Diurnal to Seasonal Meteorological Cycles in an Equatorial Andean Gradient

Abstract

The climate of the equatorial mountains of the Andes presents a pronounced spatiotemporal variability, which, coupled with limited meteorological monitoring, hampers our understanding of the regional and local atmospheric processes that govern this variability. To deepen our understanding of the climate of this region, we analyzed diurnal to seasonal meteorological patterns of the main meteorological variables: precipitation, air temperature, relative humidity, incident solar radiation, and wind speed and direction; We used a unique 10-year high-resolution dataset from March 2013 to March 2023 along an altitudinal gradient, located in southern Ecuador. Our analyses reveal a trimodal regime of precipitation; the wet seasons are associated to convective processes influenced by the Intertropical Convergence Zone (ITCZ) position over the study area around the equinoxes, and the less humid season is due to the intensification of the Walker circulation that produces subsidence over the study area. The relative humidity shows distinct daily and seasonal variation; reaching minimum values around noon, when air temperature is the highest and an annual minimum on November. Furthermore, incident solar radiation reaches its maximum values around the equinoxes when sunlight is almost perpendicular, which produces greater heating on the surface and hence a more humid atmosphere. The meridional displacement of the ITCZ around the year influences the climate, increasing humidity from March to May and wind speed from April to July. Our research reveals significant differences between diurnal and seasonal meteorological cycles, highlighting the importance of altitude, topography, and wind patterns in the climate dynamics of the equatorial Andes.