Special Issue "Tropical Atlantic Variability"

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Meteorology".

Deadline for manuscript submissions: closed (15 May 2020).

Special Issue Editors

Prof. Belen Rodriguez-Fonseca
E-Mail Website
Guest Editor
Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Madrid, Spain
Dr. Irene Polo Sánchez
E-Mail
Co-Guest Editor
Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, 28012 Madrid, Spain
Interests: tropical Atlantic Variability modes; air-sea interactions
Dr. Teresa Losada Doval
E-Mail
Co-Guest Editor
Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, 28012 Madrid, Spain
Interests: modelling and teleconnections

Special Issue Information

Dear Colleagues,

Tropical Atlantic variability (TAV) can be viewed as yearly fluctuations of the seasonal cycle of trade winds, sea surface temperature (SST), and rainfall, including air–sea interactions and teleconnections. Its study involves the understanding of the processes and interactions that can alter the climatology of this region, including its potential forcings and impacts.

The leading modes of tropical Atlantic variability can be comprised of SST anomalous structures with a zonal and meridional symmetry and named, respectively, Atlantic Niño (or equatorial mode) and the meridional mode.

TAV exerts a strong influence on regional and global climate variability, altering the zonal and meridional atmospheric circulation cells and triggering global atmospheric teleconnections. Regionally, TAV can impact West African and South American monsoons, but also equatorial and coastal upwelling regions. Among the most important global impacts of TAV is the inter-basin tropical teleconnection with ENSO and the Indian Ocean, but also extratropical impacts all around the world. Additionally, TAV can be altered by natural and anthropogenic forcings. In this way, global teleconnections associated with changes in the subtropical high-pressure systems are important in TAV. Some examples are the North Atlantic Oscillation and ENSO. Additionally, multidecadal variability associated with natural variability oceanic modes (AMV and IPO) can also exert an influence on TAV. At longer timescales, tropical Atlantic variability is also influenced by the Atlantic meridional overturning circulation (AMOC) and, in particular, by the North Brazil Current (NBC) which transports warm water from the South Atlantic to high latitudes in the North Atlantic. The Indian Ocean’s influence through the Agulhas leakage can also have an impact on the TAV.

In this Special Issue, papers related to TAV, including research dealing with seasonal cycle, air–sea interactions, forcings, and impacts are welcome.

Prof. Belen Rodriguez-Fonseca
Dr. Teresa Losada Doval
Dr. Irene Polo Sánchez
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Atmosphere is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • tropical Atlantic variability
  • Atlantic Niño
  • meridional mode
  • upwelling
  • air–sea interactions
  • teleconnections

Published Papers (6 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

Article
Tropical Atlantic Mixed Layer Buoyancy Seasonality: Atmospheric and Oceanic Physical Processes Contributions
Atmosphere 2020, 11(6), 649; https://doi.org/10.3390/atmos11060649 - 18 Jun 2020
Viewed by 764
Abstract
This study investigates the physical processes controlling the mixed layer buoyancy using a regional configuration of an ocean general circulation model. Processes are quantified by using a linearized equation of state, a mixed-layer heat, and a salt budget. Model results correctly reproduce the [...] Read more.
This study investigates the physical processes controlling the mixed layer buoyancy using a regional configuration of an ocean general circulation model. Processes are quantified by using a linearized equation of state, a mixed-layer heat, and a salt budget. Model results correctly reproduce the observed seasonal near-surface density tendencies. The results indicate that the heat flux is located poleward of 10° of latitude, which is at least three times greater than the freshwater flux that mainly controls mixed layer buoyancy. During boreal spring-summer of each hemisphere, the freshwater flux partly compensates the heat flux in terms of buoyancy loss while, during the fall-winter, they act together. Under the seasonal march of the Inter-tropical Convergence Zone and in coastal areas affected by the river, the contribution of ocean processes on the upper density becomes important. Along the north Brazilian coast and the Gulf of Guinea, horizontal and vertical processes involving salinity are the main contributors to an upper water change with a contribution of at least twice as much the temperature. At the equator and along the Senegal-Mauritanian coast, vertical processes are the major oceanic contributors. This is mainly due to the vertical gradient of temperature at the mixed layer base in the equator while the salinity one dominates along the Senegal-Mauritania coast. Full article
(This article belongs to the Special Issue Tropical Atlantic Variability)
Show Figures

