ground based uvvis - max planck...

Lecture on atmospheric remote sensing [email protected]

Ground based UV/vis observations

A) History

B) Spectroscopy

C) Basic viewing directions

D) Radiative transport modelling

E) Results from different stations


moleculesaerosols

Cloud droplets

rain droplets

Remote sensing in UV / vis spectral range

Wavelengths from ~300 to 700nm

-electronic + vibrational transitions

=> Emission can be neglected


William Hyde Wollaston1766 - 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

Philosophical Transactions of the Royal Society of London, vol. 92 (1802), p. 380 (Plate XIV).


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

Anfänge der Spektroskopie


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 identisch.


1880, Hartley:

UV Ozonabsorption

1882, Chappuis:

vis Ozonabsorption

1890, Huggins

Liniengruppe Spektrum des Sirius (langwellige UV Absorption des Ozon)

Ozon Wirkungsquerschnitt

200 400 600 800Wavelength [nm]

1E-23

1E-22

1E-21

1E-20

1E-19

1E-18

1E-17

[cm

]

Hartley Hug

gins

Chappuis

310 330 3501E-22

1E-21

1E-20

1E-19


1925: Dobson-Spekrophotometer zur Messung der Ozonschichtdicke


300 310 320 330 340 350Wellenlänge [nm]

0E+0

1E-19

2E-19

3E-19

O3-

Abso

rptio

nsqu

ersc

hnitt

[cm

]A

B

CD

1 Dobson Unit (DU) entspricht einer Säule von 10 m unter Normalbedingungen

Typische Ozonschichtdicke:

350 DU (3.5 mm unter N.B.)

Dobson-Photospektrometer

Das Intensitätsverhältnis verschiedener Wellenlängenpaare hängt von der Ozongesamtsäule ab


0

2E-19

4E-19

6E-19

8E-19

1E-18

436 438 440 442 444 446 448 450 452Wavelength [nm]

[cm

²]

0

2E-19

4E-19

6E-19

8E-19

1E-18

250 300 350 400 450 500 550 600 650Wavelength [nm]

[cm

²]

A modified Brewer instrument was used to

measure the atmosphericNO2 absorptions

Brewer et al., Nature, 1973, Uni-Toronto

3

210

2

110 log46.1log

II

IIF

1 2 3

NO2 cross section (220K) Vandaele et al., 1997

UV / vis remote sensing (of the earth‘s atmosphere)


Linear relation between functionF and the NO2column density

3

210

2

110 log46.1log

II

IIF

Confirmation by laboratory measurements

range of atmospheric NO2 columns

Brewer et al., Nature, 1973


Brewer et al., Nature, 1973

Tropospheric NO2

Strong SZA depencence => stratosphericNO2

direct sun

zenith sky

Measurements on July 23, 1973

pmam


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 tropospherictrace gases


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


l

si

ii dssII0

0 )()()(exp)()(

Only absorption => direct inversion

Lambert-Beer-Gesetz :

i: Absorptionswirkungsquerschnitt des i-ten Spurenstoffs

i: Konzentration des i-ten Spurenstoffs

s: Streukoeffizient

=> Kenntnis der Absorptionswirkungsquerschnitte ermöglicht die Bestimmung von Spurenstoffkonzentrationen


DOAS: ’Differential Optical Absorption Spectroscopy’

A) Lambert-Beer’s Law: I I c l 0 exp

B) Spectra, high pass filtering

480 500 520Wavelength [nm]

0

1

2

3

[10

-21 cm

-2 ]

-0.2

0.0

0.2

' [10

-21 cm

-2 ]

c

'

Io has not to be known very sensitive (OD0.001) several absorbers can be measured simultaneously discrimination between absorption and scattering

LII

1ln0


460 480 500 520 540

Wellenlänge [nm]

Inte

nsit

t I(

)

O3-Absorption

NO2-Absorption

Meßspektrum

'differentielle'optische DichteI’0

Die Absorptionen verschiedener Gase können in einem Spektrumanhand ihrer speziellen Form unterschieden werden.

