Influence of climate change on the frequency of daytime temperature inversions and stagnation events in the Po Valley: historical trend and future projections

This work analyzes the frequency of days characterized by daytime temperature inversion and air stagnation events in the Po valley area. The analysis is focused on both historical series and future projections under climate change. Historical sounding data from two different Italian stations are used as well as future projections data, provided by CMCC-CCLM 4-8-19 regional climate model (MED-CORDEX initiative). A new method to detect layers of temperature inversion is also presented. The developed method computes the occurrence of a temperature inversion layer for a given day at 12 UTC without a detailed knowledge of temperature vertical profile. This method was validated using sounding data and applied to the model projections, under two different emissions scenarios (RCP4.5 and RCP8.5). Under RCP4.5 intermediate emissions scenario, the occurrence of temperature inversions is projected to increase by 12 days/year (around + 10%) in the last decade of 21st century compared to 1986–2005 average. However, the increase in temperature inversions seems to be especially concentrated in the warm period. Under RCP8.5 extreme scenario, temperature inversions are still projected to increase, though to a lesser extent compared to RCP4.5 scenario (+ 6 days/year in the last decade of 21st century). A similar trend was found also for air stagnation events, which take into account the variation of precipitation pattern and wind strength. The expected increases are equal to + 13 days/year and + 11 days/year in the last decade of 21st century compared to 1986–2005 average, under RCP4.5 and RCP8.5 scenarios respectively

Particle number and mass exposure concentrations by commuter transport modes in Milan, Italy

There is increasing awareness amongst the general public about exposure to atmospheric pollution while travelling in urban areas especially when taking active travelling modes such as walking and cycling. This study presents a comparative investigation of ultrafine particles (UFP), PM10, PM2.5, PM1 exposure levels associated with four transport modes (i.e., walking, cycling, car, and subway) in the city of Milan measured by means of portable instruments. Significant differences in particle exposure between transport modes were found. The subway mode was characterized by the highest PM mass concentrations: PM10, PM2.5, PM1 subway levels were respectively about 2-4-3 times higher than those of the car and open air active modes (i.e. cycling and walking). Conversely, these latter modes displayed the highest UFP levels about 2 to 3 times higher than the subway and car modes, highlighting the influence of direct traffic emissions. The car mode (closed windows, air conditioning and air recirculation on) reported the lowest PM and UFP concentration levels. In particular, the open-air/car average concentration ratio varied from about 2 for UFP up to 4 for PM1 and 6 for PM10 and PM2.5, showing differences that increase with increasing particle size. This work points out that active mode travelling in Milan city centre in summertime results in higher exposure levels than the car mode. Walkers’ and cyclists’ exposure levels is expected to be even higher during wintertime, due to the higher ambient PM and UFP concentration. Interventions intended to re-design the urban mobility should therefore include dedicated routes in order to limit their exposure to PM and UFP by increasing their distance from road traffic

PM emission scenario from domestic biomass burning: data and uncertainties.

none3noneS. Galante; S. Caserini; S. OzgenGalante, Silvia; Caserini, Stefano; Ozgen, MUEYYET SENE

CO2eq CONTRIBUTION OF NEAR TERM CLIMATE FORCERS EMITTED BY SMALL WOODY BIOMASS APPLIANCES

CO2eq emissions of near term climate forcers (NTCF) from residential heating appliances burning wood and pellet are evaluated using emission factors from a recent experimental campaign and Global Warming Potentials proposed in literature for a time horizon of 20 years (GWP20) and 100 years (GWP100). The results show that the warming potential in terms of CO2eq is positive for every appliance, although very different in absolute terms and with different contribution of the various pollutants. For all the appliances, organic carbon (OC) emissions (that have a negative GWP, thus a cooling effect for the atmosphere) compensate a part of the warming effect given mainly by black carbon (BC) and carbon monoxide. The total CO2eq emission factors are similar for all the appliances burning log wood (open fireplace, traditional stove, closed fireplace and innovative wood stove) because most efficient appliances (i.e., advanced stove) have not only lower emissions of warming agents such as BC and CO but lower OC as well. Only the pellet stove has a significantly lower total CO2eq emission factor. The CO2eq associated to NTCF emissions from RWC is 0.7% of the total CO2eq emissions in Lombardy region using GWP20, 0.3% using GWP10