DAILY EARTH TEMPERATURES FROM SATELLITES
Daily averaged temperatures of the Earth are measured by the Advanced Microwave Sounding Unit (AMSU) flying on NASA's Aqua satellite. The satellite passes over most points on the Earth twice per day. The AMSU measures the average temperature of the atmosphere in different layers from the surface up to about 135,000 feet or 41 kilometers. During global warming, the atmosphere in the lower atmosphere (called the troposphere) is supposed to warm at least as fast as the surface warms, while the stratosphere above the troposphere is supposed to cool much faster than the surface warms.
Please select an altitude from the left-side menu to view the global temperature trend for the selected layer in the atmosphere.
What is a brightness temperature? A brightness temperature is a descriptive measure of radiation in terms of the temperature of a hypothetical blackbody emitting an identical amount of radiation at the same wavelength.
The brightness temperature is obtained by applying the inverse of the Planck function to the measured radiation. Depending on the nature of the source of radiation and any subsequent absorption, the brightness temperature may be independent of, or highly dependent on, the wavelength of the radiation.
A more technical description can be found in the Wikipedia article.
The global-average data displayed on these pages have only limited quality control, can undergo unannounced changes, and so should only be used as a general guide. Official, quality-controlled global lower-tropospheric temperatures, using more extensive processing procedures (and different satellite instruments) are updated every month and are available from the Global Hydrology Resource Center.
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