A Model Based on Station Observations for Planetary Boundary Layer (PBL) Evolution over an Andean Valley East of Quito, Ecuador

Balloon-borne measurements of the planetary boundary layer (PBL) over a populated Andean valley east of Quito, Ecuador were performed between June 2014 and June 2017. Observations were taken at Universidad San Francisco de Quito's Atmospheric Measurement Station (EMA, Spanish acronym). EMA is a rooftop facility located at coordinates 0.19°S, 78.4°W, and 2391 masl (meters above sea level). During the study time period, radio and ozonesondes were launched in different months and at different hours, from the early morning to midday. Combined information from vertical profiles of virtual potential temperature, water vapor mixing ratio, and ozone mixing ratio were used to determine PBL height (PBLh) for every experiment. Measurements of PBLh were found to correlate strongly with 10-minute ground station observations at the launching time. An equation that best fits the data was found for PBLh as a function of surface observations. In the study area, specialized PBL profiling with costly techniques is unavailable. However, knowledge of PBLh is critical for better understanding mechanisms of pollution accumulation in a city characterized by a unique and complex topography. Therefore, the proposed model is a useful tool to readily estimate PBLh in the study area using inexpensive surface measurements. The model will be presented and its applicability to interpret pollutant levels in the ambient air in Quito will be discussed.