1 Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki FI-00560, Finland; Helsinki Institute of Sustainability Science, Faculty of Science, University of Helsinki, Helsinki FI-00560, Finland. Electronic address: pak.fung@helsinki.fi.
2 Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain; Department of Mining, Industrial and ICT Engineering (EMIT), Manresa School of Engineering (EPSEM), Universitat Politècnica de Catalunya (UPC), Manresa 08242, Spain. Electronic address: marjan.savadkoohi@idaea.csic.es.
3 Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki FI-00560, Finland; Helsinki Institute of Sustainability Science, Faculty of Science, University of Helsinki, Helsinki FI-00560, Finland; Department of Computer Science, Faculty of Science, University of Helsinki, Helsinki FI-00560, Finland. Electronic address: martha.zaidan@helsinki.fi.
4 Helsinki Region Environmental Services Authority (HSY), Helsinki FI-00066, Finland. Electronic address: jarkko.niemi@hsy.fi.
5 Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki FI-00560, Finland. Electronic address: hilkka.timonen@fmi.fi.
6 Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain. Electronic address: marco.pandolfi@idaea.csic.es.
7 Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain. Electronic address: andres.alastuey@idaea.csic.es.
8 Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain. Electronic address: xavier.querol@idaea.csic.es.
9 Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki FI-00560, Finland; Environmental and Atmospheric Research Laboratory (EARL), Department of Physics, School of Science, University of Jordan, Amman 11942, Jordan. Electronic address: tareq.hussein@helsinki.fi.
10 Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki FI-00560, Finland. Electronic address: tuukka.petaja@helsinki.fi.