Valley–Mountain Circulation Associated with the Diurnal Cycle of Precipitation in the Tropical Andes (Santa River Basin, Peru)

Atmosphere

Rosmeri P. da Rocha¹  Alan G. Rosales²  Thomas Condom³  Clementine Junquas³  Jhan-Carlo Espinoza³ 

[1] Departamento de Ciências Atmosféricas, Universidade de São Paulo, São Paulo 05508, Brazil;Department of Earth and Atmospheric Science, Central Michigan University (CMU), Mount Pleasant, SC 48859, USA;University Grenoble Alpes, IRD, CNRS, Grenoble INP, IGE, 38000 Grenoble, France;

关键词: WRF model;    precipitation;    diurnal cycle;    tropical Andes;    Santa River basin;   

DOI  :  10.3390/atmos13020344

来源: DOAJ

【 摘 要 】

The Cordillera Blanca (central Andes of Peru) represents the largest concentration of tropical glaciers in the world. The atmospheric processes related to precipitations are still scarcely studied in this region. The main objective of this study is to understand the atmospheric processes of interaction between local and regional scales controlling the diurnal cycle of precipitation over the Santa River basin located between the Cordillera Blanca and the Cordillera Negra. The rainy season (December–March) of 2012–2013 is chosen to perform simulations with the WRF (Weather Research and Forecasting) model, with two domains at 6 km (WRF-6 km) and 2 km (WRF-2 km) horizontal resolutions, forced by ERA5. WRF-2 km precipitation shows a clear improvement over WRF-6 km in terms of the daily mean and diurnal cycle, compared to in situ observations. WRF-2 km shows that the moisture from the Pacific Ocean is a key process modulating the diurnal cycle of precipitation over the Santa River basin in interaction with moisture fluxes from the Amazon basin. In particular, a channeling thermally orographic flow is described as controlling the afternoon precipitation along the Santa valley. In addition, in the highest parts of the Santa River basin (in both cordilleras) and the southern part, maximum precipitation occurs earlier than the lowest parts and the bottom of the valley in the central part of the basin, associated with the intensification of the channeling flow by upslope cross-valley winds during mid-afternoon and its decrease during late afternoon/early night.

【 授权许可】

Unknown