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Atmospheric Lidar Observatory


Rayleigh Lidar Group - Green Beam (Vincent B. Wickwar)

Lidar is a radar-type technique that uses powerful lasers and large telescopes. Since 1993, the ALO has measured temperatures, densities, and waves in the mesosphere and looked for evidence of global warming. The ALO is currently being upgraded to make it the most powerful lidar in the world.  For more information:

Na Lidar Group - Gold Beam (Tao "Titus" Yuan)

It has long been a challenge for scientists to make in situ measurements of the mesopause region of the Earth’s atmosphere (80-110 km in altitude), because it is too high for airplanes and balloons, but too low for satellites. Meteorological rockets reach altitudes up to about 90 km. Although sounding rockets can reach well beyond that, they are rather infrequent and expensive. This scarcity of observations had earned for the region the nickname “the Ignorosphere”. Our work (Gold Beam-Na LIDAR) and that of others are helping to make the mesopause ignored no more. We use laser-induced fluorescence spectroscopy to study a naturally occurring layer of sodium atoms in the mesopause region, which is formed by the atomization of meteorites plunging into the Earth’s atmosphere. Our data can be processed to determine the Doppler broadening and shift by the atoms, thereby allowing us to precisely deduce atmospheric temperature and line-of-sight wind with unprecedented spatial and temporal resolutions. Our work also validates satellite data and contributes to a fuller understanding of the dynamics of the upper atmosphere. For more information: