Ground based UV/vis observations

(1)

Ground based UV/vis observations

A) History

B) Spectroscopy

C) Basic viewing directions

D) Radiative transport modelling

E) Results from different stations

(2)

molecules

aerosols

Cloud droplets

rain droplets

Remote sensing in UV / vis spectral range

Wavelengths from ~300 to 700nm

-electronic + vibrational transitions

=> Emission can be neglected

(3)

William Hyde Wollaston

1766 - 1828

1802

-Wollaston verwendet statt rundem Loch einen dünnen Spalt (1.3 mm)

-er entdeckt 7 schwarze Linien, 5 davon hält er für Grenzen zwischen ‘natürlichen’ Farben

3,50 m

(4)

Joseph von Fraunhofer (1787-1826)

„Ich fand mit dem Fernrohre fast unzählig viele starke und

schwache vertikale Linien, die aber dunkler sind als der übrige

Teil des Farbbildes; einige scheinen fast schwarz zu sein “

•

erste große achromatische Objektive für Fernrohre

•

erste Verwendung von Beugungsgittern, erste absolute Wellenlängenbestimmung

•

Bestimmung der Position von 234 der über 500 von ihm gefundenen Linien im

Sonnenspektrum; seine Benennung wird heute noch Verwendet

Von Joseph von Fraunhofer

selbst koloriertes

Sonnenspektrum, um 1814

(5)

Gustav Robert Kirchhoff

1824 - 1887

in Heidelberg:

1854 - 1874

Robert Wilhelm Bunsen

1811 - 1899

in Heidelberg:

1852 - 1899

1859, in Berichten der Preußischen

Akademie der Wissenschaften:

Über die Fraunhoferschen Linien:

Kochsalzdampf absorbiert auch

dieselben von ihm emittierten Linien;

diese sind mit den Fraunhoferlinien in

der heißen Sonnenatmosphäre

(6)

1880, Hartley:

UV Ozonabsorption

1882, Chappuis:

vis Ozonabsorption

1890, Huggins

Liniengruppe Spektrum des

Sirius (langwellige UV

Absorption des Ozon)

Ozon Wirkungsquerschnitt

200 400 600 800

Wavelength [nm]

1E-23 1E-22 1E-21 1E-20 1E-19 1E-18 1E-17 [c m ] Hartley _Hug g in s Chappuis 310 330 350 1E-22 1E-21 1E-20 1E-19

(7)

(8)

(9)

300 310 320 330 340 350 Wellenlänge [nm] 0E+0 1E-19 2E-19 3E-19 O3 -A b s o rp ti o n s q u e rs c h n it t [c m ] A B C D

1 Dobson Unit (DU) entspricht

einer Säule von 10

µ

m unter

Normalbedingungen

Typische Ozonschichtdicke:

350 DU (3.5 mm unter N.B.)

Dobson-Photospektrometer

Das Intensitätsverhältnis

verschiedener Wellenlängenpaare

hängt von der Ozongesamtsäule ab

(10)

0 2E-19 4E-19 6E-19 8E-19 1E-18 436 438 440 442 444 446 448 450 452 [c m ²] 0 2E-19 4E-19 6E-19 8E-19 1E-18 250 300 350 400 450 500 550 600 650 Wavelength [nm] [c m ²]

A modified Brewer

instrument was used to

measure the atmospheric

NO

2

absorptions

Brewer et al., Nature,

1973, Uni-Toronto

3 2 10 2 1 10

1

.

46

log

I

F

=

−

⋅

λ

1

λ

2

λ

3

NO

₂

cross section (220K)

Vandaele et al., 1997

(11)

Linear relation

between function

F and the NO

2

column density

3

2

10

2

1

10

1

.

46

log

I

F

=

−

⋅

Confirmation by laboratory measurements

range of atmospheric

NO

2

columns

(12)

Brewer et al., Nature, 1973

Tropospheric

NO

2

Strong SZA

depencence

=> stratospheric

NO

2

direct

sun

zenith

sky

Measurements on July 23, 1973

pm

am

(13)

Basic viewing

geometries:

Zenit SZA Direktlicht-Beobachtungen

Vom Zenit gestreute Intensität Spectrograph Zenith Sun Stratosphere Troposphere 45° 70° 80° 85° 88°

Direct light:

Sun, Moon, Stars

-easy geometry

-nightime measurements

Zenith scattered sun light:

-sensitive to stratospheric

trace gases

Scattered sun light in

various viewing directions

(MAXDOAS):

-sensitive to tropospheric

trace gases

(14)

Direct light observations

-light source: sun, moon or star

-direct light path, easy interpretation of the

measurement

-complex instrumental set-up, tracking system

-night-time chemistry can be investigated

(15)













⋅













+

−

⋅

=

∫ ∑

l _s i i i

s

ds

I

0 0

(

)

exp

(

)

(

)

(

)

(

λ

σ

λ

ρ

ε

λ

Only absorption => direct inversion

Lambert-Beer-Gesetz :

σ

i

:

Absorptionswirkungsquerschnitt des i-ten Spurenstoffs

ρ

_i

:

Konzentration des i-ten Spurenstoffs

ε

_s

:

Streukoeffizient

=>

Kenntnis der Absorptionswirkungsquerschnitte ermöglicht die

Bestimmung von Spurenstoffkonzentrationen

(16)

DOAS: ’

D

ifferential

O

ptical

A

bsorption

S

pectroscopy’

A)

Lambert-Beer’s Law:

I I

= ⋅

(

− ⋅ ⋅

c l

)

0

exp

σ

B)

Spectra, high pass filtering

480 500 520 Wavelength [nm] 0 1 2 3 σ [1 0 -2 1c m -2 ] -0.2 0.0 0.2 σ ' [1 0 -2 1c m -2 ] σ σc σ'

•

I

o

has not to be known

•

very sensitive (OD

≤

0.001)

•

several absorbers can be

measured simultaneously

•

discrimination between

absorption and scattering

L

I

⋅

=

=>

σ

ρ

ln

1

0

(17)

460 480 500 520 540

Wellenlänge [nm]

In te n s it t I( ) O3-Absorption NO2-Absorption Meßspektrum 'differentielle' optische Dichte

I’

₀

Die Absorptionen

verschiedener

Gase

können in

einem Spektrum

anhand ihrer speziellen Form

unterschieden werden.

