The impact of solar activity on the 2015/16 El Niño event

Abstract. We present a modeling study of the troposphere-to-stratosphere transport (TST) of pollution from major biomass burning regions to the tropical upper troposphere and lower stratosphere (UT/LS). TST occurs predominately through 1) slow ascent in the tropical tropopause layer (TTL) to the LS and 2) quasi-horizontal exchange to the lowermost stratosphere (LMS). We show that biomass burning pollution regularly and significantly impacts the composition of the TTL, LS, and LMS. Carbon monoxide (CO) in the LS in our simulation and data from the Aura Microwave Limb Sounder (MLS) shows an annual oscillation in its composition that results from the interaction of an annual oscillation in slow ascent from the TTL to the LS and seasonal variations in sources, including a semi-annual oscillation in CO from biomass burning. The impacts of CO sources that peak when ascent is seasonally low are damped (e.g. Southern Hemisphere biomass burning) and vice-versa for sources that peak when ascent is seasonally high (e.g. extra-tropical fossil fuels). Interannual variation of CO in the UT/LS is caused primarily by year-to-year variations in biomass burning and the locations of deep convection. During our study period, 1994–1998, we find that the highest concentrations of CO in the UT/LS occurred during the strong 1997–1998 El Niño event for two reasons: i. tropical deep convection shifted to the eastern Pacific Ocean, closer to South American and African CO sources, and ii. emissions from Indonesian biomass burning were higher. This extreme event can be seen as an upper bound on the impact of biomass burning pollution on the UT/LS. We estimate that the 1997 Indonesian wildfires increased CO in the entire TTL and tropical LS (>60 mb) by more than 40% and 10%, respectively, for several months. Zonal mean ozone increased and the hydroxyl radical decreased by as much as 20%, increasing the lifetimes and, subsequently TST, of trace gases. Our results indicate that the impact of biomass burning pollution on the UT/LS is likely greatest during an El Niño event due to favorable dynamics and historically higher burning rates.

Download Full-text

On Abnormally Strong Currents Observed on the Northern Coast of Peru during the 2015-2016 El Niño

Korea Society of Coastal Disaster Prevention ◽

10.20481/kscdp.2021.8.4.205 ◽

2021 ◽

Vol 8 (4) ◽

pp. 205-210

Author(s):

Chang-Woong Shin ◽

Dimitri Gutiérrez

Keyword(s):

Mixed Layer ◽

El Niño ◽

El Nino ◽

Current Data ◽

Kelvin Waves ◽

Coastal Current ◽

Northern Coast ◽

El Niño Event ◽

Strong Current ◽

The Impact

The northern coast of Peru is a region that can rapidly detect the impact of an El Niño. To investigate the effects of the 2015-2016 El Niño on the oceanographic environment of the northern coast of Peru, the temperature and current data obtained from moored equipment at an oil platform were analyzed. Strong coastal along-shore currents of more than 0.60 m·s-1 were observed three times, although the mean current speed was 0.10 m·s-1 flowing toward the south-southwest. After the first strong current, the bottom temperature increased and the mixed layer deepened and remained there during the El Niño event. The temperature reached a maximum after the strong coastal current, then decreased gradually. An analysis of wind and sea surface height anomalies revealed that the coastal strong current was caused by Kelvin waves and the deepening of the mixed layer was not related to local winds, but to coastal Kelvin waves from the equator during the El Niño event.

Download Full-text

Spatial and Temporal Analysis of El Niño Impact on Land and Forest Fire in Kalimantan and Sumatra

Agromet ◽

10.29244/j.agromet.35.1.1-10 ◽

2021 ◽

Vol 35 (1) ◽

pp. 1-10

Author(s):

Sri Nurdiati ◽

Ardhasena Sopaheluwakan ◽

Pandu Septiawan

Keyword(s):

