scholarly journals Asymmetry in ENSO Teleconnection with Regional Rainfall, Its Multidecadal Variability, and Impact

2010 ◽  
Vol 23 (18) ◽  
pp. 4944-4955 ◽  
Author(s):  
Wenju Cai ◽  
Peter van Rensch ◽  
Tim Cowan ◽  
Arnold Sullivan

Abstract An asymmetry, and its multidecadal variability, in a rainfall teleconnection with the El Niño–Southern Oscillation (ENSO) are described. Further, the breakdown of this relationship since 1980 is offered as a cause for a rainfall reduction in an ENSO-affected region, southeast Queensland (SEQ). There, austral summer rainfall has been declining since around the 1980s, but the associated process is not understood. It is demonstrated that the rainfall reduction is not simulated by the majority of current climate models forced with anthropogenic forcing factors. Examination shows that ENSO is a rainfall-generating mechanism for the region because of an asymmetry in its impact: the La Niña–rainfall relationship is statistically significant, as SEQ summer rainfall increases with La Niña amplitude; by contrast, the El Niño–induced rainfall reductions do not have a statistically significant relationship with El Niño amplitude. Since 1980, this asymmetry no longer operates, and La Niña events no longer induce a rainfall increase, leading to the observed SEQ rainfall reduction. A similar asymmetric rainfall teleconnection with ENSO Modoki exists and shares the same temporal evolutions. This breakdown is caused by an eastward shift in the Walker circulation and the convection center near Australia’s east coast, in association with a post-1980 positive phase of the interdecadal Pacific oscillation (IPO). Such a breakdown occurred before 1950, indicating that multidecadal variability alone could potentially be responsible for the recent SEQ rainfall decline. An aggregation of outputs from climate models to distill the impact of climate change suggests that the asymmetry and the breakdown may not be generated by climate change, although most models do not perform well in simulating the ENSO–rainfall teleconnection over the SEQ region.

2017 ◽  
Vol 36 (2) ◽  
pp. 77 ◽  
Author(s):  
M. Syakir ◽  
E. Surmaini

<p>Coffee is one of the Indonesian largest export commodities and has a strategic role in the economy of nearly two million farmers’ livelihood. The potency of Indonesia’s coffee export is quite high because of its preferred taste, however the trend of national coffee production is only 1-2% per year. On the other hand, the impacts of climate change also threaten the achievement of increased production targets. This paper reviews the impact climate change on coffee production and the adaptation strategies. The main coffee producing regions in Indonesia are Aceh, North Sumatera, South Sumatera, Lampung, Bengkulu, East Java and South Sulawesi Provinces. Most of these regions are vulnerable to climate change. The increasing of extreme climate events such as drought due to El Niño causes a decline in national coffee production to 10%. On the contrary, the longer wet season due to La Niña caused the decreased coffee production to 80%. Indirect impacts due to rising temperatures are increased incidence of coffee borer and leaf rust disease which can lead to a 50% decline on coffee production. Due to rising temperatures, the projected coffee production areas are projected to shift to higher elevations. Numerous adaptive technologies have been intoduced, however adaptive capacaity of farmers are still low. This condition is exacerbated by the limited access of most farmers to climate information, markets, technology, farming credits, and climate risk management information. To overcome the problem, policy makers, stakeholders and farmers have to accelerate the adaptation practices since the climate change has occurred and will continue to happen.</p><p>Keywords: Coffee, climate change, production, adaptation Top of Form</p><p> </p><p><strong>Abstrak</strong></p><p>Kopi merupakan salah satu komoditas ekspor yang berperan strategis dalam perekonomian hampir dua juta rumah petani di Indonesia. Potensi ekspor kopi Indonesia cukup tinggi karena cita rasanya yang disukai, namun tren peningkatan produksi kopi nasional hanya 1-2% per tahun. Di sisi lain, dampak perubahan iklim juga mengancam tercapainya target peningkatan produksi. Makalah ini merupakan tinjauan dampak perubahan iklim terhadap produksi kopi dan strategi adaptasinya di Indonesia. Daerah penghasil utama kopi seperti Aceh, Sumatera Utara, Sumatera Selatan, Lampung, Bengkulu, Jawa Timur dan Sulawesi Selatan rentan terhadap dampak perubahan iklim. Meningkatnya kejadian iklim ekstrim seperti kekeringan akibat El Niño mengakibatkan penurunan produksi kopi 10%. Sebaliknya, musim hujan yang panjang akibat La Niña menurunkan produksi kopi hingga 80%. Dampak tidak langsung perubahan iklim adalah meningkatnya serangan hama penggerek buah kopi dan penyakit karat daun yang menyebabkan penurunan produksi sekitar 50%. Akibat kenaikan suhu, sentra produksi kopi diproyeksikan akan berpindah ke wilayah dengan elevasi yang lebih tinggi. Berbagai teknologi adaptasi telah dihasilkan, namun tingkat adaptasi petani kopi umumnya masih rendah. Kondisi ini diperparah oleh terbatasnya akses sebagian besar petani terhadap informasi iklim, pasar, teknologi, kredit usaha tani, dan informasi pengelolaan risiko iklim. Untuk mengatasi masalah tersebut, pengambil kebijakan, stakeholder, dan petani harus mengakselerasi upaya adaptasi karena perubahan iklim telah terjadi dan akan terus berlangsung.</p><p>Kata kunci: Kopi, perubahan iklim, produksi, adaptasi</p>


