A scheme to represent the impact of urban buildings on airflow in mesoscale atmospheric models is presented. In the scheme, the buildings are not explicitly resolved, but their effects on the grid-averaged variables are parameterised. An urban quarter is characterised by a horizontal building size, a street canyon width and a building density as a function of height. The module computes the impact of the horizontal (roof and canyon floor) and vertical (walls) surfaces on the wind speed, temperature and turbulent kinetic energy. The computation of the shortwave and longwave radiation, needed to compute the temperature of the urban surfaces, takes into account the shadowing and radiation trapping effects induced by the urban canyons. The computation of the turbulent length scales in the TKE equation is also modified to take into account the presence of the buildings. The parameterisation is introduced into a mesoscale model and tested in a bidimensional case of a city over flat terrain. The new parameterisation is shown to be able to reproduce the most important features observed in urban areas better than the traditional approach which is based only on the modification of the roughness length, thereby retaining the Monin-Obukhov similarity theory. The new surface exchange parameterisation is furthermore shown to have a strong impact on the dispersion characteristics of air pollutants in urban areas.

/pdf/an-urban-surface-exchange-parameterisation-for-mesoscale-1raq9yv4sx.pdf

An Urban Surface Exchange Parameterisation for Mesoscale Models

[1] The sea breeze system (SBS) occurs at coastal locations throughout the world and consists of many spatially and temporally nested phenomena. Cool marine air propagates inland when a cross-shore mesoscale (2–2000 km) pressure gradient is created by daytime differential heating. The circulation is also characterized by rising currents at the sea breeze front and diffuse sinking currents well out to sea and is usually closed by seaward flow aloft. Coastal impacts include relief from oppressive hot weather, development of thunderstorms, and changes in air quality. This paper provides a review of SBS research extending back 2500 years but focuses primarily on recent discoveries. We address SBS forcing mechanisms, structure and related phenomena, life cycle, forecasting, and impacts on air quality.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2003RG000124

Sea breeze: Structure, forecasting, and impacts

ObjectiveBecause the state of the atmosphere determines the development, transport, dispersion, and deposition of air pollutants, there is concern that climate change could affect morbidity and mor

Climate Change, Tropospheric Ozone and Particulate Matter, and Health Impacts

Numerical studies of sea and lake breezes are reviewed. The modelled dependence of sea-breeze and lake-breeze characteristics on the land surface sensible heat flux, ambient geostrophic wind, atmospheric stability and moisture, water body dimensions, terrain height and slope, Coriolis parameter, surface roughness length, and shoreline curvature is discussed. Consensus results on the influence of these geophysical variables on sea and lake breezes are synthesized as well as current gaps in our understanding. A brief history of numerical modelling, an overview of recent high-resolution simulations, and suggestions for future research related to sea and lake breezes are also presented. The results of this survey are intended to be a resource for numerical modelling, coastal air quality, and wind power studies.

/pdf/sea-and-lake-breezes-a-review-of-numerical-studies-1pwx6578ea.pdf

Sea and Lake Breezes: A Review of Numerical Studies

Blue space, health and well-being: A narrative overview and synthesis of potential benefits.

Numerical simulations compared with field measurements are used to explain the effect of sea breezes on photochemical smog episodes in Athens during the Mediterranean Campaign of Photochemical Tracers on 12–14 September 1994. The numerical simulations, performed using a nonhydrostatic vorticity mesoscale model coupled to the Lurmann–Carter–Coyner photochemical module, are compared with ground-based lidar and aircraft measurements. The current analysis shows that the three selected days include the two main summertime flow patterns characteristic of the Athens peninsula, each of which lead to significantly different pollution amounts. On 12 and 13 September, a strong, northerly synoptic wind reduces the inland penetration of the sea breeze so that ozone concentrations within the greater Athens area remained low. In contrast, the weaker synoptic forcing on 14 September allowed the development of sea breezes over the whole peninsula and high ozone concentrations were found north and east of the city...

/pdf/effect-of-sea-breeze-on-air-pollution-in-the-greater-athens-13r2jhcv14.pdf

Effect of Sea Breeze on Air Pollution in the Greater Athens Area. Part I: Numerical Simulations and Field Observations

Atmospheric dispersion of natural gases at Vulcano island

Mesoscale circulation across the Alps: Preliminary simulation of transalp 1990 observations

Atmospheric dispersion of volcanic CO 2 at Vulcano island

Lombardy is the most industrialized and populated region in Italy. As a matter of fact it has more than 9 millions inhabitants (16% of the Italian population) over a territory of about 24000 km2 (8% of Italy). Because of its complex orography the distribution of the population is not homogeneous, for example, there are 55 compared to 1440 inhabitants per km2 in the province of Sondrio (the most northern and mountainous) to the province of Milan. The area centered in Milan city and extending north and north-west for about 30 km, can be considered a single metropolitan area, with 3,700,000 inhabitants, with 1,550,000 workers (data taken from the National Statistical Institute) and 2,500,000 vehicles running. It has been estimated that the total emissions in this area in 1990 were about 94,000 tons/year of NOx, 186,000 tons/year VOC and 529,000 tons/year of CO (ENEA, 1995).

G. Graziani

Papers

Effect of Sea Breeze on Air Pollution in the Greater Athens Area. Part I: Numerical Simulations and Field Observations

Atmospheric dispersion of natural gases at Vulcano island

Mesoscale circulation across the Alps: Preliminary simulation of transalp 1990 observations

Atmospheric dispersion of volcanic CO 2 at Vulcano island

Modelling Photochemical Smog Episodes in Lombardy Region