Die Tiefe einer Absorptionsbande

hängt von der

(18)

I_C I'₀ I₃ I₁ λ₃ λ₂ λ₁ I₀ In te n s it y [ a rb . U n it s ]

Wavelength [arb. Units]

σ₃ σ₁ σ₂ λ₃ λ₂ λ₁ σ_diff

Wavelength [arb. Units]

C ro s s s e c ti o n [ a rb . U n it s ]

Der Differentielle Wirkungsquerschnitt

Lambert-Beer-Gesetz:

I = I

₀

exp(-

σ ρ

L)

=>

Problem: I

₀

meist unbekannt

Lösung: Separierung des

Absorptionswirkungsquerschnitts

σ

in einen

breit- und schmalbandingen Anteil:

σ

=

σ

_b

+

σ

_‘

SCD: slant column density

Das Prinzip der Differentiellen

Optischen

Absorptions-Spektroskopie (DOAS)

L

I

ln

0

=

τ

=

σ

⋅

ρ

⋅

L

I

⋅

=

=>

'

1

'

ln

0

σ

ρ

(19)

250 300 350 400 450 600 650 700 0 100 200 Detection Limit 200 ppt L=1km 1 ppt L=16km 2 ppt L=12km 20 ppt L=12km 500 ppt L=5km 5 ppt L=5km 100 ppt L=5km 200 ppt L=5km 1 ppb L=5km Phenol Wavelength [nm] 0 40 80 20 ppt L=1km 50 ppt L=1km 250 ppt L=1km para-Kresol 0 5 10 Toluol 0 10 20 Benzol 0 100 200 IO 0 50 BrO 0 20 ClO 0 1 HCHO 0 100 NO₃ 0 4 _HONO 0 2 NO₂ 0 4 8 SO₂ 0 4 250 300 350 400 450 600 650 50 ppt L=5km σ '[1 0 -1 9 c m 2 ] O₃

Differentielle

Wirkungsquerschnitte

verschiedener

atmosphärischer Spurengase

(20)

Zenit SZA Direktlicht-Beobachtungen 400 500 600 700 Wavelength [nm] In te n s it y [ a rb it r. u n it s ]

spectra measured at different solar zenith angles

A: SZA=90 degrees B: SZA=65 degrees A / B: C: reference spectrum O3 D: reference spectrum O4 Stratospheric DOAS-measurements

Two measurements are needed

to remove the Fraunhofer lines:

One measurement at low SZA

(with weak atmospheric

absorptions)

and one at high

SZA

(with strong atmospheric

absorptions)

(21)

345 350 355 360

Wavelength [nm]

BrO O3 O4 Residual Atmospheric spectrum

Divided by Sun Spectrum

60 %

Ring Spectrum

7 %

0.3 %

0.2 %

1.2 %

2.2 %

Example of a DOAS

analysis of scattered

sun light (from satellite

measurements)

Target species: BrO

From spectral fit

=> Trace gas SCD

(22)

440 460 480 500 520 540 560 -0.05 -0.03 -0.01 0.01 0.03 365 370 375 380 385 390 -0.061 -0.059 -0.057 -0.055 -0.053 365 370 375 380 385 390 -0.005 -0.003 -0.001 0.001 O p ti c a l d e n s it y 348 352 356 360 Wavelength [nm] -0.004 -0.003 -0.002 -0.001 0.000 0.001 O3 16.01..1997, SZA: 91.1° NO2 18.03.97, SZA: 90.6° OClO 24.02.97, SZA: 91.1° BrO 26.02.97, SZA: 88.8°

Examples of the spectral fitting procedure of the different trace gases (data from the Kiruna instrument). Displayed are the absorption cross sections (red curves) scaled to the respective trace gas absorption in the measured spectrum (black curves).

Examples of different

trace gas analyses

(ground based

measurements at

Kiruna, northern

Sweden)

O

₃

NO

₂

OClO

BrO

(23)

Der 'Air-Mass-Faktor' (AMF)

Zenit

SZA

SCD: entlang des Lichtstrahls

integrierte Spurenstoffkonzentration

VCD: entlang der Vertikalen

integrierte Spurenstoffkonzentration

Quotient aus schräger und vertikaler Säulendichte:

AMF = SCD / VCD 1 / cos (SZA)

(24)

Direct light AMF for different (box) profile height 0 10 20 30 40 50 60 80 81 82 83 84 85 86 87 88 89 90 SZA A M F 2 5 10 16 26 35 50 geometric AMF profile height (x km - x+1 km)

Stratospheric trace gas layer

Trop. trace gas layer

(25)

Zenit

SZA

Direktlicht-Beobachtungen

The measured SCD is the difference between both measurements

:

∆

SCD = SCD

_mess

– SCD

_ref

= VCD * AMF

_mess

– VCD * AMF

_ref

=> VCD =

∆

SCD / (AMF

_mess

- AMF

_ref

)

mess

ref

(26)

0 5 10 15 20 25 AMF 0 5000 10000 S C D O 3 [D U ]

Fit: Y = 356DU * X - 454DU

O3-Langley-Plot

VCD = (SCDmess + SCDref) / AMF

SCDmess = (VCD * AMF) - SCDref

Slope = VCD

y-intercept => SCD

ref

∆

SCD

∆

SCD

VCD = (SCDmess + SCDref) / AMF

(27)

NO

2

N

2

O

5

HNO

3

langsame Gleichgewichte schnelles Gleichgewicht

Stickoxidgleichgewicht

Photolyse

Diurnal cycle of reactive nitrogen

compounds. N

₂

O

₅

is accumulated

during night and photolised during

day. Thus NO

₂

is systematically

smaller during sunrise than during

sunset [Lambert et al., 2002].

