AerosolAerosol--Warm Microphysics Closure Warm Microphysics Closure Observed from the Twin OtterObserved from the Twin Otter

W.C. Conant, T.M. W.C. Conant, T.M. VanRekenVanReken, T.A. Rissman, V. Varutbangkul, , T.A. Rissman, V. Varutbangkul, J.L. Jimenez, A.E. Delia, R. Bahreini, G.C. Roberts, A. Nenes, J.L. Jimenez, A.E. Delia, R. Bahreini, G.C. Roberts, A. Nenes,

H.H. Jonsson, R.C. Flagan, and J.H. SeinfeldH.H. Jonsson, R.C. Flagan, and J.H. Seinfeld

Review of observations from the Twin OtterReview of observations from the Twin Otter

AerosolAerosol--CCN ClosureCCN Closure

AerosolAerosol--Warm cloud microphysics closureWarm cloud microphysics closure

Goals and Role of the Twin OtterGoals and Role of the Twin Otter

Characterize the aerosol feeding the Characterize the aerosol feeding the convective systems studied by the high flying convective systems studied by the high flying aircraft aircraft (Poster: Varutbangkul)(Poster: Varutbangkul)

Provide lower boundary condition on the Provide lower boundary condition on the radiative fluxes radiative fluxes (e.g. (e.g. PilewskiePilewskie))

Understand the processes controlling warm Understand the processes controlling warm cloud microphysics cloud microphysics (Present Talk; Poster: (Present Talk; Poster: VanRekenVanReken))

CIRPAS Twin Otter

MOUDI APS

Optical Probes:CAPSPCASPFSSP

Met Sensors

H2O Vapor

Radiometers(SSFR, LEISA)

CCN CountersCPCsDMAs

Composition:AMSCOMACS

Cabin Aerosol:

Aerosol: 3nm – 10+ µmCloud: 500 nm – 1.6 mm

Morning vs. Afternoon FlightsTypical Morning Flight Typical Afternoon Flight

Alti

tude

(m)

Alti

tude

(m)

Flight Tracks for Twin Otter FlightsFlight Tracks for Twin Otter Flights

27.5

27.0

26.5

26.0

25.5

25.0

24.5

24.0

Latit

ude

-84 -83 -82 -81 -80Longitude

CF-1 CF-2 CF-3 CF-4 CF-5 CF-6 CF-8 CF-9 CF-10 CF-11 CF-12 CF-13 CF-14 CF-15 CF-16 CF-17 CF-18 CF-19 CF-20

Consistency Among Aerosol, CCN, and Consistency Among Aerosol, CCN, and Cloud Microphysical Properties:Cloud Microphysical Properties:

Aerosol Thermodynamics ModelsAerosol Thermodynamics Models

Explicitly models aerosol thermodynamic properties including kinetic and chemical effects

Models developed by A. Nenes

Input: Aerosol size distribution from DMA/PCASP measurements (10 nm – 2500 nm); Aerosol chemical composition

These cases assume Ammonium bisulfate based on preliminary AMS composition data and general agreement in CCN closure

Three applications : Aerosol hygroscopy; Modeling of CCN instrument; Adiabatic Cloud Parcel

CRYSTAL-FACE Twin Otter Cloud Research Strategy

Model of CCNinstrument

Met data

Cloud model(RAMS)Predicted cloud

vertical distributionof CDNC, Re,

LWC (adiabatic?)

Measured cloudvertical distribution

of CDNC, Re,LWC

Adiabatic parcelmodel

Measured updraftvelocity

(C-MIGITS)

Predicted CDNC@ cloud base

Measured CDNC@ cloud base(FSSP, CAPS)

Predicted sourceof aerosol from

CO level(CO)

Aerosol chemicalcomposition

(AMS, MOUDI)

Predicted CCN@ s%

by Köhler Theory

Measured CCN@ s%(CCN)

Aerosol sizedistributions at

ambient RH(DMA wet)

Dry aerosol sizedistributions below

cloud(DMA dry, CPC)

Verification ofCCN Instrument

Performance

AerosolHygroscopic

Closure

CCNClosure

CDNCClosure

CloudClosure

Evaluationof Aerosol

Source

AerosolCCN

Closure

AerosolCloud

Closure

.. . .

. .

Cloud Dynamics-Cloud Microphysics in vertical profiles of cloud:Cloud drop and precipitation size distribution, liquid water

Are there cloud regions where liquid water follows an adiabatic profile? Does effective radius follow an adiabatic profile outside adiabatic regions?What is the effect of entrainment and mixing on profile of microphysics?

What is the effect of precipitation?

Aerosol-CCN-Nd Closure Near Cloud Base:Cloud drop concentration, local cloud dynamicsIs droplet concentration consistent with parcel model given

the observed updraft velocity spectrum and aerosol characteristics?

