Nino Years Research Articles

Pengaruh Curah Hujan terhadap Tinggi Muka Air Tanah Gambut Saat Fenomena El Nino di Sub Kesatuan Hidrologis Gambut Sungai Mendahara-Sungai Lagan

This research aims to analyze the effect of rainfall on the peat groundwater level (GWL) in the Mendahara River-Lagan River Peat Hydrological Sub Unit (sub KHG) during the El Nino phenomenon. The analysis was carried out using a simple linear regression method on 3 dominant land covers, namely private oil palm plantations, community oil palm plantations and secondary swamp forests, where 2023 is an El Nino year. The results of the research show that in the year private oil palm plantation land cover had the strongest influence on the amount of rainfall distribution compared to community oil palm plantation land cover and secondary swamp forest with R2 values of 76.14%, 58.03% and 51,42%. The value of the coefficient of determination (R2) means that the dynamics of TMAT fluctuations can be explained by the amount of rainfall distribution, while the rest is influenced by other variables not studied.

Understanding the seasonal dynamics of surface PM2.5 mass distribution and source contributions over Thailand

The escalating levels of aerosols have emerged as a significant concern for climate extremes in the Southeast Asian regions, particularly accentuated during El Nino Years. In this study, we utilized a combination of atmospheric measurements and modeling to investigate the seasonal and geographical distribution of PM2.5 mass concentrations and its primary contributors across Thailand during La Nina (2017) and El Nino (2019) years. Our findings revealed the highest daily mean surface PM2.5 mass concentration during the summer season across most regions, followed by winter, and the lowest levels during the rainy season. Notably, a significant shift in daily mean PM2.5 mass was observed from 2017 to 2019 across all seasons, with a pronounced increase of 70.9% over northern Thailand during the summer, attributed to heightened biomass burning (BB) contributions. In terms of source attribution for PM2.5 mass, the primary contributors in 2017 were BB at 34.3%, followed by anthropogenic emissions (AE) at 32.4%, and natural emissions (NE) at 30.1%. However, in 2019, the BB contribution surged to 47.4% nationwide. During El Nino years, BB played a significant role in shaping concentrations during summer and winter, while NE dominated the rainy season. An important implication of our findings is the significant potential for reducing daily and annual mean PM2.5 mass levels throughout Thailand by effectively reducing BB emissions.

Untangling the dynamics of heavy rainfall events (HRE) in the Northeast monsoon season and exploring its connection to the Indian Ocean warming and the Madden Julian Oscillation

Southeastern Peninsular India witnessed heavy rainfall events (HRE) during the recent El Nino year 2015 and La Nina year 2021 in November and early December. Both these events were associated with enhanced easterly wave activity and active Madden Julian Oscillation (MJO) over the Maritime continent. The MJO was on the fourth (MJO-4) phase for 15 and 17 days in November 2015 and 2021 respectively. A weakening in the positive correlation between El Nino and Northeast monsoon rainfall and a strengthening in the positive correlation between the MJO-4 days and HRE is observed in very recent years. This study revealed that the unequal changes in Sea Surface Temperature (SST) in the Indo-Pacific region i.e., warming over the eastern Indian Ocean (IO) and cooling over the western Pacific Ocean can be favourable for the increased occurrence of MJO-4 days as well as HRE over southern Peninsular India. The easterly wind anomalies towards the southern Bay of Bengal (BoB) and southeastern Peninsular India and westerly wind anomalies over the central equatorial Indian Ocean are significantly correlated with HRE in the recent epoch (2001−2021). Warming in eastern IO brings easterlies from the cool western Pacific and westerlies from the western IO, which helps the MJO to remain active over maritime continent and inhibits its further eastward propagation. The HREs in the recent epoch are associated with the low-pressure systems and cyclonic circulation over southern Peninsular India, in which moisture transport is from the Arabian Sea to Peninsular India. The HRE in the early epoch (1981–2000) is related to the anticyclonic circulation over BoB region and the moisture transport is from BoB and southeastern IO. A proposed mechanism for the HRE in the recent epoch is as follows. The SST gradient in the Indo-Pacific Ocean is conducive for the moistening of MJO-4 region and is favourable for the enhanced easterly wave activity and the formation of low-pressure systems, which get strengthened while moving towards southern Peninsular India due to the presence of strong equatorial westerlies over IO. These strengthened low pressure systems leads to strong ascending wind anomalies over southern Peninsular India and strong descending anomalies over Central IO and HREs over southern Peninsular India.

