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

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.

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

2007 ◽  
Vol 7 (14) ◽  
pp. 3713-3736 ◽  
Author(s):  
B. N. Duncan ◽  
S. E. Strahan ◽  
Y. Yoshida ◽  
S. D. Steenrod ◽  
N. Livesey
Keyword(s):  
Biomass Burning ◽  
El Niño ◽  
Fossil Fuels ◽  
Extreme Event ◽  
El Nino ◽  
Deep Convection ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
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 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.

Analyzing Fish Condition Factor Index Through Skew-Gaussian Information Theory Quantifiers

2016 ◽  
Vol 15 (02) ◽  
pp. 1650013 ◽  
Author(s):  
Javier E. Contreras-Reyes
Keyword(s):  
Time Series ◽  
El Niño ◽  
Shape Parameter ◽  
Condition Factor ◽  
El Nino ◽  
The Body ◽  
Northern Coast ◽  
Threshold Autoregressive ◽  
El Niño Event ◽  
Engraulis Ringens

Biological-fishery indicators have been widely studied. As such the condition factor (CF) index, which interprets the fatness level of a certain species based on length and weight, has been investigated, too. However, CF has been studied without considering its temporal features and distribution. In this paper, we analyze the CF time series via skew-gaussian distributions that consider the asymmetry produced by extreme events. This index is characterized by a threshold autoregressive model and corresponds to a stationary process depending on the shape parameter of the skew-gaussian distribution. Then we use the Jensen–Shannon (JS) distance to compare CF by length classes. This distance has mathematical advantages over other divergences such as Kullback–Leibler and Jeffrey’s, and the triangular inequality property. Our results are applied to a biological catalogue of anchovy (Engraulis ringens) from the northern coast of Chile, for the period 1990–2010 that consider monthly CF time series by length classes and sex. We find that for high values of shape parameter, JS distance tends to be more sensible to detect discrepancies than Jeffrey’s divergence. In addition, the body condition of male anchovies with higher lengths coincides with the ending of the moderate-strong El Niño event 91–92 and for both males and females, the smaller lengths coincide with the beginning of the strong El Niño event 97–98.

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

Agromet ◽  
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.

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

2011 ◽  
Vol 24 (24) ◽  
pp. 6486-6500 ◽  
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.

scholarly journals ENSO Impact on Kelvin Waves and Associated Tropical Convection

2013 ◽  
Vol 70 (11) ◽  
pp. 3513-3532 ◽  
Author(s):  
Gui-Ying Yang ◽  
Brian Hoskins
Keyword(s):  
El Niño ◽  
El Nino ◽  
Tropical Convection ◽  
Kelvin Waves ◽  
La Niña ◽  
Eastern Pacific ◽  
Substantial Impact ◽  
La Nina ◽  
Central Eastern ◽  
The Impact

Abstract The impact of El Niño–Southern Oscillation (ENSO) on atmospheric Kelvin waves and associated tropical convection is investigated using the ECMWF Re-Analysis, NOAA outgoing longwave radiation (OLR), and the analysis technique introduced in a previous study. It is found that the phase of ENSO has a substantial impact on Kelvin waves and associated convection over the equatorial central-eastern Pacific. El Niño (La Niña) events enhance (suppress) variability of the upper-tropospheric Kelvin wave and the associated convection there, in both extended boreal winter and summer. The mechanism of the impact is through changes in the ENSO-related thermal conditions and the ambient flow. In El Niño years, because of SST increase in the equatorial central-eastern Pacific, variability of eastward-moving convection, which is mainly associated with Kelvin waves, intensifies in the region. In addition, owing to the weakening of the equatorial eastern Pacific westerly duct in the upper troposphere in El Niño years, Kelvin waves amplify there. In La Niña years, the opposite occurs. However, the stronger westerly duct in La Niña winters allows more NH extratropical Rossby wave activity to propagate equatorward and force Kelvin waves around 200 hPa, partially offsetting the in situ weakening effect of the stronger westerlies on the waves. In general, in El Niño years Kelvin waves are more convectively and vertically coupled and propagate more upward into the lower stratosphere over the central-eastern Pacific. The ENSO impact in other regions is not clear, although in winter over the eastern Indian and western Pacific Oceans Kelvin waves and their associated convection are slightly weaker in El Niño than in La Niña years.

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

2010 ◽  
Vol 23 (15) ◽  
pp. 4080-4095 ◽  
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.

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

2013 ◽  
Vol 10 (8) ◽  
pp. 10971-10995 ◽  
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.

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