Observations by Satellites -- Air-Quality Study from Geostationary/High-Altitude Orbits -- Aerosol Forcing and the A-Train -- Total Ozone from Backscattered Ultraviolet Measurements -- The EOS Aura Mission -- MIPAS experiment aboard ENVISAT -- Aircraft and Ground-Based Intensive Campaigns -- Probing the Atmosphere with Research Aircraft-European Aircraft Campaigns -- MOZAIC -Measuring tropospheric constituents from commercial aircraft -- Uninhabited Aerial Vehicles: Current and Future Use -- U.S. Ground-Based Campaign -PM Supersite Program -- Ground-Based Networks -- Ozone from Soundings: A Vital Element of Regional and Global Measurement Strategies -- LIDAR Networks -- U.S. Federal and State Monitoring Networks -- Autonomous Systems and the Sensor Web -- Comparison of Measurements - Calibration and Validation -- Output of the Observational Web -- The Sensor Web: A Future Technique for Increasing Science Return -- Fundamentals of Modeling, Data Assimilation, and High-Performance Computing -- Inverse Modeling Techniques. The new challenge in atmospheric chemistry is to understand the intercontinental transport and transformation of gases and aerosols. This book describes the observational and modeling techniques used to understand the atmospheric composition from satellites, aircraft and ground based platforms. The two common ideas presented throughout are the role of each component in an observing system for atmospheric composition, and the advances necessary to improve the understanding of atmospheric composition. The objective of this book is to provide a larger audience the opportunity to learn about these techniques and advances in atmospheric composition.