Figure 1

Article
Statistical-Observational Analysis of Skillful Oceanic Predictors of Heavy Daily Precipitation Events in the Sahel
Atmosphere 2020, 11(6), 584; https://doi.org/10.3390/atmos11060584 - 03 Jun 2020
Viewed by 932
Abstract
In this paper, the sea surface temperature (SST) based statistical seasonal forecast model (S4CAST) is utilized to examine the spatial and temporal prediction skill of Sahel heavy and extreme daily precipitation events. As in previous studies, S4CAST points out the Mediterranean Sea and [...] Read more.
In this paper, the sea surface temperature (SST) based statistical seasonal forecast model (S4CAST) is utilized to examine the spatial and temporal prediction skill of Sahel heavy and extreme daily precipitation events. As in previous studies, S4CAST points out the Mediterranean Sea and El Niño Southern Oscillation (ENSO) as the main drivers of Sahel heavy/extreme daily rainfall variability at interannual timescales (period 1982–2015). Overall, the Mediterranean Sea emerges as a seasonal short-term predictor of heavy daily rainfall (1 month in advance), while ENSO returns a longer forecast window (up to 3 months in advance). Regarding the spatial skill, the response of heavy daily rainfall to the Mediterranean SST forcing is significant over a widespread area of the Sahel. Contrastingly, with the ENSO forcing, the response is only significant over the southernmost Sahel area. These differences can be attributed to the distinct physical mechanisms mediating the analyzed SST-rainfall teleconnections. This paper provides fundamental elements to develop an operational statistical-seasonal forecasting system of Sahel heavy and extreme daily precipitation events. Full article
(This article belongs to the Special Issue Tropical Atlantic Variability)
Show Figures

Figure 1

Article
Southern Hemisphere Sensitivity to ENSO Patterns and Intensities: Impacts over Subtropical South America
Atmosphere 2020, 11(1), 77; https://doi.org/10.3390/atmos11010077 - 09 Jan 2020
Cited by 2 | Viewed by 811
Abstract
El Niño flavors influence Subtropical South American (SSA) rainfall through the generation of one or two quasi-stationary Rossby waves. However, it is not yet clear whether the induced wave trains depend on the El Niño pattern and/or its intensity. To investigate this, we [...] Read more.
El Niño flavors influence Subtropical South American (SSA) rainfall through the generation of one or two quasi-stationary Rossby waves. However, it is not yet clear whether the induced wave trains depend on the El Niño pattern and/or its intensity. To investigate this, we performed different sensitivity experiments using an Atmospheric General Circulation Model (AGCM) which was forced considering separately the Canonical and the El Niño Modoki patterns with sea surface temperature (SST) maximum anomalies of 1 and 3 °C. Experiments with 3 °C show that the Canonical El Niño induces two Rossby wave trains, a large one emanating from the western subtropical Pacific and a shorter one initiated over the central-eastern subtropical South Pacific. Only the shorter wave plays a role in generating negative outgoing longwave radiation (OLR) anomalies over SSA. On the other hand, 3 °C El Niño Modoki experiments show the generation of a large Rossby wave train that emanates from the subtropical western south Pacific and reaches South America (SA), promoting the development of negative OLR anomalies over SSA. Experiments with 1 °C show no impacts on OLR anomalies over SSA associated with El Niño Modoki. However, for the Canonical El Niño case there is a statistically significant reduction of the OLR anomalies over SSA related to the intensification of the upper level jet stream over the region. Finally, our model results suggest that SSA is more sensitive to the Canonical El Niño, although this result may be model dependent. Full article
(This article belongs to the Special Issue Tropical Atlantic Variability)
Show Figures

Figure 1

Article
Analyzing the Influence of the North Atlantic Ocean Variability on the Atlantic Meridional Mode on Decadal Time Scales
Atmosphere 2020, 11(1), 3; https://doi.org/10.3390/atmos11010003 - 18 Dec 2019
Viewed by 882
Abstract
Important features of the Atlantic meridional mode (AMM) are not fully understood. We still do not know what determines its dominant decadal variability or the complex physical processes that sustain it. Using reanalysis datasets, we investigated the influence of the North Atlantic Ocean [...] Read more.
Important features of the Atlantic meridional mode (AMM) are not fully understood. We still do not know what determines its dominant decadal variability or the complex physical processes that sustain it. Using reanalysis datasets, we investigated the influence of the North Atlantic Ocean variability on the dominant decadal periodicity that characterizes the AMM. Statistical analyses demonstrated that the correlation between the sea surface temperature decadal variability in the Atlantic Ocean and the AMM time series characterizes the Atlantic multidecadal oscillation (AMO). This corroborates previous studies that demonstrated that the AMO precedes the AMM. A causal inference with a newly developed rigorous and quantitative causality analysis indicates that the AMO causes the AMM. To further understand the influence of the subsurface ocean on the AMM, the relationship between the ocean heat content (0–300 m) decadal variability and AMM was analyzed. The results show that although there is a significant zero-lag correlation between the ocean heat content in some regions of the North Atlantic (south of Greenland and in the eastern part of the North Atlantic) and the AMM, their cause-effect relationship on decadal time scales is unlikely. By correlating the AMO with the ocean heat content (0–300 m) decadal variability, the former precedes the latter; however, the causality analysis shows that the ocean heat content variability drives the AMO, corroborating several studies that point out the dominant role of the ocean heat transport convergence on AMO. Full article
(This article belongs to the Special Issue Tropical Atlantic Variability)
Show Figures

