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Evaluation of the impact of atmospheric aerosols on Sierra Nevada precipitation

The study of precipitation on mountainous environments is of vital importance since they are very sensitive to climatic variations. Snow represents a crucial role on water reservoirs, taking special relevance on semiarid regions like the south of Spain. Sierra Nevada is one of the mountain ranges of higher altitude in Europe and represents a real-life laboratory for studies related to climate change and its impact on precipitation and water reservoirs.
On the process of formation and evolution of clouds, the atmospheric aerosol takes an important role, acting as cloud condensation or ice nuclei making possible the formation of cloud droplets and ice crystals respectively. Furthermore, these particles modify the microphysical properties of clouds that may cause the suppression of precipitation.
One of the most favorable scenarios for cloud and precipitation in Sierra Nevada are cyclonic systems that bring winds from the west. The air masses ascend as they find the mountain range and form orographic clouds. The particles transported in these air masses seed the clouds and determine the properties and evolution of the clouds. Granada is the urban area located just before the mountain range to the west, and situations with high pollution, along with the meteorological conditions may cause that particles are incorporated into that air mass. In the same way, the air mass may transport particles from long distances, and it is particularly important the transport of mineral dust from the Sahara given its influence on precipitation and its high impact on the study area.
In this project we are studying the situations that cause the formation of clouds and precipitation in Sierra Nevada, along with the air mass trajectories in order to determine under what circumstances the aerosol particles, local or transported are incorporated and take part in the cloud mass. At the same time we are studying with remote sensing instrumentation the vertical structure of the atmosphere over the city of Granada (optical properties of the aerosol, thermodynamic and wind profiles) in order to study the incorporation of pollutants from the city to the air mass that form the cloud. Lastly, precipitation samples from the slopes of Sierra Nevada are being analyzed chemically in order to look for trace compounds that evidence the origin of particles that seeded the clouds. All this information will serve to evaluate the scenarios that cause precipitation in form of snow or rain, and situation that may cause precipitation suppression.