scholarly journals North Tropical Atlantic influence on western Amazon fire season variability

2011 ◽  
Vol 38 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Katia Fernandes ◽  
Walter Baethgen ◽  
Sergio Bernardes ◽  
Ruth DeFries ◽  
David G. DeWitt ◽  
...  
Keyword(s):  
Fire Season ◽  
Tropical Atlantic ◽  
North Tropical Atlantic

scholarly journals Spurious North Tropical Atlantic precursors to El Niño

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjun Zhang ◽  
Feng Jiang ◽  
Malte F. Stuecker ◽  
Fei-Fei Jin ◽  
Axel Timmermann
Keyword(s):  
El Niño ◽  
Cross Correlation ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Tropical Atlantic ◽  
The North ◽  
Sst Variability ◽  
Primary Driver ◽  
North Tropical Atlantic

AbstractThe El Niño-Southern Oscillation (ENSO), the primary driver of year-to-year global climate variability, is known to influence the North Tropical Atlantic (NTA) sea surface temperature (SST), especially during boreal spring season. Focusing on statistical lead-lag relationships, previous studies have proposed that interannual NTA SST variability can also feed back on ENSO in a predictable manner. However, these studies did not properly account for ENSO’s autocorrelation and the fact that the SST in the Atlantic and Pacific, as well as their interaction are seasonally modulated. This can lead to misinterpretations of causality and the spurious identification of Atlantic precursors for ENSO. Revisiting this issue under consideration of seasonality, time-varying ENSO frequency, and greenhouse warming, we demonstrate that the cross-correlation characteristics between NTA SST and ENSO, are consistent with a one-way Pacific to Atlantic forcing, even though the interpretation of lead-lag relationships may suggest otherwise.

Interannual sea surface chlorophyll-a signature in the tropical Atlantic

2021 ◽  
Author(s):  
Fanny Chenillat ◽  
Julien Jouanno ◽  
Serena Illig ◽  
Founi Mesmin Awo ◽  
Gaël Alory ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface ◽  
Tropical Atlantic ◽  
Cold Tongue ◽  
Equatorial Atlantic ◽  
Atlantic Region ◽  
The North ◽  
Sst Anomaly ◽  
Equatorial Band ◽  
North Tropical Atlantic

<div><span>Surface chlorophyll-<em>a </em>concentration (CHL-<em>a</em>) remotely observed by satellite shows a marked seasonal and interannual variability in the Tropical Atlantic, with potential consequences on the marine trophic web. Seasonal and interannual CHL-<em>a </em>variability peaks in boreal summer and shows maxima in the equatorial Atlantic region at 10˚W, spreading from 0 to 30˚W. In this study, we analyze how the remotely-sensed surface CHL-<em>a </em>responds to the leading climate modes affecting the interannual equatorial Atlantic variability over the 1998-2018 period, namely the Atlantic Zonal Mode (AZM) and the North Tropical Atlantic Mode (NTA, also known as the Atlantic Meridional Mode). The AZM is characterized by anomalous warming (or cooling) along the eastern equatorial band. In contrast, the NTA is characterized by an interhemispheric pattern of the sea surface temperature (SST), with anomalous warm (cold) conditions in the north tropical Atlantic region and weak negative (positive) SST anomalies south of the equator. We show that both modes significantly drive the interannual Tropical Atlantic surface CHL-<em>a </em>variability, with different timings and contrasted modulation on the eastern and western portions of the cold tongue area. Our results also reveal that the NTA slightly dominates (40%) the summer tropical Atlantic interannual variability over the last two decades, most probably because of a positive phase of the Atlantic multidecadal oscillation. For each mode of variability, we analyze an event characterized by an extreme negative sea surface temperature (SST) anomaly in the Atlantic equatorial band. Both modes are associated with a positive CHL-<em>a </em>anomaly at the equator. In 2002, a negative phase of the NTA led to cold SST anomaly and high positive CHL-<em>a </em>in the western portion of the cold tongue, peaking in June-July and lasting until the end of the year. In contrast, in 2005, a negative phase of the AZM drove cool temperature and positive CHL-<em>a </em>in the eastern equatorial band, with a peak in May-June and almost no signature after August. Such contrasted year to year conditions can affect the marine ecosystem by changing temporal and spatial trophic niches for pelagic predators, thus inducing significant variations for ecosystem functioning and fisheries.</span></div>

scholarly journals Interannual variability of the tropical Atlantic independent of and associated with ENSO: Part I. The North Tropical Atlantic

2006 ◽  
Vol 26 (14) ◽  
pp. 1937-1956 ◽  
Author(s):  
Itsuki C. Handoh ◽  
Adrian J. Matthews ◽  
Grant R. Bigg ◽  
David P. Stevens
Keyword(s):  
Interannual Variability ◽  
Tropical Atlantic ◽  
The North ◽  
North Tropical Atlantic

scholarly journals Understanding the 2017 warm event in North Tropical Atlantic

2020 ◽  
Author(s):  
Ana Trindade ◽  
Marta Matín-Rey ◽  
Marcos Portabella ◽  
Eleftheria Exarchou ◽  
Pablo Ortega ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Large Scale ◽  
Temporal Frequency ◽  
Surface Wind ◽  
Sea Surface ◽  
Earth Model ◽  
Tropical Atlantic ◽  
Ocean Wind ◽  
North Tropical Atlantic

