Bastiaan van Diedenhoven, Brian Cairns, Ann M. Fridlind, Kenneth Sinclair, Andrzej Wasilewski -NASA GISS- Cynthia A. Randles, Arlindo da Silva -GESTAR/Morgan State University/GSFC – John Yorks, Steve Platnick, Tom Arnold -GSFC- Variation of Ice Crystal Size, Shape, and Asymmetry Parameter in Tops of Convective Storm Systems Observed during SEAC 4 RS bastiaan.vandiedenhoven@nasa. SEAC 4 RS science team meeting, Pasadena CA, 2015 Supported by NASA grant #NNX15AD44G (ROSES ACCDAM)
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Bastiaan van Diedenhoven, Brian Cairns, Ann M. Fridlind, Kenneth Sinclair, Andrzej Wasilewski -NASA GISS- Cynthia A. Randles, Arlindo da Silva -GESTAR/Morgan.
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Bastiaan van Diedenhoven, Brian Cairns, Ann M. Fridlind, Kenneth Sinclair, Andrzej Wasilewski
-NASA GISS-
Cynthia A. Randles, Arlindo da Silva-GESTAR/Morgan State University/GSFC –
John Yorks, Steve Platnick, Tom Arnold-GSFC-
Variation of Ice Crystal Size, Shape, and Asymmetry Parameter in Tops of Convective Storm Systems
MODIS: Aqua & Terra Neural Net Retrievals (NNR)MISR: Bright surfaces only (albedo > 15%)AERONET: Level 2
Resolution ~25 km (0.25° 0.3125° latitude longitude), 72 layers, top ~85 km⨉ ⨉Aerosol Species
Dust (DU), sea-salt (SS), sulfates (SO4), organic and black carbon (OC and BC)
Carbon Species CO2, CO with several geographically tagged tracers
Smoke “Age” Tracers
Provides “age” of un-assimilated biomass burning OC AOT with 1 day time resolution (smoke “age” histogram)
GEOS-5 SEAC4RS Mini-Reanalysis
C. A. Randles1,2, Arlindo da Silva2, Peter R. Colarco3,, Virginie Buchard2,4, Anton Darmenov2, Valentina Aquila3,5, Ed Nowottnick, 3,4, and Ravi Govindaraju2,6
1. GESTAR/Morgan State University, 2. NASA Global Modeling and Assimilation Office, 3. NASA Atmospheric Chemistry and Dynamics Laboratory, 4. GESTAR/USRA, 5. GESTAR/Johns Hopkins University, 6. SSAI
Radiosonde data
64 radiosonde measurements at Houston University, Ellington airfield and Smith point were interpolated on a 500-m altitude grid before averaging.
Cold point tropopause(CPT)
Homo-geneousfreezing Level(HFL)
Level of neutral buoyancy(LNB)
adiabatic parcel
Selection of convective cloud data
GOES imagery RSP COT>5CPL and RSP CTH
RSP retrievalsCloud top height
Multi-angle contrast approach (See poster Kenneth Sinclair)
Excellent agreement with CPL
Cloud phaseStrength of cloudbow feature in polarization:
Liquid indexExcellent agreement with CPLVan Diedenhoven et al., JAS 2012
RSP retrievalsIce shape and asymmetry parameter
Using multi-directional polarization at 865 nmHexagonal columns and plates as proxies for complex
particlesRetrieving:
Aspect ratio of crystal components (AR)Surface roughness/distortion parameter (δ)Asymmetry parameter g consistent with AR and δ
Tested on simulated measurements based on complex ice
Van Diedenhoven et al., AMT 2012; ACP 2013; JGR 2014; 2015 paper in prep.
Cloud optical thickness and effective radius:Nakajima-King (670/865 nm + 1590/2250 nm)Ice model consistent with retrieved g
RSP Optical thickness – Cloud top height
40552 data points in total
Melting level
Homogeneous freezing
level
Level of neutral
buoyancy
Cold point tropopause
Variation of glaciation level
RSPCPL
CPL liquid: depolarization ratio <0.15RSP liquid: Liquid index >0.3 (van Diedenhoven et al., JAS 2012)
Ice clouds with liquid underneath
Multiple scatterin
g
RH: average RH wrt liquid between 900-500 hPa
RSP
RSP
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
RSP
RSP
Ice properties vs cloud top height
Using 2.25 μm channel
-20oC
-37oC
-52oC
-52oC
-75oC
-20oC
-37oC
-52oC
-52oC
-75oC
Ice properties vs cloud top height
Cold point tropopause
Homogeneous freezing level
Level of neutral buoyancy
Ice properties vs cloud top height
CPL cold tops in TTL examples 30/
8
11/9
• Outflow of overshooting tops?
• Originating from continental MCS’s (see Lenny Pfister’s talk)
Ice properties vs cloud top height
Ice properties vs cloud top height
CPL depol Ice clouds only
Variation: Land vs Ocean
LandOcean
Variation: Vertical pressure velocity at cloud top
ϖ < -0.08 Pa/sϖ >-0.08 Pa/s
Variation: RH wrt ice (500-100 hPa mean)
RHi > 100%RHi < 100%
RSP oriented ice vs cloud top winds
RSP measurement at ~19:05 UTC on
2 Sept.
Windspeed at cloud top (ws))
Specular reflection
Ice properties vs cloud top height
Tropical storm Ingrid
ConclusionsFrequency of supercooled tops correlates with RH wrt to liquidWith increasing cloud top height