scholarly journals Impact of Severe Drought during the Strong 2015/2016 El Nino on the Phenology and Survival of Secondary Dry Dipterocarp Species in Western Thailand

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 967
Author(s):  
Rungnapa Kaewthongrach ◽  
Yann Vitasse ◽  
Taninnuch Lamjiak ◽  
Amnat Chidthaisong
Keyword(s):  
El Niño ◽  
Tree Mortality ◽  
Secondary Forest ◽  
El Nino ◽  
Leaf Phenology ◽  
Severe Drought ◽  
Deciduous Species ◽  
El Niño Event ◽  
El Niño Events ◽  
El Nino Events

Secondary forest areas are increasing worldwide and understanding how these forests interact with climate change including frequent and extreme events becomes increasingly important. This study aims to investigate the effects of the strong 2015/2016 El Niño-induced drought on species-specific leaf phenology, dieback and tree mortality in a secondary dry dipterocarp forest (DDF) in western Thailand. During the 2015/2016 El Niño event, rainfall and soil water content were lower than 25 mm and 5% during 5–6 consecutive months. The dry season was 3–4 months longer during the El Niño than during non-El Niño events. We found that this prolonged drought induced the earlier shedding and a delay in leaf emergence of the DDF. The deciduousness period was also longer during the El Niño event (5 months instead of 2–3 months during non-El Niño event). We found that the DDF species showed different phenological responses and sensitivities to the El Niño-induced drought. The leaf phenology of stem succulent species Lannea coromandelica (Houtt.) Merr. and a complete deciduous species with low wood density. Sindora siamensis Teijsm. ex Miq. was only slightly affected by the El Niño-induced drought. Conversely, a semi-deciduous species such as Dipterocarpus obtusifolius Teijsm. ex Miq. showed a higher degree of deciduousness during the El Niño compared to non-El Niño events. Our results also highlight that dieback and mortality during El Niño were increased by 45 and 50%, respectively, compared to non-El Niño events, pointing at the importance of such events to shape DDF ecosystems.

Summer Cooling Driven by Large Volcanic Eruptions over the Tibetan Plateau

2018 ◽  
Vol 31 (24) ◽  
pp. 9869-9879 ◽  
Author(s):  
Jianping Duan ◽  
Lun Li ◽  
Zhuguo Ma ◽  
Jan Esper ◽  
Ulf Büntgen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
El Niño ◽  
El Nino ◽  
Volcanic Eruptions ◽  
The Tibetan Plateau ◽  
Temperature Deviation ◽  
El Niño Event ◽  
El Niño Events ◽  
Large Volcanic Eruptions ◽  
El Nino Events

Large volcanic eruptions may cause abrupt summer cooling over large parts of the globe. However, no comparable imprint has been found on the Tibetan Plateau (TP). Here, we introduce a 400-yr-long temperature-sensitive network of 17 tree-ring maximum latewood density sites from the TP that demonstrates that the effects of tropical eruptions on the TP are generally greater than those of extratropical eruptions. Moreover, we found that large tropical eruptions accompanied by subsequent El Niño events caused less summer cooling than those that occurred without El Niño association. Superposed epoch analysis (SEA) based on 27 events, including 14 tropical eruptions and 13 extratropical eruptions, shows that the summer cooling driven by extratropical eruptions is insignificant on the TP, while significant summer temperature decreases occur subsequent to tropical eruptions. Further analysis of the TP August–September temperature responses reveals a significant postvolcanic cooling only when no El Niño event occurred. However, there is no such cooling for all other situations, that is, tropical eruptions together with a subsequent El Niño event, as well as extratropical eruptions regardless of the occurrence of an El Niño event. The averaged August–September temperature deviation ( Tdev) following 10 large tropical eruptions without a subsequent El Niño event is up to −0.48° ± 0.19°C (with respect to the preceding 5-yr mean), whereas the temperature deviation following 4 large tropical eruptions with an El Niño association is approximately 0.23° ± 0.16°C. These results indicate a mitigation effect of El Niño events on the TP temperature response to large tropical eruptions. The possible mechanism is that El Niño events can weaken the Indian summer monsoon with a subsequent decrease in rainfall and cooling effect, which may lead to a relatively high temperature on the TP, one of the regions affected by the Indian summer monsoon.

scholarly journals Three Putative Types of El Niño Revealed by Spatial Variability in Impact on Australian Wheat Yield