(28)

1/25/94 04:48 1/25/94 16:48 1/26/94 04:48 1/26/94 16:48 0 1 2 3 4 V C D N O3 [ 1 0 1 3m o le c /c m ] Kiruna, 25./26.Jan 1994 0 1 2 3 4 V C D N O2 [ 1 0 1 5 m o le c /c m ] VCD NO2 night VCD NO2 day

Direct

moonlight

measurements

Zenith scattered

sunlight

measurements

(29)

Zenith scattered light observations

-simple instrumental set-up

-restricted during daylight

(30)

Vom Zenit gestreute Intensität

=> Radiative transfer

modelling is required

Spectroscopy of zenith scattered light

Sensitivity:

-is high for low sun (large solar zenith angle, SZA)

(sensitivity for stratosphere is higher than for direct

light observations)

-depends on many parameters:

-wavelength

-concentration profile

-aerosol profile

(31)

Dependence of the AMF on SZA and surface albedo

0

2

4

6

8

10

12

14

0

10

20

30

40

50

60

70

80

90

SZA [°]

A

M

F

1/cos(SZA)

trop. AMF,

albedo: 80%

trop. AMF,

albedo: 5%

strat. AMF,

albedo: 80% & 5%

(32)

Monte Carlo Radiative transfer models

(e.g. MCARTIM, Tim Deutschmann)

- individual photon paths are modelled

-atmospheric processes like scattering and absorption and also

surface reflection are simulated statistically

- advantages:

- full 3D geometry

- ‘most realistic’ simulation of the reality

- disadvantages:

(33)

(34)

Look from above

Look from the side

satellite

• Rayleigh-scattering

• ground reflection

TRACY-II

Tim Deutschmann,

Example of radiative transfer

modelling for satellite nadir

geometry,

370 nm, no clouds

(35)

Lecture on atmospheric remote sensing [email protected]

Look from above

Look from the side

satellite

• Rayleigh-scattering

• ground reflection

• particle scattering

Example of radiative transfer

modelling for satellite nadir

geometry,

370 nm, with cloud

(OD 40) from the surface to 8

km

TRACY-II

Tim Deutschmann,

IUP Heidelberg

(36)

Instrument

Green points indicate scattering points of

photons => reception area of the detector

Backward

Monte Carlo

modelling

Photon paths for different

aerosol phase functions

Strong

forward

peak

Moderate

forward

peak

Suniti Sanghavi, IUP Heidelberg

Realistic modelling of microscopic cloud properties:

aerosol layer

(37)

24.06., 04:01

The sky is

more bright

at the horizon

0 0.02 0.04 0.06 0.08 0.1 0.12 0 20 40 60 80 100 Elevation angle N o rm a lis e d R a d ia n c e Reihe1 Reihe2 Reihe3 420 nm (blue) 500 nm (green) 600 nm (red) 0 0.02 0.04 0.06 0.08 0.1 0.12 0 20 40 60 80 100 Elevation angle N o rm a lis e d R a d ia n c e Reihe1 Reihe2 Reihe3 420 nm (blue) 500 nm (green) 600 nm (red)

Simulated Intensity

no

aerosols

AOD:

0.1

(38)

24.06., 04:01

The sky is

more white

at

the horizon

Simulated colour ratio

(blue / red)

High value: blue sky

Low value: white sky

0 1 2 3 4 5 0 20 40 60 80 100 Elevation angle C o lo u r R a ti o ( 4 2 0 / 6 0 0 n m ) Reihe2 Reihe1 No aerosols AOD: 0.1

(39)

AMF calculation from simulated radiances

1) The atmospheric properties for a given measurement (e.g. the SZA, the trace gas profile, etc.)

are defined.

2) The intensity is modelled for two cases: with (I) and without (I

₀

) the absorbing species. From

the calculated intensities the corresponding optical density for the trace gas SCD is determined:

3) The ratio of this optical density and the absorption cross section for the selected trace gas

absorption yields the trace gas SCD:

4) The trace gas profile defined in the first step is integrated to yield the respective VCD. The

AMF is determined from the SCD and VCD according to the ‚AMF-equation‘:

AMF = SCD / VCD

( )

τ

SCD

λ

I

= −

ln

0

( )

SCD

=

τ

SCD

λ

σ λ

(40)

Transitions for rotational and

vibrational Raman scattering on

O

2

and N

2

molecules

(41)

395 396 397 398 399 Wavelength [nm] in te n s it y [ a rb it ra ry u n it s ]

earth shine spectrum dirct sun light spectrum

Auffüllen von (Fraunhofer-)

Linien durch inelastische

Streuung (Ring-Effekt)

Im UV bis zu 10% optische

Dichte

(42)

Fig.Sample Ring spectrum (I(

_Ring

)) calculated for the evaluation of UV spectra taken during

ALERT2000. Shown is also the logarithm of the Fraunhofer reference spectrum(I

_meas

) used for

the calculation.

(43)

345 350 355 360

Wavelength [nm]

BrO O3 O4 Residual Atmospheric spectrum

Divided by Sun Spectrum

60 %

Ring Spectrum

7 %

0.3 %

0.2 %

1.2 %

2.2 %

Example of a DOAS

analysis of scattered

sun light (from satellite

measurements)

Target species: BrO

Ring spectrum

(44)

Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Kiruna Paramaribo Neumayer Arrival Heigts MAXDOAS

Overview on the Heidelberg network of ground based DOAS stations. The instrument at

Paramaribo (Suriname) was build and installed within the project.

Periods of successful measurements. The Paramaribo measurements started in May 2002. In early

2003 the instrument at the Neumayer station was equipped with a MAXDOAS telescope.