Global Precipitation for the Year 2023 and How It Relates to Longer Term Variations and Trends

Global Precipitation for the Year 2023 and How It Relates to Longer Term Variations and Trends

Relationship of ENSO and Standardized Precipitation Index (SPI) to Characterize Drought at Different Locations of Punjab, India

Drought is generally considered as a deficiency in precipitation over an extended period usually a season or more. It is a natural hazard that differs from other hazards since it has a slow onset, evolves over months or even years and its severity is often difficult to determine. Standardized Precipitation Index (SPI) is a widely used index to characterize drought on a range of timescales. In this study SPI was calculated annually and season (Kharif and Rabi) wise to correlate drought with ENSO events at different locations of Punjab viz. Amritsar, Ballowal Saunkhri, Bathinda, Ludhiana and Patiala. The historical data of rainfall for different locations of Punjab viz. Amritsar (1971-2017), Ballowal Saunkhri (1984-2018), Bathinda (1971-2018), Ludhiana (1971-2018) and Patiala (1971-2018) were collected from the Department of Climate Change and Agricultural Meteorology, PAU, Ludhiana and Met Centre, India Meteorological Department, Chandigarh. It was found that at all the locations very strong El Nino of 1997-98 resulted in above normal rainfall. Drought like conditions was observed during El Nino years as value of SPI was negative but with few exceptions. The SPI values were positive during La Nina and neutral years. Droughts during kharif season were found to be more related to El Nino years compared to La Nina years.

The Characteristics Of The Mixed Layer Depth During La Niña, El Niño, And Normal Years In The North Natuna Sea

The Natuna Sea is one of the seas located in the northern part of Indonesia, which is influenced by several oceanographic climate phenomena, including the El Nino-Southern Oscillation (ENSO) system, such as La Nina and El Nino, which cause vertical temperature dynamics. This study aims to examine the relationship between La Nina, El Nino, and normal years on the variability of the mixed layer depth in the Natuna Sea. The study utilizes temperature data from the World Ocean Database (WOD) and Marine Copernicus for a period of 3 years, including years with La Nina, El Nino, and normal conditions, as well as mixed layer depth (defined by sigma theta) data from Marine Copernicus. The occurrence of La Nina, El Nino, and normal years is obtained from the Southern Oscillation Index (SOI). The research findings indicate a correlation between the SOI values and the Maximum Mixed Layer Depth (MLD) during weak and very weak El Nino and La Nina conditions, while the correlation is weak during normal years. During the La Nina, normal, and El Nino periods, the deepest MLD occurs during the west monsoon season at depths ranging from 7 to 60 meters. The shallowest MLD occurs during the first transition season at depths ranging from 7 to 25 meters. The MLD values during the east monsoon season range from 7 to 43 meters, and during the second transition season, the MLD ranges from 7 to 44 meters.

Paradoxical behaviour of rainfall and temperature over ecologically sensitive areas along the Western Ghats.

