The Variation of Observed Ice Cloud Microphysics and Possible Links to the Environment
Breakout:
How do ice properties vary?
• With height/temperature?• With cloud type?• With location (land vs Ocean; Latitude)• With humidity?• With dynamics (ω, shear, etc.)?• With distance to cloud top/bottom?• With aerosol load?
Can we relate any variation in properties with processes?
• Correlation -> Causation • Consistency with other campaigns?• Global ‘validation’ using satellite observations• LES/CRM/SCM modeling tests• Significant for consideration in GCMs?
SEAC4RS data sources• Remote sensing
– ER-2: CPL, RSP, eMAS, AirMSPI, SSFR– DC-8: SSFR, APR-2, DIAL, RPI– Satellite: GOES, MODIS, CLOUDSAT/CALIPSO
• In situ cloud microphysics– DC8 & Learjet: SPEC package
• Meteorology & Chemistry– DC-8 and ER-2: Various packages– Radiosondes – Reanalysis (Randles/Da Silva. Subsets at DC-8 and ER-2 tracks available)– Back-trajectories – WRF-Chem
• Aerosol– DC8 & Learjet (& ER-2): Various in situ packages + 4STAR + DIAL– ER-2 remote sensing: AirMSPI, RSP, CPL– AERONET– Reanalysis (Randles/Da Silva. Subsets at DC-8 and ER-2 tracks available)
Variation of glaciation level
RSPCPL
Homogeneous freezing level
Melting level
LNB
CPT
CPL liquid: depolarization ratio <0.15RSP liquid: Liquid index >0.3 (van Diedenhoven et al., JAS 2012)
RH: average RH wrt liquid between 900-500 hPa
Ice properties vs cloud top height
Using 2.25 μm channel
-20oC
-37oC
-52oC
-58oC
-75oC
-20oC
-37oC
-52oC
-58oC
-75oC
LearjetDC-8
Variation: Land vs Ocean
LandOcean
Variation: RH wrt ice (500-100 hPa mean)
RHi > 100%RHi < 100%
MODIS+POLDER retrievals at TWP
From van Diedenhoven et al., JGR, 2014
16 Jan.-20 Feb. 2006
COT>5
In situ measured aspect ratios from CPIUm, McFarquhar et al., ACP, 2015 TWP-ICESPARTICUSISDAC
Lawson et al. 2010
Difference between SWIR band retrievals
Lidar Penetration depth:H(τ=0.1)-H(τ=3)
Using 2.25 μm channelUsing 1.59 μm channel
2.25 m μ channel sees (optically) deeper into cloud
Difference in size from two channels increases with ‘fluffiness’ of top
COT>5
Restricted to
COT>5
• CTH ~ 11 km
• Distorted compact crystals
• Reff ~ 30-40 μm
• g ~ 0.75• Extended
tops
• CTH ~ 8-10 km
• plate-like crystals, some oriented
• Reff ~ 20-40 μm
• g ~ 0.76-0.8• Extended
tops
• CTH ~ 12 km
• Distorted plate-like and compact crystals
• Reff ~ 15-20 μm
• g ~ 0.75-0.79
• Compact tops
PREMIMINARY