TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) Doppler Interferometer (TIDI)
Long-term (1991-present) MLT winds available at UM-SPRL
The MLT (Mesosphere-Lower Thermosphere) has been sampled continously by UM-SPRL space borne experiments since 1991. Long-term sampling of the low-latitude meridional wind may be used to extract the strength of the migrating diurnal tide, the Hough (1,1) mode. This tide is dominant in March and has been sampled, independently, by WINDII (1992-1997), by HRDI (1992-2005), and by TIDI (2003-present). [WINDII operated by York University, Toronto] The data show consistency during correlative operations. Long-term variability in the migrating diurnal tide is related to the phase of the QBO (Quasi-Biennial Oscillation) in the tropical stratosphere.

TIDI observes thermospheric winds during the
2015 St Patrick's Day storm

Using the newly validated OI (6300Å) mode, TIDI is monitoring winds in the upper thermosphere, 160 - 300 km altitude. A strong geomagnetic storm occurred on 17-MAR-2015, Day 76 in 2015, and it's effect on the dynamics in the thermosphere was captured by TIDI. Neutral horizontal winds approached 500 m/s at high latitudes during the storm, where typical winds are ~100 m/s.

The TIMED Doppler Interferometer (TIDI) is investigating the dynamics and energetics of the Earth's mesosphere and lower-thermosphere. TIDI measurements allow us to obtain a global description of the vector wind fields, as well as important information on gravity waves, species densities, airglow and auroral emission rates and noctilucent clouds. TIDI provides basic information about global winds. TIDI also contributes to the study of energetics.

Science Objectives
The TIDI interferometer (or Profiler) primarily measures horizontal vector winds from the Earth's limb, with a vertical resolution 2.5 km and with an accuracy that approaches ~3 m/sec under optimum viewing conditions. The TIDI design allows for 100% duty cycle instrument operation during daytime, nighttime, and in auroral conditions. TIDI views emissions from OI 557.7 nm and O2(0-0) to determine Doppler wind.

TIDI comprises three major subsystems: four identical telescopes, a Fabry-Perot interferometer with a CCD detector, and an electronics box. Light from the selected regions of the atmosphere is collected by the telescopes and fiber-optically coupled to the detection optics. The four fields of view are scrambled along with a calibration field input and converted to an array of five concentric circular wedges. This input then passes through a selected filter, then through a Fabry-Perot etalon, and is finally imaged onto a CCD via a circle to line imaging optic (CLIO) device.

  • Click here for the TIDI Fact Sheet.

  • Related sites:

    Location: http://tidi.engin.umich.edu/
    Page Source: Original Web Document
    Creation Date: September 2, 1999
    Last Modified: April 21, 2015 - mlc
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