1) The document summarizes research from January to June 2009 analyzing satellite data from the IASI instrument to track volcanic eruptions and atmospheric gases. 2) Analysis of the 2008 Kasatochi volcano eruption in Alaska tracked the SO2 plume and detected signatures of ash and H2SO4-H2O aerosols in IASI spectra. 3) A year of IASI observations were used to map formic acid (HCOOH) globally and correlate detections with fire events, showing both pyrogenic and biogenic sources of HCOOH.

1. Research activity from January to June 2009
Federico Karagulian
Service de Chimie Quantique et Photophysique
Université Libre de Bruxelles (ULB)

2. Eruption of Volcano Kasatochi in the Alaska’s Aeuletian Island Chain
(night of 7 August 2008, 22:00 GMT)
IASI….
The SO2 plume emitted during the
eruption was tracked by monitoring the
brightness temperature difference
referred to the ν3 absorption band of
SO2 at 1362 cm-1.

3. 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.

4. Analysis of IASI spectra:
-6
-1
Radiance (W/cm .Sr.m )
8x10
6
2
 Retrieval of SO2 concentration
 Detection of H2SO4 signature in IASI spectra
ν 1 + ν 3 (2500 cm-1)
workable to retrieve
high SO2 concentrations
4
Observed
Calculated
Residual
2
0
2460
2480
2500
-1
wavenumber (cm )
25
2520
0.01
Max SO2 peak at 4ppm
Altitude (km)
1
15
10
10
Pressure (hPa)
0.1
20
100
1000
-1
0
1
2
3
SO2 [ppmv]
4
5
20
8-10 km
10-12 km
12-14 km
14-16 km
16-18 km
18-20 km
20-22 km
Altitude (km)
18
Used to retrieve low
SO2 concentrations
6
16
14
12
10
Presence of aerosols
8
-0.1
0.0
0.1
0.2
Averaging Kernel
0.3
0.4

5. first 3 days after the eruption
5
BTD spectra between two spectra
taken inside and outside the SO2 plume:
 Subtraction of O3 and SO2
 Smoothing
830
0
08-am
-5
-10
-15
09-am/pm
1018
1066
t
Aug08 am
Aug08 pm
Aug09 am
Aug09 pm
Aug10 am
Aug10 pm
800
1047
08-pm
900
1081
10-am/pm
1000
1100
-1
wavenumber (cm )
1200
Radiative transfer
simulations (Mie theory)
Advanced Doubling Adding
method (ADA) by Lieven
1300
10
Observation of:
 volcanic ash
 H2SO4-H2O aerosols
(BTin- BTout) (K)
(BTin- BTout) (K)
10
5
first 3 days after the eruption
ash
0
t
-5
-10
Aug08 am
Ash r = 0.75µm
Aug10 pm
H2SO4 - H2O, r = 1.2µm
800
900
1000
1100
-1
wavenumber (cm )
H2SO4 - H2O
1200
1300

6. 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.

7. 2.0x10
1080
9pm
10am
10pm
1.5
1070
11am
1060
20am
1.0
18pm
9pm
1050
20pm
26am
1040
26pm
0.5
30pm
1030
SO 2 + OH M HSO 3
→
Loss reaction rate:
k = 7.0 x 10-7 s-1
0
18 days
(k = 5.5 x 10-7 s-1 (Mt. Pinatubo))*
1020
0.0
e-folding
-1
30am
∆BT(K) minimum (cm )
8pm
SO2 mass (Tons)
SO2 depletion kinetics
6
5
10
15
20
days from 08 August 2008
∆BT (K)
BTD spectrum between two
Averaged spectra recorded on
5 August and 6 September 2008
0.2
904
Clear signature of the presence
of H2SO4-H2O in the atmosphere
after one month from the
Kasatochi eruption.
0.0
1042
-0.2
1160
-0.4
-0.6
-0.8
Mie theory
Simualtions
Lieven
800
* Read W.G. et al. GRL, 1993
900
1000
1100
-1
wavenumber (cm )
1200
1300

8. 1 year of IASI observations for HCOOH
Pyrogenic and biogenic sources for HCOOH
Channels : 1103-1109cm-1 (baseline); 1105 cm-1 (target)
BTD (K) for formic acid
(HCOOH daytime, nighttime)
Cloud coverage < 25%
Kurtosis = 0.83
BTD (HCOOH) has been averaged
on a grid of 1°x1°
Background correction
O3 and H2O have been
subtracted from the
background

9. BTD (K)
1

10. BTD (K)

11. BTD (K)
Removal of
O3 and H2O

12. BTD (K)

13. MODIS fire observation
October 2008
http://rapidfire.sci.gsfc.nasa.gov/firemaps/

14. HCOOH spectrum
Channels : 1103-1109cm-1 (baseline); 1105 cm-1 (target)
1.0
-1
0
2
0.8
-1
0.6
-2
-3x10
Residual from retrieval
-5
1070
Residual (HCOOH)
HCOOH (reference)
1080
1105 cm-1
1090 1100 1110 1120
-1
wavenumber (cm )
1130
Trasmittance (a.u)
Radiance (W/cm .Sr.m )
IASI spectrum
Lat = -17.63
Lon= 128.67
20081020.011756_005.amp (AUSTRALIA)
0.4
1140
 Fitted molecules: H2O, O3, NH3, HCOOH, CFC-12
 Tropical model
HCOOH is present in the
observed IASI spectra

15. Retrievals for HCOOH in the region (1070-1109 cm-1)
AUSTRALIA
0-30 km  15 partial columns of 2 km thickness
a priori concentration of HCOOH = 0.1 ppb
AFRICA
BRAZIL

16. Quality of the retrievals
Correlations
AUSTRALIA
16
2.0x10
AFRICA
16
3.0x10
1.5
1.0
0.5
2
2.0
Total Column (#/cm )
2
Total Column (#/cm )
2
Total Column (#/cm )
2.5x10
1.5
1.0
0.5
0.0
0.0
0.0
0.5
1.0
1.5
2.0
BTD (K)
2.5
2.5
2.0
1.5
1.0
0.5
0.0
0.0
3.0
16
0.5
1.0
1.5
BTD (K)
2.0
0.0
0.5
1.0
BTD (K)
1.5
2.0
Averaging kernels
AUSTRALIA
5 Km
17 Km
15
10
20
15
10
0.00
0.05
0.10
0.15
Averaging Kernel
0.20
0.00
Altitude profile of the
concentration
0.05
0.10
0.15
Averaging Kernel
30
AFRICA
25
Altitude (Km)
20
15
10
5
5
5
BRAZIL
7 Km
15 Km
25
Altitude (Km)
20
AFRICA
5 Km
15 Km
25
Altitude (Km)
Altitude (Km)
25
0.20
0.00
0.05
0.10
Averaging Kernel
0.15
0.20
Correlations and altitude profiles are
not optimal
20
15
~ 1 ppb
10
5
0.0
0.5
1.0
1.5
molecules cm-3
10
2.0x10
Waiting for a suitable global
atmospheric model for HCOOH from
the Belgian Institute for Space Aeronomy
(BIRA-IASB).

17. 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!