calipso water cloud phase statistics and …...calipso water cloud phase statistics and comparison...
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![Page 1: CALIPSO water cloud phase statistics and …...CALIPSO water cloud phase statistics and comparison with model CALIPSO Payload Three Near Nadir Viewing Instruments CALIOP Cloud-Aerosol](https://reader031.vdocuments.net/reader031/viewer/2022040800/5e34db73b289e133fa7a012b/html5/thumbnails/1.jpg)
Kuanman Xu, Anning Cheng
Yongxiang Hu CALIPSO team
NASA LaRC
CALIPSO water cloud phase statistics and comparison with model
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CALIPSO Payload Three Near Nadir Viewing Instruments
CALIOP Cloud-Aerosol Lidar with Orthogonal Polarization
2 wavelength polarization sensitive lidar:
1064 nm, 532 nm (parallel and perpendicular)
Wide Field Camera (WFC)
High-resolution image (125m resolution)
Vertical profiles of atmosphere
Lidar Imaging Infrared Radiometer (IIR)
High-resolution image (swath product)
IIR
WFC
CALIOP Laser Transmitter
CALIPSO Payload
CALIOP Receiver Telescope
1 meter
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CALIPSO unambiguously discriminates water and ice phase at cloud top
Blue: ice Red: water
532 nm Level 1
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Technique in discriminating liquid and ice phase
• MODIS: absorption of solar infrared radiation (ice absorbs slightly more than liquid for each scattering event)
• Parasol: linear polarization of reflected sunlight at rainbow angles (liquid: highly polarized)
• CALIPSO: polarization change of backscattered laser light (ice: yes; water: no); lidar backscatter intensity (water > 0.04 sr-1; ice< 0.035 sr-1) more straight forward; less assumptions; works for multi-layered clouds
These technique only valid at cloud top
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Cloud Phase discrimination from Lidar Depolarization:
δsphere = 0 – 0.3; δnonsphere-R=0.3 – 0.55
E
E
Laser Beam
Backscatter Backscatter
Laser Beam
Water Cloud Ice Cloud
EE
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Impact of Multiple Scattering and Particle Orientation on
CALIPSO’s Cloud Phase from Depolarization
Jun 2006 – Dec 2007: 0.3 off-nadir Dec 2007 – end of CALIPSO: 3 degree
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Aircraft measurements confirms CALIPSO phase [Noh, Y.-J., C. Seaman, T. H. Vonder Haar, D. R. Hudak, and P. Rodriguez (2011), Comparisons And Analyses Of Aircraft And
Satellite Observations For Wintertime Mixed-Phase Clouds, J. Geophys. Res., doi:10.1029/2010JD015420]
Twater cloud = -280C CALIPSO: Water; CloudSat: Ice; Aircraft: Water
CALIPSO:Water; CloudSat:Ice; Aircraft:Water Twater cloud = -230C
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Occurrence of the supercooled water clouds
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CALIPSO provides cloud top liquid water content and droplet concentration
Using a simple physics relation for deriving water cloud droplet number concentration from CALIPSO depolarization measurement (Hu et al., ACP, 2007): Lidar depolarization ratio of water clouds multiple scattering extinction coefficient add MODIS droplet size water cloud droplet concentration
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Cloud top water droplet number concentration (N) statistics from CALIPSO N for winter-time clouds over ocean very small
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Water cloud top height and cloud top LWC from CALIPSO
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Spatial distribution of supercooled water clouds
Polar region
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Comparisons of cloud liquid water content
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Comparisons of albedo
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Summary • CALIPSO provides unambiguous information about cloud thermodynamic phase,
liquid water content and water droplet number concentration at CLOUD TOP
• CALIPSO data suggests that there are a lot more supercooled liquid water clouds over ocean and at high latitude
• Water cloud droplet number concentration at cloud top derived from CALIPSO are considerably low. The lowest number concentrations are around 10 per cc (most water clouds over ocean during winter-time)
• Liquid water content at cloud top, derived from CALIPSO, reduces slowly with cloud top height
• Applying the cloud phase – temperature relation from CALIPSO, CAM4 produces slightly more liquid water between -150C and -300C
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Comparisons of cloud ice water content
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CALIPSO identifies cloud layers and aerosol layers accurately
June 9, 2006