investigating global long-term data sets of the atmospheric h 2 o vcd and of cloud properties
DESCRIPTION
Investigating Global Long-term Data Sets of the Atmospheric H 2 O VCD and of Cloud Properties T. Wagner 1 , S Beirle 1 , M. Grzegorski 1 , M. Penning de Vries 1 , U. Platt 2 MPI für Chemie, Mainz, Germany Institut für Umweltphysik, University of Heidelberg, Germany. MPI Mainz Germany. - PowerPoint PPT PresentationTRANSCRIPT
[email protected] Satellite group MPI Mainz
Investigating Global Long-term Data Sets of the Atmospheric H2O VCD and of Cloud Properties
T. Wagner1, S Beirle1, M. Grzegorski1, M. Penning de Vries1, U. Platt2
(1) MPI für Chemie, Mainz, Germany (2) Institut für Umweltphysik, University of Heidelberg, Germany
• What can new satellite observations offer? (spectral measurements)
• Model results & measurements of O4 & O2 absorption and Ring effect
• Case studies
• Conclusions
MPI Mainz
Germany
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GOME & SCIA spectral propertiesO3 UV
O3 vis
HCHO
OClO
O4
O2
H2O
SO2 NO2
BrO
Satellite group: http://satellite.iup.uni-heidelberg.de
Set of Atmospheric Absorbers Identified in GOME Spectra at the Satellite Group at the Institut für Umweltphysik
0.0
0.2
0.4
0.6
???
????
?????
300 400 500 600 700 800W avelength [nm ]
Spe
ctra
l alb
edo
Both, trace gas absorptions and Ring effect (Raman scattering) are affected by modifications of the atmospheric light path, especially due to clouds.
=> They can provide information about the internal cloud structure
What additional information can be expected from spectral measurements? (e.g. GOME)
O4 360 nm
-0.025
-0.02
-0.015
-0.01
-0.005
0
0.005
348 353 358 363 368 373
Wavelength [nm]
ODO4
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320 340 360 380 400W avelength [nm ]
Ref
lect
ivity
Solar Fraunhofer line in direct and scattered light
Ratio spectrum of scattered and direct solar light
344 348 352 356 360
W avelength [nm ]
5.0E-2
1.0E-1
1.5E-1
-1.0E-2
0.0E+0
1.0E-2
-1.0E-2
0.0E+0
-6.0E-3
-4.0E-3
-2.0E-3
-2.0E-2
-1.0E-2
0.0E+0-2.0E-3
0.0E+0
2.0E-3
optic
al d
epth
-5.0E-3
0.0E+0
-1.0E-3
0.0E+0
1.0E-3
B r O
O 3 2 2 1 K
O 3 2 4 1 K
N O 2
O C l O
O 4
R i n g
r e s i d u a l344 348 352 356 360
W avelength [nm ]
5.0E-2
1.0E-1
1.5E-1
-1.0E-2
0.0E+0
1.0E-2
-1.0E-2
0.0E+0
-6.0E-3
-4.0E-3
-2.0E-3
-2.0E-2
-1.0E-2
0.0E+0-2.0E-3
0.0E+0
2.0E-3
optic
al d
epth
-5.0E-3
0.0E+0
-1.0E-3
0.0E+0
1.0E-3
B r O
O 3 2 2 1 K
O 3 2 4 1 K
N O 2
O C l O
O 4
R i n g
r e s i d u a l
610 630 650 670
W avelength [nm ]
-0.03
-0.01
-0.10
-0.05
0.00
-0.10
-0.05
0.00
Opt
ical
den
sity
-0.01
0.00
0.01
G O M E, 04.12.1996, 08:30 UT SZA: 33°, Lat: 5°, Long 31°
O4
O2
H2O
residual
29.6
30.0
30.4 Raw Spectrum
-0.06
-0.04
Ring
610 630 650 670
W avelength [nm ]
-0.03
-0.01
-0.10
-0.05
0.00
-0.10
-0.05
0.00
Opt
ical
den
sity
-0.01
0.00
0.01
G O M E, 04.12.1996, 08:30 UT SZA: 33°, Lat: 5°, Long 31°
O4
O2
H2O
residual
29.6
30.0
30.4 Raw Spectrum
-0.06
-0.04
Ring
Optical depth
10%
Optical depth
2%
The Ring effect is strongest in the UV
GOME UVGOME red
Ring effect:
‚Filling-in‘ of Fraunhofer lines due to rotational Raman-scattering
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NOAA GOES-8
Satellite, 16:02 UTC
0
0.2
0.4
0.6
-10 -5 0 5 10 15 20 25 30 35 400
1
2
3
O2_630OD_O2_761nm
0
0.05
0.1
0.15
0.2
0.25
0.3
-10 -5 0 5 10 15 20 25 30 35 40
O4_360O4_577O4_630
0
1
2
3
-10 -5 0 5 10 15 20 25 30 35 40
Latitude
Ring_360Ring_380
Cloud effectsHurrican Fran, 04.09.1996:
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Instrument
Green points indicate scattering points of photons => reception area of the detectorBackward Monte Carlo
(TRACY-II, T. Deutschmann)
Tim Deutschmann, IUP Heidelberg
Realistic modelling of microscopic and macroscopic cloud properties
aerosol layer
Instrument
aerosol layer
Tim Deutschmann, IUP Heidelberg
Instrument
Strong forward peak
aerosol layer
Moderate forward peak
Suniti Sanghavi, IUP Heidelberg
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Different dependence for O2 and O4
• Absorption is expresses as air mass factor (AMF)
• It is a measure of sensitivity