2005 ◽  
Vol 18 (10) ◽  
pp. 1566-1574 ◽  
Author(s):  
A. B. Potgieter ◽  
G. L. Hammer ◽  
H. Meinke ◽  
R. C. Stone ◽  
L. Goddard
Keyword(s):  
Spatial Patterns ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Wheat Yield ◽  
Severe Drought ◽  
Seasonal Forecasts ◽  
El Niño Events ◽  
Australian Wheat ◽  
El Nino Events

Abstract The El Niño–Southern Oscillation (ENSO) phenomenon significantly impacts rainfall and ensuing crop yields in many parts of the world. In Australia, El Niño events are often associated with severe drought conditions. However, El Niño events differ spatially and temporally in their manifestations and impacts, reducing the relevance of ENSO-based seasonal forecasts. In this analysis, three putative types of El Niño are identified among the 24 occurrences since the beginning of the twentieth century. The three types are based on coherent spatial patterns (“footprints”) found in the El Niño impact on Australian wheat yield. This bioindicator reveals aligned spatial patterns in rainfall anomalies, indicating linkage to atmospheric drivers. Analysis of the associated ocean–atmosphere dynamics identifies three types of El Niño differing in the timing of onset and location of major ocean temperature and atmospheric pressure anomalies. Potential causal mechanisms associated with these differences in anomaly patterns need to be investigated further using the increasing capabilities of general circulation models. Any improved predictability would be extremely valuable in forecasting effects of individual El Niño events on agricultural systems.

Maritime Adaptations at Cerro Azul, Peru

2020 ◽  
pp. 351-365
Author(s):  
Joyce Marcus ◽  
Kent V. Flannery ◽  
Jeffrey Sommer ◽  
Robert G. Reynolds
Keyword(s):  
20Th Century ◽  
El Niño ◽  
El Nino ◽  
Late Intermediate Period ◽  
Intermediate Period ◽  
El Niño Event ◽  
Peruvian Coast ◽  
Maritime Adaptations ◽  
El Niño Events ◽  
El Nino Events

Chapter 13 discusses Late Intermediate Period (~1000–1400 cal AD) and 20th-century fishing at Cerro Azul, a large site in the Cañete Valley on the Peruvian coast south of Lima. The authors provide data on the effects of the 1982–83 El Niño event on the local fisheries and use these data to examine the Cerro Azul zooarchaeological assemblage for evidence of El Niño events; they did not find signs of El Niño although events occurred while the site was inhabited.

Volcanoes and ENSO over the Past Millennium

2008 ◽  
Vol 21 (13) ◽  
pp. 3134-3148 ◽  
Author(s):  
Julien Emile-Geay ◽  
Richard Seager ◽  
Mark A. Cane ◽  
Edward R. Cook ◽  
Gerald H. Haug
Keyword(s):  
El Niño ◽  
El Nino ◽  
Volcanic Eruptions ◽  
Explosive Volcanism ◽  
The Past ◽  
El Niño Event ◽  
Volcanic Forcing ◽  
El Niño Events ◽  
Past Millennium ◽  
El Nino Events

Abstract The controversial claim that El Niño events might be partially caused by radiative forcing due to volcanic aerosols is reassessed. Building on the work of Mann et al., estimates of volcanic forcing over the past millennium and a climate model of intermediate complexity are used to draw a diagram of El Niño likelihood as a function of the intensity of volcanic forcing. It is shown that in the context of this model, only eruptions larger than that of Mt. Pinatubo (1991, peak dimming of about 3.7 W m−2) can shift the likelihood and amplitude of an El Niño event above the level of the model’s internal variability. Explosive volcanism cannot be said to trigger El Niño events per se, but it is found to raise their likelihood by 50% on average, also favoring higher amplitudes. This reconciles, on one hand, the demonstration by Adams et al. of a statistical relationship between explosive volcanism and El Niño and, on the other hand, the ability to predict El Niño events of the last 148 yr without knowledge of volcanic forcing. The authors then focus on the strongest eruption of the millennium (A.D. 1258), and show that it is likely to have favored the occurrence of a moderate-to-strong El Niño event in the midst of prevailing La Niña–like conditions induced by increased solar activity during the well-documented Medieval Climate Anomaly. Compiling paleoclimate data from a wide array of sources, a number of important hydroclimatic consequences for neighboring areas is documented. The authors propose, in particular, that the event briefly interrupted a solar-induced megadrought in the southwestern United States. Most of the time, however, volcanic eruptions are found to be too small to significantly affect ENSO statistics.