2013 ◽  
Vol 26 (14) ◽  
pp. 5139-5149 ◽  
Author(s):  
Evan Weller ◽  
Wenju Cai

Abstract Recent studies have shown that the impact of the Indian Ocean dipole (IOD) on southern Australia occurs via equivalent barotropic Rossby wave trains triggered by convective heating in the tropical Indian Ocean. Furthermore, the El Niño–Southern Oscillation (ENSO) influence on southern Australian climate is exerted through the same pathway during austral spring. It is also noted that positive phase [positive IOD (pIOD) and El Niño] events have a much larger impact associated with their respective skewness. These phenomena play a significant role in the region's rainfall reduction in recent decades, and it is essential that climate models used for future projections simulate these features. Here, the authors demonstrate that climate models do indeed simulate a greater climatic impact on Australia for pIOD events than for negative IOD (nIOD) events, but this asymmetric impact is distorted by an exaggerated influence of La Niña emanating from the Pacific. The distortion results from biases in the Pacific in two respects. First, the tropical and extratropical response to La Niña is situated unrealistically too far westward and hence too close to Australia, leading to an overly strong impact on southeast Australia that shows up through the nIOD–La Niña coherence. Second, the majority of models simulate a positive sea surface temperature skewness in the eastern Pacific that is too weak, overestimating the impact of La Niña relative to that of El Niño. As such, the impact of the positive asymmetry in the IOD only becomes apparent when the impact of ENSO is removed. This model bias needs to be taken into account when analyzing projections of regional Australian climate change.


2021 ◽  
Vol 892 (1) ◽  
pp. 012057
Author(s):  
D Firda ◽  
W Estiningtyas

Abstract Climate change has had a significant impact on the agricultural sector and the impact is different in each place due to spatial variations in Indonesia. One of the efforts that must be made to reduce risk is to adapt. The purpose of this paper is to determine the key locations and their relationship to rice production for adaptation to climate change. Rainfall data and Oceanic Nino Index (ONI) are used to see the relationship between these two parameters through regression analysis and significance in El Niño and La Niña conditions. In El Niño conditions 24 key locations were obtained and in La Niña 3 priority locations. From the selected key locations, regression analysis was performed to determine the relationship between rainfall and rice production. The regression results at the sample locations show a fairly high R2 value, namely 0.4 to 0.9, namely in Juntinyuat (West Java), Palasari (Bali), and Detusoko (East Nusa Tenggara). Other key locations are also found in several provinces. This key location is a priority location where the rainfall is strongly influenced by the extreme climate phenomenon El Niño and La Niña so that it can be used to assess the impact and monitor its impact on food farming. Socialization of the use of climate information to extension workers and farmers will greatly help reduce risks and increase capacity to adapt to climate change.


2016 ◽  
Vol 35 (1) ◽  
pp. 29 ◽  
Author(s):  
Agung Budi Santoso

This study was aimed to determine the impact of climate change on food crops performance in the Maluku province, based on the climatological data from 1995 to 2012, and to find out crop commodities that are adaptable to climate change. This study used four models of trend analysis: linear least square pattern, quadratic, exponential, and moving averages. The results of forecasting were used to estimate food crop production in the year of climate change to determine the impact of climate change on crop production. Results showed that soybean was the most sensitive crop to climate change, it had the biggest impact on production, yield declined on both El Nino (10.7%) and La Nina (11.4%). Paddy which is generally cultivated on the wetlands, El Nino had the smallest effect on a decrease of production of 2.9% and 2.4% increased on the La Nina. Corn production decreased 7.4% on the El Nino and 3.9% increased during the La Nina. Sweet potatoes was the most resistant crop to climate change, the impact was increased production by 2.5% during El Nino. To reduce the impacts of climate changes could be done through some efforts, namely: (1) to identify areas of potential drought, floods, pests and diseases endemic based on climate and soil conditions, (2) to develop prediction techniques, based on weather and climate forecasts to provide early warning to farmers, (3) to prepare and disseminate a package of technology which is able to withstand the adverse conditions of the El Nino and La Nina, including varieties, pest and disease prevention, and production inputs which are easily obtained by farmers, (4) to improve irrigation and drainage channels, mainly on the paddy fields to increase production capacity and to prevent crop failure during the dry season.


