Jacques van Oene
January 19th 05, 04:07 PM
Sodium Lidar Set Up at National MST Radar Facility (NMRF)
January 19,2004
The National MST Radar Facility at Gadanki near Thirupati, under the
Department of Space, has set up a Sodium Lidar, which is a ground based
instrument for studying vertical and temporal structure of mesosphere and
lower thermosphere (MLT) region. This is the first of its kind in India and
will help in characterising the wind and wave induced sodium density. The
first observation from the new Sodium Lidar was made on January 10, 2005.
The occurrence of sporadic layers of neutral sodium and other metals at
around 100 km heights is a phenomenon that is both interesting and puzzling.
The shooting meteors are the genesis for the formation of atmospheric metal
layers. As meteors enter the atmosphere, they burn-up or ablate and leave
debris in their path. This ablation occurs near altitudes of 80 to100 km.
Part of this debris is neutral metal atoms and ions such as sodium, iron,
potassium and calcium, which exist in this unique region as the air is thin
for them to be trapped in compounds with oxygen but too thick to allow
ionisation of all the neutral atoms into ions. This region of the atmosphere
also hosts the airglow layers. Metal atoms are useful for remote sensing as
they are shiny at specific resonant wavelengths. For atmospheric sodium this
resonant wavelength is 589 nm, which appears as bright orange. Atmospheric
sodium layer acts as tracers of winds and waves in this region.
National MST Radar Facility is one of the prime centers for advanced
research in atmospheric sciences. In addition to the state of art
Mesosphere-Stratosphere-Troposphere (MST) radar, it has facilities such as
the Lower Atmospheric Wind Profiler and Rayleigh/Mie Lidar. Very recently,
Raman Lidar and Boundary Layer Lidar were set up. These facilities
complement and supplement the MST radar for an integrated and comprehensive
study of lower, middle and upper atmosphere.
Sodium Lidar has further enhanced the scope of atmospheric research at this
national facility.
--
--------------
Jacques :-)
www.spacepatches.info
January 19,2004
The National MST Radar Facility at Gadanki near Thirupati, under the
Department of Space, has set up a Sodium Lidar, which is a ground based
instrument for studying vertical and temporal structure of mesosphere and
lower thermosphere (MLT) region. This is the first of its kind in India and
will help in characterising the wind and wave induced sodium density. The
first observation from the new Sodium Lidar was made on January 10, 2005.
The occurrence of sporadic layers of neutral sodium and other metals at
around 100 km heights is a phenomenon that is both interesting and puzzling.
The shooting meteors are the genesis for the formation of atmospheric metal
layers. As meteors enter the atmosphere, they burn-up or ablate and leave
debris in their path. This ablation occurs near altitudes of 80 to100 km.
Part of this debris is neutral metal atoms and ions such as sodium, iron,
potassium and calcium, which exist in this unique region as the air is thin
for them to be trapped in compounds with oxygen but too thick to allow
ionisation of all the neutral atoms into ions. This region of the atmosphere
also hosts the airglow layers. Metal atoms are useful for remote sensing as
they are shiny at specific resonant wavelengths. For atmospheric sodium this
resonant wavelength is 589 nm, which appears as bright orange. Atmospheric
sodium layer acts as tracers of winds and waves in this region.
National MST Radar Facility is one of the prime centers for advanced
research in atmospheric sciences. In addition to the state of art
Mesosphere-Stratosphere-Troposphere (MST) radar, it has facilities such as
the Lower Atmospheric Wind Profiler and Rayleigh/Mie Lidar. Very recently,
Raman Lidar and Boundary Layer Lidar were set up. These facilities
complement and supplement the MST radar for an integrated and comprehensive
study of lower, middle and upper atmosphere.
Sodium Lidar has further enhanced the scope of atmospheric research at this
national facility.
--
--------------
Jacques :-)
www.spacepatches.info