Initial reports signify some specific isolated locations in different latitudes, revealing a paradoxical increase in both heavy and very heavy rainfall events and also an increment in total, i.e., in both rainfall and temperature, over ecologically sensitive areas along the Western Ghats (WG). This paper presents a coherent study of the full-scale of daily rainfall and temperature over 27 well-spaced stations in the study area to determine its extent and investigate whether or not this contradictory behaviour is real. Also, an attempt has been made to assess the differential behaviour of rainfall, temperature, and heavy rainfall events in association with land use and land cover change (LULC). The analysis revealed that rainfall and temperature over the study area are increasing, whereas heavy rainfall events have increased during 1981-2020 with strong peaks after 2000 around 18-19°N (Mumbai metropolitan region), 14-16°N (mining and quarrying regions in Goa), and 9-12°N (a narrow strip of land spanning across the coastal towns of Karnataka and Kerala) latitudes. The majority of the rainfall excess years coincided with El Nino years, indicating that El Nino does not affect rainfall negatively. However, rainfall over the WG is influenced by local relief and cascading topography. The spatial pattern of average annual rainfall shows a decreasing trend from south to north because the elevation and span of rainfall occurrence are higher in the southern part of WG. The findings of the current research will help in building a strategy to address trends and patterns of climatic variables in association with LULC.

Exploring dominant processes for multi-month predictability of western Pacific precipitation using deep learning

Over the past half-century, there has been an increasing trend in the magnitude and duration of the Madden-Julian Oscillation (MJO) attributable to the significant warming trend in the Western Pacific (WP). The MJO, bridging weather and climate, influences global and regional climate through atmospheric teleconnections, and climate models can predict it for up to 4–5 weeks. In this study, we use deep learning (DL) methods to investigate the predictability of the MJO-related western Pacific precipitation on a multi-month time scale (5–9 weeks). We examine numerous potential predictors across the tropics, selected based on major MJO theories and mechanisms, to identify key factors for long-term MJO prediction. Our results show that DL-based useful potential predictability of the WP precipitation can be extended up to 6–7 weeks, with a correlation coefficient skill ranging from 0.60 to 0.65. Observational and heat map analysis suggest that cooling anomalies in the central Pacific play a crucial role in enhancing westerly anomalies over the Indian Ocean and warming in the WP, thereby strengthening the Walker circulation in the equatorial Pacific. In addition, the predictability of WP precipitation is higher in La Nina years than in El Nino or normal years, suggesting that mean cooling in the central Pacific may contribute to increased predictability of the MJO-related WP precipitation on the multi-month time scale. Additional model experiments using observed sea surface temperature (SST) anomalies over the central Pacific confirmed that these anomalies contribute to enhanced MJO-related convective anomalies over the WP. The study highlights that DL is a valuable tool not only for improving MJO-related WP prediction but also for efficiently exploring potential mechanisms linked to long-term predictability.

Impact of El-Nino and La-Nina Episodes on Rainfall Variability and Crop Yield

El Nino and La Nina events have an impact on the Indian monsoon in terms of less rainfall than average and more rainfall in La Nina years. El-Nino events are more likely to see rainfall variability during the monsoon and depressions over the Bay of Bengal (July-August). ENSO is a disruption in ocean surface temperatures and atmospheric circulation over the Pacific Ocean leading to wide spread changes in rainfall/precipitation regimes around the world. El Nino years' effects on crop production in India as a result of lower rainfall during the south-west monsoon. In the kharif season (June to September), crops suffer from moisture and have lower yields in El-Nino years, but the opposite in La-Nina years. The El Nino is associate with the possibility of drought like situation at many occasions and La Nina is the opposite of El-Nino events.

