Solar-Terrestrial Physics (SCOSTEP). The STEP program seeks to better understand the coupling of energy and mass throughout the various parts of the solar-terrestrial system. A related ICSU program is Stratospheric Processes and their Relation to Climate (SPARC), an adopted program of the World Climate Research Program (WCRP). Its emphasis is on understanding the role of the stratosphere in the climate system. Both of these international programs include components involving solar influences on global change.
The International Solar Terrestrial Physics Program (ISTP) is a cooperative effort involving the U.S., Japan, and Europe. The program consists of several spacecraft to be launched in the 1990s by NASA, ISAS, and ESA. The overall scientific objectives of ISTP are to develop a comprehensive, global understanding of the generation and flow of energy from the Sun through the interplanetary medium and into the Earth's space environment, and to define the cause and effect relationships between the physical processes that link different regions of this dynamic environment. The ISTP will provide major contributions to the understanding of the energy flow between the Sun and the Earth's magnetosphere, but its principal objectives do not, at present, include study of energy flow into the lower atmosphere.