Position of the Bolivian High system: climatology and its relationship with precipitation and streamflow in the southern highlands of Peru

The Bolivian High (BH) is an upper-tropospheric anticyclonic circulation associated with the South American Monsoon System, exerting a significant influence on the seasonal hydroclimate of the Andes. However, its short-term (daily and monthly) relationship with Andean hydrology remains understudied due to challenges in long-term detection of BH. An automatic method for tracking the BH applied to the ERA5 reanalysis was used to examine its short-term position (latitude, longitude, and altitude) in relation to precipitation and streamflow in the Southern Highlands of Peru (SHP), with emphasis on droughts during ENSO phases. Climatologically, the BH centre lies at 16.5°S, 65.2°W, and 12448.6 mgp at 200 hPa during December–February (1981–2020). Daily positions vary more in longitude than in latitude. A seasonal migration pattern is observed between November-April, with the BH shifting from northeast Bolivia to the south-southwest and returning northeast. A south-westward (north-eastward) BH shift usually brings wetter (drier) SPH conditions, especially along the western Andes. These shifts enable or inhibit the moisture transport from the Amazon basin to the Andes. Droughts in the SHP are linked to El Niño's northeastward shift since January. Conversely, during La Niña, the BH shifts southward, favouring above-average precipitation and streamflow, particularly on the western slope. This study improves understanding of the short-term relationship between the BH and hydroclimatic conditions in the SHP. It provides a tool for BH monitoring in the context of weather and climate prediction and climate change scenarios.