KEMAMPUAN RAMAL SISTEM PERKIRAAN IKLIM MUSIMAN MENGGUNAKAN FENOMENA ENSO DI KABUPATEN LOMBOK TENGAH, NUSA TENGGARA BARAT

Lombok Island, particularly the southern central part of Lombok, often experiences droughts that result in failed cultivation or harvests due to the El Nino and Southern Oscillation (ENSO) phenomena. Therefore, the objective of this research is to determine the forecasting skill or predictive ability of a seasonal climate prediction system using the ENSO indicator in the Central Lombok regency, West Nusa Tenggara Province. This study employs a descriptive method by comparing the average rainfall in El Nino years with non-El Nino years. The research is conducted in the Central Lombok regency, which is divided into the northern and southern parts. The data used includes monthly precipitation recorded by BMKG for approximately 50 years (1970-2019) in all districts of Central Lombok. The SOI data is accessed at http://www.bom.gov.au/climate/current/soi2.shtml. The results of this study indicate that the use of the ENSO indicator to forecast seasonal rainfall patterns in the Central Lombok regency shows high consistency and significant predictive ability. There is no significant difference in the predictive ability and consistency of the forecast results between the northern and southern parts of Central Lombok. In general, the predictive ability during the dry season exhibits higher consistency (25%) compared to the rainy season (14%).

Middle atmospheric structure, dynamics, and coupling from three decades of Indian MST radar and complimentary observations: An overview

The genesis for Indian Mesosphere-Stratosphere-Troposphere (MST) radar came from the Indian Middle Atmospheric Programme (IMAP) to study the middle atmospheric dynamics and its underlying processes. During the early 1990s VHF radar operating at 53 MHz has been set up at Gadanki (13.5°N, 79.2°E), India, which started operating initially in the stratospheric and tropospheric (ST) mode. It is upgraded to MST mode in 1993. Since then, it has served various scientific experiments not only from India but under international collaboration. Numerous focused campaigns that have national and international importance were conducted. Using this unique data in the last 30 years along with complementary measurements, several stimulating results has been reported covering a wide range of topics that includes gravity wave characteristics, tides, planetary waves, oscillations, tropopause dynamics and stratosphere-troposphere exchange processes, monsoon dynamics and circulations, mesospheric structure and dynamics, vertical and lateral coupling and long-term trends. The present communication will highlight the unique results obtained using long-term observations of Indian MST radar and complementary techniques covering the complete middle atmosphere. Unique results include quantification of the momentum carried by the high-frequency waves generated in the troposphere up to the mesosphere, demarcating the complete tropical tropopause layer using MST radar observations alone, indication for the strengthening of the tropical easterly jet in the recent decade, unusual behavior of the Hadley circulation during drought and El Nino years, the revelation of the mechanisms for the occurrence of mesospheric echoes at the tropical latitudes, quantification of the turbulence, evidence for the role of anthropogenic changes on the dynamics of the mesosphere and generation of the empirical model by combing multi-instrument data sets. These data set also served in validating numerous ground-based and space-borne measurements including several re-analysis products over a tropical latitude. Issues remained unresolved and ways to tackle in future experiments are highlighted.

El Nino/La Nina and IOD impact on Kharif season crops over western agro-climatic zones of India

Climate modes like ENSO (El Nino Southern Oscillation) and IOD (Indian Ocean Dipole) produce an impact on the monsoon rainfall over India. Monsoon rainfall is extremely important for the agriculture of our country. The impact of these climate modes on monsoon rainfall thus in turn affects the rain-fed crops (kharif). In this study, four kharif season crops namely rice (Oryza sativa), maize (Zea mays), pulses and sugarcane (Saccharum officinarum) are chosen over four arid/semi-arid agro-climatic zones of western India to study the effect of the climate modes on selected crops. The detailed analysis has been carried out to show the impact of rainfall in the El Nino/La Nina (phases of ENSO) and IOD years on the crop productions over the mentioned zones viz. (Central plateau and hills region; Western plateau and hills region; Gujarat hills and plains region; Western dry region) from 1966–2011. The results show that rice productions which require hot and humid conditions have been largely affected during drought years associated with El Nino which results in poor rainfall over all the zones. The production of pulses which does not require excess humid conditions shows marginal improvement during the neutral years or non-El Nino/non-La Nina years. Maize production seems to be better in La Nina years and worst in the El Nino years as La Nina years are responsible for good rainfall in all zones. El Nino years provide a minor impact on sugarcane productions in different zones. La Nina years are well suited for sugarcane production in all zones of our study as sugarcane requires a good amount of moisture. Positive IOD years are associated with poor crop productions as compared to negative IOD years mostly in all zones as most of the positive IOD years happen to be El Nino years. El Nino-rainfall relation being dominant than positive IOD-rainfall relation is, therefore, responsible for negative rainfall anomalies over the selected zones.