Die Tiefe einer Absorptionsbande hängt von der Spurestoffkonzentration ab


IC

I'0

I3

I1

321

I0

Inte

nsity

[arb

. Uni

ts]

Wavelength [arb. Units]

3

1

2

321

diff

Wavelength [arb. Units]

Cro

ss s

ectio

n [a

rb. U

nits

]

Der Differentielle WirkungsquerschnittLambert-Beer-Gesetz:

I = I0 exp(- L)

=>

Problem: I0 meist unbekannt

Lösung: Separierung des Absorptionswirkungsquerschnitts in einen breit- und schmalbandingen Anteil:

= b + ‘

SCD: slant column density

Das Prinzip der Differentiellen Optischen Absorptions-Spektroskopie (DOAS)

LIIln 0

LII

'1

'ln

0


250 300 350 400 450 600 650 7000

100200

Detection Limit

200 pptL=1km

1 pptL=16km

2 pptL=12km

20 pptL=12km

500 pptL=5km

5 pptL=5km

100 pptL=5km

200 pptL=5km

1 ppbL=5km

Phenol

Wavelength [nm]

04080

20 pptL=1km

50 pptL=1km

250 pptL=1km

para-Kresol

05

10

Toluol

01020

Benzol

0100200

IO

050 BrO

020 ClO

01

HCHO

0100 NO3

04

HONO

0

2NO2

048

SO2

0

4250 300 350 400 450 600 650

50 pptL=5km

'[1

0-19 c

m2 ]

O3

Differentielle Wirkungsquerschnitte verschiedener atmosphärischer Spurengase


Zenit

SZA


400 500 600 700

Wavelength [nm]

Inte

nsity

[arb

itr. u

nits

]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)

=> only differences!



BrO

O3

O4

Residual

Atmospheric spectrum

Divided by Sun Spectrum

60 %

Ring Spectrum

7 %

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


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

Opt

ical

den

sity


-0.004

-0.003

-0.002

-0.001

0.000

0.001

O316.01..1997, SZA: 91.1°

NO218.03.97, SZA: 90.6°

OClO24.02.97, SZA: 91.1°

BrO26.02.97, 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)

O3

NO2

OClO

BrO


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)



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

AM

F

251016263550geometric AMF

profile height(x km - x+1 km)

Stratospheric trace gas layer

Trop. trace gas layer

The AMF depends on the altitude of the trace gas profile


Zenit

SZA


The measured SCD is the difference between both measurements:SCD = SCDmess – SCDref

= VCD * AMFmess – VCD * AMFref

=> VCD = SCD / (AMFmess- AMFref)

mess

ref


0 5 10 15 20 25AMF

0

5000

10000

SCD

O3[

DU

]

Fit: Y = 356DU * X - 454DU

O3-Langley-Plot

VCD = (SCDmess + SCDref) / AMF

SCDmess = (VCD * AMF) - SCDref

Slope => VCD

y-intercept => SCDref

SCD

SCD

Dmess + SCDref) / AMFVCD = (SCD



-2.0E-2

-1.8E-2

-1.6E-2

-1.4E-2


-2.0E-3

0.0E+0

2.0E-3

NO3

NO2

NO2-evaluation, Kiruna, 23.02.1994, LZA: 84.4°


0 10 20 30

0 4 8 12 16

0 4 8 12 16

SCD

NO

3

0 4 8 12

0 4 8 12AMF

Langley-plots for different profiles

pure tropospheric

50% tropospheric

25% tropospheric

10% tropospheric

pure stratospheric

For a mainly stratospheric profiles the measurements lie best on a straight line


NO NO2

N2O5

HNO3langsameGleichgewichte

schnellesGleichgewicht

Stickoxidgleichgewicht

Photolyse


Diurnal cycle of reactive nitrogen compounds. For most observations N2O5 is accumulated during night and photolised during day. Under these conditions the NO2VCD during sunrise is systematically smaller than during sunset [Lambert et al., 2002].

