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