Malformation in coccolithophores in low pH waters: evidences from the eastern Arabian Sea.

Oceanic calcifying plankton such as coccolithophores is expected to exhibit sensitivity to climate change stressors such as warming and acidification. Observational studies on coccolithophore communities along with carbonate chemistry provide important perceptions of possible adaptations of these organisms to ocean acidification. However, this phytoplankton group remains one of the least studied in the northern Indian Ocean. In 2017, the biogeochemistry group at the Council for Scientific and Industrial Research-National Institute of Oceanography (CSIR-NIO) initiated a coccolithophore monitoring study in the eastern Arabian Sea (EAS). Here, we document for the first time a detailed spatial and seasonal distribution of coccolithophores and their controlling factors from the EAS, which is a well-known source of CO2 to the atmosphere. To infer the seasonality, data collected at three transects (Goa, Mangalore, and Kochi) during the Southwest Monsoon (SWM) of 2018 was compared with that of the late SWM of 2017. Apart from this, the abundance of coccolithophores was studied at the Candolim Time Series (CaTS) transect, off Goa during the Northeast Monsoon (NEM). The most abundant coccolithophore species found in the study region was Gephyrocapsa oceanica. A high abundance of G. oceanica (1800 × 103cells L-1) was observed at the Mangalore transect during the late SWM despite experiencing low pH and can be linked to nitrogen availability. The high abundance of G. oceanica at Mangalore was associated with high dimethylsulphide (DMS). Particulate inorganic carbon (PIC) and scattering coefficient retrieved from satellites also indicated a high abundance of coccolithophores off Mangalore during the late SWM of 2017. Interestingly, G. oceanica showed malformation during the late SWM in low pH waters. Malformation in coccolithophores could have a far-reaching impact on the settling fluxes of organic matter and also on the emissions of climatically important gases such as DMS and CO2, thus influencing atmospheric chemistry. The satellite data for PIC in the EAS indicates a high abundance of coccolithophore in recent years, especially during the warm El Nino years (2015 and 2018). This warrants the need for a better assessment of the fate of coccolithophores in high-CO2 and warmer oceans.

The role of Weather Modification Technology for forest and land fire disaster mitigation in the perspective of carbon emission reduction in Indonesia

This paper reviews the effectiveness of implementing Weather Modification Technology (WMT) in efforts to control forest and land fire disasters in Indonesia. Analysis is carried out on several parameters in the field that can be measured and observed. WMT has been proven to be able to increase rainfall intensity by 12.9% and shorten the duration of Consecutive No Rain Days, which in turn can reduce the number of hotspot events in the target area. The implementation of WMT during the rainy season transition period has also been proven to be able to increase the peatland groundwater level, which ultimately shortens the drought period in the target area. The WMT implementation program, which has become increasingly well-planned in the last 4 years (2020-2023), has proven to be able to reduce the number of hotspot incidents, the extent of forest and land fires, and the amount of carbon emissions in Indonesia quite significantly. Based on updated data until September 2023, the number of hotspots, burnt area, and total carbon emissions in Indonesia were "only" 22%, 38.9%, and 5.3% respectively compared to the numbers in 2019, which was both an El Nino year.