Diurnal variation of Stratospheric nitrogen compounds


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

VCD

NO

3 [1

013 m

olec

/cm

]

Kiruna, 25./26.Jan 1994

0

1

2

3

4

VCD

NO

2 [1

015

mol

ec/c

m]

VCD NO2 night

VCD NO2 day

Direct moonlight measurements

Zenith scattered sunlight measurements


Zenith scattered light observations

-simple instrumental set-up

-restricted during daylight

-high sensitivity for stratospheric trace gases


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-clouds


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 90SZA [°]

AM

F

1/cos(SZA)

trop. AMF,albedo: 80%

trop. AMF,albedo: 5%

strat. AMF,albedo: 80% & 5%


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:

- computational expensive

(1 Million photons need ~10 min on ‘typical PC, 2008)


© Deutschmann et al. 2011

MCARTIM, Tim Deutschmann

Lecture on atmospheric remote sensing [email protected] from above

Look from the side

satellite

• Rayleigh-scattering

• ground reflection

TRACY-II

Tim Deutschmann, IUP Heidelberg

Example of radiative transfer modelling for satellite nadir geometry, 370 nm, no clouds

Lecture on atmospheric remote sensing [email protected] 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



Instrument

Instrument

Green points indicate scattering points of photons => reception area of the detectorBackward Monte Carlo

modelling

Photon paths for different aerosol phase functions

Strong forward peak

Moderateforward peak

Suniti Sanghavi, IUP Heidelberg


Realistic modelling of microscopic cloud properties:

aerosol layer

aerosol layer


24.06., 04:01

The sky is more bright and more white at the horizon

0

0.02

0.04

0.06

0.08

0.1

0.12

0 20 40 60 80 100Elevation angle

Nor

mal

ised

Rad

ianc

e

Reihe1Reihe2Reihe3

420 nm (blue)500 nm (green)600 nm (red)

0

0.02

0.04

0.06

0.08

0.1

0.12


Nor

mal

ised

Rad

ianc

e

Reihe1Reihe2Reihe3

420 nm (blue)500 nm (green)600 nm (red)

Simulated Intensity

no aerosols

AOD: 0.1


24.06., 04:01

The sky is more bright and more white at the horizon

Simulated colour ratio (blue / red)

High value: blue skyLow value: white sky

0

1

2

3

4

5


Col

our R

atio

(420

/ 60

0nm

)

Reihe2Reihe1No aerosolsAOD: 0.1


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 (I0) 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

SCD

II

ln0

SCD SCD


Transitions for rotational and vibrational Raman scattering on O2 and N2 molecules

Raman Scattering on Air Molecules (Ring effect)


395 396 397 398 399Wavelength [nm]

intens

ity [a

rbitrar

y un

its]

earth shine spectrum

dirct sun light spectrum

Auffüllen von (Fraunhofer-) Linien durch inelastischeStreuung (Ring-Effekt)

Im UV bis zu 10% optische Dichte


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(Imeas) used for the calculation.



BrO

O3

O4

Residual

Atmospheric spectrum

Divided by Sun Spectrum

60 %

Ring Spectrum

7 %

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


Jan-01 Jan-02 Jan-03 Jan-04 Jan-05

Kiruna

Paramaribo

Neumayer

Arrival HeigtsMAXDOAS

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.

Time series from zenith sky observations at different locations


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).


4:48 7:12 9:36 12:00 14:24 16:48Zeit

0

4000

8000

SCD

O3

[DU

]

0

100

200

300

400

VCD

O3

[DU

]

O3-Auswertung

Opt

isch

e D

icht

e [

rel.

Einh

eite

n]

O3-Fitergebnis

Tagesgang, Kiruna, 11.03.1994

SCD O3

VCD O3


400 405 410 415 420 425Wellenlänge [nm]

Opt

isch

e D

icht

e[r

el. E

inhe

iten]

NO2-Auswertung

7:12 9:36 12:00 14:24Zeit

0

10

20

30

SCD

NO

2[1

e15

mol

ec/c

m]

1.5

2.0

2.5

3.0

VCD

NO

2[1

e15

mol

ec/c

m]

Tagesgang, Kiruna, 26.02.1994

SCD NO2

VCD NO2

NO2-Fitergebnis


Mean annual cycle (1996 - 2001) of the stratospheric NO2 VCD analysed from GOME observations. Each pixel represents zonal mean values. The contour lines are in units of 1015 molecules/cm2 [Wenig et al., 2004].


