Re-Blogged From Space Weather
The daily Thermosphere Climate Index (TCI) is now on Spaceweather.com. TCI is a relatively new space weather metric that tells us how the top of Earth’s atmosphere (or “thermosphere“) is responding to solar activity. During Solar Maximum, the top of our atmosphere heats up and expands. Right now the opposite is happening. Solar Minimum conditions are in effect, and this is causing the upper atmosphere to cool off:
TCI was invented by Martin Mlynczak of the Langley Research Center along with other NASA and university colleagues. For the past 17 years they have been using the SABER instrument onboard NASA’s TIMED satellite to monitor the wattage of infrared emissions from the top of the atmosphere. Recently, they realized that those measurements could be used to summarize the state of the thermosphere in a single daily index, the TCI, expressed in watts (W). Moreover, they learned to calculate TCI going back in time all the way to the 1940s, thus placing current conditions in a historical context.
So where do we stand? Right now TCI=4.3×1010 W. That means the top of Earth’s atmosphere is approximately 10 times cooler than it was during the record-setting Solar Max of 1957-58 (TCI=49.4×1010 W). The record low value for TCI, 2.1×1010 W, was set during the Solar Minimum of 2009. It’s still not that cold in the thermosphere, although we’re getting close.
You can monitor daily values of TCI right here on SpaceWeather.com. TCI not only tracks the slow progression of the 11-year solar cycle, but also it can change suddenly in response to solar flares and geomagnetic storms. As these events occur, we’ll be writing about them to raise awareness of the many ways the sun can dump energy into Earth’s atmosphere. Stay tuned!
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