scholarly journals Analisis Kejadian El Nino dan Dampaknya Terhadap Musim Tanam dan Produktivitas Kacang Tanah (Arachis hypogaea L.) di Pulau Kei Kecil Kabupaten Maluku Tenggara

2021 ◽  
Vol 17 (1) ◽  
pp. 52-58
Author(s):  
Esterlina Kelbulan ◽  
Samuel Laimeheriwa ◽  
Jacob R Patty
Keyword(s):  
Regression Analysis ◽  
El Niño ◽  
El Nino ◽  
Growing Season ◽  
Average Technique ◽  
El Niño Events ◽  
Normal Rainfall ◽  
Planting Season ◽  
Extreme El Niño ◽  
El Nino Events

Climate change has an impact that includes extreme climate events such as El Nino. Experience in recent decades has shown that the El Nino climate anomaly has caused prolonged droughts. Peanut are susceptible to drought in part or all of its growth phases due to below-normal rainfall. This study aimed to describe the occurrence of extreme El-Nino rainfall on Kei Kecil Island, Maluku Province, and how much the El-Nino events affected the planting season and peanut production on Kei Kecil Island. This was carried out using the algebraic average technique for calculating the average (normal) rainfall and the FAO (1978) method for determining the growing season. The variables observed were rainfall data and peanut plant productivity data. Data were analyzed using simple regression analysis. The results of the study showed that the El Nino phenomenon generally took place in the period from April to November; mostly starting in April, May, June and September, October and November. Drought events on Kei Kecil Island did not always coincide with El Nino events, and El Nino events did not always cause drought or rainfall below normal. In 1993, 2003, 2007, and 2012 the amount of rainfall on Kei Kecil Island was below normal (<2,308 mm per year) but these years were not recorded as El Nino years. Whereas, 1994, 2009, 2014, and 2018 were recorded as El Nino years but did not cause drought or rainfall under normal conditions on Kei Kecil Island. During the last 30 years, this incident occurred 3 times, i.e. in 1991, 1997, and 2015. The results of the analysis of the growing season showed that the planting season on Kei Kecil Island under conditions of average (normal) rainfall lasted for 289 days or 9 months 16 days (November 1 to August 16). Meanwhile, the growing season when extreme El Nino rainfall occurred, lasted for 201 days or 6 months 20 days (November 1 to May 20). This indicated that when El Nino occurred on Kei Kecil Island, there was a shift in the growing season (ending sooner). The results of the regression analysis illustrated that the increase of the value of rainfall would increase the productivity of peanut crop. Keywords: El Nino phenomenon, growing season, peanut, productivity, rainfall   ABSTRAK Perubahan iklim berdampak di antaranya terhadap kejadian iklim ekstrim seperti El Nino. Pengalaman dalam beberapa dekade terakhir ini menunjukkan bahwa anomali iklim El Nino telah menyebabkan kekeringan berkepanjangan. Kacang tanah rentan oleh deraan kekeringan pada sebagian ataupun seluruh fase pertumbuhannya akibat curah hujan yang di bawah normal. Penelitian ini bertujuan untuk mempelajari kejadian curah hujan ekstrim El-Nino di Pulau Kei Kecil, Provinsi Maluku, dan seberapa besar kejadian El-Nino mempengaruhi musim tanam dan produksi kacang tanah di Pulau Kei Kecil. Ini dilaksanakan dengan menggunakan metode teknik rata-rata aljabar untuk perhitungan curah hujan rata-rata (normal) dan metode FAO (1978) untuk penentuan musim tanam. Variabel yang diamati adalah data curah hujan dan data produktifitas tanaman kacang tanah. Data dianalisis menggunakan analisis regresi sederhana. Hasil penelitian menunjukkan fenomena El Nino umumnya berlangsung dalam periode April hingga November; terbanyak mulai bulan April, Mei, Juni dan September, Oktober dan November. Kejadian kekeringan di Pulau Kei Kecil tidak selalu bersamaan dengan kejadian El Nino, dan kejadian El Nino tidak selalu menyebabkan kekeringan atau curah hujan di bawah normal. Pada tahun 1993, 2003, 2007, dan 2012 jumlah curah hujan di Pulau Kei Kecil berada pada kondisi di bawah normal (<2.308 mm per btahun) tetapi tahun-tahun tersebut tidak tercatat sebagai tahun-tahun El Nino. Sementara itu, tahun 1994, 2009, 2014, dan 2018 tercatat sebagai tahun-tahun El Nino tetapi tidak menyebabkan kekeringan atau curah hujan di bawah kondisi normalnya di Pulau Kei Kecil. Selama periode 30 tahun terakhir kejadian ini berlangsung selama 3 kali, yaitu pada tahun 1991, 1997, dan 2015. Hasil analisis musim tanam menunjukkan bahwa musim tanam di Pulau Kei Kecil pada kondisi curah hujan rata-rata (normal) berlangsung selama 289 hari (1 November sampai dengan 16 Agustus; 9 bulan 16 hari). Sedangkan musim tanam ketika curah hujan ekstrim El Nino berlangsung selama 201 hari (1 November sampai dengan 20 Mei). Hal ini mengindikasikan bahwa ketika El Nino berlangsung di Pulau Kei Kecil, akan terjadi pergeseran musim tanam (berakhir lebih cepat). Hasil analisis regresi menggambarkan bahwa penigkatan nilai curah hujan akan menigkatkan produktivitas tanaman kacang tanah. Kata kunci: curah hujan, fenomena El Nino, kacang tanah, musim tanam, produktivitas