(45)

Instrumental set-up at Kiruna. Three spectrometers

are mounted on a high table directly below the

plexi-glass dome. The controlling devices are placed below.

The telescope lenses for the three spectrometers are mounted on a common frame over which a black shielding or a halogen lamp is automatically moved during night. These measurements are important for the calibration of the instrument and the correction of dark current and electronic offset (Bugarski, 2003).

(46)

4:48 7:12 9:36 12:00 14:24 16:48 Zeit 0 4000 8000 S C D O 3 [ D U ] 0 100 200 300 400 V C D O 3 [ D U ]

O3-Auswertung

O p ti s c h e D ic h te [r e l. E in h e it e n ] O3-Fitergebnis Tagesgang, Kiruna, 11.03.1994 SCD O3 VCD O3

(47)

400 405 410 415 420 425 Wellenlänge [nm] O p ti s c h e D ic h te [r e l. E in h e it e n ]

NO

₂

-Auswertung

7:12 9:36 12:00 14:24 Zeit 0 10 20 30 S C D N O2 [1 e 1 5 m o le c /c m ] 1.5 2.0 2.5 3.0 V C D N O2 [1 e 1 5 m o le c /c m ] Tagesgang, Kiruna, 26.02.1994 SCD NO2 VCD NO2 NO2-Fitergebnis

(48)

NO

2

N

2

O

5

HNO

3

langsame Gleichgewichte schnelles Gleichgewicht

Stickoxidgleichgewicht

Photolyse

Diurnal cycle of reactive nitrogen

compounds. N

₂

O

₅

is accumulated

during night and photolised during

day. Thus NO

₂

is systematically

smaller during sunrise than during

sunset [Lambert et al., 2002].

(49)

Mean annual cycle (1996 - 2001) of the stratospheric NO

₂

VCD analysed from

GOME observations. Each pixel represents zonal mean values. The contour

lines are in units of 10

15

molecules/cm

2

[Wenig et al., 2004].

(50)

0.0E+00 1.0E+15 2.0E+15 3.0E+15 4.0E+15 5.0E+15 6.0E+15 7.0E+15 8.0E+15

Nov. 96 Nov. 97 Nov. 98 Nov. 99 Nov. 00 Nov. 01 Nov. 02 Nov. 03 Nov. 04

Time N O 2 V C D [ m o le c /c m ²] VCD Reihe2 Reihe3

Average NO2 VCD from SCIAMACHY at noon MAXDOAS NO2 VCD sunrise 90° SZA

MAXDOAS NO2 VCD sunset 90° SZA

SCIAMACHY NO2 VCD © Andreas Richter

Time series of NO

₂

VCDs measured by the Kiruna instrument since December 1996.

From 2002 to 2005 also the time series of average SCIAMACHY NO

₂

VCDs (within

200km, scientific product of the University of Bremen) are shown.

(51)

0.0E+00 1.0E+15 2.0E+15 3.0E+15 4.0E+15 5.0E+15 6.0E+15 7.0E+15 8.0E+15

Jan. 05 Feb. 05 Mrz. 05 Apr. 05 Mai. 05 Jun. 05

Time N O 2 V C D [ m o le c /c m ²] VCDmin Reihe2 Reihe3

Minimum NO2 VCD from SCIAMACHY at noon MAXDOAS NO2 VCD sunrise 90° SZA

MAXDOAS NO2 VCD sunset 90° SZA

SCIAMACHY NO2 VCD © Andreas Richter

Time series of NO

₂

VCDs measured by the Kiruna instrument and minimum

SCIAMACHY NO

₂

VCDs (within 200km, scientific product of the University of

Bremen) for the first half of 2005. The SCIAMACHY NO

₂

VCDs are between the

Kiruna AM and PM data probably indicating remaining low NO

₂

contributions from the

troposphere.

(52)

Time series of NO

₂

VCDs measured by the Kiruna

instrument between January 1997 to December 2014. In

addition satellite results (GOME-1, SCIAMACHY,

GOME-2) analysed by the University of Bremen are

shown.

(53)

Monthly means NO₂ slant column measurements at Lauder (45ºS, 170ºE). http://www.geomon.eu/images/science/act4/Lauder_DOAS_NO2.jpg

(54)

Spectrograph UV

Spectrograph Visible

Meteorological Office Building

Electronics Computer Telescope Quartz glass fiber bundles Observation platform

Top: Building of the meteorological

service of Suriname in Paramaribo. The

telescopes of the MAXDOAS instrument

are seen at the top. Right: The telescope

units outside the building are connected

to the spectrometers inside via glass

fibre bundles.

(55)

SCIAMACHY NO2 VCD © Andreas Richter 0.0E+00 5.0E+14 1.0E+15 1.5E+15 2.0E+15 2.5E+15 3.0E+15 3.5E+15 4.0E+15

Apr. 02 Okt. 02 Apr. 03 Okt. 03 Apr. 04 Okt. 04 Apr. 05

Time N O 2 V C D [ m o le c /c m ²] VCDmin Reihe2 Reihe3

Min NO2 VCD from SCIAMACHY at noon MAXDOAS NO2 VCD sunrise 90° SZA MAXDOAS NO2 VCD sunset 90° SZA

Time series of NO

₂

VCDs measured by the Paramaribo instrument and minimum

SCIAMACHY NO

₂

VCDs (within 200km, scientific product of the University of

Bremen) for the period 2002 – 2005.

(56)

A b u n d a n ce Time Surface reactions Gas phase reactions ClONO2 HCl ClO + 2 Cl2O2

Fall Early winter Late winter Spring

End of polar night

photochemical ozone destruction Denitrification

Dehydration

Dynamical and photochemical development in the

stratosphere during polar winter

CFC →

Stratosphere

→

Reservoir compounds

→

active comp.

