Simulating ultrafine particle formation in Europe using a regional CTM: contribution of primary emissions versus secondary formation to aerosol number concentrations
C. Fountoukis, I. Riipinen, H. A. C. Denier van der Gon, P. E. Charalampidis, C. Pilinis, A. Wiedensohler, C. O'Dowd, J. P. Putaud, M. Moerman, and S. N. Pandis