scholarly journals Effects of Excessive Equatorial Cold Tongue Bias on the Projections of Tropical Pacific Climate Change. Part II: The Extreme El Niño Frequency in CMIP5 Multi-Model Ensemble

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 851
Author(s):  
Gen Li ◽  
Zhiyuan Zhang ◽  
Bo Lu
Keyword(s):  
El Niño ◽  
Climate Models ◽  
El Nino ◽  
Equatorial Pacific ◽  
Western Pacific ◽  
Warming Pattern ◽  
El Niño Events ◽  
Rcp 8.5 ◽  
Extreme El Niño ◽  
El Nino Events

Under increased greenhouse gas (GHG) forcing, climate models tend to project a warmer sea surface temperature in the eastern equatorial Pacific than in the western equatorial Pacific. This El Niño-like warming pattern may induce an increase in the projected occurrence frequency of extreme El Niño events. The current models, however, commonly suffer from an excessive westward extension of the equatorial Pacific cold tongue accompanied by insufficient equatorial western Pacific precipitation. By comparing the Representative Concentration Pathway (RCP) 8.5 experiments with the historical simulations based on the Coupled Model Intercomparison Project phase 5 (CMIP5), a “present–future” relationship among climate models was identified: models with insufficient equatorial western Pacific precipitation error would have a weaker mean El Niño-like warming pattern as well as a lower increase in the frequency of extreme El Niño events under increased GHG forcing. Using this “present–future” relationship and the observed precipitation in the equatorial western Pacific, this study calibrated the climate projections in the tropical Pacific. The corrected projections showed a stronger El Niño-like pattern of mean changes in the future, consistent with our previous study. In particular, the projected increased occurrence of extreme El Niño events under RCP 8.5 forcing are underestimated by 30–35% in the CMIP5 multi-model ensemble before the corrections. This implies an increased risk of the El Niño-related weather and climate disasters in the future.

