TIMED Doppler Interferometer (TIDI)

Fact Sheet (Requires Adobe Acrobat Reader )

Instrument Web Site

TIDI is globally measuring the winds and temperature profiles of the MLTI region. It is determining, on a global basis, the speed and direction of winds in the atmosphere by measuring tiny changes in the color of light emitted from individual chemical constituents in the atmosphere, such as atomic oxygen, molecular oxygen, oxygen-hydrogen, and sodium. Similar to how the change in pitch from a passing ambulance's siren helps determine its speed, scientists will use changes in color of light emitted by atmospheric particles to determine atmospheric wind speed and direction.

TIDI employs a spectrally-resolving optical element to determine the color, or wavelength, of light to a tremendously high degree of precision. Its high sensitivity and precise observations are accomplished by four telescopes looking simultaneously in perpendicular directions – two in front of the satellite at 45 degrees and two in the opposite direction at 135 degrees.

TIDI is measuring winds of a few meters per second, and like all of the instruments onboard the spacecraft, TIDI will continuously collect data throughout the duration of the mission. Its continuous data collection allows TIDI to make the best possible use of available light in the atmosphere.