OLYMPUS v1.0: Development of an integrated air pollutant and GHG urban emissions model – Methodology and calibration over the greater Paris

Abstract

Abstract. Air pollutants and greenhouse gases have many effects on health, the economy, urban climate and atmospheric environment. At the city level, the transport and heating sectors contribute significantly to air pollution. In order to quantify the impact of urban policies on anthropogenic air pollutants, the main processes 15 leading to emissions need to be understood: they principally include mobility for work and leisure as well as household behavior, themselves impacted by a variety of social parameters. In this context, the Olympus modeling platform has been designed for environmental decision support. It generates a synthetic population of individuals and defines the mobility of each individual in the city through an activitybased approach of travel demand. The model then spatializes road traffic by taking into account congestion on the 20 road network. It also includes a module that estimates the energy demand of the territory by calculating the unit energy consumption of households and the tertiary sector. Finally, the emissions associated with all the modeled activities are calculated using the COPERT emission factors for the traffic, and the European Environmental Agency (EEA) methodology for heating-related combustions. The comparison of emissions with AIRPARIF's regional inventory shows discrepancies that are consistent with differences in assumptions and input data, mainly 25 in the sense of underestimation. The methodological choices, as well as the potential ways of improvement, including the refinement of traffic congestion modeling and of the transport of goods, are discussed.

OLYMPUS-POPGEN: A synthetic population generation model to represent urban populations for assessing exposure to air quality

“…Under a GNU open-source license, this code includes a data preprocessor, a synthetic population generator, and a housing allocator. It forms an integral part of the OLYMPUS, an emission modeling platform which relies on an activity-based travel demand model to produce diurnal mobility matrices and modal share for all individuals of the synthetic population, over the region of interest [31]. Mobility matrices are used to produce OLYMPUS's air pollutant emission inventory, which is further used in an air quality model.…”

Addressing the issue of exposure to primary pollution in urban areas: Application to Greater Paris

“…More precisely, this paper aims to explore the impact of new approaches to urban modeling, on the representation of daily exposure to air pollutants in dense urban spaces. Our works are based on a new modelling platform, designed around the OLYMPUS emission model (Elessa Etuman and Coll, 2018), the CHIMERE air quality model (Menut et al, 2013), statistical downscaling of the CTM outputs and dynamic exposure calculations. The emission and air quality modelling step is described in section 2.…”

“…OLYMPUS was then successfully implemented in the Île-de-France region, a territory which has an increasing density of activities towards a large urban city core. A fully detailed presentation of the operating principles of the model and its implementation on Îlede-France can be found in Elessa Etuman and Coll (2018). For the record, the OLYMPUS configuration and simulation steps can be summarized as follows.…”

“…In the end, OLYMPUS provides a population mobility matrix, timed vehicle fluxes on all road axes and an emission inventory from the energy-consuming activities described above, spatialized on the 1x1km² computation grid. The emissions produced by OLYMPUS in the Île-de-France region for the year 2009 have been deeply analyzed and validated by comparison with other institutional emission inventories available on this area (Elessa Etuman and Coll, 2018). With regard to the model transferability, a study was carried out in parallel on the French Pays-de-la-Loire region, which demonstrated the ability of OLYMPUS to simulate mobility fluxes in a rural territory where multiple urban centers have developed.…”