EARLINET APPROACH TO OPTIMISATION OF INDIVIDUAL NETWORK INSTRUMENTS WITH THE AIM OF HOMOGENISATION OF AEROSOL DATA PRODUCTS AND INCREASED DATA COVERAGE Arnoud Apituley * (RIVM, Bilthoven, The Netherlands) Volker Freudenthaler (University of Munich, Germany) Adolfo Comerón, Francesc Rocadenbosch (Universitat Politècnica de Catalunya (UPC, Barcelona, Spain) * RIVM – National Institute for Public Health and the Environment, P.O. Box 1, NL3720BA Bilthoven, The Netherlands. Email: Arnoud.Apituley@rivm.nl. ABSTRACT The European Aerosol Research LIdar NETwork (EARLINET) is an aerosol lidar network on a continental scale. EARLINET is now a leading network in quality- controlled quantitative aerosol profiling performing a schedule of routine measurements and presently consists of 28 stations distributed over Europe. The construction of an un-biased spatio-temporal database of vertical profiles of aerosol optical properties on a regional scale for climate and air quality research is the main objective of EARLINET and is accomplished through application of Raman lidars. One of the tasks in the EC-funded project EARLINET-ASOS is to optimize individual instruments with the aim of homog- enization of aerosol data products over the network and in- creased data coverage by automation. This task is ap- proached by selection of optimal solutions existing in the pool of individual stations. This is done for components, subsystems as well as for system integration. In system inte- gration emphasis lies on automation to reduce the amount of manpower needed, to improve temporal coverage, and to make performance independent from individual operators. The procedure to perform these tasks is outlined and the set of tools enabling the assessment of performance under de- velopment is described. Index Terms— Lidar, network, aerosol, harmonization, automation 1. INTRODUCTION Among the factors causing the largest uncertainties in the understanding of climatic change are aerosols and cloud feedback mechanisms involving the role of aerosols. This is due to the variable nature in space and time of the aerosols, that are relatively short-lived atmospheric species, but can still be distributed over large distances when the conditions are right. Aerosols and their climatic impact are therefore much more difficult to catch in atmospheric models than long-lived greenhouse gases such as carbondioxide. Better knowledge of the spatio-temporal distrubution of aerosols is critically needed to better assess their role in climate change [1]. The European Aerosol Research LIdar NETwork (EARLINET) started in 2000 under the EC 5th Framework Program. The network presently consists of 28 stations dis- tributed over Europe (from Norway to Spain and from Ire- land to Georgia). The construction of an un-biased spatio- temporal database of vertical profiles of aerosol optical properties on a regional scale for climate and air quality research is the main objective of EARLINET. This cannot be accomplished by backscatter lidars since these do not provide quantitative optical aerosol data without critical assumptions. Therefore, EARLINET aims to apply mainly Raman lidars that are quantitative. The increasing number of participating stations illustrate the success of this initiative. However, in order to build the aerosol database, rigorous quality assurance is needed and also homogeneous data quality is desired so that the network can be used truly as a single instrument. Most stations in the network have lidars that were not series-produced and con- sequently these instruments have differences in set-up and construction. Consequently, the performance of the individ- ual instruments may be different, for instance with respect to the altitude range covered or the number of operating wave- lengths. From 2006 until 2011, the network’s development is supported by the EC-project EARLINET– ASOS (Ad- vanced Sustainable Observation System). The main objec- tive of this Coordination Action is to improve the EARLINET infrastructure for better spatial and temporal coverage of the observations, continuous quality control for the complete observation system, and fast delivery of stan- dardized data products. One of the tasks in EARLINET- ASOS is to optimize individual instruments with the aim of homogenization of aerosol data products over the network and increased data coverage by automation. This will be accomplished by selecting the optimal ap- proach from the various solutions existing at individual sta- tions for components and subsystems as well as for system II - 414 978-1-4244-2808-3/08/$25.00 ©2008 IEEE IGARSS 2008 Authorized licensed use limited to: UNIVERSITAT POLITECNICA DE CATALUNYA. Downloaded on July 22,2010 at 16:28:07 UTC from IEEE Xplore. Restrictions apply.