Journal Article

Climatological assessment of the vertically resolved optical and microphysical aerosol properties by lidar measurements, sun photometer, and in situ observations over 17 years at Universitat Politècnica de Catalunya (UPC) Barcelona

Comeron, Adolfo, Lolli, Simone, Querol, Xavier, Sicard, Michaël, Reche, Cristina, Amato, Francesco, Alastuey, Andrés, Oliveira, Daniel, Rodriguez-Gomez, Alejandro, Landi, Tony C., Dios Otin, Federico, Gíl-Diaz, Cristina, Munoz-Porcar, Constantino, Rocadenbosch, Francesc

2023

Overview

Aerosols are one of the most important pollutants in the atmosphere and have been monitored for the past few decades by remote sensing and in situ observation platforms to assess the effectiveness of government-managed reduction emission policies and assess their impact on the radiative budget of the Earth's atmosphere. In fact, aerosols can directly modulate incoming short-wave solar radiation and outgoing long-wave radiation and indirectly influence cloud formation, lifetime, and precipitation. In this study, we quantitatively evaluated long-term temporal trends and seasonal variability from a climatological point of view of the optical and microphysical properties of atmospheric particulate matter at the Universitat Politècnica de Catalunya (UPC), Barcelona, Spain, over the past 17 years, through a synergy of lidar, sun photometer, and in situ concentration measurements. Interannual temporal changes in aerosol optical and microphysical properties are evaluated through the seasonal Mann–Kendall test. Long-term trends in the optical depth of the recovered aerosol; the Ångström exponent (AE); and the concentrations of PM10, PM2.5, and PM1 reveal that emission reduction policies implemented in the past decades were effective in improving air quality, with consistent drops in PM concentrations and optical depth of aerosols. The seasonal analysis of the 17-year average vertically resolved aerosol profiles obtained from lidar observations shows that during summer the aerosol layer can be found up to an altitude of 5 km, after a sharp decay in the first kilometer. In contrast, during the other seasons, the backscatter profiles fit a pronounced exponential decay well with a well-defined scale height. Long-range transport, especially dust outbreaks from the Sahara, is likely to occur throughout the year. During winter, the dust aerosol layers are floating above the boundary layer, while during the other seasons they can penetrate the layer. The analysis also revealed that intense, short-duration pollution events during winter, associated with dust outbreaks, have become more frequent and intense since 2016. This study sheds some light on the meteorological processes and conditions that can lead to the formation of haze and helps decision makers adopt mitigation strategies to preserve large metropolitan areas in the Mediterranean basin.

• Publisher: Copernicus GmbH,European Geosciences Union,Copernicus Publications
• Subject: Aerosol layers / Aerosol optical depth / Aerosol properties / Aerosols / Air pollution / Air quality / Analysis / Atmosphere / Atmospheric aerosols / Atmospheric and Oceanic Physics / Atmospheric particulate matter / Atmospheric particulates / Backscatter / Boundary layers / Climate change / Climatology / Cloud formation / Clouds / Decay / Dust / Earth Sciences / Emission analysis / Emissions / Emissions control / Evaluation / Haze / Lasers / Lidar / Lidar measurements / Lidar observations / Long wave radiation / Long-range transport / Metropolitan areas / Mitigation / Optical analysis / Optical instruments / Optical properties / Optical radar / Optical thickness / Outbreaks / Outdoor air quality / Outgoing long-wave radiation / Particulate emissions / Particulate matter / Photometers / Physics / Policies / Precipitation (Meteorology) / Radiation / Remote sensing / Rites, ceremonies and celebrations / Scale height / Sciences of the Universe / Seasonal variability / Seasonal variation / Seasonal variations / Seasons / Short wave radiation / Solar radiation / Suspended particulate matter / Temporal variations / Trends / Winter