Effect of sea breeze regime on aerosol optical properties over the city of Rome, Italy.
- 1Sapienza University of Rome, Department of Physics, Rome, Italy; (annalisa.dibernardino@uniroma1.it)
- 2SERCO SpA, Frascati, Italy;
- 3ISAC-CNR, Rome, Italy;
- 4LuftBlick, Mutters, Austria.
Mesoscale meteorological phenomena, such as sea-land breeze regime, strongly impact meteorological conditions of coastal areas, affecting wind intensity, moisture, heat and momentum fluxes and polluted air masses dispersion. This effect must be considered in order to correct design urban spaces, predict the possible influence of land use change on air pollution and climate change and, consequently, improve the quality of life and urban comfort.
In recent years, it has been shown that the breeze regime does not only affect microclimatic conditions but also air quality in coastal areas, because of the mixing of different types of aerosols and condensable gases. Moreover, the advection of marine, colder and more humid air leads to the decrease of the boundary layer height and, consequently, to the increase of the surface concentration of locally emitted pollutants, that are trapped within the boundary layer itself.
The effect of breeze regime is particularly interesting in coastal cities, where the sea breeze entails large modification of physical, optical, chemical, and hygroscopic properties of the urban aerosol.
In this work, we developed an approach to determine the breeze effect on aerosol in correspondence of the BAQUNIN [1] Super-site urban location, in the centre of Rome, Italy. The city is about 28 km far from the Tyrrhenian coast and is often exposed to sea-breeze circulation and to extreme aerosol events [2] [3].
In-situ measurements obtained from different remote sensing instruments are used: (i) vertical profile of horizontal wind velocity and direction by means of SODAR wind profiler; (ii) moisture, air temperature and wind speed from ground-based meteorological station; (iii) aerosol optical depth (AOD), height and evolution of the Boundary Layer from Raman and elastic LIDAR; (iv) precipitable water, AOD, Ångström exponent (AE) and single-scattering albedo (SSA) from sun-photometer CIMEL [4], (v) AOD, AE and SSA from POM 01 L Prede sun-sky radiometer [5][6], (vi) superficial NO2 and formaldehyde amounts from PANDORA spectrometer [7], (vii) particulate matter (PM2.5 and PM10) concentrations from ground-based air quality station.
The investigation is focused on several days, during summer of 2019, characterized by anemological breeze regime conditions.
In this study, we present preliminary results aimed to the in-depth analysis of the effects of the breeze regime on the optical properties of aerosols in coastal, urban environment and the impact of the aerosol vertical stratification on ground-level PM concentrations.
References:
[1] BAQUNIN Boundary-layer Air Quality-analysis Using Network of Instruments, www.baqunin.eu
[2] Petenko I. et al. (2011) “Local circulation diurnal patterns and their relationship with large-scale flows in a coastal area of the Tyrrhenian sea”, Boundary-Layer Meteorology, 139:353-366.
[3] Ciardini V. et al. (2012) “Seasonal variability of tropospheric aerosols in Rome”, Atmospheric Research, 118:205-214.
[4] AERONET, https://aeronet.gsfc.nasa.gov/new_web/index.html
[5] EUROSKYRAD http://www.euroskyrad.net/
[6] Campanelli M. et al. (2019) “Aerosol optical characteristics in the urban area of Rome, Italy, and their impact on the UV index”, Atmospheric Measurement Techniques Discussion.
[7] PGN, https://www.pandonia-global-network.org/
How to cite: Di Bernardino, A., Iannarelli, A. M., Casadio, S., Mevi, G., Campanelli, M., Casasanta, G., Cede, A., Tiefengraber, M., and Cacciani, M.: Effect of sea breeze regime on aerosol optical properties over the city of Rome, Italy., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9065, https://doi.org/10.5194/egusphere-egu2020-9065, 2020.
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Dear all,
can I please ask a question about the sea-breeze detection method ? Have any applied any thresholds to the variables involved? If so, how have you chosen them.
Thanks,
Carlo Cafaro
Dear Carlo,
thank you for your comment.
The classification of the breeze days has been carried out considering the variation of wind speed and direction, air temperature, total column water vapor, and specific humidity.
For the Tyrrhenian coast of central Italy, the breeze starts when the wind blows from the South-West quadrant.
In the front days, the following thresholds were used: variation >10% for total column water vapor and specific humidity, variation >5% for temperature. Also the gradients of air temperature and specific humidity have been considered in order to better highlight temporal variations.
In the no front days, however, there are no sharp gradients of these quantities, therefore the development of the breeze has been identified basing on wind speed and direction variation.
Dear Annalisa,
thanks for your quick reply.
It is interesting your classification between front days and no front days. I had asked because I had developed a method to detect sea breezes either using high-resolution models or observations without using thresholds of the variables.
You can check it here if you want:
Thanks again,
Carlo
I see that the link to my paper is not showing up for some reasons. I can send you by e-mail if interested.
Thanks,
Carlo
Yes of course, please send me your work. I'm very interested in this topic!
My mail is annalisa.dibernardino@uniroma1.it