Moisture flows on Southeast Brazil: Present and future climate

Abstract

The characterization of the moisture flows over South America, with a special focus on the Southeast Brazil (SEB), was performed through the analysis of 21 Earth System Models (ESMs) belonging to the Coupled Model Intercomparison Project Phase 5 (CMIP5) for the present climate (1971-2000) and projections for the late 21st century (2071-2100) using a scenario of high radiative forcing (RCP 8.5). The results show that the ESMs simulate well the spatial distribution of the flow and the divergence of moisture in the present climate, when compared with the 20CRv2c reanalysis, although some biases have been identified. In relation to the magnitude of the moisture flow, the models underestimate the moisture convergence mainly on the central, south and southeast regions of South America. On SEB, the simulations show that the main sources of moisture for the region come from the north and east edges, confirming the contribution of moisture from the Amazon Basin and the South Atlantic Ocean. Climate change projections indicate an increase in moisture flow across South America, and regions of moisture convergence (divergence) in the present climate are projected to be even more convergent (divergent) in the future climate. In addition, the moisture flow over the SEB also showed to be more intensified on all lateral edges, as well as the moisture balance. This result is consistent with some studies on projections of climate change towards the end of the 21st century, which indicate that there will be an intensification of meteorological systems such as the Low Level Jet and the South American Monsoon System, contributing to the increase of moisture transport to the SEB region.

Uncertainties in projections of climate extremes indices in South America via Bayesian inference

“…South America is among the regions that can be most impacted, and the projected changes in the mean and extreme regimes of precipitation, temperature, humidity transport (e.g., PBMC, 2014;Torres and Marengo, 2014;Avila-Diaz et al, 2020b;Penna et al, 2021;Torres et al, 2021), among other climate disturbances, can considerably affect agricultural production, water, energy and food security nexus, frequency and intensity of droughts, floods and heat waves, among countless other impacts (Field et al, 2012(Field et al, , 2014IPCC, 2012;Marengo et al, 2014Marengo et al, , 2021Debortoli et al, 2017;Betts et al, 2018;Feron et al, 2019;Lapola et al, 2019Lapola et al, , 2020Mahlknecht et al, 2020). For example, Betts et al (2018), using climate projections compatible with the warming thresholds of the Paris Agreement (1.5 C and 2 C), identified that temperature extremes could get even hotter.…”

Drought Assessment in the São Francisco River Basin Using Satellite-Based and Ground-Based Indices

“…The concurrence of different climate modes of natural variability may explain part of the intensification of drought conditions in recent decades, as suggested by Kayano et al [97]. They may act in synergy blocking the moisture transport from different oceanic regions to the basin, triggering strong drought conditions [99,100]. This statement is confirmed by several studies that found that the extreme drought events during the austral rainy season have been consistent with near surface atmospheric circulation changes and a reduced moisture flow coming from the tropical Atlantic region [10,12,18].…”

Amazon savannization and climate change are projected to increase dry season length and heat waves over Brazil

“…The Amazon moisture recycling system has been examined on its role to maintain some of the global climate processes 6,7 . The equatorial Atlantic Ocean provides moisture to the northern region of South America, promoting precipitation along the Amazon basin 8, 9,10 . A portion of the transported water vapor reaches the western portion of the basin with replenished water vapor content supplied by the Amazon forest evapotranspiration 11 .…”