Service de Chimie Quantique et PhotophysiqueUniversité Libre de Bruxelles (ULB)

Research activity from January to June 2009

Federico Karagulian

Eruption of Volcano Kasatochi in the Alaska’s Aeuletian Island Chain (night of 7 August 2008, 22:00 GMT)

The SO2 plume emitted during the eruption was tracked by monitoring thebrightness temperature differencereferred to the 3 absorption band of SO2 at 1362 cm-1.

IASI….

Starting from 11 August 2008,the SO2 plume separated in two parts,one traveling between 30 and 60°N and the other one between 60 and 90°N.

After one month, small amounts of SO2 are still present in the stratosphere.

8x10-6

6

4

2

0Ra

dia

nce

(W

/cm

2 .Sr.

m-1

)

2520250024802460wavenumber (cm

-1)

Observed Calculated Residual

25

20

15

10

Alti

tude

(km

)

6543210-1SO2 [ppmv]

0.01

0.1

1

10

100

1000

Pre

ssure (hP

a)

20

18

16

14

12

10

8

Alti

tud

e (

km)

0.40.30.20.10.0-0.1Averaging Kernel

8-10 km 10-12 km 12-14 km 14-16 km 16-18 km 18-20 km 20-22 km

Analysis of IASI spectra:

Retrieval of SO2 concentration Detection of H2SO4 signature in IASI spectra

1 + 3 (2500 cm-1) workable to retrieve high SO2 concentrations

Used to retrieve low SO2 concentrations Presence of aerosols

Max SO2 peak at 4ppm

-15

-10

-5

0

5

10(B

Tin-

BT

out)

(K)

1300120011001000900800wavenumber (cm

-1)

t Aug08 am Aug08 pm Aug09 am Aug09 pm Aug10 am Aug10 pm

08-am

08-pm

09-am/pm

10-am/pm

830

1018

1047

1066

1081

-10

-5

0

5

10

(BT

in-

BT

ou

t) (K

)

1300120011001000900800wavenumber (cm

-1)

t

Aug08 am Ash r = 0.75m Aug10 pm H2SO4 - H2O, r = 1.2m

ash

H2SO4 - H2O

BTD spectra between two spectra taken inside and outside the SO2 plume: Subtraction of O3 and SO2

Smoothing

Observation of: volcanic ash H2SO4-H2O aerosols

Radiative transfer simulations (Mie theory)Advanced Doubling Adding method (ADA) by Lieven

first 3 days after the eruption

first 3 days after the eruption

Aerosol plume

BTD between IASI channels at 1072 and 1215 cm-1 to track the aerosol plume.

From 11 August 2008 it was not possible to track the aerosol plume because of the high signal-noise ratio.

-0.8

-0.6

-0.4

-0.2

0.0

0.2

BT

(K

)

1300120011001000900800wavenumber (cm

-1)

904

1160

1042

2.0x106

1.5

1.0

0.5

0.0

SO

2 m

ass

(Ton

s)

20151050days from 08 August 2008

1080

1070

1060

1050

1040

1030

1020

B

T(K

) min

imu

m (cm

-1)

8pm

9pm

10am10pm

11am

18pm 20pm

20am

26am

26pm

30pm

30am

9pm

BTD spectrum between two Averaged spectra recorded on 5 August and 6 September 2008

Mie theorySimualtionsLieven

Clear signature of the presenceof H2SO4-H2O in the atmosphere after one month from theKasatochi eruption.

SO2 depletion kinetics

3M

2 HSOOHSO

k = 7.0 x 10-7 s-1 18 dayse-folding

Loss reaction rate:

(k = 5.5 x 10-7 s-1 (Mt. Pinatubo))*

* Read W.G. et al. GRL, 1993

BTD (K) for formic acid(HCOOH daytime, nighttime)

Cloud coverage < 25%Kurtosis = 0.83BTD (HCOOH) has been averaged on a grid of 1°x1°

Pyrogenic and biogenic sources for HCOOH

Background correction

1 year of IASI observations for HCOOH

O3 and H2O have been subtracted from the background

Channels : 1103-1109cm-1 (baseline); 1105 cm-1 (target)

1

BT

D (

K)

BT

D (

K)

Removal of O3 and H2O

BT

D (

K)

BT

D (

K)

MODIS fire observation October 2008

http://rapidfire.sci.gsfc.nasa.gov/firemaps/

-3x10-5

-2

-1

0

Ra

dia

nce

(W

/cm

2 .Sr.

m-1

)11401130112011101100109010801070

wavenumber (cm-1

)

1.0

0.8

0.6

0.4

Tra

smitta

nce

(a.u)

Residual (HCOOH) HCOOH (reference)

Residual from retrieval

HCOOH spectrumChannels : 1103-1109cm-1 (baseline); 1105 cm-1 (target)

Fitted molecules: H2O, O3, NH3, HCOOH, CFC-12 Tropical model

1105 cm-1

IASI spectrumLat = -17.63 Lon= 128.6720081020.011756_005.amp (AUSTRALIA)

HCOOH is present in the observed IASI spectra

Retrievals for HCOOH in the region (1070-1109 cm-1)

AUSTRALIA

AFRICA

BRAZIL

0-30 km 15 partial columns of 2 km thicknessa priori concentration of HCOOH = 0.1 ppb

25

20

15

10

5

Alti

tud

e (

Km

)

0.200.150.100.050.00Averaging Kernel

AUSTRALIA 5 Km 17 Km

2.5x1016

2.0

1.5

1.0

0.5

0.0

Tot

al C

olum

n (#

/cm

2)

3.02.52.01.51.00.50.0BTD (K)

AUSTRALIA 2.0x1016

1.5

1.0

0.5

0.0

Tot

al C

olum

n (#

/cm

2)

2.01.51.00.50.0BTD (K)

AFRICA3.0x10

16

2.5

2.0

1.5

1.0

0.5

0.0

Tot

al C

olum

n (#

/cm

2)

2.01.51.00.50.0BTD (K)

25

20

15

10

5

Alti

tude

(K

m)

0.200.150.100.050.00Averaging Kernel

BRAZIL 7 Km 15 Km

25

20

15

10

5

Alti

tude

(K

m)

0.200.150.100.050.00Averaging Kernel

AFRICA 5 Km 15 Km

30

25

20

15

10

5

Alti

tud

e (K

m)

2.0x1010

1.51.00.50.0molecules cm-3

AFRICA

Quality of the retrievalsCorrelations

Averaging kernels

Altitude profile of the concentration

Correlations and altitude profiles are not optimal

Waiting for a suitable global atmospheric model for HCOOH fromthe Belgian Institute for Space Aeronomy (BIRA-IASB).

~ 1 ppb

Acknowledgments:

• Pierre, for help and discussions

• Lieven for “initiation”, programming, discussion and troubleshooting

• Chaterine, Ariane and Daniel for miscellaneous

• Antoine for help with Kasatochi images

Thanks for your attention!