ARM May 2003 Aerosol IOPMission Objectives

(based on Schmid/Pilewskie/Strawa/Russell/Redemann/BergstromARM ST proposal plus possible add-ons)

Vertically resolved aerosol optical properties over the ARM SGP site Motivation: unrealistic SSA, no closure IAP, BBHR VAP

•Extinction closure•Absorption closure

Ad-ons•Satellite validation•Spatial variability

DOE/ARM May 2003 Aerosol IOP

Aerosol: number, size distr., hygroscopicity scattering, absorption (PSAP, photo-acoustic, CRD)

Cloud: liquid water, CCN, size distr.

Radiation: solar and IR up and downwellingbroadband and spectral.

Aerosol Optical Depth, H2O

Groundbased: same + lidars+…Groundbased: same + lidars+…

In-situ Aerosol Profiles at SGPIn-situ Aerosol Profiles at SGP

CIRPAS Twin OtterCIRPAS Twin Otter

Extinction closure

• "Can in situ measurements of aerosol properties account for the solar beam attenuation (extinction) by an aerosol layer or column?"

• “How about lidars or satellites?”• Measuring solar beam attenuation by an AATS on the

same aircraft as in situ sensors allows an exact match in the aerosol layers described by the attenuation and in situ measurements.

• Such comparisons have revealed important insights about aerosol sampling and inadvertent modification in such previous experiments as TARFOX, ACE-2, SAFARI, ACE-Asia, CLAMS …

Extinction closure

• AATS-14

• CW-CRD

• Neph+PSAP (or Photoacoustic)

• From Size Distr. and Comp. (TDMA, PCASP, CAPS, FSSP, APS)

• Lidars (CARL, MPL, …)

• IAP

Extinction closure between AATS-14 and Neph+PSAP for 14 profiles

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

is = (1.03±0.09) sp ± 0.052)

r2 = 0.98

Layer AOD from Sun photometer,sp

Laye

r A

OD

fro

m in

situ

mea

sure

men

ts,A

OD

is

Best fit to ax+b1 to 1 line

AOD

AOD

AOD

Layer AOD Closure in SAFARI-200015 vertical profiles, from Magi et al., subm. JGR 2002

How well did past campaigns do on AATS vs Neph+PSAP comparisons?

U.S. East Coast, 1996 (Hegg et al., 1997, Hartley et al., 2000)

Canary Islands, 1997 (Schmid et al., 2000)

Eastern Asia, 2001

C-130: Redemann et al., 2003

Twin Otter: Schmid et al., 2003

Southern Africa (Magi et al., 2002)

U.S. East Coast, 2001 Hobbs et al., (in preparation)

Absorption Closure

• PSAP

• CW-CRD

• Photoacoustic

• Aeronet Cimel

• Flux Divergence (SSFR)

Downwelling Flux: F

Upwelling Flux: F

Net Flux: F- F

Flux Divergence (absorption):

(F- F)2000m- (F- F)43m

Fractional absorption:

[(F- F)2000m- (F- F)43m]/ F2000m

2000 m

43 m

Satellite Validation (over land)MISR, MODIS, ATSR/2

Spatial Variability (MFRs at SPG)

CIRPAS Twin Otter Payload May 2003 IOP

Available Measurement Instrument PI/Organization

Aerosol size distribution 10 nm-1µm at 2 RH (one can be ambient)

TDMA System (cabin) Caltech 

Aerosol/cloud size distribution d=0.1-2.5 µm d>0.3 µm

PCASP probeCAPS probe

CIRPAS

Aerosol/cloud size distribution d>0.5 µm

FSSP probe CIRPAS

Aerosol size distribution d>0.5 µm

TSI Aerodynamic Particle Sizer (wing) CIRPAS

Total aerosol number concentration Condensation Nucleus Counters (CNCs)

CIRPAS

Cloud liquid water contentGerber PVMJohnson probe on CAPS CIRPAS

 

Meteorological state parameters:Dry-bulb temperatureDew point temperaturePressureWind vector (mean)

    Gust probe

CIRPAS 

Aircraft state parameters:PositionAirspeedPressure altitudeAttitude (pitch, roll, yaw)

 CIRPAS

Cloud condensation nuclei supersaturation spectrum

New Caltech CCN instrument. Flew in CRYSTAL-FACE

Caltech 

Available Measurement Instrument PI/Organization

Aerosol optical properties TSI Nephelometer 3 wavelengthsSoot Photometer (PSAP 550 nm) (cabin)

D. Covert/ U. Wash.

Aerosol hygroscopic properties Humidigraph (cabin) 550 nm, RH=20,60,85%

D. Covert/ U. Wash

Aerosol optical depth (354-1560 or 2140 nm, 14 channels), water vapor, extinction and water vapor density in feasible profiles

NASA Ames Airborne Tracking Sunphotometer (AATS-14)

B. Schmid/NASA Ames

Aerosol light extinction coefficient (690 and 1550 nm)

Cavity ring-down extinction cell A. Strawa/NASA Ames

Downwelling and Upwelling Solar Irradiance (broadband)Stabilized platform

Kipp and Zonen CM-22 pyranometersA. Buchholz/NRLMcCoy/SANDIA

Downwelling andUpwelling SolarSpectral Irradiance,1320 channels

NASA Ames Solar Spectral Flux Radiometer (cabin)

P. Pilewskie/NASA Ames

Aerosol absorption Photoacoustic Instrument Pat Arnott/DRI

NASA Ames Airborne

14-channel

Sunphotometer (AATS-14)

AOD and H2O