Investigating Global Long-term Data Sets of the Atmospheric H 2 O VCD and of Cloud Properties

[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


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


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


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:


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


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:


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


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%


Normalised O2 absorption

Derived cloud top height [km]

Long time mean 1996-2003 from GOME

Wagner et al., 2008


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.


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.


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.


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


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


-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


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)


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


clou

dcl

oudModelled

Radiance

3-D effects(TRACY-2)


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


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


clou

dcl

oud

Modelled O4 AMF



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


clou

dcl

oudModelled

Ring effect



1 day of H2O from GOME-1


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)


H2O anomalies during ENSO


Cloud fraction anomalies during ENSO


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!


• 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


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.

Investigating Global Long-term Data Sets of the Atmospheric H 2 O VCD and of Cloud Properties

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