The new challenge in atmospheric chemistry is to understand the intercontinental transport and transformation of gases and aerosols. To address this issue, a global observations systems network of ground based sites and aircraft measurement campaigns are highly requested by scientists. The book describes the latest methods for observations from space, by aircraft, and at the surface as well as the sensor web concept. Additionally, it reports the latest results from GOME, SCIAMACHY, AURA, and TOMS satellite missions as well as the most relevant aircraft and ground based campaigns conducted in the last few years in the US and Europe. The book discusses data handling as well as new directions in the atmospheric observational techniques. The book provides a thorough overview of satellite and aircraft observations and describes new techniques that have been developed in the last decade. In addition, it gives an introduction to the sensor web concept.