Figure 1

Article
SST Indexes in the Tropical South Atlantic for Forecasting Rainy Seasons in Northeast Brazil
Atmosphere 2019, 10(6), 335; https://doi.org/10.3390/atmos10060335 - 19 Jun 2019
Cited by 5 | Viewed by 2236
Abstract
May-to-July and February-to-April represent peak rainy seasons in two sub-regions of Northeast Brazil (NEB): Eastern NEB and Northern NEB respectively. In this paper, we identify key oceanic indexes in the tropical South Atlantic for driving these two rainy seasons. In Eastern NEB, the [...] Read more.
May-to-July and February-to-April represent peak rainy seasons in two sub-regions of Northeast Brazil (NEB): Eastern NEB and Northern NEB respectively. In this paper, we identify key oceanic indexes in the tropical South Atlantic for driving these two rainy seasons. In Eastern NEB, the May-to-July rainfall anomalies present a positive relationship with the previous boreal winter sea surface temperature anomalies (SSTA) in the southeast tropical Atlantic (20°–10° S; 10° W–5° E). This positive relationship, which spread westward along the southern branch of the South Equatorial Current, is associated with northwesterly surface wind anomalies. A warmer sea surface temperature in the southwestern Atlantic warm pool increases the moisture flux convergence, as well as its ascending motion and, hence, the rainfall along the adjacent coastal region. For the Northern NEB, another positive relationship is observed between the February-to-April rainfall anomalies and the SSTA of the previous boreal summer in the Atlantic Niño region (3° S–3° N; 20° W–0°). The negative remote relationship noticeable between the Northern NEB rainfall and the concomitant Pacific Niño/Niña follows cold/warm events occurring during the previous boreal summer in the eastern equatorial Atlantic. The southeastern tropical Atlantic and Atlantic Niño SSTA indexes may, then, be useful to predict seasonal rainfall over the Eastern and Northern NEB, respectively, for about a 6 month leading period. The ability of both southeastern tropical Atlantic and Atlantic Niño SSTA indexes to forecast the Eastern and Northern NEB rainfall, with about a 6 month lead time, is improved when these indexes are respectively combined with the Niño3 (5° S–5° N; 150°–90° W) and the northeast subtropical Atlantic (20° N–35° N, 45° W–20° W), mainly from the 1970’s climate shift. Full article
(This article belongs to the Special Issue Tropical Atlantic Variability)
Show Figures

Figure 1

Review

Jump to: Research

Review
Tropical Atlantic Variability: Observations and Modeling
Atmosphere 2019, 10(9), 502; https://doi.org/10.3390/atmos10090502 - 27 Aug 2019
Cited by 7 | Viewed by 1589
Abstract
We review the state-of-the-art knowledge of Tropical Atlantic Variability (TAV). A well-developed observing system and sustained effort of the climate modeling community have improved our understanding of TAV. It is dominated by the seasonal cycle, for which some mechanisms have been identified. The [...] Read more.
We review the state-of-the-art knowledge of Tropical Atlantic Variability (TAV). A well-developed observing system and sustained effort of the climate modeling community have improved our understanding of TAV. It is dominated by the seasonal cycle, for which some mechanisms have been identified. The interannual TAV presents a marked seasonality with three dominant modes: (i) the Atlantic Zonal Mode (AZM), (ii) the Atlantic Meridional Mode (AMM) and (iii) the variability in the Angola–Benguela Front (ABF). At longer time scales, the AMM is active and low-frequency variations in the strength, periodicity, and spatial structure of the AZM are observed. Also, changes in the mean position of the ABF occur. Climate models still show systematic biases in the simulated TAV. Their causes are model-dependent and relate to drawbacks in the physics of the models and to insufficient resolution of their atmospheric and oceanic components. The identified causes for the biases can have local or remote origin, involving the global ocean and atmospheric circulation. Although there is not a clear consensus regarding the role of model resolution in the representation of the TAV, eddy-resolving ocean models combined with atmospheric models with enhanced horizontal and vertical resolutions simulate smaller biases. Full article
(This article belongs to the Special Issue Tropical Atlantic Variability)
Show Figures

Figure 1

Back to TopTop