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    Impacts of the future Amazon deforestation on the precipitation over the Peruvian central Andes and related atmospheric features
    (Elsevier BV, 2026-10-01)
    This study investigates the impact of a 40% Amazon deforestation scenario (projected for 2050) on precipitation over the central Peruvian Andes during five austral summer seasons (DJF 2001–2006) using high-resolution (1 km) WRF simulations. While a widespread rainfall reduction pattern is observed over the Amazon-Andes transition zone, statistically significant decreases ( p < 0.10) at the gridpoint level are primarily concentrated near rainfall hotspots in the Amazon-Andes transitions zone, reaching an average reduction of 12% (−1.4 mm day −1 ). This drying signal is physically associated with a weakening of the South American Low-Level Jet (LLJ) and reduced moisture influx, which specifically inhibits convective activity during the morning peak hours (23–11 LT). In the high-altitude Mantaro Basin, we observe a consistent drying pattern (−5%) that extends from the transition zone; although these changes are not statistically significant due to high interannual variability, the physical signal of precipitation reduction and dry air advection remains clear. Conversely, the western Andean ridges exhibit a localized precipitation increase (up to 20%) linked to intensified cross-barrier easterly wind anomalies reinforcing diurnal anabatic circulation. We further find that while 5 km resolution captures broad basin-scale patterns, convection-permitting scales (1 km) are essential for resolving these complex topographic effects. These findings highlight a critical vulnerability concentrated along the eastern slopes and the high Andes. The identified drying patterns, which are particularly pronounced in the Andes-Amazon transition zone (a global biodiversity hotspot) and extend into the highlands, pose a significant threat to endemic ecosystems and regional water security, specifically through reservoir inflow reduction and negative impacts on agriculture.
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    Influence of local topographic structures on the atmospheric mechanisms related to the Andean-Amazon rainiest zone
    (Elsevier, 2025)
    The Andes-Amazon transition region features critically important ecological services on the local, regional and global scales. This region is among the rainiest zones in the world, with rainfall rates of up to 7000 mm/year. However, the physical mechanisms leading to the existence of these “precipitation hotspots” remain poorly known. Here, we attempt to disentangle the controlling atmospheric mechanisms exerted by local topographic structures that started to uplift about 5–10 million years ago in response to the Nazca Ridge subduction, in the vicinity of the Quincemil hotspot, the most intense of them. We first use the Weather Research and Forecasting model to conduct sensitivity tests to planetary boundary layer parameterizations at 5 km horizontal grid spacing during the austral summer of 2012–13. After finding the most suitable configuration in terms of the diurnal cycle of rainfall intensity and extent, we further perform topographic sensitivity tests by reducing the Fitzcarrald Arch lowlands and, on top of it, by removing the Camisea mountain. The Fitzcarrald Arch deflects moisture flux towards Quincemil, while the Camisea mountain induces local vortical circulations that increase moisture transport, convergence and rainfall over Quincemil, ultimately controlling its location and intensity by up to 40 %. When reducing the height of the Andes in half, we find that it sustains the development of precipitation hotspots, accounting for up to 60 % of rainfall, by providing a mechanical forcing to increase regional-scale moisture fluxes. Such mechanisms dominate during nighttime, when rainfall peaks in the region, and might explain the existence of the rainiest zone in the Andes-Amazon transition.
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