A global analysis of climate-relevant aerosol properties retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
Authors: Laj Paolo , Bigi Alessandro , Rose Clémence , Andrews Elisabeth , Lund Myhre Cathrine , Collaud Coen Martine , Lin Yong , Wiedensohler Alfred , Schulz Michael , Ogren John A. , Fiebig Markus , Gliß Jonas , Mortier Augustin , Pandolfi Marco , Petäja Tuukka , Kim Sang-Woo , Aas Wenche , Putaud Jean-Philippe , Mayol-Bracero Olga , Keywood Melita , Labrador Lorenzo , Aalto Pasi , Ahlberg Erik , Alados Arboledas Lucas , Alastuey Andrés , Andrade Marcos , Artíñano Begoña , Ausmeel Stina , Arsov Todor , Asmi Eija , Backman John , Baltensperger Urs , Bastian Susanne , Bath Olaf , Beukes Johan Paul , Brem Benjamin T. , Bukowiecki Nicolas , Conil Sébastien , Couret Cedric , Day Derek , Dayantolis Wan , Degorska Anna , Eleftheriadis Konstantinos , Fetfatzis Prodromos , Favez Olivier , Flentje Harald , Gini Maria I. , Gregorič Asta , Gysel-Beer Martin , Hallar A. Gannet , Hand Jenny , Hoffer Andras , Hueglin Christoph , Hooda Rakesh K. , Hyvärinen Antti , Kalapov Ivo , Kalivitis Nikos , Kasper-Giebl Anne , Kim Jeong Eun , Kouvarakis Giorgos , Kranjc Irena , Krejci Radovan , Kulmala Markku , Labuschagne Casper , Lee Hae-Jung , Lihavainen Heikki , Lin Neng-Huei , Löschau Gunter , Luoma Krista , Marinoni Angela , Martins Dos Santos Sebastiao , Meinhardt Frank , Merkel Maik , Metzger Jean-Marc , Mihalopoulos Nikolaos , Nguyen Nhat Anh , Ondracek Jakub , Pérez Noemi , Perrone Maria Rita , Petit Jean-Eudes , Picard David , Pichon Jean-Marc , Pont Veronique , Prats Natalia , Prenni Anthony , Reisen Fabienne , Romano Salvatore , Sellegri Karine , Sharma Sangeeta , Schauer Gerhard , Sheridan Patrick , Sherman James Patrick , Schütze Maik , Schwerin Andreas , Sohmer Ralf , Sorribas Mar , Steinbacher Martin , Sun Junying , Titos Gloria , Toczko Barbara , Tuch Thomas , Tulet Pierre , Tunved Peter , Vakkari Ville , Velarde Fernando , Velasquez Patricio , Villani Paolo , Vratolis Sterios , Wang Sheng-Hsiang , Weinhold Kay , Weller Rolf , Yela Margarita , Yus-Diez Jesus , Zdimal Vladimir , Zieger Paul , Zikova Nadezda 
Published: August 2020

Abstract. Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and
absorbing solar radiation, and indirectly by acting as cloud condensation
nuclei. In contrast to most greenhouse gases, aerosol particles have short
atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at
regional scale through observations involving, in particular, the in situ
near-surface segment of the atmospheric observation system. This paper will provide the widest effort so far to document variability of climate-relevant
in situ aerosol properties (namely wavelength dependent particle light
scattering and absorption coefficients, particle number concentration and
particle number size distribution) from all sites connected to the Global
Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported
for a reference year in 2017, providing a very extended and robust view of
the variability of these variables worldwide. The range of variability
observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with
model simulation for the different stations. The scope of the present paper
is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of
the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in
the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate
monitoring system.