Zhaoyan Liu, Peter Voelger, and Nobuo Sugimoto, "Simulations of the observation of clouds and aerosols with the Experimental Lidar in Space Equipment system," Appl. Opt. 39, 3120-3137 (2000)
We carried out a simulation study for the observation of clouds and
aerosols with the Japanese Experimental Lidar in Space Equipment
(ELISE), which is a two-wavelength backscatter lidar with three
detection channels. The National Space Development Agency of Japan
plans to launch the ELISE on the Mission Demonstrate Satellite 2
(MDS-2). In the simulations, the lidar return signals for the
ELISE are calculated for an artificial, two-dimensional atmospheric
model including different types of clouds and aerosols. The signal
detection processes are simulated realistically by inclusion of various
sources of noise. The lidar signals that are generated are then
used as input for simulations of data analysis with inversion
algorithms to investigate retrieval of the optical properties of clouds
and aerosols. The results demonstrate that the ELISE can provide
global data on the structures and optical properties of clouds and
aerosols. We also conducted an analysis of the effects of cloud
inhomogeneity on retrievals from averaged lidar profiles. We show
that the effects are significant for space lidar observations of
optically thick broken clouds.
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The Si APD is made by EG&G for space
operation. The dark count at maximum is 500 s-1 for
photocounting, the dark current is 1.31 × 10-12 A
Hz-1/2 for analog detection; the excess noise factor is
4, and the multiplication factor is 100.
Table 2
Typical Scattering Parameters of Clouds and Aerosols in
Visible and Near-Infrared Regions
Noise Level in Lidar Signals (Photoelectron Number)
Caused by the Background Lights, the Dark Counts or Noise Currents, and
the Scattering Signal at 35 km
Spectal radiance, 0.17 ×
10-6 and 0.46 × 10-6 (W
m-2 sr-1 nm-1) for 1053 and
532 nm (night), 0.17 (W m-2 sr-1
nm-1) for 1053 nm (day).
Dark-count rate of the Si APD for the PC
detection mode, 500 (s-1).
Noise current of the Si APD for the AN
detection mode, 1.31 × 10-12 (A
Hz-1/2).
Table 4
Minimum Backscatter Coefficients of a Homogeneous Cloud
Required for Detection of Its Top and
Basea
Cloud physical thickness, 1 km; lidar
ratio, S1 = 20 sr; vertical resolution,
100 m; TNR, 2; SNR, 4.
Three values are given, for altitudes of 20,
10, and 4 km, where PSC, cirrus, and water clouds, respectively, are
assumed typically to exist.
Ci, cirrus; W Cl, water cloud.
Tables (4)
Table 1
ELISE Major Specifications (Design)
Satellite
Orbit
Sun-synchronous circular
Height
550 ± 5 km
Ground speed
6.983 km/s
Period
95.6 min
Inclination angle
97.59°
Transmitter
Laser
Laser-diode-pumped Nd:YLF (fundamental and second harmonic)
The Si APD is made by EG&G for space
operation. The dark count at maximum is 500 s-1 for
photocounting, the dark current is 1.31 × 10-12 A
Hz-1/2 for analog detection; the excess noise factor is
4, and the multiplication factor is 100.
Table 2
Typical Scattering Parameters of Clouds and Aerosols in
Visible and Near-Infrared Regions
Noise Level in Lidar Signals (Photoelectron Number)
Caused by the Background Lights, the Dark Counts or Noise Currents, and
the Scattering Signal at 35 km
Spectal radiance, 0.17 ×
10-6 and 0.46 × 10-6 (W
m-2 sr-1 nm-1) for 1053 and
532 nm (night), 0.17 (W m-2 sr-1
nm-1) for 1053 nm (day).
Dark-count rate of the Si APD for the PC
detection mode, 500 (s-1).
Noise current of the Si APD for the AN
detection mode, 1.31 × 10-12 (A
Hz-1/2).
Table 4
Minimum Backscatter Coefficients of a Homogeneous Cloud
Required for Detection of Its Top and
Basea
Cloud physical thickness, 1 km; lidar
ratio, S1 = 20 sr; vertical resolution,
100 m; TNR, 2; SNR, 4.
Three values are given, for altitudes of 20,
10, and 4 km, where PSC, cirrus, and water clouds, respectively, are
assumed typically to exist.
Ci, cirrus; W Cl, water cloud.