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Faculty of Physics and Earth Science
Leipzig Institute for Meteorology ‐ LIM
EAGLE – Cirrus Observations
André Ehrlich, Frank Heyner, Eike Bierwirth
CARRIBA meeting, Hamburg, 24. Oct. 2011
Faculty of Physics and Earth Science
‐ Field of view 39.7°
‐ 1024 spatial pixel
‐ Spatial resolution aa
7 m at 10 km
‐ 400 – 970 nm
‐ 488 spectral pixel
‐ Spectral resolutionaa1.2 nm
EAGLE – Cirrus Observations
Faculty of Physics and Earth Science
EAGLE – Cirrus Observations
April 18, 2011
Subvisible Cirrus
Faculty of Physics and Earth Science
EAGLE – Cirrus Observations
Calibrated Measurement for 530 nm
Faculty of Physics and Earth Science
Simulations and Ambiguity
Previous knowledge necessary: LIDAR, All‐Sky Camera, Satellite Measurements
Cirrus‐Optical Depth
Radiance
(W m
‐2sr
‐1nm
‐1)
‐ Effektive Radius Reff = 20 μm
‐ Surface Albedo above water (0.063)
‐ Cloud Hight 10 km
EAGLE – Cirrus Observations
Faculty of Physics and Earth Science
Retrieved Optical Depth
Distance in km
Optical Dep
th
Distance in
km
EAGLE – Cirrus Observations
Faculty of Physics and Earth Science
Histogram
Optical Depth
Num
bero
fpixel
Mean optical thickness = 0.034
EAGLE – Cirrus Observations
Subvisible Cirrus τ=0.03 (Sassen et al (1989)
Faculty of Physics and Earth Science
EAGLE – Cirrus Observations
Future Plans
‐ analyse more data‐ comparison with lidar cloud optical thickness‐ implementation of measured aerosol profile into simulations
Faculty of Physics and Earth Science
Retrieval Uncertainties
Cloud High negligible, |Uncertainty| < 0.5%
Used Parameter UncertaintyMaximum Uncertainty in
optical depth(without Cumulus)
Albedo0.068(Water)
0.073 (Gras) to0.314 (Sand)
28.6%(0.04)
Reff
20 μm15 ‐ 40 μm possible
(satellite measurements)2.8% to ‐12.2%(0.005) (‐0.02)
Ulbricht‐Sphere + / ‐ 6 % ‐ / + 15.4 %(‐ / + 0.02)
EAGLE – Cirrus Observations