Aerosol-CCN Closure in Boundary Layer:Boundary layer aerosol size, chemistry, and CCN spectrumCan Köhler theory predict CCN spectrum from aerosol

Warm Cloud Aerosol Sampling Strategy

Cloud Profiling Strategy

AMS Mass Distribution (SO4 Only)

Aerosol Size and Composition Measurements

10

2

4

68

100

2

4

68

Parti

cle

Dia

met

er (n

m)

12:00 PM 1:00 PM 2:00 PM 3:00 PM

UTC Time

2.5

2.0

1.5

1.0

0.5

0.0

dV/dlogDp (µm

3cm-3)

DMA Volume Distribution

Source: Varutbangkul et al. (Poster)

12:00 PM 1:00 PM 2:00 PM 3:00 PM

CCN Instrument ConfigurationsCCN Instrument Configurations

Scripps

Sheath Air

Aerosol SampleWater

Heating/CoolingSections(fixed)

Optics/Detector

Column

Roberts and coRoberts and co--authors authors determined that a stable determined that a stable supersaturation profile could supersaturation profile could be obtained by continuously be obtained by continuously increasingincreasing the temperature the temperature axially along the column wall.axially along the column wall.

The water vapor diffuses The water vapor diffuses more rapidly than heat; more rapidly than heat; inducing a stable inducing a stable supersaturation at the supersaturation at the centerline.centerline.

Source: VanReken et al. (Poster)

Laboratory Verification: ResultsLaboratory Verification: ResultsActivated Fraction vs. Critical SupersaturationActivated Fraction vs. Critical Supersaturation

1.0

0.8

0.6

0.4

0.2

0.0

Act

ivate

d Fr

actio

n

0.12 3 4 5 6 7 8 9

1Sc(%)

Ammonium Sulfate Sodium Chloride

Source: VanReken et al. (Poster)

Closure Analysis: S=0.8%Closure Analysis: S=0.8%

Line Fit: Slope=1.23 R2=0.82Source: VanReken et al. (Poster)

78

102

2

3

4

5

678

103

2

3

4

5678

104

2

Cal

cula

ted

Con

cent

ratio

n (c

m-3

)

7 8 9

102

2 3 4 5 6 7 8 9

103

2 3 4 5 6 7 8 9

104

2

Observed Concentration (cm-3

)

CF-1 CF-2 CF-3 CF-4 CF-5 CF-6 CF-10 CF-11 CF-12 CF-13 CF-14 CF-15 CF-16 CF-17 CF-18 CF-19 CF-20 1:1 Line

.. . .

. .

Cloud Dynamics-Cloud Microphysics in vertical profiles of cloud:Cloud drop and precipitation size distribution, liquid water

Are there cloud regions where liquid water follows an adiabatic profile? Does effective radius follow an adiabatic profile outside adiabatic regions?What is the effect of entrainment and mixing on profile of microphysics?

What is the effect of precipitation?

Aerosol-CCN-Nd Closure Near Cloud Base:Cloud drop concentration, local cloud dynamicsIs droplet concentration consistent with parcel model given

the observed updraft velocity spectrum and aerosol characteristics?

Aerosol-CCN Closure in Boundary Layer:Boundary layer aerosol size, chemistry, and CCN spectrum

Can Köhler theory predict CCN spectrum from aerosol properties?

Warm Cloud Aerosol Sampling Strategy

Cloud Base Pass

Aerosol-Cloud Drop Closure

Agreement found for the 13 vertically profiled cumulus

.. . .

. .

Cloud Dynamics-Cloud Microphysics in vertical profiles of cloud:Cloud drop and precipitation size distribution, liquid water

Are there cloud regions where liquid water follows an adiabatic profile? Does effective radius follow an adiabatic profile outside adiabatic regions?What is the effect of entrainment and mixing on profile of microphysics?

What is the effect of precipitation?

Aerosol-CCN-Nd Closure Near Cloud Base:Cloud drop concentration, local cloud dynamicsIs droplet concentration consistent with parcel model given

the observed updraft velocity spectrum and aerosol characteristics?

Aerosol-CCN Closure in Boundary Layer:Boundary layer aerosol size, chemistry, and CCN spectrum

Can Köhler theory predict CCN spectrum from aerosol properties?

Warm Cloud Aerosol Sampling Strategy

Cloud ProfilingAdiabatic?Environment

Θe (°C)

Land-Ocean Contrast

“Dirty Case”July 18

CCN = 2700/ccNC = 1400/cc

“Cleaner Case”June 27

CCN = 510/ccNC = 380/cc

Aerosol is the primary driver of droplet concentration and effective radius throughout the column.

What Next?What Next?

How does the warm cloud indirect effect affect ice How does the warm cloud indirect effect affect ice nucleation (and anvil radiative properties)?nucleation (and anvil radiative properties)?

Are variations in chemistry (measured by AMS) Are variations in chemistry (measured by AMS) influencing warm cloud activation?influencing warm cloud activation?

Can we elucidate the processes governing cloud Can we elucidate the processes governing cloud drop dispersion?drop dispersion?

Can we discern the roles of concentration, Can we discern the roles of concentration, dispersion and giant nuclei on precipitation dispersion and giant nuclei on precipitation formation?formation?

More Twin Otter Science at More Twin Otter Science at T/T/ThTh Poster SessionsPoster Sessions

VanRekenVanReken et al. et al. –– Aerosol/CCN closure using in situ Aerosol/CCN closure using in situ measurements from the Twin Ottermeasurements from the Twin Otter

Varutbangkul et al. Varutbangkul et al. –– Aerosol Size and Composition from Aerosol Size and Composition from the Twin Otter during CRYSTALthe Twin Otter during CRYSTAL--FACEFACE

Campos et al. Campos et al. –– Lower Lower tropospherictropospheric measurements of water measurements of water vapor and COvapor and CO