<p>The Atlantic Ocean has suffered tremendous warming during recent decades as a consequence of anthropogenic forcing, modulated by the natural low frequency variability. Special attention should be paid to the high temporal frequency of warm interannual events in the North Tropical Atlantic (NTA) since the early 2000s, resulting in the most intense hurricane seasons on record (Hallam et al., 2017; Lim et al., 2018; Murakami et al., 2018; Klotzbach et al., 2018; Camp et al., 2018). Moreover, NTA sea surface temperature anomalies during boreal spring have been suggested as a potential precursor to the Equatorial Mode (Foltz and McPhaden, 2010ab; Burmeister et al., 2016; Martín-Rey and Lazar, 2019; Martín-Rey et al., 2019).<strong> </strong></p><p>This study aims to investigate the development of the 2017 NTA spring-summer warming event, which was the strongest of the last decade, as well as the importance of an accurate ocean forcingin the simulation of this event. For such purpose, a set of four simulations using distinct ocean wind forcing products, namely from the EC-Earth model, ERA-Interim (ERAi) reanalysis and a new ERAi-corrected ocean wind product (ERAstar), have been performed and analysed.The latter consists of average geolocated scatterometer-based corrections applied to ERAi output (Trindade et al., 2019).In this sense, ERAstar includes some of the physical processes missing or misrepresented by ERA-i, and corrects for large-scale NWP parameterization and dynamical errors.</p><p>The air-sea processes underlying the onset and development of the warm 2017 NTA event and the wave activity present in the equatorial Atlantic will be explored to determine their possible connection with the equatorial sea surface temperature variability. Furthermore, the comparison between the different experiments allows us to validate the new surface wind dataset and evaluate the importance of accurate, high-resolution ocean forcing in the representation of tropical Atlantic variability.</p>

scholarly journals Dominant role of North tropical Atlantic 2017 warm event on equatorial variability

2021 ◽  
Author(s):  
Ana Trindade ◽  
Marta Martín-Rey ◽  
Marcos Portabella ◽  
Eleftheria Exarchou ◽  
Pablo Ortega ◽  
...  
Keyword(s):  
Wind Stress ◽  
Wave Activity ◽  
Small Scale ◽  
Tropical Atlantic ◽  
Equatorial Atlantic ◽  
Sst Variability ◽  
Hurricane Season ◽  
The Impact ◽  
North Tropical Atlantic

<p>Multiple lines of new evidence suggest that the Atlantic Ocean plays an active role in the modulation of global climate. Special attention deserves tropical Atlantic extreme events that have increased from 2000s causing severe winter conditions in the Euro-Atlantic region and originating the most devastating hurricane seasons on record (Foltz and McPhaden 2006; Bucham et al. 2014; Lim et al. 2018; Klotzbach et al. 2018). In 2017, the north Tropical Atlantic (NTA) experienced a profound warming, resembling the Atlantic Meridional Mode (AMM) pattern, that originated a destructive hurricane season with catastrophic social and economic damages (Klotzbach et al. 2018). Previous studies focused their attention on the description of the precursors and predictability of the 2017 hurricane season. Nevertheless, the impact of the 2017 NTA warming on equatorial SST variability has not been explored so far. Recent findings put forward the key role of the AMM-associated cross-equatorial wind to trigger oceanic waves that impact on equatorial SSTs (Martín-Rey and Lazar 2019; Foltz and McPhaden 2010).</p><p>Thus, in the present study, we investigate the connection between NTA and equatorial variability during 2017, as well as the importance of an accurate ocean forcing to correctly simulate this event. For such purpose, a suite of three initialized climate predictions, performed with the climate model EC-Earth (version3.3), are analyzed. Two sets of predictions apply a wind stress correction over the Tropical Atlantic (35S-35N) using two distinct wind stress products: ERA-Interim (ERAI) reanalysis and a new ERAI-corrected (ERA*) wind product, which are compared to a control prediction with model-generated wind stress (MOD). ERA* has been developed based on means of a geolocated scatterometer-based correction applied to the ERA-interim reanalysis (Trindade et al. 2019). The high-quality of the scatterometer stress-equivalent winds (Portabella and Stoffelen 2009; De Kloe et al., 2017) allows ERA* to contain some of the physical processes missing or misrepresented (i.e., small-scale ocean processes, such as wind-current interaction) in ERAI.</p><p>Using more realistic surface wind stress (ERAI or ERA* with respect to MOD) considerably improves the simulation of eastern NTA and equatorial warming. The novel wind stress product (ERA*) respect its precursor ERAI, better represents the off-shore warm SSTs in the NTA and along eastern equatorial Atlantic and south African coast. It is worth mentioning that oceanic wave activity proves highly sensitivity when forced by realistic ERAI and ERA* wind stress products. In the wind-corrected experiments, an anomalous wind stress curl north of the equator during March-April excites a downwelling Rossby wave that propagates to the west and is boundary reflected in June-July, becoming an equatorial downwelling Kelvin wave (dKW). This dKW displaces eastward favouring the development of an equatorial warming in late-summer and fall. ERA* does not show significant changes in the RW generation, but in the amplitude of equatorial KW during summer season.</p><p>Our results highlight the importance of using improved wind stress products to achieve a correct simulation of ocean wave activity and in turn equatorial Atlantic SST variability. This information is of great value for improving current seasonal forecast systems.</p>

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