In the sprawling, urban area of Rome, where atmospheric composition is impacted by complex coastal weather and pollution, ESA supports a powerful observatory spread across several locations. Multiple ground based active and passive instruments operate in synergy to create validated satellite atmospheric products, ranging from aerosol and wind measurements, to trace gas concentrations.

As the world’s population continues to grow, the number of urban inhabitants is expected to reach almost 70 percent of our population by 2050, according to the United Nations. Tracking atmospheric composition in urban areas is challenging as urban infrastructure, such as high-rise buildings and roads, add complexity to atmospheric processes by limiting ventilation and pollution dispersion in the atmosphere closest to the ground - the so-called urban boundary layer.

Densely populated urban areas are also troubled by air quality degradation, with increases in anthropogenic gases and particulate matter threatening human health. Thermal imbalance is another problem, with phenomena such as the urban heat island effect.

The Boundary-layer Air Quality-analysis Using Network of INstruments (BAQUNIN) supersite aims to support the validation and calibration of satellite data products in urban areas, as well as providing long-term, high-resolution datasets on the urban environment.

See an infographic summary of BAQUNIN. 

The project provides an infrastructure for the validation of present and future satellite atmospheric products, so that several existing and new space atmospheric missions of ESA’s Third Party mission programme, benefit from BAQUNIN. Data emerging from the Japanese environmental monitoring Greenhouse Gases Observing Satellites (GOSAT) and the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite, are already using BAQUNIN to validate their data products. The data from these missions can be accessed for free for research and application projects via ESA’s TPM programme.

BAQUNIN serves as an excellent tool for such data products, due to the variety of remote sensing instruments available, and the carefully chosen locations of the measurement sites. Supersites are essentially measurement observatories composed of multiple instruments across extensive areas. The BAQUNIN supersite consists of three observation sites, one in the highly urban Rome city centre, and another two in the city’s surrounding semirural and rural areas. It has multiple passive and active remote sensing ground-based instruments at these various observation sites, managed by different research institutions.

The main BAQUNIN site is in the densely populated Rome city centre, on the rooftop of a six-floor building. The second site is in a flat, semi-rural environment about 13 km southeast of Rome, close to the Alban hills. Finally, the third site is in the Tiber valley area, about 26 km northeast of Rome, where it functions as a reference for rural background measurements.

Rome is a coastal city with varied topography and peculiar local circulation patterns. It is also prone to experiencing extreme aerosol events, such as Saharan dust. By choosing these differing locations, the supersite allows in-depth studies of urban research, such as urban heat island, under different atmospheric conditions. Across these locations, there is a plethora of in situ and ground based remote sensing instruments, operating in synergy – ranging from lidars, sodars, photometers, passive in-situ instruments and RGB (red, green, and blue colour) imagers.

The BAQUNIN supersite collects pollutant concentrations and meteorological parameters. It acquires, homogenises, and distributes high quality data products, such as aerosols, atmospheric trace gases and greenhouse gases, as well as various meteorological products, such as wind, turbulence, and water vapour.

The consortium behind BAQUNIN is comprised of multiple entities based in Rome; Serco, the Atmospheric Physics Laboratory of Rome’s Sapienza University, the National Research Council (CNR) Institute of Atmospheric Sciences and Climate (CNR-ISAC), and the CNR Institute of Atmospheric Pollution Research (CNR-IIA) who manage the vast array of instruments.

The data are disseminated via six well-established international networks, which enforce rigorous application of protocols, instrument calibration and retrieval algorithms. This ensures the highest quality of the reference datasets, available for free to the wider remote sensing scientific community. Data are freely available via ESA’s EVDC and BAQUNIN portals.

While creating atmospheric data products in urban areas is challenging due to strong pollution gradients, different cloud conditions, varied infrastructure and high aerosol loads, the BAQUNIN observatory helps provide high quality datasets, and boosts further investigation of the planetary and urban boundary layers.

References

Iannarelli et al. "The Boundary Layer Air Quality Analysis Using Network of Instruments (BAQUNIN) Supersite for Atmospheric Research and Validation over Rome Area", Bulletin of the American Meteorological Society, 599-618, February 2022.