• AMF = 1 indicates an absorption corresponding to the vertical atmospheric column
Model results as function of cloud altitude:
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Model results as function of cloud altitude:
Ring effect shows monotonous decrease
Different dependence for O2 and O4
-In general, clouds cause a decrease of the absorptions of O2 and O4 and of the strength of the Ring effect
-the Ring effect hardly depends on the surface albedo
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0
0.2
0.4
0.6
0.8
1
0% 20% 40% 60% 80% 100%Cloud fraction
No
rma
lis
ed
O 2 a
bs
orp
tio
n
CTH: 1km
12km
9km
7km
4km
2km
Dependence of the O2 absorption on cloud fraction and cloud altitude (vertical thickness: 1km,OD: 50)
Results for surface albedo of 2%
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Normalised O2 absorption
Derived cloud top height [km]
Long time mean 1996-2003 from GOME
Wagner et al., 2008
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Spatial correlation analyses between the GOME and ISCCP data sets (annual average) of effective cloud fraction (red) and cloud amount (blue). After the ISCCP cloud amount is corrected for the effect of changing optical depth, improved agreement with the GOME data is found.
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Correlation analyses between the GOME and ISCCP data sets (spatial variation of the annual average) of cloud height (red: uncorrected ISCCP top height, blue corrected ISCCP effective cloud top height). After the ISCCP data is corrected for the effect of changing optical depth, improved agreement with the GOME data is found.
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Correlation between effective cloud top height from FRESCO and derived from our Ring analysis (GOME observations in November 2000 for SZA 19-23°, CF >50%). Depending on the assumed cloud properties in the forward model, different effective cloud top heights are derived from the Ring effect observations.
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0 . 0 0
0 . 0 5
0 . 1 0
0 . 1 5
0 . 2 0
4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 00
1
2
3
4O D _ O 2 _ 6 3 0 n mO D _ O 2 _ 7 6 1 n m
0 . 3
0 . 3 5
0 . 4
0 . 4 5
0 . 5
0 . 5 5
4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0
P o l a r i s a t i o n _ U VP o l a r i s a t i o n _ v i sP o l a r i s a t i o n _ I R
0 . 0
0 . 5
1 . 0
1 . 5
2 . 0
4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0
C I _ U VC I _ v i s
0
0 . 2
0 . 4
0 . 6
4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0
O 4 _ 3 6 0O 4 _ 6 3 0O 4 _ 5 7 7
0
1
2
3
4
5
4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0
L a t i t u d e
R i n g _ 3 8 0R i n g _ 3 6 0
C h a n g e f r o m s n o w c o v e r e d l a n d t o o p e n o c e a n
Dundee Satellite Receiving Station, Dundee University, Scotland
(http://www.sat.dundee.ac.uk/).
Dundee Satellite Receiving Station, Dundee University, Scotland
(http://www.sat.dundee.ac.uk/).
Special cases:
I) Separation of the effects of clouds and snow/ice
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Typically the shielding effect of clouds is dominant
It can be caused by clouds or mountains
-60 -30 0 30 60Latitude
0.2
0.4
0.6
[rel
. uni
ts]
2 0
4 0
6 0
SZ
A [°
]
R ing 370nm
O 2 630nm
O 4 630nm
SZA
O 4 370nm
G O M E orbit, 81120145
0.0
0.5
1.0
Clo
ud F
ract
ion
0
2
4
6
[rel
. uni
ts]
0
1
2
3
O4
AM
F0
1
2
3
O4
AM
F
A B C
Special cases:
II) Increased absorptions of O2 and O4
[email protected] Satellite group MPI Mainz
-60 -30 0 30 60Latitude
0.2
0.4
0.6
[rel
. uni
ts]
2 0
4 0
6 0
SZ
A [°
]
R ing 370nm
O 2 630nm
O 4 630nm
SZA
O 4 370nm
G O M E orb it, 81120145
0.0
0.5
1.0
Clo
ud F
ract
ion
0
2
4
6
[rel
. uni
ts]
0
1
2
3
O4
AM
F0
1
2
3
O4
AM
F
D
Sometimes, strongly enhanced absorptions indicate long light paths inside clouds
The Ring effect shows no enhancement
Special cases:
II) Increased absorptions of O2 and O4
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The cloud is also seen by the microwave measurements (liquid water path)
[email protected] Satellite group MPI Mainz -60 -30 0 30 60
Latitude
0.2
0.4
0.6
rel.