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

NO

2 VC

D [m

olec

/cm

²]

VCDReihe2Reihe3

Average NO2 VCD from SCIAMACHY at noonMAXDOAS NO2 VCD sunrise 90° SZAMAXDOAS NO2 VCD sunset 90° SZA

SCIAMACHY NO2 VCD © Andreas Richter

Time series of NO2 VCDs measured by the Kiruna instrument since December 1996. From 2002 to 2005 also the time series of average SCIAMACHY NO2 VCDs (within 200km, scientific product of the University of Bremen) are shown.


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

NO

2 VC

D [m

olec

/cm

²]

VCDminReihe2Reihe3

Minimum NO2 VCD from SCIAMACHY at noonMAXDOAS NO2 VCD sunrise 90° SZAMAXDOAS NO2 VCD sunset 90° SZA


Time series of NO2 VCDs measured by the Kiruna instrument and minimum SCIAMACHY NO2 VCDs (within 200km, scientific product of the University of Bremen) for the first half of 2005. The SCIAMACHY NO2 VCDs are between the Kiruna AM and PM data probably indicating remaining low NO2 contributions from the troposphere.


SpectrographUV

SpectrographVisible

Meteorological Office Building

ElectronicsComputer

Telescope

Quartz glassfiber 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.



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. 05Time

NO

2 VC

D [m

olec

/cm

²]

VCDminReihe2Reihe3

Min NO2 VCD from SCIAMACHY at noonMAXDOAS NO2 VCD sunrise 90° SZAMAXDOAS NO2 VCD sunset 90° SZA

Time series of NO2 VCDs measured by the Paramaribo instrument and minimum SCIAMACHY NO2 VCDs (within 200km, scientific product of the University of Bremen) for the period 2002 – 2005.


Abun

danc

e

Time

Surface reactions

Gas phasereactions

ClONO2

HCl

ClO + 2 Cl2O2

Fall Early winter Late winter Spring

End of polar nightphotochemical ozone destruction

DenitrificationDehydration

Dynamical and photochemical development in the stratosphere during polar winter

CFC Stratosphere Reservoir compounds active comp. OClO(HCl, ClONO2) (Cl, ClO)

Ozone destruction

Transport hv (UV) PSC BrO


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

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

During polar night a vortex formes in the stratosphere. No effectivemixing appears between air inside and outside this polar vortex.


High values of OClO (indicating stratospheric chlorine activation)are found only when the polar vortex is over Kiruna.


-5.0E +13

0.0E +00

5.0E +13

1.0E +14

1.5E +14

2.0E +14

2.5E +14

3.0E +14

Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04 Jan. 05

Tim e

OC

lO D

SCD

[mol

ec/c

m²]

R eihe1R eihe2K iruna O C lO D S C D A MK iruna 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


01.01

.9901

.02.99

01.03

.9901

.04.99

01.05

.9901

.06.99

01.07

.9901

.08.99

01.09

.9901

.10.99

01.11

.9901

.12.99

01.01

.0001

.02.00

01.03

.0001

.04.00

01.05

.0001

.06.00

01.07

.0001

.08.00

01.09

.0001

.10.00

01.11

.0001

.12.00

01.01

.0101

.02.01

01.03

.0101

.04.01

01.05

.0101

.06.01

01.07

.0101

.08.01

01.09

.0101

.10.01

01.11

.0101

.12.01

01.01

.0201

.02.02

01.03

.0201

.04.02

01.05

.0201

.06.02

80100120140160180200220240260280300320340

DOAS (84°<=SZA<=90°) DOAS (88°<=SZA<=94°) Ozone soundings TOMS

VCD

O3 [D

U]

Date

01.01

.9901

.02.99

01.03

.9901

.04.99

01.05

.9901

.06.99

01.07

.9901

.08.99

01.09

.9901

.10.99

01.11

.9901

.12.99

01.01

.0001

.02.00

01.03

.0001

.04.00

01.05

.0001

.06.00

01.07

.0001

.08.00

01.09

.0001

.10.00

01.11

.0001

.12.00

01.01

.0101

.02.01

01.03

.0101

.04.01

01.05

.0101

.06.01

01.07

.0101

.08.01

01.09

.0101

.10.01

01.11

.0101

.12.01

01.01

.0201

.02.02

01.03

.0201

.04.02

01.05

.0201

.06.02

0

1

2

3

4

5

6

7

am pmVC

D N

O2 [1

015 m

olec

/cm

2 ]

