The over-arching objective of this study is to perform a substantially improved integrated assessment, regarding Helsinki’s urban air quality and meteorology. For this aim, we will combine (i) the new, high-quality and extensive observations from both air-quality-measurement supersites in Helsinki, and additional AMS (aerosol mass spectrometer) and aerosol chemical speciation monitor (ACSM) measurements; with (ii) the drastically improved meteorological and climate measurement data that is available from "Helsinki UrBAN".

The FMI and the University of Helsinki have launched a state-of-the-art observational network for Helsinki’s urban atmosphere, called Helsinki UrBAN (Urban Boundary-layer Atmosphere Network, http://urban.fmi.fi). The instruments within this network include a lidar, a ceilometer, weather stations, a sodar, eddy-covariance flux towers, a thermal camera, building surface thermometers and scintillometers. These measurements have not yet been used in an air-quality context.

The Kumpula air-quality supersite (Helsinki: SMEAR III) has been operational since 2004. Continuous measurements include particle size distributions, several gas phase compounds, and elemental/organic carbon (EC/OC). Since 2009, measurements have been with different aerosol mass spectrometers: AMS and ACSM. In this study, the AMS data from SMEAR III and downtown Helsinki will be used to characterize particulate matter. The latter is a monitoring station, in which measurements have already been conducted for one year using ACSM. AMS data will be used for source identification and for timing of certain types of pollution. Typical cases include long-range transport of particulate matter or formation of ground-level elevated concentrations of particles, due to temperature inversion.

Recently, AMSs have been used for better identification of particulate-matter emission sources. AMS-data benefits are: (i) fine temporal resolution (1s – 15min) allows superior comparison with modelling results, and (ii) detailed chemical composition (and for certain instruments also chemical size distributions) enable a more accurate identification of pollution sources.

We aim to improve and use the regional and urban-scale air quality models, the open road dispersion model CAR-FMI and the regional chemical transport model SILAM. The crucial meteorological quantities for dispersion will be assessed based on Helsinki UrBAN measurements, substantially better than has been possible previously.

In this presentation, we will show progress on this endeavour.

How people live, work, move from place to place, what they consume and the technology they use, all affect the fabric, morphology and emissions in a city and in turn its climate. To understand the relations between urban form, energy use and carbon emissions an important challenge is to disaggregate urban areas into different spatial units and evaluate their impacts on energy fluxes and greenhouse gas emissions. There is a need in Earth system science communities for spatially disaggregated anthropogenic heat data, at local and city scales. The anthropogenic heat flux is the heat flux resulting from vehicular emissions, space heating and cooling of buildings, industrial processing and the metabolic heat release by people. Such information is practically impossible to derive by point in-situ flux measurements, while satellite remote sensing has proven a valuable tool for estimating energy budget parameters exploiting Earth Observation (EO) data. While EO data are widely used for urban studies, their main application area is limited to land cover mapping and similar applications. Nevertheless, currently available EO data and forthcoming satellite systems can considerably contribute to the study of urban climate. To this aim the recently launched H2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of EO to retrieve anthropogenic heat flux, as a key component in the urban energy budget. The urban energy budget is considered in the context of a volume because of the three dimensional nature of the city, and includes the fluxes into, or out of, or the storage change within the control volume. URBANFLUXES advances existing EO-based methods for estimating spatial patterns of turbulent sensible and latent heat fluxes, as well as urban heat storage flux at city scale and local scale. Independent methods and models are engaged to evaluate the derived products and statistical analyses provide uncertainty measures. Optical, thermal and SAR data from existing satellite sensors are exploited to improve the accuracy of the energy budget components spatial distribution calculation. Synergistic use of different types and of various resolution EO data allows estimates in local and city scale. In-situ reflectance measurements of urban materials for calibration. The URBANFLUXES project prepares the ground for further innovative exploitation of EO data in scientific activities involving Earth system modelling and climate change studies in cities. The URBANFLUXES products will support system models to provide more robust climate simulations. Ultimate goal of the URBANFLUXES is to develop a highly automated method for estimating urban energy budget components to use with Copernicus Sentinel data, enabling its integration into applications and operational services. The improved data quality, spatial coverage and revisit times of the Copernicus data will allow support of future emerging applications regarding sustainable urban planning, with the objective of improving the quality of life in cities.