Recurrent dinoflagellate blooms in the South-eastern Arabian Sea - A preliminary assessment with focus on Ornithocercus magnificus blooms along the nearshore waters off Dakshina Kannada, South-west coast of India

Frequent bloom incidences of the dinoflagellate Ornithocercus magnificus Stein, 1883 along the surface waters off South-eastern Arabian Seas (SEAS) have been reported since 2015 and specifically during the years 2015, 2019 and 2020. All these blooming incidences coincided with the strong El Nino phases in the Indian Ocean. The present study addressed the bloom (1.65 x 106 cells l-1) of this species in the nearshore waters (7 m depth) off Dakshina Kannada (Surathkal and Chitrapur) on 11.02.2016 which occurred during pre-monsoon period and corresponding to the super El Nino year 2015/2016. A detailed evaluation of the physico-chemical characteristics and phytoplankton abundance as well as community structure was made, concurrent to the three phases viz., pre-bloom, bloom and post-bloom periods in this region. The study revealed that the bloom occurred in high saline (35.0±0.91 PSU), well oxygenated (7.414±0.823 mg l-1) and nitrogen limited waters (oligotrophic conditions) and had a positive correlation with oceanic nino index (ONI; rs= 0.790, p<0.001). Some of the O. magnificus (3%) harboured ectosymbionts probably cyanobacteria in their cingulum in response to the beginning of a stratified oligotrophic condition in this region. The water quality was fair during the bloom period with no conspicuous discolouration of the surface waters. The present study also attempted to evaluate the influence of the increasing frequency of the O. magnificus blooms on the oilsardine fishery along the SEAS. Keywords: Cyanobacteria, Dinoflagellate, Ectosymbionts, Nitrogen limited waters, Pre-monsoon season, SEAS, Sea surface temperature (SST), Oilsardine

Impact of the El Niño–Southern Oscillation on upper-tropospheric water vapor

The majority of present-day and future global warming is related to various positive feedbacks in the climate system that tend to amplify the initial radiative forcing from increasing greenhouse gases in the atmosphere. One essential positive feedback is the rise in upper tropospheric water vapor (UTWV) or the specific humidity (SH) that acts as an intense greenhouse gas trapping in additional heat released from the Earth's surface. In this paper we expand on previous studies showing that the interannual variability of UTWV in the tropical and extratropical climates is strongly linked with the El Nino-Southern Oscillation (ENSO). We have expanded on previous studies by looking at the response of the long-term UTWV concentrations to the ENSO over a 41-year period (1979–2019) using the ERA5 reanalysis data. For the first time we look at the physical mechanism for the El Nino and La Nina connections to UTWV that is shown to be related to changes in deep convection over the central and eastern Pacific Ocean. In agreement with previous studies, we find that El Nino years have positive anomalies in UTWV, while in La Nina years there are negative anomalies in UTWV (±10%).

Forest Management Units’ Performance in Forest Fire Management Implementation in Central Kalimantan and South Sumatra

Wildfires in Indonesia are an annual phenomenon which peak in dry El Nino years, with up to 2.6 million ha of forest and land burnt in the drought year of 2015. This is an annual disaster for the country and surrounding region, with severe impacts on the environment, as well as human health, economic and social factors. Forest Management Units (FMUs, known locally as Kesatuan Pengelolaan Hutan, KPH) are the implementation agencies on the ground that play a strategic role in both the prevention and suppression of forest fires. FMUs are mandated to establish a local fire brigade, to provide adequate personnel and equipment, and to carry out fire prevention as well as suppression programs. This research aimed to analyze the performance of forest fire-related policy implementation. The study was based on five FMUs in fire-prone regions of Central Kalimantan and South Sumatra, Indonesia. The performance of the FMUs is measured by achievement of the policy objectives and effectiveness of policy implementation. Our analysis shows the policies, standards and objectives to manage fire are clear for FMUs, but there are challenges in their implementation, such that fire control activities have not been fully implemented. Most FMUs have limited capacity and resources, as well as complicated budget mechanisms and low community participation. Strengthening FMU capacity will significantly improve their performance in forest fire control, particularly in the initial stages. This can be done at three scales: personnel, organization and system.