Date

180

190

200

210

220

230

240

250

Temperature @

50hPa [K]

01.01

.9901

.02.99

01.03

.9901

.04.99

01.05

.9901

.06.99

01.07

.9901

.08.99

01.09

.9901

.10.99

01.11

.9901

.12.99

01.01

.0001

.02.00

01.03

.0001

.04.00

01.05

.0001

.06.00

01.07

.0001

.08.00

01.09

.0001

.10.00

01.11

.0001

.12.00

01.01

.0101

.02.01

01.03

.0101

.04.01

01.05

.0101

.06.01

01.07

.0101

.08.01

01.09

.0101

.10.01

01.11

.0101

.12.01

01.01

.0201

.02.02

01.03

.0201

.04.02

01.05

.0201

.06.02

0

1

2

3

4

5

6

7

8

9

10 am, SZA = 90° pm, SZA = 90° am, SZA = 94° pm, SZA = 94°

SCD

OC

lO [1

014 m

olec

/cm

2 ]

Date

-20

-30

-40

-50

-60

-70

PV @

475K (PVU

)

DOAS- Messungen auf der Neumayer- Station/Antarktis © Udo Frieß


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

Long time series allow to investigate trends...


Mie-Vielfach-Streuung

Spektrograph

Absorptionserhöhung durch BewölkungEffects of clouds II

-clouds enhance the light path inside the cloud


400 450 500 550 600 6500E+0

1E+6

2E+6

inte

nsity

[cou

nts]

1

2

3

Quo

tient

A /

B

400 450 500 550 600 650

0.97

0.98

0.99

1.00

1.01

1.02

Quo

tient

C /

Poly

nom

ial

400 450 500 550 600 650wavelength [nm]

O4

H2O

cloudy sky (04.02.1994, SZA: 85.4°)

clear sky (22.03.1994, SZA: 85.5°)

A:

B:

C = A / B2

1

AB


7:12 9:36 12:00 14:24Zeit

0

300

600

[DU

]

0.0

0.0

0.1

OD

0.02

0.04

0.06

OD

0E+0

5E-4

1E-3

OD

0.00

1.00

2.00

Inte

nsit

tsqu

otie

nt 6

82nm

/ 38

8 nm

0E+0

1E+4

2E+4

3E+4

Aver

age

[1/s

]38

0-68

0 nm

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)


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

Multi-Axis Observation Geometry


Mini-MAX-DOAS during theCINDI campaign, Cabauw, The Netherlands, 2009

Compact (Mini) MAX-DOAS instrumentThe whole instrument is turned by stepper motor

Hoffmann Messtechnik, Germanyhttp://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 connection

Lecture on atmospheric remote sensing [email protected] et al., AMT 2010

‚Advanced‘ MAX-DOAS set-up

spectrometer inside moveable telescope outside

two-axis ‚sun tracker‘


Same azimuth angle

Different azimuth angles

Three UV spectra on the CCD

‚Return‘ to moveable telescopes

Wagner et al., AMT 2011


‚High-speed‘ 2-D MAX-DOAS instruments

moveable telescope with strong & precise motor

Similar instruments are used by Uni ColoradoUni HeidelbergAIOFM HefeiBIRA Brussels


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 16:0010.09.2003

O3

DS

CD

[mol

ec/c

m²]

Reihe1Reihe2Reihe3Reihe4

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

Altit

ude

[km

]

O3

O3 DSCD


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

SCD

HC

HO

[mol

ec/c

m²]


Elevation:3°6°10°18°

10.09.2003

ReihReihReihReih

3°6°10°18°

0

10

20

30

Altit

ude

[km

]

O4


HCHO


For Absorbers located also in the free troposphere (e.g. theoxygen 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

O4

DS

CD

[104

0mol

ec2/

cm5]


18°10°6°3°

elevation angleO4 DSCD

0

10

20

30

Altit

ude

[km

]

