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