Final Report Summary - LAIC (Land-Atmosphere Interactions in China (LAIC)) The main objective of Land-Atmosphere Interactions in China (LAIC) joint research programme was to increase mobility and exchange of researchers between EU countries and China to obtain better understanding of land-atmosphere interactions for climate change research and environmental policy in China.The programme focus was in the following four areas: 1) megacities, atmospheric composition and air quality, including aerosol particles; 2) drylands and the hydrological cycle; 3) process modelling and regional climate modelling 4) carbon cycle and trace gas flux measurements, including research and knowledge transfer at comprehensive flux measurement sites.All the four scientific foci in the LAIC project are critical and intertwined issues in terms of regional and global climate change. This is especially in view of the Asian megacities, the large region and its vast influence locally, regionally and globally on atmospheric composition, water and carbon cycles, land-atmosphere interactions.The aim of LAIC programme was to build a basis for long-term collaboration between EU and Chinese research organizations in the area of climate change and air quality research. Also, in collaboration with other research projects and programmes, the LAIC programme was aimed, during the project and also in the longer term, to be followed by joint research efforts.A total of 17 early stage researcher and experienced researcher exchanges between Europe and China took place within the LAIC project during the reported period covering the four scientific foci. Majority of the exchanges were from China to European institutes. The researcher exchange included both Early Stage Researchers (5) and Experienced Researchers (12). All the work packages 1-4 were covered in the exchanges.The Chinese institutions engaged in the LAIC project are: Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP-CAS, Beijing), Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI, Lanzhou), Institute of Geographic Sciences and Natural Resources Research (IGSNRR-IAP, Beijing), Nanjing University (IAP/NJU Nanjing) and Peking University (PKU, Beijing).The European institutes are University of Helsinki (Finland), Wageningen University and Research Centre (Netherlands), Max-Planck-Institute for Meteorology (Hamburg, Germany), University of Bristol School of Geographical Sciences (UK). The researcher exchanges included working towards planning and establishment of comprehensive measurement station in Nanjing. Experimental studies include aerosol, trace gas and meteorological measurements and study of new particle formation events in Nanjing and Beijing. Modeling activities on trace gases, aerosol particles were conducted for the Beijing area.Chinese researchers were trained in Hamburg to use the REMO regional model, with application to China to assess and analyze regional feedback mechanisms in the East Asian region. Initiation of further collaboration on testing and application of REMO in China. In addition, exchanges worked towards collaboration and knowledge transfer in planning of joint research projects, such as the Pearl River Basin Project.Main results include the establishment of a comprehensive measurement station in Nanjing, including training activities of the technical staff and early-career scientists, especially training of staff on novel measurement techniques and data-analysis, installation and instrumentation of measurement sites.Aerosols and new particle formation were studied in the western part of the Yangtze River Delta (YRD), at the SORPES station of Nanjing University and in the Beijing area. Sulfuric acid plays an mportant role in new particle formation. The highly polluted air of the YRD provides both the potential source (SO2) and the sink (particulate matter) for sulfuric acid, leaving radiation as the determining force behind new particle formation. Accordingly, a good correlation was found between new particle formation rate and radiation values. Modeling studies on new aerosol particle formation focused at improvement of sulfuric acid closure for highly polluted areas such as Beijing.REMO regional model was developed to provide high-resolution climate predictions in geographically limited areas. The REMO modelers aim to understand factors that influence regional climate and climate change, also how processes on the regional and sub-regional scale may propagate upscale, hence having an effect on global scale circulations. REMO simulations for two extreme climate events showed good performance in regional climate simulation in East Asia. Generally, the model reproduced the spatial distribution of precipitation and surface temperature in China. Ongoing further work on East Asia Monsoon simulation, suggestion of REMO participation in Regional Climate Model Intercomparison Project for East Asia (RMIP).Collaboration in connection with Pearl River Delta area initiative on identification of trends and main driving forces, mechanisms underlying land use change in Pearl River Basin, including a workshop on regional water cycle and water management. Exchanges related to modeling, coupled climate and hydrological models, coupled land surface and hydrological models.Final results include diurnal and seasonal variation of aerosol particle, trace gas and related data at the Nanjing comprehensive measurement station. Results increase understanding of new particle formation phenomena especially in highly polluted areas. The exchanges stimulate the development, use and comparison of regional modeling in China, especially the European REMO regional model. LAIC exchanges also lead to new initiatives in process modeling, for example new aerosol particle formation, and joint new research efforts as the Pearl River Delta project.In summary, the LAIC IRSES project serves as a platform for increased scientific collaboration, capacity building and also for training purposes within the wide area of climate change and land-ecosystem interactions.