To understand the impact of climate change on mesoscale convective systems (MCSs), we need to understand how the environment in which they are generated influences them. That is, it is essential to understand the dynamic and thermodynamic atmospheric patterns associated with the occurrence of MCSs in the current climate to advance our understanding of future climate conditions using climate change scenarios.

In the Amazon basin, this type of investigation presents a high degree of difficulty, mainly due to the lack of homogeneity and scarcity of observational data and the high variability of larger scale systems and circulations. Furthermore, the Amazon basin exhibits relatively constant convective instability and abundant convection while various MCSs occur throughout the territory. In addition to these factors, the interaction of atmospheric variables with physical territorial elements, such as topography, river intermittency, vegetation, constant and accelerated changes in land use, among others, can be added.

Climate projections indicate a continuous increase in air temperature and reduction in precipitation over the Amazon basin until the end of this century. However, what will actually cause the reduction (and how) in precipitation is not yet well understood. One thing that is known is that one of the main meteorological systems causing precipitation in the Amazon basin, mesoscale convective systems (MCSs), have shown negative occurrence trends between September and November (SON) over the Amazon basin and positive trends between June and August (JJA) in the southern part since 1950 until the near future (Rehbein, 2021).

However, the conditions associated with their formation and maintenance are not well understood over the Amazon basin, and several gaps remain open. For example, what has caused these trends? Is the increase in MCSs, mainly in the southern part of the Amazon basin, in JJA associated with the frequency and intensity of extratropical cyclones that disturb the Amazonian synoptic environment, increasing wind shear, favoring instability, and the formation of clustered systems? Or is it due to changes in the position of the Intertropical Convergence Zone or the descending branch of the Hadley cell? Or simply due to local temperature increase, temperature gradients, and thermodynamic factors?

On the other hand, what are the factors leading to the decrease in MCSs during SON? Therefore, within this context, the objective of this study is to identify the factors that have impacted and will impact the long-term trends in MCS occurrences in the Amazon basin and consequently its precipitation. Additionally, this study will contribute to understanding the interactions between climatic scales and higher-frequency scales, generating methodology and data that may assist future research.