| definition |
-
The Cloud Physics Lidar (CPL) (successor to the Cloud Lidar
System is an airborne lidar system designed specifically for
studying clouds and aerosols using the ER-2 High Altitude
Aircraft. Because the ER-2 typically flies at 65,000 feet (20
km), its instruments are above 94% of the earth's atmosphere,
thereby allowing ER-2 instruments to function as spaceborne
instrument simulators. The Cloud Physics Lidar provides a unique
tool for atmospheric profiling and is sufficiently small and low
cost to include in multiple instrument missions.
The Cloud Physics Lidar flies on the ER-2 along with other
instruments and is typically located in the forward section of
the left wing superpod. A window in the bottom of the superpod
allows the instrument to look directly at nadir (this is a
non-scanning system). The Cloud Physics Lidar provides a
complete battery of cloud physics information. Data products
include:
Cloud profiling with 30 m vertical and 200 m horizontal
resolution at 1064 nm, 532 nm, and 355 nm, providing cloud
location and internal backscatter structure.
Aerosol, boundary layer, and smoke plume profiling at all three
wavelengths.
Depolarization ratio to determine the phase (e.g., ice or water)
of clouds using the 1064 nm output.
Cloud particle size determined from a multiple field-of-view
measurement using the 532 nm output (off-nadir multiple
scattering detection).
Direct determination of the optical depth of cirrus clouds (up
to ~OD 3) using the 355 nm output. The CPL provides information
to permit a comprehensive analysis of radiative and optical
properties of optically thin clouds. To determine the effects of
particulate layers on the radiative budget of the
earth-atmosphere system certain information about the details of
the layer and its constituents is required. The effect of clouds
is often referred to as cloud radiative forcing. Cloud radiative
forcing, in general, is the alteration that the presence of
clouds has on the energy budget. The information required to
compute the radiative forcing includes the vertical distribution
of short wave cross section, a parameter that the CPL provides
up to the limits of optical signal attenuation.
Additional information available at
"http://cpl.gsfc.nasa.gov/"
[Summary provided by NASA]
|
