The ISTP9 AMT special issue aims at collecting innovative and comprehensive contributions presented at ISTP9 and focusing on tropospheric measurement and modeling. The selected papers will set the stage for identifying the state of the art and discussing future directions of research and technology development. Profiling of atmospheric state parameters and constituents, the understanding of tropospheric processes, and the use of experimental data in atmospheric models are the major areas of interest. Specific topics are: Aerosols, clouds and precipitation, Algorithms for improved parameter retrievals, Atmospheric radiation, Boundary layer and mesoscale studies, Evaluation of models and data assimilation, Networks, satellites, and aircrafts, New instruments, Temperature, wind, waves, and turbulence, Validation, instrument synergies, and field experiments, Water vapor, ozone and trace gases.