units
2 0
4 0
6 0
SZ
A
R ing 370nm
O 2 630nm
O 4 630nm
SZA
O 4 370nm
G O M E orbit, 81114194 (narrow m ode)
0.0
0.5
1.0
Clo
ud r
actio
n
0
1
2
3
O4
AM
F
0
1
2
3O
4 A
MF
0
2
4
6
rel.
units
Additional examples of strongly enhanced absorptions
(about 10 per month for GOME-1 observations)
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0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0 10 20 30 40 50 60 70 80 90SZA
No
rma
lise
d R
ad
ian
ce 3
70
nm
radiance_180radiance_0radiance_1D
Sun behind cloudSun in front of cloudno cloud
0
0.005
0.01
0.015
0.02
0.025
0 10 20 30 40 50 60 70 80 90SZA
No
rma
lise
d R
ad
ian
ce 6
30
nm
radiance_180radiance_0radiance_1D
Sun behind cloudSun in front of cloudno cloud
clou
dcl
oudModelled
Radiance
3-D effects(TRACY-2)
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0
0.5
1
1.5
2
2.5
0 10 20 30 40 50 60 70 80 90SZA
O4
AM
F 3
70
nm
O4-AMF_180O4-AMF_0O4-AMF_1D
Sun behind cloudSun in front of cloudno cloud
0
2
4
6
8
10
12
14
0 10 20 30 40 50 60 70 80 90SZA
O4
AM
F 6
30
nm
O4-AMF_180O4-AMF_0O4-AMF_1D
Sun behind cloudSun in front of cloudno cloud
clou
dcl
oud
Modelled O4 AMF
3-D effects(TRACY-2)
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0
1
2
3
4
5
6
7
8
0 10 20 30 40 50 60 70 80 90SZA
Rin
g e
ffect
37
0n
m [
%]
Ring effect_180Ring effect_0Ring effect_1D
Sun behind cloudSun in front of cloudno cloud
clou
dcl
oudModelled
Ring effect
3-D effects(TRACY-2)
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1 day of H2O from GOME-1
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H2O SCD derived from GOME-2 for 20.01.2008. Due to the high spatial resolution and almost daily global
coverage many details of the atmospheric H2O circulation can be seen.
1 day of H2O from GOME-2(similar results from S. Noel, IUP Bremen)
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H2O anomalies during ENSO
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Cloud fraction anomalies during ENSO
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1996 1997 1998 1999 2000 2001 2002 2003 2004Tim e
-0.40
0.00
0.40
tem
p.
anom
. [K
]
-0.04
0.00
0.04
HIC
RU
an
omal
y
-0.04
0.00
0.04
O2
anom
aly
M onth ly anom alies from 30°S to 30°N
-5E+21
0
5E+21
H2O
anom
aly
1996 1997 1998 1999 2000 2001 2002 2003 2004Tim e
-0.80-0.400.000.400.80
tem
p.
anom
. [K
]
-0.04
0.00
0.04
HIC
RU
an
omal
y
-0.04
0.00
0.04
O2
anom
aly
M onth ly anom alies from 30°N to 60°N
-5E+21
0
5E+21
H2O
anom
aly
1996 1997 1998 1999 2000 2001 2002 2003 2004Tim e
-0.80-0.400.000.400.80
tem
p.
anom
. [K
]
-0.04
0.00
0.04
HIC
RU
an
omal
y
-0.04
0.00
0.04
O2
anom
aly
M onth ly anom alies from 30°S to 60°S
-5E+21
0
5E+21
H2O
anom
aly
No Cloud anomalies in time series!
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• Spectral measurements (O2 & O4 absorption & Ring effect) are well suited for cloud retrievals
• Monte-Carlo radiative transfer modelling provides optimum link between observations and macroscopic and microscopic cloud properties; 3-D effects should be considered
• Ring effect and O2/O4 absorptions are affected by clouds and snow/ice differently
• Strongly enhanced absorptions found in GOME data (about 10 times per month, especially frequent for narrow swath mode)
• New H2O product from GOME-2
• Application to atmospheric studies, e.g. ENSO
Conclusions
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Global average distribution of the Ring effect for November and December 2000 (left: cloud fraction <5%, right: cloud fraction >20%). In areas with high clouds, especially over the continents, the weakest Ring effect is found.