scholarly journals MLS measurements of stratospheric hydrogen cyanide during the 2015–16 El Niño event

2017 ◽  
Author(s):  
Hugh C. Pumphrey ◽  
Norbert Glatthor ◽  
Peter F. Bernath ◽  
Christopher D. Boone ◽  
James Hannigan ◽  
...  
Keyword(s):  
El Niño ◽  
Hydrogen Cyanide ◽  
Lower Stratosphere ◽  
El Nino ◽  
Good Qualitative Agreement ◽  
Mixing Ratios ◽  
El Niño Event ◽  
El Niño Events ◽  
El Nino Events ◽  
Enso Indices

Abstract. It is known from ground-based measurements made during the 1982–83 and 1997–98 El Niño events that atmospheric HCN tends to be higher than usual during such years. The Microwave Limb Sounder (MLS) on Aura has been measuring HCN mixing ratios since launch in 2004; the measurements are ongoing at the time of writing. The winter of 2015–16 has seen the largest El Niño event since 1997–98. We present MLS measurements of HCN in the lower stratosphere for the Aura mission to date, comparing the 2015–16 El Niño period to the rest of the mission. HCN in 2015–16 is higher than at any other time during the mission, but ground based measurements suggest that it may have been even more elevated in 1997–98. As the MLS HCN data are essentially un-validated, we show them alongside data from the MIPAS and ACE-FTS instruments; the three instruments agree reasonably well in the tropical lower stratosphere. Global HCN emissions calculated from the GFED (V4.1) database are very much greater during large El Niño events and are greater in 1997–98 than in 2015–16, thereby showing good qualitative agreement with the measurements. Correlation between ENSO indices, measured HCN and GFED HCN emissions is less clear away from the 2015–16 event. In particular, the 2009–10 winter had fairly strong El Niño conditions and fairly large GFED HCN emissions, but very little effect is observed in the MLS HCN.

scholarly journals Tropical Ocean Contributions to California’s Surprisingly Dry El Niño of 2015/16

2017 ◽  
Vol 30 (24) ◽  
pp. 10067-10079 ◽  
Author(s):  
Nicholas Siler ◽  
Yu Kosaka ◽  
Shang-Ping Xie ◽  
Xichen Li
Keyword(s):  
El Niño ◽  
Radiative Forcing ◽  
Large Scale ◽  
El Nino ◽  
Principal Component ◽  
Severe Drought ◽  
Tropical Ocean ◽  
Sst Variability ◽  
El Niño Events ◽  
El Nino Events

The major El Niño of 2015/16 brought significantly less precipitation to California than previous events of comparable strength, much to the disappointment of residents suffering through the state’s fourth consecutive year of severe drought. Here, California’s weak precipitation in 2015/16 relative to previous major El Niño events is investigated within a 40-member ensemble of atmosphere-only simulations run with historical sea surface temperatures (SSTs) and constant radiative forcing. The simulations reveal significant differences in both California precipitation and the large-scale atmospheric circulation between 2015/16 and previous strong El Niño events, which are similar to (albeit weaker than) the differences found in observations. Principal component analysis indicates that these ensemble-mean differences were likely related to a pattern of tropical SST variability with a strong signal in the Indian Ocean and western Pacific and a weaker signal in the eastern equatorial Pacific and subtropical North Atlantic. This SST pattern was missed by the majority of forecast models, which could partly explain their erroneous predictions of above-average precipitation in California in 2015/16.

Effective population size for South American sea lions along the Peruvian coast: the survivors of the strongest El Niño event in history

2012 ◽  
Vol 92 (8) ◽  
pp. 1835-1841 ◽  
Author(s):  
Larissa Rosa de Oliveira ◽  
Lúcia Darsie Fraga ◽  
Patricia Majluf
Keyword(s):  
Population Size ◽  
El Niño ◽  
El Nino ◽  
South American ◽  
Effective Population ◽  
Sea Lions ◽  
El Niño Event ◽  
Peruvian Coast ◽  
El Niño Events ◽  
El Nino Events