O4



0

1000

2000

3000

4000

5000

6000

7000

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

O4 D

SCD

[1040

mol

ec2 /c

m5 ]

1.8

2.8

3.8

4.8

5.8

6.8

7.8Reihe1Reihe2Reihe3Reihe4Reihe5Reihe6

90°18°10°6°3°

Telescope elevation

O4 A

MF (reference added)

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

Increasing aerosol optical depth


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


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

altit

ude

Concentration

DSC

D

Elevation angle


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

-vertically integrated amount (trace gas VCD or AOT)


Comparison of measured O4DAMFs (black dots) to the results of the forward model (coloured lines)

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

f: 1.1 AOD: 0.40f: 1.0 AOD: 0.85f: 0.8 AOD: 1.28f: 1.1 lin AOD: 1.28


15.09. 12:00 19.09. 8:00f: 1.1 AOD: 0.40f: 1.0 AOD: 0.85f: 0.8 AOD: 1.28f: 1.1 lin AOD: 1.28


15.09. 12:00 19.09. 8:00

0

0.2

0.4

0.6

0.8

1

0 5 10 15 20Elevation angle [°]

O4 d

AMF

Reihe1Reihe2Reihe9Reihe8Reihe3

MeasurementS = 1.1S = 1.0S = 0.8S = 1.1 (linear)

0

0.2

0.4

0.6

0.8

1


O4 d

AM

F


MeasurementS = 1.1S = 1.0S = 0.8S = 1.1 (linear)


Comparison of measured DSCDs of NO2 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


dAM

F ra

tio

(or

dS

CD

ratio

)


MeasurementS = 1.1S = 1.0S = 0.8S = 0.5

NO2

0

0.2

0.4

0.6

0.8

1

1.2

1.4


dAM

F ra

tio

(or

dS

CD

ratio

)


MeasurementS = 1.1S = 1.0S = 0.8S = 0.5

HCHO

S: 0.5, L=183m, VCD=6.08 1016 molec/cm² S: 0.8, L=267m, VCD=5.67 1016 molec/cm² S: 1.0, L=320m, VCD=5.48 1016 molec/cm² S: 1.1, L=254m, VCD=5.09 1016 molec/cm²

S: 0.5, L=282m, VCD=2.23 1016 molec/cm² S: 0.8, L=445m, VCD=2.13 1016 molec/cm² S: 1.0, L=515m, VCD=2.01 1016 molec/cm² S: 1.1, L=350m, VCD=1.70 1016 molec/cm²


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

OD

Reihe7 Reihe6 Reihe5 AOT_350south north west AERONET

0

10

20

30

40

50

60

5:00 7:00 9:00 11:00 13:00 15:00 17:00

HC

HO

mix

ing

ratio

[ppb

]

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

OD


0

10

20

30

40

50

60

5:00 7:00 9:00 11:00 13:00 15:00 17:00

HC

HO

mix

ing

ratio

[ppb

]


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

NO

2 mix

ing

ratio

[ppb

]

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

Laye

r hei

ght [

m]

NO2 southHCHO southaerosols southnorthwest

northwest

northwest

0

50

100

150

200

250

300

350

5:00 7:00 9:00 11:00 13:00 15:00 17:00

NO

2 mix

ing

ratio

[ppb

]


0

1000

2000

3000

4000

5000

6000

5:00 7:00 9:00 11:00 13:00 15:00 17:00

Laye

r hei

ght [

m]


northwest

northwest

telescopes directed to different azimuth angles


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

OD


0

10

20

30

40

50

60

5:00 7:00 9:00 11:00 13:00 15:00 17:00

HC

HO

mix

ing

ratio

[ppb

]


19 September 2003

0

0.4

0.8

1.2

5:00 7:00 9:00 11:00 13:00 15:00 17:00

OD


0

10

20

30

40

50

60

5:00 7:00 9:00 11:00 13:00 15:00 17:00

HC

HO

mix

ing

ratio

[ppb

]


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

NO

2 mix

ing

ratio

[ppb

]