Longer Duration of the Weak Stratospheric Vortex During Extreme El Niño Events Linked to Spring Eurasian Coldness

2020 ◽  
Vol 125 (16) ◽  
Author(s):  
Xin Zhou ◽  
Quanliang Chen ◽  
Zhenglin Wang ◽  
Mian Xu ◽  
Sen Zhao ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events

The Extreme El Niño Events Suppressing the Intraseasonal Variability in the Eastern Tropical Indian Ocean

2020 ◽  
Vol 50 (8) ◽  
pp. 2359-2372
Author(s):  
Gengxin Chen ◽  
Dongxiao Wang ◽  
Weiqing Han ◽  
Ming Feng ◽  
Fan Wang ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Intraseasonal Variability ◽  
Tropical Indian Ocean ◽  
Ocean Dynamics ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events

AbstractIn the eastern tropical Indian Ocean, intraseasonal variability (ISV) affects the regional oceanography and marine ecosystems. Mooring and satellite observations documented two periods of unusually weak ISV during the past two decades, associated with suppressed baroclinic instability of the South Equatorial Current. Regression analysis and model simulations suggest that the exceptionally weak ISVs were caused primarily by the extreme El Niño events and modulated to a lesser extent by the Indian Ocean dipole. Additional observations confirm that the circulation balance in the Indo-Pacific Ocean was disrupted during the extreme El Niño events, impacting the Indonesian Throughflow Indian Ocean dynamics. This research provides substantial evidence for large-scale modes modulating ISV and the abnormal Indo-Pacific dynamical connection during extreme climate modes.

The impacts of extreme El Niño events on sea turtle nesting populations

2020 ◽  
Vol 159 (2) ◽  
pp. 163-176 ◽  
Author(s):  
P. Santidrián Tomillo ◽  
L. G. Fonseca ◽  
M. Ward ◽  
N. Tankersley ◽  
N. J. Robinson ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Sea Turtle ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events

scholarly journals Mechanisms Reducing ENSO Amplitude and Asymmetry via an Enhanced Seasonal Cycle in the Mid-Holocene

2019 ◽  
Vol 32 (23) ◽  
pp. 8069-8085
Author(s):  
Tomoki Iwakiri ◽  
Masahiro Watanabe
Keyword(s):  
El Niño ◽  
Seasonal Cycle ◽  
El Nino ◽  
Present Climate ◽  
Proxy Records ◽  
Thermocline Feedback ◽  
Equatorial Thermocline ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events

Abstract Paleo proxy records have suggested that El Niño–Southern Oscillation (ENSO) variability during the mid-Holocene [8200 to 4200 years ago (8.2–4.2 ka)] was weaker than during the instrumental periods, but the mechanisms remain unclear. We examined processes of ENSO suppression using a coupled general circulation model (CGCM) that simulates ENSO amplitude and skewness under the present climate reasonably well. Two long simulations were performed: one using the preindustrial condition (CTRL) and the other using the 8-ka insolation having a greater seasonal cycle (MH8K). Consistent with proxy records and previous modeling studies, the ENSO amplitude weakened by 20% in MH8K compared to CTRL, mainly because of reduced thermocline feedback during the mature and decay phases. The weak thermocline feedback, likely a result of the loose equatorial thermocline in the mid-Holocene, suppresses the occurrence of extreme El Niño events and consequently explains the reduction in both ENSO amplitude and asymmetry. In MH8K, strengthened trade winds over the western-central Pacific Ocean act to cool the surface via evaporation while warmer water in the southern subtropical Pacific is transported beneath the equatorial thermocline, both contributing to diffuse the thermocline. Multimodel simulations for the mid-Holocene showed mean state changes and ENSO weakening similar to MH8K, but most models did not show reduced ENSO skewness, probably because of the failure in reproducing extreme El Niño events under the present climate.

scholarly journals Historical change of El Niño properties sheds light on future changes of extreme El Niño

2019 ◽  
Vol 116 (45) ◽  
pp. 22512-22517 ◽  
Author(s):  
Bin Wang ◽  
Xiao Luo ◽  
Young-Min Yang ◽  
Weiyi Sun ◽  
Mark A. Cane ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Historical Change ◽  
Western Pacific ◽  
Intensity Change ◽  
Cmip5 Models ◽  
Central Pacific ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events