→

OClO

(HCl, ClONO

₂

) (Cl, ClO)

Ozone destruction

(57)

http://www.awi.de/en/news/press_releases/detail/item/arctic_on_the_verge_o f_record_ozone_loss_arctic_wide_measurements_verify_rapid_depletion_in_ recent/?cHash=ee2ef56e0dedac781a0eddcb73f26bdc

http://oceanworld.tamu.edu/resources/en vironment-book/Images/polarvortex.jpg

During polar night a vortex formes in the stratosphere. No effective

mixing appears between air inside and outside this polar vortex.

(58)

High values of OClO (indicating stratospheric chlorine activation)

are found only when the polar vortex is over Kiruna.

(59)

-5 .0 E + 1 3 0 .0 E + 0 0 5 .0 E + 1 3 1 .0 E + 1 4 1 .5 E + 1 4 2 .0 E + 1 4 2 .5 E + 1 4 3 .0 E + 1 4 J a n . 0 0 J a n . 0 1 J a n . 0 2 J a n . 0 3 J a n . 0 4 J a n . 0 5 T im e O C lO D S C D [ m o le c /c m ²] R e ih e 1 R e ih e 2 K iru n a O C lO D S C D A M

K iru n a O C lO D S C D P M

OClO DSCDs over Kiruna for

different polar winters. High values

were detected for the cold winters

1999/2000 and 2004/2005.

Volume of polar stratospheric

clouds and Ozone loss for different

Antarctic winters (© Markus Rex,

see http://www.realclimate.org/).

Strong ozone destruction was

observed during the winters with

high chlorine activation indicated

by high OClO DSCDs over Kiruna

(60)

L e c tu re o n a tm o s p h e ri c r e m o te s e n s in g th o m a s .w a g n e r@ m p ic .d e 01 .0 1. 99 01 .0 2. 99 01 .0 3. 99 01 .0 4. 99 01 .0 5. 99 01 .0 6. 99 01 .0 7. 99 01 .0 8. 99 01 .0 9. 99 01 .1 0. 99 01 .1 1. 99 01 .1 2. 99 01 .0 1. 00 01 .0 2. 00 01 .0 3. 00 01 .0 4. 00 01 .0 5. 00 01 .0 6. 00 01 .0 7. 00 01 .0 8. 00 01 .0 9. 00 01 .1 0. 00 01 .1 1. 00 01 .1 2. 00 01 .0 1. 01 01 .0 2. 01 01 .0 3. 01 01 .0 4. 01 01 .0 5. 01 01 .0 6. 01 01 .0 7. 01 01 .0 8. 01 01 .0 9. 01 01 .1 0. 01 01 .1 1. 01 01 .1 2. 01 01 .0 1. 02 01 .0 2. 02 01 .0 3. 02 01 .0 4. 02 01 .0 5. 02 01 .0 6. 02 8 0 1 0 0 1 2 0 1 4 0 1 6 0 1 8 0 2 0 0 2 2 0 2 4 0 2 6 0 2 8 0 3 0 0 3 2 0 3 4 0 D O A S ( 8 4 °< = S Z A < = 9 0 °) D O A S ( 8 8 °< = S Z A < = 9 4 °) O z o n e s o u n d in g s T O M S VC D O 3 [D U] D a te 01 .0 1. 99 01 .0 2. 99 01 .0 3. 99 01 .0 4. 99 01 .0 5. 99 01 .0 6. 99 01 .0 7. 99 01 .0 8. 99 01 .0 9. 99 01 .1 0. 99 01 .1 1. 99 01 .1 2. 99 01 .0 1. 00 01 .0 2. 00 01 .0 3. 00 01 .0 4. 00 01 .0 5. 00 01 .0 6. 00 01 .0 7. 00 01 .0 8. 00 01 .0 9. 00 01 .1 0. 00 01 .1 1. 00 01 .1 2. 00 01 .0 1. 01 01 .0 2. 01 01 .0 3. 01 01 .0 4. 01 01 .0 5. 01 01 .0 6. 01 01 .0 7. 01 01 .0 8. 01 01 .0 9. 01 01 .1 0. 01 01 .1 1. 01 01 .1 2. 01 01 .0 1. 02 01 .0 2. 02 01 .0 3. 02 01 .0 4. 02 01 .0 5. 02 01 .0 6. 02 0 1 2 3 4 5 6 7 a m p m VC D N O 2 [1 0 15 m ole c/c m 2 ] D a te 1 8 0 1 9 0 2 0 0 2 1 0 2 2 0 2 3 0 2 4 0 2 5 0 Temperature @ 50hPa [K] 01 .0 1. 99 01 .0 2. 99 01 .0 3. 99 01 .0 4. 99 01 .0 5. 99 01 .0 6. 99 01 .0 7. 99 01 .0 8. 99 01 .0 9. 99 01 .1 0. 99 01 .1 1. 99 01 .1 2. 99 01 .0 1. 00 01 .0 2. 00 01 .0 3. 00 01 .0 4. 00 01 .0 5. 00 01 .0 6. 00 01 .0 7. 00 01 .0 8. 00 01 .0 9. 00 01 .1 0. 00 01 .1 1. 00 01 .1 2. 00 01 .0 1. 01 01 .0 2. 01 01 .0 3. 01 01 .0 4. 01 01 .0 5. 01 01 .0 6. 01 01 .0 7. 01 01 .0 8. 01 01 .0 9. 01 01 .1 0. 01 01 .1 1. 01 01 .1 2. 01 01 .0 1. 02 01 .0 2. 02 01 .0 3. 02 01 .0 4. 02 01 .0 5. 02 01 .0 6. 02 0 1 2 3 4 5 6 7 8 9 1 0 a m , S Z A = 9 0 ° p m , S Z A = 9 0 ° a m , S Z A = 9 4 ° p m , S Z A = 9 4 ° SC D O ClO [1 0 14 m ole c/c m 2 ] D a te -2 0 -3 0 -4 0 -5 0 -6 0 -7 0 PV @ 475K (PVU)