The South American sea lion, Otaria flavescens, has been considered vulnerable and under the threat of extinction in Peru due to the drastic demographic changes as a result of the impact of low food availability and the unusual timing of the severe El Niño event of 1997–1998. We present the first estimate of effective population size (Ne) for the species that takes into account the effects of mating system and variation in population size in different generations caused by the severe El Niño event of 1997–1998. The resulting Ne was 7715 specimens. We believe that the estimated Ne for the Peruvian population is not a critical value, because it is higher than the mean minimum viable population generally accepted for vertebrates (ca. 5000 breeding adults). However, the viability of O. flavescens on the Peruvian coast may depend primarily on local availability of food resources. Climatic change models predict stronger and more frequent El Niño events. In this sense, the Ne of 7715 should be considered as a value to be maintained in order to keep the population large enough to avoid inbreeding or to retain adaptive genetic variation to survive to future El Niño events. Moreover, this Ne estimate is important data in discussions about resuming culling activities, based on the statement of an increasing competition between fishery activity and sea lions during El Niño events. Thus, this Ne should be taken into account in future management plans to ensure the conservation of the species on the Peruvian coast.

scholarly journals ENSO diversity driving low-frequency change in mesoscale activity off Peru and Chile

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Carlos Conejero ◽  
Boris Dewitte ◽  
Véronique Garçon ◽  
Joël Sudre ◽  
Ivonne Montes
Keyword(s):  
El Niño ◽  
El Nino ◽  
Low Frequency ◽  
Altimeter Data ◽  
Central Pacific El Niño ◽  
Central Chile ◽  
El Niño Event ◽  
El Niño Events ◽  
Ep El Niño ◽  
El Nino Events

Abstract Transient mesoscale oceanic eddies in Eastern Boundary Upwelling Systems are thought to strongly affect key regional scale processes such as ocean heat transport, coastal upwelling and productivity. Understanding how these can be modulated at low-frequency is thus critical to infer their role in the climate system. Here we use 26 years of satellite altimeter data and regional oceanic modeling to investigate the modulation of eddy kinetic energy (EKE) off Peru and Chile by ENSO, the main mode of natural variability in the tropical Pacific. We show that EKE tends to increase during strong Eastern Pacific (EP) El Niño events along the Peruvian coast up to northern Chile and decreases off central Chile, while it is hardly changed during Central Pacific El Niño and La Niña events. However the magnitude of the EKE changes during strong EP El Niño events is not proportional to their strength, with in particular the 1972/1973 El Niño event standing out as an extreme event in terms of EKE increase off Peru reaching an amplitude three times as large as that during the 1997/1998 El Niño event, and the 2015/2016 El Niño having instead a weak impact on EKE. This produces decadal changes in EKE, with a similar pattern than that of strong EP El Niño events, resulting in a significant negative (positive) long-term trend off Peru (central Chile).

scholarly journals Contrasting impacts of two types of El Niño events on winter haze days in China's Jing-Jin-Ji region

2020 ◽  
Author(s):  
Xiaochao Yu ◽  
Zhili Wang ◽  
Hua Zhang ◽  
Jianjun He ◽  
Ying Li
Keyword(s):  
El Niño ◽  
El Nino ◽  
Eastern China ◽  
Cp El Niño ◽  
El Niño Event ◽  
Haze Pollution ◽  
El Niño Events ◽  
Ep El Niño ◽  
Haze Days ◽  
El Nino Events

Abstract. El Niño is a complex system with diverse distribution features and intensities. The regional climate anomalies caused by different types of El Niño event likely lead to various impacts on winter haze pollution in China. Based on long-term site observations of haze days in China from 1961 to 2013, this study explores the effects of Eastern Pacific (EP) and Central Pacific (CP) types of El Niño event on winter haze days (WHD) in China's Jing-Jin-Ji (JJJ) region and the physical mechanisms underlying WHD changes. The results show statistically significant positive and negative correlations, respectively, between WHD in the JJJ region and EP and CP El Niño events. At most sites in the JJJ region, the average WHD are increased in all EP El Niño years, with the maximum change exceeding 2.0 days. Meanwhile the average WHD are decreased at almost all stations over this region in all CP El Niño years, with the largest change being more than −2.0 days. The changes in large-scale circulations indicate obviously positive surface air temperature (SAT) anomalies and negative sea level pressure (SLP) anomalies over North China, and southerly wind anomalies at the mid-low troposphere over eastern China in the winters of EP El Niño years. These anomalies are conducive to increases in WHD in the JJJ region. However, there are significant northerly and northwesterly wind anomalies at the mid-low troposphere over eastern China, and stronger and wider precipitation anomalies in the winters of CP El Niño years, which contribute to decreased WHD over the JJJ region. Changes in local synoptic conditions indicate negative SLP anomalies, positive SAT anomalies, and weakened northerly winds over the JJJ region in the winters of EP El Niño years. The occurrence frequency of circulation types conducive to the accumulation (diffusion) of aerosol pollutants is increased (decreased) by 0.4 % (0.37 %) in those winters. However, the corresponding frequency is decreased (increased) by 0.54 % (0.56 %) in the winters of CP El Niño years. Our study highlights the importance of distinguishing the impacts of two types of El Niño events on winter haze pollution in China's JJJ region.

