Total Solar Irradiance (TSI), together with the absorption and reflection of this radiation by Earth's atmosphere, determines the global average temperature of Earth.

The TIM will collect high accuracy, high precision measurements of total solar irradiance using an active cavity radiometer that monitors changes in incident sunlight to Earth's atmosphere.

Changes in both the solar irradiance and in the composition of the atmosphere can cause global climate change. Solar irradiance is a purely a natural phenomenon, while the composition of the atmosphere is strongly influenced by the byproducts of modern industrial societies. Over the past century, the average surface temperature of Earth has increased by about 0.5 degrees Celsius.

The continued measurement of TSI to determine the Sun's effects on Earth's climate, at current state-of-the-art accuracy and without temporal gaps in the dataset, constitutes the solar irradiance requirement for the Glory mission. It is essential that there be no temporal gaps in the data, as any measured changes in climate must be appropriately interpreted in the context of any changes in the solar irradiance. The TIM will collect high accuracy, high precision measurements of total solar irradiance using an active cavity radiometer that monitors changes in incident sunlight to Earth's atmosphere. Because the TIM is designed to operate nominally in a solar-viewing orientation, it is mounted on a gimbaled platform that accommodates targeting independently of the spacecraft's nadir viewing attitude.

The TIM is a heritage-design instrument that was originally flown on the SORCE satellite launched in January 2003.

TIM Data

The fundamental requirement for the TIM is to make precise and accurate daily measurements of TSI and connect them to previous TSI measurements to form the long-term climate record.

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