D

OA

S

-M

e

s

u

n

g

e

n

a

u

f

d

e

r

N

e

u

m

a

y

e

r-S

ta

ti

o

n

/A

n

ta

rk

ti

s

©

U

d

o

F

ri

e

ß

(61)

Mie-Vielfach-Streuung

Spektrograph

Absorptionserhöhung durch Bewölkung

Effects of clouds II

-clouds enhance the

light path inside the

cloud

(62)

400 450 500 550 600 650 0E+0 1E+6 2E+6 in te n s it y [ c o u n ts ] 1 2 3 Q u o ti e n t A / B 400 450 500 550 600 650 0.97 0.98 0.99 1.00 1.01 1.02 Q u o ti e n t C / P o ly n o m ia l 400 450 500 550 600 650 wavelength [nm] O4 H2O

cloudy sky (04.02.1994, SZA: 85.4°)

clear sky (22.03.1994, SZA: 85.5°)

A:

B:

C =

A

/

B

2 1

A

B

(63)

7:12 9:36 12:00 14:24 Zeit 0 300 600 [D U ] 0.0 0.0 0.1 O D 0.02 0.04 0.06 O D 0E+0 5E-4 1E-3 O D 0.00 1.00 2.00 In te n s it ts q u o ti e n t 6 8 2 n m / 3 8 8 n m 0E+0 1E+4 2E+4 3E+4 A v e ra g e [ 1 /s ] 3 8 0 -6 8 0 n m VCD NO2 SCD H2O Diff. SCD O4 Trop. O3Absorption klarer Tag 05.03.1994 klarer Tag 05.03.1994 Colour-Index Intensität

Thick cloud over

Kiruna, 5.3.1994

The strongest

absorption

enhancement

occurs when a very

thick cloud

waslocated over the

measurement site

(low intensity)

(64)

Spectrograph Zenith Sun Stratosphere Troposphere 45° 70° 80° 85° 88°

•

Scattered light measurements

in different viewing directions

(close to the horizon to the

zenith)

•

Zenith sky measurements are

sensitive mainly to the

stratospheric column

•

Measurements close to the

horizon have a long light path

through the troposphere and

are therefore sensitive for trace

gases near the surface

•

Multi-Axis DOAS allows to

gain information on the

vertical distribution of

atmospheric trace gases

(65)

Mini-MAX-DOAS during the

CINDI campaign, Cabauw, The

Netherlands, 2009

Compact (Mini) MAX-DOAS instrument

The whole instrument is turned by stepper motor

Hoffmann Messtechnik, Germany

http://www.hmm.de/

Advantages:

- rather cheap, commercially

available

- simple operation (only battery and

notebook needed)

Disadvantages:

- poor spectral quality

- low quantum efficiency in UV

- often problems with USB

(66)

Clemer et al., AMT 2010

‚Advanced‘ MAX-DOAS set-up

spectrometer inside

moveable telescope outside

two-axis

‚sun tracker‘

(67)

Same azimuth angle

Different azimuth angles

Three UV spectra on the CCD

‚Return‘ to moveable telescopes

(68)

‚High-speed‘ 2-D MAX-DOAS instruments

moveable telescope with strong & precise motor

Similar instruments

are used by

Uni Colorado

Uni Heidelberg

AIOFM Hefei

BIRA Brussels

(69)

For (mainly)

stratospheric Absorbers

(e.g. O3) all elevation

angles yield the same DSCDs

0.E+00 2.E+19 4.E+19 6.E+19 8.E+19 1.E+20 4:00 6:24 8:48 11:12 13:36 16:00 10.09.2003 O 3 D S C D [ m o le c /c m ²] Reihe1 Reihe2 Reihe3 Reihe4 3° 6° 10° 18° elevation angle

O4 DSCD

The ‚U-shape‘ is caused by the changing SZA

MAX-DOAS observations at Milano, 2003

0 10 20 30 A lt it u d e [ k m ]

O3

O3 DSCD

(70)

For

surface-near Absorbers

(e.g. HCHO) all elevation angles

yield different DSCDs

0.0E+00 2.0E+16 4.0E+16 6.0E+16 8.0E+16 1.0E+17 4:00 6:24 8:48 11:12 13:36 16:00 Time S C D H C H O [ m o le c /c m ²] Reihe1 Reihe2 Reihe3 Reihe4 Elevation: 3° 6° 10° 18°

10.09.2003

Reihe1

Reihe2

Reihe3

Reihe4

3°

6°

10°

18°

0 10 20 30 A lt it u d e [ k m ]

O4

MAX-DOAS observations at Milano, 2003

(71)

For Absorbers located also in the

free troposphere

(e.g. the

oxygen dimer O4) the difference between the DSCDs is small

The ‚U-shape‘ is caused by the changing SZA

10.09.2003

0

2000

4000

6000

4:00

6:24

8:48

11:12

13:36

16:00

Date

O

4

D

S

C

D

[

1

0

4

0

m

o

le

c

2

/c

m

5

]

Reihe2

Reihe3

Reihe4

Reihe5

18°

10°

6°

3°

elevation angle

O4 DSCD

0 10 20 30 A lt it u d e [ k m ]

O4

(72)

0 1000 2000 3000 4000 5000 6000 7000

14. Sep. 15. Sep. 16. Sep. 17. Sep.

Date O4 D S C D [ 1 0 4 0 m o le c 2 /c m 5 ] 1.8 2.8 3.8 4.8 5.8 6.8 7.8 Reihe1 Reihe2 Reihe3 Reihe4 Reihe5 Reihe6 90° 18° 10° 6° 3° Telescope elevation O 4 A M F ( re fe re n c e a d d e d )

Increasing aerosol laod leads to a decreas of the absorption paths and thus to a

decrease of the measured absorptions.

