Change of the Rainfall Seasonality Over Central Peruvian Andes: Onset, End, Duration and Its Relationship With Large-Scale Atmospheric Circulation

Abstract

Changes of the onset dates, end dates, and duration of the rainy season over central Peruvian Andes (Mantaro river basin, MRB) could severely affect water resources management and the main economic activities (e.g., rainfed agriculture, raising cattle, among others). Nonetheless, these changes have not been documented for the Tropical Andes. To asses that, we used daily datasets of observed rainfall during the 1965–2013 period. For this period, the average onset (end) date of the rainy season over the MRB occurs in the pentad 17 (19–23 September) [pentad 57 (7–11 April)]. The duration of the rainy season mainly is modulated by the onset dates due to it has higher variability than end dates. There is a reduction of 3 days/decade in the duration of wet season over the MRB for the last four decades due to the delay of the onset days. Furthermore, El Niño favors late-onset and early end of the rainy season, while La Niña favors early onset and late end of the rainy season in the MRB. Onset dates are related to the propagation of the convective region of the South American Monsoon System (SAMS), from the Caribbean region toward the central Amazon basin. Early (late)-onset days are associated with a southward (northward) shift of the South Atlantic Convergence Zone (SACZ) and weak (strong) convection over equatorial Atlantic that induces the southernmost propagation (eastward shift) of the SAMS.

Comparative Analysis of Climate Change Impacts on Meteorological, Hydrological, and Agricultural Droughts in the Lake Titicaca Basin

“…The projected precipitation increases in January (the wettest month) and the rise of the coefficient of variation of annual precipitation suggest an intensification of the hydrological cycle. This is consistent with recent studies that suggest rainfall concentration [10,92,93]. Meteorological droughts in the Altiplano have been associated with El Niño-Southern Oscillation (ENSO events) [94,95].…”

Spatiotemporal patterns of ENSO‐precipitation relationships in the tropical Andes of southern Peru and Bolivia

“…In an additional study (Perry et al ., 2017), La Paz exhibited negative precipitation anomalies during both phases of ENSO from 1979 to 2009, whereas Cusco exhibited positive precipitation anomalies during El Niño and negative anomalies during La Niña from 1963 to 2009 (Perry et al ., 2014; Perry et al ., 2017). In the Mantaro River Basin of Peru, El Niño favours a late onset and early end to the wet season whereas an early onset and late end with La Niña (Giráldez et al ., 2020). ENSO variability may also be influencing long‐term trends in precipitation across the region (Heidinger et al ., 2018).…”

Assessment of CMIP6 Performance and Projected Temperature and Precipitation Changes Over South America

“…Like many other regions across the planet, South America has experienced environmental changes during the twentieth century, including increasing surface temperatures (Salviano et al 2016;de Barros Soares et al 2017;Dereczynski et al 2020;Pabon-Caicedo et al 2020), shifting precipitation patterns (Espinoza et al 2019;Paca et al 2020;Marrafon et al 2020;Carvalho 2020;Giráldez et al 2020;Pabon-Caicedo et al 2020), vanishing Andean glaciers (Schauwecker et al 2014;Malmros et al 2016;Drenkhan et al 2018;Vuille et al 2018;Somers et al 2019;Masiokas et al 2020), and an increase in weather and climate extremes, such as droughts, floods, and wildfires (Barros et al 2015;Martins et al 2018;Viganó et al 2018;Cunha et al 2019;Feron et al 2019;Lemes et al 2020;Debortoli et al 2020;…”