Rainfall Variability during El Nino, La Nina and Neutral Years Over Karnataka

The El Niño-Southern Oscillation (ENSO) is a recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean. The three phases of the El Niño–Southern Oscillation (ENSO) namely the neutral phase, El Niño and La Niña oscillations. El Niño refers to the above-average sea-surface temperatures that periodically develop across the east-central equatorial Pacific. It represents the warm phase of the ENSO cycle. La Niña refers to the periodic cooling of sea-surface temperatures across the east-central equatorial Pacific. The state of Karnataka is located on a table land in the angle where the Western and Eastern Ghat ranges converge into the Nilgiri hill complex. 41 year (1980-2020) average annual rainfall of Karnataka collected from the rain gauge station located under the farm universities of Karnataka and, SST and SOI data collected from NOAA were used to study the rainfall variability while ENSO events. The El Niño events will deviate the rainy winds towards eastern pacific region causing lesser rainfall on Indian sub-continent or draughts in some years, but when it comes to Karnataka El Niño events have given above average rainfall. There were 8 episodes of excess rainfall and 6 episodes of deficient rainfall during the 14 El Niño episodes, and 3 episodes of excess rainfall and 8 episodes of deficient rainfall during the 11 La Niña episodes. The remaining 16 episodes were neutral years, with 10 episodes having excessive rainfall and the remaining 6 having deficient rainfall. Hence the El Niño episodes is good when compared to La Niña episodes over Karnataka.

Assessment the impacts of climate change on drought in the Ba River basin, Central Vietnam using Landsat remote sensing data

Sustainable management of the river basin is a profound challenge for environmental management in the context of climate change. Drought situations in a basin occur in relation to meteorological, hydrological, agricultural factors and climate change as well. In this study, remote sensing technology was applied to assess the impacts of climate change on drought in the Ba River basin, Central Vietnam. Drought in the basin has been created by land use/land cover changes in recent years, which has resulted in a sharp decrease in forest area in the period 1989 to 2019 (-41.5%) and a significant increase of agricultural land with 38.2%. Following that, the area of drought agriculture rose by 28.8%. The remarkably high drought areas in agricultural land were in El Nino years, 2016 (99.2%) and 2019 (87.3%), which indicated that under climate change impacts, a drought occurred more severely. Moreover, drought also appeared in the forest. The forest area deceased but the drought levels in the forest increased slightly since 2005 and hit a peak drought value in 2016 with 97.0% of forest area. During El Niño years, the precipitation, atmospheric moisture, and water flow in the basin were all lower than in previous years.

Investigating El Nino Southern Oscillation as the main driver of forest fire in Kalimantan

Strong El Nino events have been identified as major factors contributing to the forest fire in Indonesia. This is due to El Nino Southern Oscillation (ENSO) variability has a distinct connection with tropical precipitation, mainly in Indonesia. El Nino years are typically drier, while La Nina events generally increase precipitation in Indonesia. Although very strong El Nino events have been connected with massive forest fires, fire continue to occur during the other phases of ENSO: La Nina and normal. Here, the research reports a time series of monthly counted fires in Kalimantan between the period 2001-2020 from MODIS fire hotspot and MODIS Burned Area products. The region is divided into three categories, Primary Intact Forest, Primary Degraded Forest and Outside Forest/ Deforested area. This categorization validates the location of the fire. Our results show that in general wildfires in Kalimantan follow a similar temporal pattern with Oceanic Nino Index (ONI), with several anomalies. If ONI is high, wildfires are more intense and vice versa. The wildfire appears almost every month and increases drastically in June-October of El Nino years. However, the proportion of wildfires in Primary Intact Forest are tiny and insignificant. The primary intact forest fire only appears in July-October and have a different pattern with wildfires in general. In conclusion, wildfires are highly correlated with El Nino but limited in primary intact forests. The fires dominantly appear in the deforested area, about 80%. The rest 20% are in degraded forest and only less than 1% in primary intact forest. Keywords: Deforested, degraded forest, ENSO, forest fire, ONI, primary intact forest