=> From MAX-DOAS measurements aerosol profiles can be inverted

=> Only after aerosol profiles are known, trace gas profiles can be inverted

(73)

How to derive profiles (trace gases and aerosols)

from measured DSCDs?

-compare results from forward model to

measurements

-iterate assumed profiles until forward model and

measurements agree

-information content is limited (typically 1-3 pieces

of information)

-Optimal estimation and parameterised inversion

algorithms are used

(74)

Forward model:

A) aerosol or

trace gas profile

B) Radiative

transfer model

Trace gas

DSCDs

MCARTIM

(T. Deutschmann)

3D spherical MC model

- Raman scattering

- Polarisation

a

lt

it

u

d

e

Concentration

D

S

C

D

Elevation

angle

(75)

S = 0.5 S = 0.8 S = 1.0 S = 1.2 two layers

Trace gas concentration or aerosol extinction S = 1.2 linear

S = 0.5 S = 0.8 S = 1.0 S = 1.2

two layers

Trace gas concentration or aerosol extinction S = 1.2 linear

We use simple parameterisation (1-3 independent

pieces of information) for tropospheric profiles:

-layer height

-shape factor

(76)

Comparison of

measured O

₄

DAMFs (black dots)

to the results of the

forward model

(coloured lines)

15.09., 12:00 19.09., 8:00

f: 1.1 AOD: 0.40 f: 1.0 AOD: 0.85 f: 0.8 AOD: 1.28 f: 1.1 lin AOD: 1.28 f: 1.1 AOD: 0.61 f: 1.0 AOD: 0.77 f: 0.8 AOD: 0.73 f: 1.1 lin AOD: 0.78 15.09. 12:00 _{19.09. 8:00} f: 1.1 AOD: 0.40 f: 1.0 AOD: 0.85 f: 0.8 AOD: 1.28 f: 1.1 lin AOD: 1.28 f: 1.1 AOD: 0.61 f: 1.0 AOD: 0.77 f: 0.8 AOD: 0.73 f: 1.1 lin AOD: 0.78 15.09. 12:00 _{19.09. 8:00} 0 0.2 0.4 0.6 0.8 1 0 5 10 15 20 Elevation angle [°] O4 d A M Fα Reihe1 Reihe2 Reihe9 Reihe8 Reihe3 Measurement S = 1.1 S = 1.0 S = 0.8 S = 1.1 (linear) 0 0.2 0.4 0.6 0.8 1 0 5 10 15 20 Elevation angle [°] O4 d A M Fα Reihe1 Reihe2 Reihe9 Reihe8 Reihe3 Measurement S = 1.1 S = 1.0 S = 0.8 S = 1.1 (linear)

(77)

Comparison of measured DSCDs of NO

₂

and HCHO (black dots) to the

results of the forward model (coloured lines)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 5 10 15 20 Elevation angle [°] d A M Fα r a ti o ( o r d S C Dα r a ti o ) Reihe1 Reihe2 Reihe9 Reihe8 Reihe3 Measurement S = 1.1 S = 1.0 S = 0.8 S = 0.5

NO

₂ 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 5 10 15 20 Elevation angle [°] d A M F α r a ti o ( o r d S C D α r a ti o ) Reihe1 Reihe2 Reihe9 Reihe8 Reihe3 Measurement S = 1.1 S = 1.0 S = 0.8 S = 0.5

HCHO

S: 0.5, L=183m, VCD=6.08

⋅

10

16

molec/cm²

S: 0.8, L=267m, VCD=5.67

⋅

10

16

molec/cm²

S: 1.0, L=320m, VCD=5.48

⋅

10

16

molec/cm²

S: 1.1, L=254m, VCD=5.09

⋅

10

16

molec/cm²

S: 0.5, L=282m, VCD=2.23

⋅

10

16

molec/cm²

S: 0.8, L=445m, VCD=2.13

⋅

10

16

molec/cm²

S: 1.0, L=515m, VCD=2.01

⋅

10

16

molec/cm²

S: 1.1, L=350m, VCD=1.70

⋅

10

16

molec/cm²

(78)

Results for selected days

0 0.4 0.8 1.2 5:00 7:00 9:00 11:00 13:00 15:00 17:00 O D

Reihe7 Reihe6 Reihe5 AOT_350

south north west AERONET

0 10 20 30 40 50 60 5:00 7:00 9:00 11:00 13:00 15:00 17:00 H C H O m ix in g r a ti o [ p p b ]

Reihe2 Reihe3 #DIV/0! HCHO_[ppb] HCHO-PPB

south north west LP-DOAS Hantzsch

14 September 2003

0 0.4 0.8 1.2 5:00 7:00 9:00 11:00 13:00 15:00 17:00 O D

14 September 2003

0 50 100 150 200 250 300 350 5:00 7:00 9:00 11:00 13:00 15:00 17:00 N O2 m ix in g r a ti o [ p p b ]

Reihe2 Reihe3 Reihe1 NO2_[ppb] south north west _LP-DOAS

0 1000 2000 3000 4000 5000 6000 5:00 7:00 9:00 11:00 13:00 15:00 17:00 L a y e r h e ig h t [m ] NO2 south HCHO south aerosols south north

west northwest northwest 0 50 100 150 200 250 300 350 5:00 7:00 9:00 11:00 13:00 15:00 17:00 N O2 m ix in g r a ti o [ p p b ]

west northwest northwest

telescopes directed to different

azimuth angles

(79)

Results for selected days

0 0.4 0.8 1.2 5:00 7:00 9:00 11:00 13:00 15:00 17:00 O D

19 September 2003

0 0.4 0.8 1.2 5:00 7:00 9:00 11:00 13:00 15:00 17:00 O D

19 September 2003

0 50 100 150 200 250 300 350 5:00 7:00 9:00 11:00 13:00 15:00 17:00 N O2 m ix in g r a ti o [ p p b ]

west northwest

north west 0 50 100 150 200 250 300 350 5:00 7:00 9:00 11:00 13:00 15:00 17:00 N O2 m ix in g r a ti o [ p p b ]

west northwest

north west

(80)

30.06.2009

03.07.2009

24.06.2009

Aerosol

extinction

NO2

concen-tration

Examples for MAX-DOAS profile inversion,

(81)

Ceilometer data

Optimal

Estimation

Paramerised

retrievals

Udo Friess, IUP

Heidelberg

Cabauw,

24.06.2009

(82)

Ceilometer data

Optimal

Estimation

Paramerised

retrievals

Udo Friess, IUP

Heidelberg

Cabauw,

03.07.2009

(83)

Clemer et al., ACP 2010

Comparison of MAX-DOAS AODs at 360, 477, 577, and

630 nm and a co-located sun photometer observations.

