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Scientific Report 2007-2009<br />
Laboratories and Facilities of the Department of Physics<br />
L27. Atmospheric Physics Lab<br />
The Atmospheric Physics laboratory has been engaged in experimental and theoretical researches regarding radiative and<br />
thermodynamical properties of the Earth atmosphere for more than 25 years.<br />
Most of the instruments are based on remote sensing techniques and are<br />
routinely run for probing the atmosphere above the campus location: several<br />
Rayleigh LIDARs (LIght Detection And Ranging) with different characteristics<br />
and able to measure the aerosol or the temperature through the<br />
stratosphere (Figure 1), a Raman Lidar able to measure the water vapor<br />
through the troposphere, a SODAR (SOund Detection And Ranging) able<br />
to measure the three components of the wind vertical profile and the turbulence<br />
structure up to 600 m, a MFRSR (MultiFilter Rotating Shadowband<br />
Radiometer) able to measure the total optical depth of the atmospheric<br />
aerosol in several visible bands, a microbarograph able to record the passage<br />
of pressure atmospheric disturbances. The instruments are used in<br />
conjunction with satellite overpasses for ground truth comparisons and calibration<br />
studies. They are used also in joint measurement campaigns for data<br />
assimilation in computer models. Very recently (April 2010) the measurements<br />
over the campus were used to monitor the presence of the Icelandic<br />
volcano eruption cloud above Rome.<br />
During the years in some cases measurements of important geophysical<br />
quantities were carried on and prototipe instruments were tested within the<br />
lab at controlled conditions.<br />
The know-how on remote sensing techniques has been applied for the design<br />
and development of an air born lidar (Air Born Lidar Experiment,<br />
ABLE) that flew during several international measurements campaigns Figure 1: The Rayleigh Lidar with three<br />
aimed at monitoring the presence of aerosol in critical regions of the Earth channels for monitoring the atmospheric<br />
(Antarctica, Tropical Regions and Actica). Presently a lidar of the group is aerosol through the lower stratosphere.<br />
operational at the Arctic station of Thule (Greenland) which is part of the<br />
Network for the Detection of Atmospheric Change (NDACC).<br />
The lidar is able to measure the tropospheric<br />
arctic haze, aerosol profiles up<br />
to the stratosphere and temperature profiles<br />
through the mesosphere. All lidars<br />
were totally built in the lab using commercially<br />
available components. The optical<br />
sources are Nd:YAG lasers with second and<br />
third hamonic generators (the latter when<br />
needed). Some of the lasers are two stage<br />
systems: Q-switched oscillator and one-pass<br />
amplifier. Presently in the lab there are several<br />
Italian made pulsed lasers with outputs<br />
in the 10 MW power range.<br />
Figure 2: The roof of the lab with 6 Sodar antennas and the astronomical<br />
dome for hosting lidars looking at zenith angles different from zero. The three<br />
Sodar antennas in the foreground are presently deployed elsewhere.<br />
The receivers are based on: 1) optical<br />
telescopes, 2) narrow band interference filters,<br />
3) photmultipliers (for the visible) and<br />
avalance diodes (for near IR), 4) photon<br />
counting or analog sampling channels with<br />
bandpasses of the order of 20MHz or higher<br />
and 5) home developed computer programs.<br />
The lab is placed at the last floor of the<br />
building where all the lidars usually sit. Access<br />
to the sky in a zenith only direction is<br />
obtained through hatches either manually<br />
or electrically controlled. The three antennas of the Sodar are sitting directly on the roof of the building (Figure 2) and a<br />
4m astronomical dome allows the usage of remote instruments at different zenithal/azimuthal angles.<br />
http://g24ux.phys.uniroma1.it/<br />
Related research activities: G3, G4.<br />
<strong>Sapienza</strong> Università di Roma 195 Dipartimento di Fisica