
Vol 33 (14) ◽  
pp. 6009-6024
Author(s):  
Bor-Ting Jong ◽  
Mingfang Ting ◽  
Richard Seager ◽  
Weston B. Anderson
Keyword(s):  
United States ◽  
Life Cycle ◽  
North America ◽  
El Niño ◽  
El Nino ◽  
The United States ◽  
La Niña ◽  
Central Pacific ◽  
Enso Teleconnections ◽  
La Nina

AbstractEl Niño–Southern Oscillation (ENSO) teleconnections have been recognized as possible negative influences on crop yields in the United States during the summer growing season, especially in a developing La Niña summer. This study examines the physical processes of the ENSO summer teleconnections and remote impacts on the United States during a multiyear La Niña life cycle. Since 1950, a developing La Niña summer is either when an El Niño is transitioning to a La Niña or when a La Niña is persisting. Due to the distinct prior ENSO conditions, the oceanic and atmospheric characteristics in the tropics are dissimilar in these two different La Niña summers, leading to different teleconnection patterns. During the transitioning summer, the decaying El Niño and the developing La Niña induce suppressed deep convection over both the subtropical western Pacific (WP) and the tropical central Pacific (CP). Both of these two suppressed convection regions induce Rossby wave propagation extending toward North America, resulting in a statistically significant anomalous anticyclone over northeastern North America and, therefore, a robust warming signal over the Midwest. In contrast, during the persisting summer, only one suppressed convection region is present over the tropical CP induced by the La Niña SST forcing, resulting in a weak and insignificant extratropical teleconnection. Experiments from a stationary wave model confirm that the suppressed convection over the subtropical WP during the transitioning summer not only contributes substantially to the robust warming over the Midwest but also causes the teleconnections to be different from those in the persisting summer.

Rain-on-Snow Events in the Western United States

2007 ◽  
Vol 88 (3) ◽  
pp. 319-328 ◽  
Author(s):  
Gregory J. McCabe ◽  
Martyn P. Clark ◽  
Lauren E. Hay
Keyword(s):  
United States ◽  
El Niño ◽  
Temporal Variability ◽  
El Nino ◽  
Flood Hazard ◽  
La Niña ◽  
Western United States ◽  
Spatial And Temporal Variability ◽  
Southwestern United States ◽  
La Nina

Rain-on-snow events pose a significant flood hazard in the western United States. This study provides a description of the spatial and temporal variability of the frequency of rain-on-snow events for 4318 sites in the western United States during water years (October through September) 1949–2003. Rain-on-snow events are found to be most common during the months of October through May; however, at sites in the interior western United States, rain-on-snow events can occur in substantial numbers as late as June and as early as September. An examination of the temporal variability of October through May rain-on-snow events indicates a mixture of increasing and decreasing trends in rain-on-snow events across the western United States. Decreasing trends in rain-on-snow events are most pronounced at lower elevations and are associated with trends toward fewer snowfall days and fewer precipitation days with snow on the ground. Rain-on-snow events are more (less) frequent in the northwestern (southwestern) United States during La Niña (El Niño) conditions. Additionally, increases in temperature in the western United States appear to be contributing to decreases in the number of rain-on-snow events for many sites through effects on the number of days with snowfall and the number of days with snow on the ground.

scholarly journals Long-Term Variation in Survival of A Neotropical Freshwater Turtle: Habitat and Climatic Influences

Diversity ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 97 ◽  
Author(s):  
Mario F. Garcés-Restrepo ◽  
John L. Carr ◽  
Alan Giraldo
Keyword(s):  
El Niño ◽  
Transition Probabilities ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Freshwater Turtle ◽  
Freshwater Turtles ◽  
La Nina ◽  
Enso Phases

Few long-term demographic studies have been conducted on freshwater turtles of South America, despite the need for this type of inquiry to investigate natural variation and strengthen conservation efforts for these species. In this study, we examined the variation in demography of the Chocoan River Turtle (Rhinoclemmys nasuta) based on a population from an island locality in the Colombian Pacific region between 2005 and 2017. We calculated survival, recapture, and transition probabilities, and the effects of stream substrate and El Niño–Southern Oscillation (ENSO) phases (El Niño, Neutral, La Niña) on these variables using a multi-state model. We found differences in survival probabilities between ENSO phases, likely as a consequence of an increase in flood events. In addition, we found support for survival being greater in muddy streams than rocky streams, possibly because it is easier to escape or hide in mud substrates. Recapture probabilities varied by life stages; differences in the probability of recapture between size classes were associated with the high fidelity to territories by adults. The present increases in frequency and severity of El Niño and La Niña may exacerbate the consequences of climatic regimes on natural populations of turtles by increasing the mortality caused by drastic phenomena such as floods.

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