The lack of evapotranspiration and radiative trapping which is caused by land surface modification in metropolitan areas can lead to Urban Heat Island (UHI) effect all year around in some cities like New York City. This phenomenon is known as Urban Heat Island. UHI refers to an increase in air and surface temperatures in urban centers as compared to surrounding suburban and rural areas. New York City is one of United States’ most high densely populated cities with 27,000 people per Kilometer square and due to its different elevations and water bodies, the temperature is not uniformly distributed and some areas may heat up more than other. The urban heat island of a city can be subdivided into physically defined neighborhoods that can respond differently to large scale environmental forcing. The UHI effect can be amplified or reduced by land surface characteristics. Further more warming and increase in frequency of heat waves might increase the UHI effect and therefore factoring in the regional climate impacts are important. Therefore, to study the impacts of land surface characteristics and climate change in New York City UHI, field campaigns of temperature and relative measurements have been formed for the summer of 2012 and 2013.Two types of field campaigns have been done to complete temperature measurements. One is the suite of mobile sensors to measure temperature and relative humidity. The sensors are deployed by foot simultaneously for measuring street level environmental conditions. This measurement is high spatial resolution and it contains data from the hottest part of the day. Another field campaign measurement is done by 10 fixed sensors which were deployed to measure temperature, relative humidity and sunlight. These sensors were installed at select locations throughout New York City for high temporal resolution. The spatial and temporal variability sampled by these two campaigns provide complementary information that can help in predicting environmental variability throughout New York City. To understand the impact of UHI on New York City’s land cover, this study has created high resolution neighborhood-scale data sets using three basic approaches; employing fixed stations, walking campaign data, and Landsat satellite data. This project is the first high resolution street level neighborhood study on a metropolitan city. To anticipate climate adaptation and mitigation at the neighborhood scale and to prepare the health community for climate induced increases in heat wave frequency/intensity, this project has been working to develop a neighborhood based temperature predictions using large scale measurements with down-scaling techniques for both near term and long term climate projections.

FluxSAP 2010 and 2012 urban hydrometeorology measurement campaigns were performed within the VegDUD ANR program that aimed at clarifying the role of vegetation in the climatology of urban areas. These experimental campaigns were devoted to heat and water fluxes over an heterogeneous urban area, and on the vegetation contribution to theses fluxes. They combined a ground-based experimental set-up with airborne remotely-sensed observations in 2010, and with a focus on latent heat observations in 2012. The scientific objectives of the FluxSAP campaigns were (i) to obtain heat and vapour transfer reference data allowing to assess urban hydro-climatological models, identifying their sources and separating the contributions from the bare and covered soils, from the buildings, and from the vegetated areas and (ii) to determine the spatial distribution of the observed latent and sensible heat fluxes in a district of Nantes, within the ONEVU long-term observatory area, during a spring period.

The current communication aims at presenting the Fluxsap2012 experimental set up and the first results qualifying the energy budget on this area. The experimental set up includes:

- meteorological variables and aerodynamic turbulent fluxes from 8 instrumented flux towers of 10 to 30 m, at open areas of the district ;

- wind profile observations,

- temperature and water content in the soil and at the surface at 8 points,

- temperature and humidity at 2-3 m above the surface at 14 points,

- mobile air and surface temperatures and humidity observations on streets,

- individual garden energy budget components,

- transpiration observations in green areas,

- integrated heat fluxes from 5 large aperture and one small aperture scintillometers set on flat roofs of elevated buildings;

- spatial distribution of rainfall using radar data during rain events,

- passive tracer concentration horizontal and vertical dispersions along a mast and under a small tethered balloon.

