Identificação das causas climáticas dos eventos extremos e dos impactos dos ENOS Canônico e Modoki nas macrorregiões de Alagoas

Abstract

Anomalies of sea surface temperature that occur in some regions of the Equatorial Pacific Ocean are being studied because their cause different impacts and originate in different ways, are the ENOS, Modoki and Canonical. The objective of this work is to identify the climatic causes of the extreme events that occurred in the macro-regions of Alagoas, and at the same time, to compare the effects of ENOS Canonical and Modoki and their classes on the macro-regions of Alagoas. The daily precipitation data for 21 municipalities in the State of Alagoas were obtained through the National Water Agency from 1963 to 2014. EN Modoki and low promoted an increase in rainfall in the Eastern region. EN Fortes, on the other hand, caused a decrease in rainfall in the Sertão. Canonical LN events caused a significant increase in rainfall in the three macro-regions, but the effect was better in LN Forte. During the phases of the Atlantic Dipole, the negative phase generated positive SPI across the state, and in the positive phase, there was a decrease in SPI in the East, and a negative SPI record in Sertão and Agreste. The climatic causes of the extreme events were the combination of semiannual, interannual scales, scale between 1-2 years of ENOS, scale of ENOS extended and scale of 11 years (Dipole and sunspots), potentiating the local total rainfall, and for cases of drought , your absence. It was found, through cluster analysis, similarity between the SPIs of La Niña low and La Niña Canonical, and between El Niño Canonical is linked to El Niño Forte. Mathematically, the categories of El Niño and La Niña strong and weak showed better correlations with ENOS Modoki and Canonical, suggesting a pattern for Alagoas.

Effects of extreme phases of El Niño–Southern Oscillation on rainfall extremes in Alagoas, Brazil

“…In all 3 years evaluated in the study (1983, 1998 and 2015), the highest values were recorded in the northern part of the East Alagoas region, resembling the results obtained by Da Silva et al (2021), which showed positive SPI values for the region. Regardless of the Very Strong El Niño events, the region stood out with the highest rainfall totals, indicating the influence of other synoptic and mesoscale meteorological systems, such as EWD, breeze circulation, the position of the ITCZ, and SST anomalies near the NEB coast, which contribute to increased rainfall totals in this region (Lyra et al, 2014, 2017).…”

“…These variations are directly associated with the influence of sea surface temperature variability in the tropical South Atlantic, in contrast to Pacific tropical conditions (Kayano and Andreoli, 2006). Recently, some authors have identified the association of various simultaneous and multiscale systems/phenomena, for example, Oliveira‐Júnior et al (2021a, 2021b), Santos Rocha et al (2022), Silva et al (2020) and Da Silva et al (2021), mainly in the ENEB, with an influence on the occurrence of extreme rainfall and drought.…”

“…It is worth noting that the NEB exhibits natural climatic variability associated with large-scale anomalous patterns, mainly influenced by climate variability modes such as El Niño-Southern Oscillation (ENSO), Madden-Julian Oscillation (MJO) (Kane, 1997;Marengo et al, 2017;Silva et al, 2020;Da Silva et al, 2021), the Interhemispheric Gradient of Sea Surface Temperature of the Atlantic (IGSSTA), formerly known as the Atlantic Dipole (Lyra et al, 2017;Oliveira-Júnior et al, 2021a, 2021b, and the Pacific Decadal Oscillation (PDO), which can decrease or enhance extreme events in the region, particularly in the East NEB (ENEB) (Lyra et al, 2014(Lyra et al, , 2017. The NEB is the region in the country with a high long-term climate risk concerning the population of the semiarid region (rainfall deficit) and, in recent decades, the population residing in metropolitan areas (extreme rainfall), and consequently, these are areas that also suffer from flash floods, landslides, urban drainage problems and waterborne diseases (Correia Filho et al, 2013;Costa et al, 2015;Marengo et al, 2020;Monteiro et al, 2022;Oliveira et al, 2013;Oliveira-Júnior et al, 2021a, 2021bSantos et al, 2023).…”

“…Alagoas is plagued by severe droughts, recurrent floods and flash floods (Costa et al, 2020a(Costa et al, , 2020bLyra et al, 2014Lyra et al, , 2017Oliveira Júnior et al, 2012), despite being one of the states with the smallest territorial area in Brazil (IBGE, 2023). Studying the extreme phases of ENSO is important to understand the impacts on various areas of society, particularly in agriculture and tourism, which are the main economic sectors in Alagoas (Oliveira-Júnior et al, 2021a, 2021bSilva et al, 2020;Da Silva et al, 2021;Souza et al, 2012) and to support the state's Civil Defense (Silva Junior et al, 2022). However, few studies have focused on the effects of extreme ENSO phases and their influence on ENEB, especially in Alagoas, using historical observed time series, with particular attention to the occurrence of Mega El Niño (Wang et al, 2015;Zeng & Sun, 2022).…”

Long‐term trend analysis in annual, seasonal and monthly rainfall in East Northeast of Brazil and the influence of modes of climate variability

“…Thus, the effects of modes of climate variability could be examined and related to temporal trends in rainfall patterns. Trends detected mostly in months of transition from the dry and rainy season (March, April and September), between 1995 and 2000, coincide with changes in the PDO phase from warm to cold in 1999 (NASA, 2022) and the very strong El Niño event of 1997/98, one of the strongest of the 20th century (Ballester et al, 2016; Costa et al, 2020; Da Silva et al, 2021; Oliveira‐Júnior et al, 2021).…”