2010 ◽  
Vol 67 (9) ◽  
pp. 2854-2870 ◽  
Author(s):  
Tingting Gong ◽  
Steven B. Feldstein ◽  
Dehai Luo

Abstract This study examines the relationship between intraseasonal southern annular mode (SAM) events and the El Niño–Southern Oscillation (ENSO) using daily 40-yr ECMWF Re-Analysis (ERA-40) data. The data coverage spans the years 1979–2002, for the austral spring and summer seasons. The focus of this study is on the question of why positive SAM events dominate during La Niña and negative SAM events during El Niño. A composite analysis is performed on the zonal-mean zonal wind, Eliassen–Palm fluxes, and two diagnostic variables: the meridional potential vorticity gradient, a zonal-mean quantity that is used to estimate the likelihood of wave breaking, and the wave breaking index (WBI), which is used to evaluate the strength of the wave breaking. The results of this investigation suggest that the background zonal-mean flow associated with La Niña (El Niño) is preconditioned for strong (weak) anticyclonic wave breaking on the equatorward side of the eddy-driven jet, the type of wave breaking that is found to drive positive (negative) SAM events. A probability density function analysis of the WBI, for both La Niña and El Niño, indicates that strong anticyclonic wave breaking takes place much more frequently during La Niña and weak anticyclonic wave breaking during El Niño. It is suggested that these wave breaking characteristics, and their dependency on the background flow, can explain the strong preference for SAM events of one phase during ENSO. The analysis also shows that austral spring SAM events that coincide with ENSO are preceded by strong stratospheric SAM anomalies and then are followed by a prolonged period of wave breaking that lasts for approximately 30 days. These findings suggest that the ENSO background flow also plays a role in the excitation of stratospheric SAM anomalies and that the presence of these stratospheric SAM anomalies in turn excites and then maintains the tropospheric SAM anomalies via a positive eddy feedback.


2022 ◽  
Author(s):  
Paul C. Rivera

An alternative physical mechanism is proposed to describe the occurrence of the episodic El Nino Southern Oscillation (ENSO) and La Nina climatic phenomena. This is based on the earthquake-perturbed obliquity change (EPOCH) model previously discovered as a major cause of the global climate change problem. Massive quakes impart a very strong oceanic force that can move the moon which in turn pulls the earth’s axis and change the planetary obliquity. Analysis of the annual geomagnetic north-pole shift and global seismic data revealed this previously undiscovered force. Using a higher obliquity in the global climate model EdGCM and constant greenhouse gas forcing showed that the seismic-induced polar motion and associated enhanced obliquity could be the major mechanism governing the mysterious climate anomalies attributed to El Nino and La Nina cycles.


Author(s):  
Arini Wahyu Utami ◽  
Jamhari Jamhari ◽  
Suhatmini Hardyastuti

Paddy and maize are two important food crops in Indonesia and mainly produced in Java Island. This research aimed to know the impact of El Nino and La Nina on paddy and maize farmer’s supply in Java. Cross sectional data from four provinces in Java was combined with time series data during 1987-2006. Paddy supply was estimated using log model, while maize supply used autoregressive model; each was estimated using two types of regression function. First, it included dummy variable of El Nino and La Nina to know their influence into paddy and maize supply. Second, Southern Oscillation Index was used to analyze the supply changing when El Nino or La Nina occur. The result showed that El Nino and La Nina did not influence paddy supply, while La Nina influenced maize supply in Java. Maize supply increased when La Nina occurred.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Michiya Hayashi ◽  
Fei-Fei Jin ◽  
Malte F. Stuecker

Abstract The El Niño-Southern Oscillation (ENSO) results from the instability of and also modulates the strength of the tropical-Pacific cold tongue. While climate models reproduce observed ENSO amplitude relatively well, the majority still simulates its asymmetry between warm (El Niño) and cold (La Niña) phases very poorly. The causes of this major deficiency and consequences thereof are so far not well understood. Analysing both reanalyses and climate models, we here show that simulated ENSO asymmetry is largely proportional to subsurface nonlinear dynamical heating (NDH) along the equatorial Pacific thermocline. Most climate models suffer from too-weak NDH and too-weak linear dynamical ocean-atmosphere coupling. Nevertheless, a sizeable subset (about 1/3) having relatively realistic NDH shows that El Niño-likeness of the equatorial-Pacific warming pattern is linearly related to ENSO amplitude change in response to greenhouse warming. Therefore, better simulating the dynamics of ENSO asymmetry potentially reduces uncertainty in future projections.


2004 ◽  
Vol 24 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Matthew Collins ◽  
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  

Sign in / Sign up

Export Citation Format

Share Document