This communication adresses the data quality and shows the coherence between the sensors (Li-COR and ultrasonic anemo-thermometers intercomparisons, scintillometry), the coherence between different observation averages (wind velocity and direction, soil temperature and humidity), and the variability of some other physical variables (heat fluxes, soil moisture…). The first analyses of this variability are discussed, and prove the complexity of urban climatology.

Currently, different urban planning strategies are proposed to cool the micro-climate (especially in summer) acting on the temperature, wind and humidity. The frequently cited cooling devices are physical proceedings such as the vegetation cover expansion. The most prominent examples are the living walls and roofs. The proposed project intends to deeply develop the scientific analysis of the performance and impact of vegetative green roofs (VGR) on urban climate, environment and health.

The scientific approach aims to achieve three main objectives: task 1 is to assess the refreshing potential of a VGR; task 2 to develop relevant indicators dedicated to VGR environmental impacts; task 3 to establish a link between VGR performance and spreading potential in urban zones.

The task 1 is to qualify and quantify the changes in the urban energy balance induced by the introduction of vegetation. These modifications are associated with the physical properties of green surfaces and increased evapotranspiration. Estimation of evapotranspiration by VGR is important to assess the cooling potential of this system, in nowadays climate conditions but also under climate change GIEC projections. Several criteria will be used (vegetation type, substrate thickness, geographic context...).

The task 2 is to evaluate health and environment risks and benefits of VGR in their local urban context. These indicators can then help create an index that can be used by planners and decision makers. Analysis will be done specifically on water to evaluate potential metal and microbiological contamination.

The task 3 is to allow mapping the potential of VGR at the scale of an agglomeration using a building typology classification This latter will be based on land use database, technical characteristics of the buildings (roof slope, age, etc.) and urban data (PLU, architectural history, etc.). This representation will be coupled with the results of tasks 1 and 2 in order to obtain thematic maps.

This communication addresses the methodology selected, the experimental protocols developed and the first results on the three tasks.

TERRACES project (ImpacT of vEgetative Roofs on uRban Ambiances: Cooling effects, Environment and Spreading) consists of five partners (Cerema - Directions territoriales Est and Ile de France, CSTB, LEESU and GEMCEA) and is financially supported by the ADEME.

The Program MCITY BRAZIL is designed to assess the main features of the urban climate of the major Brazilian cities and to systematize this procedure of investigation to be easily extended to other Brazilian urban areas. The major focus of this program is to estimate the observationally the major components of the energy budget at the surface and associate them to the dynamic and thermodynamic properties of the urban boundary layer over urban areas. As an starting point it was set up a network of 4 micrometeorological towers in the Metropolitan Regions of São Paulo (3) and Rio de Janeiro (1) cities. They are the largest conurbations of Brazil corresponding, respectively, to areas of 8051 and 5682 km2, occupied by 19.7 and 11.9 million inhabitants, and by a fleet of 7.0 and 3.6 million vehicles. In this work the Program MICITY BRAZIL and major urban features of climate the São Paulo and Rio de Janeiro Metropolitan Regions are described. The seasonal evolution of major components of the energy and radiation balance at the surface, both estimated from observations carried out in the 4 micrometeorological towers in operation since 2012, are presented. Besides, the diurnal evolution of urban boundary layer observed during 4 field campaigns carried in 2013 where 3-hours interval radiosounding were carried out during 10 consecutive days provided the vertical dynamic and thermodynamic structure of the atmosphere in São Paulo and Rio de Janeiro during summer (2 campaigns) and winter (2 campaigns) seasons. The urban boundary layer height estimated from radiosounding are compared with LIDAR and WRF numerical estimates. The implementation of MCITY BRAZIL to other metropolitan regions in the Southeast of Brazil is analyzed.