Better agreement for short wavelengths

(84)

South

0 50 100

NO2 mixing ratio LP-DOAS

N O2 m ix in g r a ti o S o u th slope: 0.76 ± 0.02_{r²: 0.81} 0 5 10 15 20 0 5 10 15 20

HCHO mixing ratio LP-DOAS [ppb]

H C H O m ix in g r a ti o S o u th [ p p b ] slope: 1.11 r: 0.89 0 5 10 15 20 0 5 10 15 20

slope: 1.16 r: 0.84 0 5 10 15 20 0 5 10 15 20

slope: 0.98 r: 0.91

Comparison of trace gas

mixing ratios

from

MAX-DOAS and LP-DOAS (towards north-west)

NO

2

North

0 50 100 0 50 100

slope: 1.00 ± 0.03 r²: 0.74

West

0 50 100 0 50 100

slope: 1.16 ± 0.03 r²: 0.73

(85)

Jamie Halla et al., ACP 2011

Extinction coefficient retrieved by MAX-DOAS vs. in-situ

pm

2.5

measurements

Border Air Quality and Meteorology Study

(BAQS-Met) at Ridgetown 2007

(86)

Paul Zieger et al., ACP 2011

Extinction coefficient retrieved by MAX-DOAS vs. in-situ

measurements. The color code denotes the AOD.

Good qualitative agreement, but poor quantitative agreement

(87)

(88)

The whole route of Polarstern on ANT/XX in the year 2002/2003. The cruise started on

26.10.2002 and ended on 16.2.2003.

(89)

Top: NO

₂

VCDs for the Atlantic traverse during May 2004 as a function of latitude.

Bottom: Latitudinal mean VCDs of BrO in May 2005 for SZA between 84 and 86

°

.

0.0E+00 1.0E+15 2.0E+15 3.0E+15 4.0E+15 5.0E+15 6.0E+15 -60 -40 -20 0 20 40 60 L a ti tu d e morning NO2 V CD af ternoon NO2 V CD 1 . 5 E + 1 3 2 . 0 E + 1 3 2 . 5 E + 1 3 3 . 0 E + 1 3 3 . 5 E + 1 3 4 . 0 E + 1 3 4 . 5 E + 1 3 5 . 0 E + 1 3 5 . 5 E + 1 3 - 7 0 - 5 0 - 3 0 - 1 0 1 0 3 0 5 0 7 0 L a t i t u d e B rO V C D [ m o le c /c m ²] P o la r s t e r n B r O V C D A M 2 0 0 4 P o la r s t e r n B r O V C D P M 2 0 0 4

NO2

VCD

BrO

VCD

(90)

Enhanced BrO in Antarctica

Wagner et al., ACP, 2007

(91)

Elevation angles: 22°

45°

90°

Typical integration time: 30 s

Car MAX-DOAS measurements

- determination of emissions

- validation of satellite observations

•

Paris Summer 2009 (30

measurement days)

•

Paris Winter 2010 (20

measurement days)

•

New Dehli 2010 & 2011

(8 measurement days)

(92)

Emission estimates for Paris from car MAX-DOAS

Car MAX-DOAS

24.01.2010

Car MAX-DOAS

25.01.2010

(93)

2

x

L

NO

c

F

=

⋅

τ

⋅

∫

⋅

=

S

2

NO

2

NO

VCD

(

s

)

w

n

ds

F

v

Correction for

NO

_x

to NO

₂

ratio

Correction for

NO

_x

lifetime

Wind

vector

Normal vector of

driving route

A)

B)

(94)

Extrapolation of encircled emissions to total

emission (New Delhi)

30 sec spatial resolutin

http://www.ngdc.noaa.gov/dmsp/download_radcal.html

Correction factor derived

from light distribution

measured from sky

NO

₂

VCD from car

MAX-DOAS

(95)

Shaiganfar et al., ACP 2011

(96)

Comparison to Chimere model simulations (Paris)

(97)

Validation of OMI satellite observations

Paris, Summer 2009

(98)

Paris

New Delhi

winter

summer

Over polluted regions satellite observations systematically

(99)

Comparison of tropospheric NO

2

VCD over Beijing. Satellite

data are systematically lower than the MAX-DOAS. Why?

•

Coarse spatial resolution of satellite data

•

Too large AMF used in satellite data analysis (aerosols

shield part of the tropospheric NO

2

)

Ma et al., ACP 2013

(100)

Imaging DOAS: 2-dimensional information

(101)

NO2-chimney plume,

Power plant

‚Fernheizkraftwerk‘

Heidelberg

F. Hoffmann,

IUP-Heidelberg

(102)

Imaging DOAS of volcanic emissions

SO

2

at Popocatepetl, 15 April, 2009

(103)

Short summary for UV/vis ground based observations:

-in general simple retrieval algorithms because thermal

emission can be neglected

-scattered light observations are limited to daylight

-from spectral effects (almost) no information on vertical

distribution can be derived

-several ‚sophisticated‘ techniques exist (e.g. MAX-DOAS) for

the retrieval of profile information

-instruments at different platforms and with different viewing

geometries (and light sources: scattered light and direct light)

-typically simple instrumentation