Forest Fire ◽

Forest Fires ◽

El Niño ◽

Fire Regime ◽

El Nino ◽

Function Analysis ◽

Spatial And Temporal Patterns ◽

El Niño Event ◽

Dry Spell ◽

The Impact

Land and forest fires in Kalimantan and Sumatra, Indonesia occurred annually at different magnitude and duration. Climate and sea interaction, like El Niño, influences the severity of dry seasons preceding the fires. However, research on the influence of El Niño intensity to fire regime in Kalimantan and Sumatra is limited. Therefore, this study aims to analyze the spatial and temporal patterns of the effects of El Niño intensity on land and forest fires in fire-prone provinces in Indonesia. Here, we applied the empirical orthogonal function analysis based on singular value decomposition to determine the dominant patterns of hotspots and rainfall data that evolve spatially and temporally. For analysis, the study required the following data: fire hotspots, dry-spell, and rainfall for period 2001-2019. This study revealed that El Niño intensity had a different impacts for each province. Generally, El Niño will influence the severity of forest fire events in Indonesia. However, we found that the impact of El Niño intensity varied for Kalimantan, South Sumatra, and Riau Province. Kalimantan was the most sensitive province to the El Niño event. The duration and number of hotspots in Kalimantan increased significantly even in moderate El Niño event. This was different for South Sumatra, where the duration and number of hotspots only increased significantly when a strong El Niño event occurred.

Download Full-text

On Changing El Niño: A View from Time-Varying Annual Cycle, Interannual Variability, and Mean State

Journal of Climate ◽

10.1175/jcli-d-10-05012.1 ◽

2011 ◽

Vol 24 (24) ◽

pp. 6486-6500 ◽

Cited By ~ 49

Author(s):

Cheng Qian ◽

Zhaohua Wu ◽

Congbin Fu ◽

Dongxiao Wang

Keyword(s):

Interannual Variability ◽

Annual Cycle ◽

El Niño ◽

El Nino ◽

Warm Period ◽

Secular Change ◽

Enso Events ◽

El Niño Event ◽

The Impact ◽

Mean State

Abstract This study investigates changes in the frequency of ENSO, especially the prolonged 1990–95 El Niño event, in the context of secular changes in the annual cycle, ENSO interannual variability, and background mean state of the tropical eastern Pacific sea surface temperature (SST). The ensemble empirical mode decomposition (EEMD) method is applied to isolate those components from the Niño-3 SST index for the period 1880–2008. It is shown that the annual cycle [referred to as a refined modulated annual cycle (MAC)] has strong interannual modulation and secular change in both amplitude and phase: a clear transition from increasing to decreasing amplitude around 1947/48, with both linear trends before and after this turning point statistically significant and the amplitude decreasing by 14% since then, and a significant phase delay trend for the period 1881–1938, but hardly any thereafter. A clear transition from significant deceasing to increasing by about 30% in the amplitude of the ENSO interannual variability around 1937 is also found. When El Niño events are represented as the collective interannual variability, their frequency is found to be almost equivalent to that of La Niña events after 1976. A method for conducting synthetic experiments based on time series analysis further reveals that the apparent prolonged 1990–95 El Niño event was not caused solely by ENSO interannual variability. Rather, the 1991/92 warm period is attributable to an interannual variation superimposed by change in the background mean state; the 1993 warm period is attributable to change in the mean state; and the 1994/95 warm period is attributable to a residual annual cycle, which cannot be fully excluded by a 30-yr mean annual cycle approach. The impact that changing base periods has on the classification of ENSO events and possible solutions is also discussed.

Download Full-text

The Impact of Ocean Data Assimilation on Seasonal-to-Interannual Forecasts: A Case Study of the 2006 El Niño Event

Journal of Climate ◽

10.1175/2010jcli3319.1 ◽

2010 ◽

Vol 23 (15) ◽

pp. 4080-4095 ◽

Cited By ~ 15

Author(s):

Shu-Chih Yang ◽

Michele Rienecker ◽

Christian Keppenne

Keyword(s):

