0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 20 40 60 80 100

RH, %

Slo

pe

of

PA

S v

s P

SA

P

Upper curve obtained by restricting the dataset for RH < X (X from 40 to 65%)

Lower curve obtained by restricting the dataset for RH > Y (Y from 55 to 85%)

Influence of RH on the Absorbance measurement

Slope close to one for dry air

Important decrease for RH ~65%

Max Planck Institute for Chemistry P.O. Box 3060

Biogeochemistry DepartmentD-55020 Mainz, Germany

Manaus plume tracking

LBA-Claire 2001

Manaus

Fligh track

Overview : The aim of the experiment was

1. To evaluate the impact of anthropogenic emissions (Ozone, CN, …) on the biogenic VOCs emissions

2. To better describe the vertical profiles of CN & CCN in remote areas over the tropical forest

Overview of the MINOS Campaign : Aerosol optical properties derived from the Advanced Very High Resolution Radiometer (AVHRR) pointed out the Mediterranean Sea as one of the areas with the highest Aerosol optical depths in the world (Husar et al., 1997). Importance of satellite derived measurements to describe the aerosol loads above the Mediterranean was also demonstrated by Moulin et al. (1997) who reported that year-to-year changes in Aerosol optical depths in Mediterranean were driven by African dust and was closely related to air masses circulation and the Northern Oscillation Index. Recent model studies reproduced satellite observations and demonstrated the role of three major components of aerosols in surrounding regions of the Mediterranean basin (sulfate, black carbon and dust), having very high direct radiative forcing of aerosols at the top of the atmosphere (Jacobsen, 2001). This model estimates a negative radiative forcing for aerosols in Mediterranean, which could compare with greenhouse gases (e.g. -3 to -4 W/m²). Thus, transport of aerosols and their precursors from these regions will have dramatic impact not only on radiative properties over the Mediterranean Sea but even on cloud properties. Rosenfeld (2000) showed that Turkish power plants using high sulfur containing lignite were identified from satellite-derived pictures as influencing downwind cloud radius droplets. As a matter of fact, the most complete characterization of aerosols emitted from each of these regions and reaching the Mediterranean basin will undoubtedly be needed to validate model calculations and remote sensing observations.

Jean SciarePh-D thesis (LSCE, France, May 2000)Post-doc MPI Mainz (2001) / Biogeochemistry (M.O. Andreae)CR2 – CNRS, LSCE, France (since October 2001)

Acknowledgements : I would like to address grateful thanks to Prof. Dr. M.O. Andreae who accepted to review my Ph-D thesis and who accepted me in his group in Mainz for a post-doctoral position. Thanks to the results obtained during my Ph-D and during my post-doc in Mainz I obtained in October 2001 a permanant position at CNRS. Many thanks go also to my co-workers (Greg, Olga, Pascal and Bim) who made to my stay in Mainz an unforgotable memory.

Large discrepancies between the 2 techniques

0

5

10

15

20

25

30

35

28/07 02/08 07/08 12/08 17/08

Ab

sorb

ance

fro

m P

SA

P, 1

/Mm

0

5

10

15

20

Ab

sro

ban

ce f

rom

PA

S, 1

/Mm

PSAP

PAS

Absorbance Measurements(all dataset 28/07-19/08)

0.6

0.7

0.8

0.9

1.0

28/07 02/08 07/08 12/08 17/08 22/08

Sin

gle

Sc

att

eri

ng

Alb

ed

o

0.0E+00

5.0E-05

1.0E-04

1.5E-04

2.0E-04

Sc

att

eri

ng

Co

eff

., 1

/Mm

Single Scattering Albedo

Scattering

Single scattering AlbedoFinokalia

1

1.25

1.5

1.75

2

50 55 60 65 70

Relative Humidity, %

Sc

att

eri

ng

ch

an

ge

, %

15/07

16/07

17/07

Scattering set at 1 for 55% RH

RH increase

Growth factors from Nephelometer measurements

Measurements from 0900 to 2100 LT

y = 0.57x + 0.11

R2 = 0.78

0

5

10

15

20

25

0 10 20 30

Abs (PSAP), 1/Mm

Ab

s (

PA

S),

1/M

m

Abs (PAS) vs Abs (PSAP)(all dataset 28/07-19/08)

Long-range transport of soot aerosols over the Eastern Mediterranean Basin

Calculations were performed using hourly 5-day backtrajectoriesFrom Hysplit 4.0 model (FNL data)

