Ultraviolet (UV) solar irradiance measurements performed in the central Andes, Huancayo, Peru (12.0°S, 75.3°W, 3313 m asl) at 1 min intervals between January 2003 and December 2006 were used to analyse daily, monthly, and annual cycles of UV solar irradiance. The measurements were performed using a GUV-511 multi-channel filter radiometer at four wavelengths: 305, 320, 340, and 380 nm. UV irradiance data under clear sky and all sky conditions were separated using a procedure based on calculation of normalized irradiance. In February, the highest hourly mean value at noon for the UV Index reached 18.8 for clear sky conditions and 15.5 for all sky conditions, with outlier peaks close to UVI = 28. In addition, the highest mean value for the daily erythemal dose was found also in February, reaching 7.5 kJ m−2 d−1 with a maximum outlier value close to 10.1 kJ m−2 d−1. Comparisons bet...

The study evaluated the sensitivity of the precipitation forecast in the central Andes of Peru of Weather Research and Forecasting (WRF) model to change the planetary boundary layer (PBL) schemes. In that region is located the Mantaro basin, which is one of the most important in the region. Here, the rainfall is very important to the agriculture and to the reserves of drinking water. The simulations were carried out with ten PBL schemes for 19 days in January, February, and March, between 2009 and 2012. Based on the statistical analysis (model vs. observation), the more efficient schemes were determined and analyses of the vertical profiles of some variables are shown. As a result, the schemes that most helped the model in rainfall forecasting were MYNN3 (general and north sector of the basin), Bou-Lac (central sector) and Bretherton-Park (southern sector). The model generally overestima...