El Niño ◽

Initial Conditions ◽

El Nino ◽

Warm Pool ◽

Breeding Method ◽

Central Pacific ◽

Background Error ◽

Mature Phase ◽

El Niño Event ◽

The Impact

Abstract This study investigates the impact of four different ocean analyses on coupled forecasts of the 2006 El Niño event. Forecasts initialized in June 2006 using ocean analyses from an assimilation that uses flow-dependent background error covariances are compared with those using static error covariances that are not flow dependent. The flow-dependent error covariances reflect the error structures related to the background ENSO instability and are generated by the coupled breeding method. The ocean analyses used in this study result from the assimilation of temperature and salinity, with the salinity data available from Argo floats. Of the analyses, the one using information from the coupled bred vector (BV) replicates the observed equatorial long wave propagation best and exhibits more warming features leading to the 2006 El Niño event. The forecasts initialized from the BV-based analysis agree best with the observations in terms of the growth of the warm anomaly through two warming phases. This better performance is related to the impact of the salinity analysis on the state evolution in the equatorial thermocline. The early warming is traced back to salinity differences in the upper ocean of the equatorial central Pacific, while the second warming, corresponding to the mature phase, is associated with the effect of the salinity assimilation on the depth of the thermocline in the western equatorial Pacific. The series of forecast experiments conducted here show that the structure of the salinity in the initial conditions is important to the forecasts of the extension of the warm pool and the evolution of the 2006 El Niño event.

Download Full-text

Droughts and floods over the upper catchment of the Blue Nile and their connections to the timing of El Niño and La Niña Events

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-10971-2013 ◽

2013 ◽

Vol 10 (8) ◽

pp. 10971-10995 ◽

Cited By ~ 3

Author(s):

M. A. H. Zaroug ◽

E. A. B. Eltahir ◽

F. Giorgi

Keyword(s):

El Niño ◽

River Flow ◽

El Nino ◽

La Niña ◽

Blue Nile ◽

El Niño Event ◽

La Nina ◽

Extreme Flood ◽

Droughts And Floods ◽

The Impact

Abstract. The Blue Nile originates from Lake Tana in the Ethiopian Highland and contributes about 67% of the discharge in the main Nile River. Previous studies investigated the relationship of sea surface temperature (SST) in the Pacific Ocean (Nino 3.4 region) to occurrence of floods and droughts in rainfall and river flow over the Nile basin. In this paper we focus on the dependence of occurrence of droughts and floods in the upper catchment of the Blue Nile on the timing of El Niño and La Niña events. Different events start in different times of the year and follow each other exhibiting different patterns and sequences. Here, we study the impact of this timing and temporal patterns on the Nile droughts and floods. We analyze discharge measurements (1965–2012) at the outlet of the upper catchment of the Blue Nile in relation to the El Niño index. When an El Niño event is followed by a La Niña event, there is a 67% chance for occurrence of an extreme flood. The association of start dates of El Niño with occurrence of droughts in the upper catchment of the Blue Nile is evaluated. An El Niño event that starts in (April–June) is associated with a significant drought occurrence in 83% of the cases. We propose that observations as well as global model forecasts of SST during this season could be used in seasonal forecasting of the Blue Nile flow.

Download Full-text

The Impact of the 1997/98 El Niño Event on the Atlantic Ocean

Journal of Climate ◽

10.1175/1520-0442(2001)014<1069:tioten>2.0.co;2 ◽

2001 ◽

Vol 14 (6) ◽

pp. 1069-1077 ◽

Cited By ~ 21

Author(s):

J. R. Elliott ◽

S. P. Jewson ◽

R. T. Sutton

Keyword(s):

Atlantic Ocean ◽

El Niño ◽

El Nino ◽

El Niño Event ◽

The Impact

Download Full-text

Impact of El Niño 2015-2016 on the coral reefs of the Pacific of Costa Rica: the potential role of marine protection

Revista de Biología Tropical ◽

10.15517/rbt.v68is1.41190 ◽

2020 ◽

Vol 68 (S1) ◽

pp. S271-S282 ◽

Cited By ~ 2

Author(s):

Juan José Alvarado ◽

Celeste Sánchez-Noguera ◽

Gustavo Arias-Godínez ◽

Tatiana Araya ◽

Cindy Fernández-García ◽

...