FINOKALIA STATION

MINOS campaign

Environmental Chemical Processes Laboratory

Air masses origin during the Minos campaign(25/07-25/08/01)

Averaged radiative forcing of Greenhouse gases and tropospheric aerosols / (IPCC report, 2001)

Gob

al m

ean

rad

iati

ve f

orci

ng

(W m

-2)

CO2

Sulfates

Anthropogenic Aerosols

1

-1

-2

3

2

C soot

C orga

Greenhouse gases

War

min

gC

ooli

ng

Glo

bal

mea

n r

adia

tive

for

cin

g (W

m-2)

CO2

CH4

N2OHalocarbons

TroposphericOzone

Sulfates

Fossilefuel

Tropospheric Aerosols(indirect effect)

Anthropogenic Aerosols

1

-1

-2

3

2

C soot

C orga

Greenhouse gases

War

min

gC

ooli

ng

C soot

C orga

20022002

Horizon 2100Horizon 2100

Mineraldust

Annual mean and global radiative forcing (at the top of the atmosphere) due to anthropogenic activities from 1750 to 2000 (no squares = no possible estimation). Vertical barres = uncertainty level.

BiomassBiurning

Expected increasing impact of carbonaceous aerosols compared to sulfate aerosols in the future

Increasing uncertainties on the climate forcing of aerosols compares to greenhouse gases

Need for a better understanding the role of soot and organic aerosols

and their interaction with water (indirect aerosol)

Tropospheric Aerosols(indirect effect)

Aerosols and Climate

Large uncertainties on the climate forcing of aerosols compared to greenhouse gases No estimation can be done for the indirect effect of aerosols

Instruments

0

0.5

1

1.5

0 50 100 150 200

Aerosol diameter, nm

CC

N b

ehav

ior

(NH4)2SO4

Humic Acid Like

Adipic Acid

CalibrationCalibration

T = 5°C Supersaturation 1%

Humid plates

Laser beamAir

Video acquisition

PrinciplePrinciple

Instrument developped in Mainz by G. Robert

CCN counter: settings / calibration

PhotoAcoustic System (PAS)

A 670 nm photodiode laser illumaniates the activated droplets while the digital camera, normal to the laser beam , registers digital images every second during the supersaturation cycle. The CCN concentration at a particular supersaturation is calculated by imaging sofware, which automatically determines the number of activated droplets in each picture (extracted from G. Roberts Ph-D dissertation)

Principle : CCN measurements are made using a static thermal-gradient diffusion instrument. It is fitted with a photodiode laser and digital camera to measure droplet concentrations. Activated CCN particles quickly grow to several micrometers in diameter and gravitationally settle out of the chamber.

Principle : An alternative to filter-based methods for light absorption measurement is to use a photoacoustic instrument. No filters are used in these intruments, but instead, the sample air can be continuously drawn through a acoustical waveguide. A periodically modulated laser beam passes through the waveguide. Concomitant with light absorption by either gas or particles is heat transfer to the surrounding air. The waveguide can be designed at a frequency such that all the heat from light absorption is transferred during the period of oscillation. upon receiving this heat, from light absorption, the surrounding air expands and this expansion contributes to the acoustic standing wave in the waveguide. Measurement is made with a microphone. The microphone is linearly proportional to the aerosol light absorption coefficient. (extracted from Arnott et al., 2001)

Aerosol absorption

Noise of the instrument

Aerosol free air

0

5000

10000

15000

20000

25000

30000

0.58 0.59 0.6 0.61 0.62 0.63

Time, UTC

CN

, #/c

m3

0

500

1000

1500

2000

2500

3000

CC

N, #

/cm

3

CNCCN

210 m 70 m 540 m 860 m 1190 m 860 m

A A A A B

Alt =

AB

Manaus

Ratio CCN/CN ~10%

Plume of pollution located in the PBL

Well-mixed plume within the first hundreds meters

Plume Study(Flight 18 – 19/07/01)

0

500

1000

1500

2000

2500

3000

0 200 400 600 800

Particle Number, #/cm3

Alt

itu

de

, m

CCN

CN

30 40 50 60 70

Ratio CCN/CN, %

Alt

itu

de

, m

0

500

1000

1500

2000

2500

3000

Ratio CCN/CN

Vertical profile(Flight 15 – 18/07/01)

Ratio CCN/CN ~50-60%