SOHO

Solar and Heliospheric Observatory

SOLSTICE

Solar Stellar Irradiance Comparison Experiment

SOURCE

Solar Ultraviolet Radiation and Correlative Emissions

SPARC

Stratospheric Processes and their Relation to Climate

STEP

Solar-Terrestrial Energy Program

SUSIM

Solar Ultraviolet Spectral Irradiance Monitor

TIMED

Thermosphere Ionosphere Mesosphere Energetics and Dynamics

TOMS

Total Ozone Mapping Spectrometer

TTO

Ten to Twelve Year Oscillation

UARS

Upper Atmosphere Research Satellite

USGCRP

United States Global Change Research Program

UV

Ultraviolet

WCRP

World Climate Research Program

WMO

World Meteorological Organization