Keyword(s):

Coral Reef ◽

Coral Reefs ◽

El Niño ◽

El Nino ◽

Coral Cover ◽

Live Coral ◽

El Niño Event ◽

Live Coral Cover ◽

The Pacific ◽

The Impact

Introduction: El Niño 2015-2016 was considered one of the most severe worldwide, causing the third global event of coral bleaching. Previous high-intensity El Niño events (1982-83 and 1997-98) caused high coral mortalities and deterioration of coral reef structures along the Eastern Tropical Pacific, affecting both ecosystem and associated economical activities. Objective: The aim of this study was to determine the impact of the most recent El Niño event on coral reefs from Cocos Island and the Pacific coast of southern Costa Rica. Methods: Coral reefs were surveyed before (2013-2014) and after (2016) the disturbance, using underwater visual censuses within belt transects, to quantify the bottom coverage at different depths. Results: In general, average live coral cover decreased 50% after the 2015-2016 El Niño event, with Golfo Dulce being the most affected area with 75% of live coral cover decline. However, in certain localities such as Isla del Coco and Isla del Caño, the effects of El Niño were apparently minimal, since no substantial loss of live coral cover was detected. Differences in the level of deterioration found between coral reefs could be related to several factors, including the age of the protected area, the distance to centers of human population, and the effectiveness in the application of management strategies. Conclusions: The synergistic impact of the 2015-16 El Niño event and other stressors (e.g. illegal fishing and unregulated coastal human development) increased the levels of disturbance on coral reefs, threatening their structure and functioning. It is necessary to strengthen conservation strategies in order to improve the resilience of coral reefs to the impact of natural and anthropogenic disturbances. Concrete actions such as coral reef restoration, marine environmental education, and marine spatial planning must become important tools to maintain the good health of coral reefs and ensure the sustainability of the goods and services provided by these ecosystems.

Download Full-text

Model study of the cross-tropopause transport of biomass burning pollution

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-2197-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 2197-2248 ◽

Cited By ~ 3

Author(s):

B. N. Duncan ◽

S. E. Strahan ◽

Y. Yoshida

Keyword(s):

Biomass Burning ◽

El Niño ◽

Fossil Fuels ◽

Extreme Event ◽

El Nino ◽

Deep Convection ◽

Tape Recorder ◽

Boreal Winter ◽

El Niño Event ◽

The Impact

Abstract. We present a modeling study of the troposphere-to-stratosphere transport (TST) of pollution from major biomass burning regions to the tropical tropopause layer (TTL) and lower stratosphere (LS). We show that biomass burning pollution regularly and significantly impacts the composition of the TTL/LS. TST occurs through 1) slow ascent in the TTL and 2) quasi-horizontal exchange in the regions of the subtropical jets; we find both pathways to be important. The seasonal oscillation in CO in the TTL/LS (i.e., the CO "tape recorder") is caused largely by seasonal changes in biomass burning. Another contributing factor is the long-range transport of northern hemispheric pollution (e.g., biofuels and fossil fuels) to the northern tropics in boreal winter. Other tropical sources of CO (e.g., methane oxidation) have insignificant seasonal variation, contributing little to the tape recorder. Interannual variation of CO in the TTL/LS is caused by year-to-year variations in biomass burning and the strength, frequency, and locations of deep convection, which lofts pollution to the upper troposphere. During our study period, 1994–1998, we find that the highest concentrations of CO in the TTL/LS occur during the strong 1997/98 El Niño event for two reasons: i.~tropical deep convection was stronger and ii.~emissions were higher. This extreme event can be seen as an upper bound on the impact of biomass burning pollution on the TTL/LS. We estimate that the 1997 Indonesian wildfires increased CO in the entire TTL and tropical LS (<60 mb) by more than 40% and 10%, respectively, for several months. Zonal mean ozone increased and the hydroxyl radical decreased by as much as 20%, increasing the lifetimes and, subsequently TST, of trace gases. Our results indicate that the impact of biomass burning pollution on the TTL/LS is likely greatest during an El Niño event due to favorable dynamics and historically higher burning rates.

Download Full-text