scholarly journals Pengaruh El Niño Terhadap Pola Distribusi Klorofil-a dan Pola Arus di Wilayah Perairan Selatan Maluku

2021 ◽  
Vol 24 (3) ◽  
pp. 364-374
Author(s):  
Yosafat Donni Haryanto ◽  
Hadiman Hadiman ◽  
Rezfiko Agdialta ◽  
Nelly Florida Riama
Keyword(s):  
Chlorophyll A ◽  
El Niño ◽  
Positive Impact ◽  
El Nino ◽  
Chlorophyll A Concentration ◽  
El Niño Event ◽  
A Value ◽  
Weather And Climate ◽  
El Niño Events ◽  
El Nino Events

El Niño is a phenomenon that can affect changes in weather and climate elements in Indonesia, especially rainfall. During the El Niño events, the rainfall in Maluku region tended to decrease. This condition can indeed cause prolonged drought. However, El Niño events also have a positive impact, especially in water areas. During the El Niño events, the chlorophyll-a concentration in the water will increase. This is due to the upwelling process that removes nutrients from the sea. High chlorophyll-a concentrations will bring pelagic fish species in the waters. The correlation test between sea surface temperature (SST) during El Niño and chlorophyll-a has a value of -0.91. This correlation value indicates that when SST increases, the chlorophyll-a concentration in the waters will decrease, on the other hand, if SST has decreased, the chlorophyll-a concentration in the water will increase. The value of chlorophyll-a concentration in the water during the El Niño event (July - February) showed a significant increase compared to during normal conditions. Of all the El Niño events, 2015 to 2016 was the year with the strongest El Niño events. The chlorophyll-a concentration during El Niño 2015 to 2016 was very high, ranging from 0.2 to 1.0 mg / m3. The results obtained indicate that the El Niño event has a positive correlation with the increase in chlorophyll-a concentration in the water. El Niño merupakan fenomena yang tidak bisa dihindari, kejadian El Niño  dapat mengurangi curah hujan seperti di wilayah Maluku. Namun, kejadian El Niño  juga mempunyai dampak postif khususnya di wilayah perairan. Pada saat terjadi El Niño  maka konsentrasi klorofil-a di perairan akan meningkat. Hal ini disebabkan karena adanya proses upwelling yang mengangkat nutrisi dari dalam laut. Konsentrasi klorofil-a yang tinggi akan mendatangkan jenis ikan pelagis di perairan. Uji  korelasi antara suhu permukaan laut (SST) pada saat El Niño  dengan klorofil-a memiliki nilai  - 0.91. Nilai korelasi ini menunjukkan bahwa pada saat SST mengalami kenaikan maka konsentrasi klorofil di perairan akan menurun, sebaliknya jika SST mengalami penurunan maka konsentrasi klorofil diperairan akan meningkat. Nilai konsentrasi klorofil-a diperairan pada saat kejadian El Niño  (Juli - Februari) menunjukkan peningkatan yang cukup signifikan dibandingkan pada saat tidak terjadi El Niño . Dari semua kejadian El Niño , tahun 2015 - 2016 merupakan kejadian dengan El Niño  yang sangat kuat. Konsentrasi klorofil-a pada saat El Niño  2015 - 2016 sangat tinggi berkisar 0.2 - 1.0 mg/m3. Dari hasil yang didapatkan menunjukkan bahwa kejadian El Niño  dapat mempengaruhi konsentrasi klorofil-a diperairan.

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