El Niño’s intensity change under anthropogenic warming is of great importance to society, yet current climate models’ projections remain largely uncertain. The current classification of El Niño does not distinguish the strong from the moderate El Niño events, making it difficult to project future change of El Niño’s intensity. Here we classify 33 El Niño events from 1901 to 2017 by cluster analysis of the onset and amplification processes, and the resultant 4 types of El Niño distinguish the strong from the moderate events and the onset from successive events. The 3 categories of El Niño onset exhibit distinct development mechanisms. We find El Niño onset regime has changed from eastern Pacific origin to western Pacific origin with more frequent occurrence of extreme events since the 1970s. This regime change is hypothesized to arise from a background warming in the western Pacific and the associated increased zonal and vertical sea-surface temperature (SST) gradients in the equatorial central Pacific, which reveals a controlling factor that could lead to increased extreme El Niño events in the future. The Coupled Model Intercomparison Project phase 5 (CMIP5) models’ projections demonstrate that both the frequency and intensity of the strong El Niño events will increase significantly if the projected central Pacific zonal SST gradients become enhanced. If the currently observed background changes continue under future anthropogenic forcing, more frequent strong El Niño events are anticipated. The models’ uncertainty in the projected equatorial zonal SST gradients, however, remains a major roadblock for faithful prediction of El Niño’s future changes.

scholarly journals Tropical Pacific Climate Variability under Solar Geoengineering: Impacts on ENSO Extremes

2019 ◽  
Author(s):  
Abdul Malik ◽  
Peer J. Nowack ◽  
Joanna D. Haigh ◽  
Long Cao ◽  
Luqman Atique ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Tropical Pacific ◽  
La Niña ◽  
La Nina ◽  
Solar Geoengineering ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events ◽  
The Tropical Pacific

Abstract. Many modelling studies suggest that the El Niño Southern Oscillation (ENSO), in interaction with the tropical Pacific background climate, will change under rising atmospheric greenhouse gas concentrations. Solar geoengineering (reducing the solar flux from outer space) has been proposed as a means to counteract anthropogenic greenhouse-induced changes in climate. Effectiveness of solar geoengineering is uncertain. Robust results are particularly difficult to obtain for ENSO because existing geoengineering simulations are too short (typically ~ 50 years) to detect statistically significant changes in the highly variable tropical Pacific background climate. We here present results from a 1000-year sunshade geoengineering simulation, G1, carried out with the coupled atmosphere-ocean general circulation model HadCM3L. In agreement with previous studies, reducing the shortwave solar flux more than compensates the warming in the tropical Pacific that develops in the 4×CO2 scenario: we observe an overcooling of 0.3 °C (5 %) and 0.23-mm day−1 (5 %) reduction in mean rainfall relative to preindustrial conditions in the G1 simulation. This is due to the different latitudinal distributions of the shortwave (solar) and longwave (CO2) forcings.The location of the Intertropical Convergence Zone (ITCZ) located north of equator in the tropical Pacific, which moved 7.5° southwards under 4×CO2, is also restored to its preindustrial location. However, other aspects of the tropical Pacific mean climate are not reset as effectively. Relative to preindustrial conditions, in G1 the zonal wind stress, zonal sea surface temperature (SST) gradient, and meridional SST gradient are reduced by 10 %, 11 %, and 9 %, respectively, and the Pacific Walker Circulation (PWC) is consistently weakened. The overall amplitude of ENSO strengthens by 5–8 %, but there is a 65 % reduction in the asymmetry between cold and warm events: cold events intensify more than warm events. Importantly, the frequency of extreme El Niño and La Niña events increases by 44 % and 32 %, respectively, while the total number of El Niño events increases by 12 %. Paradoxically, while the number of total and extreme events increase, the most extreme El Niño events also become weaker relative to preindustrial state while the La Niña events become stronger. That is, extreme El Niño events in G1 become less extreme than in preindustrial conditions, but extreme El Niño events become more frequent. In contrast, extreme La Niña events become stronger in G1. This is in agreement with the general overcooling of the tropical Pacific in G1 relative to preindustrial conditions, which depict a shift towards generally more La Niña-like conditions.

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