0

1000

2000

3000

4000

5000

6000

5:00 7:00 9:00 11:00 13:00 15:00 17:00

Laye

r hei

ght [

m]


northwest

northwest

0

50

100

150

200

250

300

350

5:00 7:00 9:00 11:00 13:00 15:00 17:00

NO

2 mix

ing

ratio

[ppb

]


0

1000

2000

3000

4000

5000

6000

5:00 7:00 9:00 11:00 13:00 15:00 17:00

Laye

r hei

ght [

m]


northwest

northwest


30.06.2009 03.07.200924.06.2009

Aerosol extinction

NO2 concen-tration

Examples for MAX-DOAS profile inversion,

CINDI campaign, Cabauw, The Netherlands, Summer 2009


Ceilometer data

Optimal Estimation

Paramerised retrievals

Udo Friess, IUP Heidelberg

Cabauw, 24.06.2009


Ceilometer data

Optimal Estimation

Paramerised retrievals

Udo Friess, IUP Heidelberg

Cabauw, 03.07.2009


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

Validation for column data and surface values


South

0

50

100

0 50 100NO2 mixing ratio LP-DOAS

NO

2 mix

ing

ratio

Sou

thslope: 0.76 ± 0.02 r²: 0.81

0

5

10

15

20

0 5 10 15 20HCHO mixing ratio LP-DOAS [ppb]

HC

HO

mix

ing

ratio

Sou

th [p

pb]

slope: 1.11 r: 0.89

0

5

10

15

20


slope: 1.16 r: 0.84

0

5

10

15

20


slope: 0.98 r: 0.91

Wagner et al., AMT 2011

Comparison of trace gas mixing ratios fromMAX-DOAS and LP-DOAS (towards north-west)

NO2

North

0

50

100


slope: 1.00 ± 0.03 r²: 0.74

West

0

50

100


slope: 1.16 ± 0.03 r²: 0.73

HCHO

Lecture on atmospheric remote sensing [email protected] Halla et al., ACP 2011

Extinction coefficient retrieved by MAX-DOAS vs. in-situ pm2.5 measurements

Border Air Quality and Meteorology Study(BAQS-Met) at Ridgetown 2007

Good qualitative agreement


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

slope: 3.4 slope: 1.5


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.


Top: NO2 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

Latit

ude

morning NO2 VCD

af ternoon NO2 VCD

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 tu d e

BrO

VC

D [m

olec

/cm

²]

P o la rs te rn B rO V C D A M 2 0 0 4P o la rs te rn B rO V C D P M 2 0 0 4

NO2 VCD

BrOVCD


Enhanced BrO in Antarctica

Wagner et al., ACP, 2007


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)

R. Shaiganfar, MPIC Mainz


Emission estimates for Paris from car MAX-DOAS

Car MAX-DOAS 24.01.2010

Car MAX-DOAS 25.01.2010


2x NOLNO FccF

S

2NO2NO dsnw)s(VCDF

Correction for NOx to NO2 ratio

Correction for NOx lifetime

Wind vector

Normal vector of driving route

A)

B)

Emission estimates from car MAX-DOAS


Extrapolation of encircled emissions to total emission (New Delhi)

30 sec spatial resolutinhttp://www.ngdc.noaa.gov/dmsp/download_radcal.html

Correction factor derived from light distribution measured from sky

NO2 VCD from car MAX-DOAS

C)


Shaiganfar et al., ACP 2011

NOx emissions New Delhi


Comparison to Chimere model simulations (Paris)

Hervé Pepetin, Matthias Beekmann, LISA, Paris


Validation of OMI satellite observations

Paris, Summer 2009


Paris New Delhi

winter

summer

Over polluted regions satellite observations systematically underestimate the tropospheric NO2 VCD


Comparison of tropospheric NO2 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 NO2)

Ma et al., ACP 2013

(2008–2010) (2008–2011)


Imaging DOAS: 2-dimensional information

F. Hoffmann, IUP-Heidelberg


NO2-chimney plume,

Power plant ‚Fernheizkraftwerk‘ Heidelberg

F. Hoffmann,

IUP-Heidelberg


Imaging DOAS of volcanic emissions

SO2 at Popocatepetl, 15 April, 2009

Diploma Thesis, Peter Lübcke, IUP Heidelberg


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

ground based uvvis - max planck...

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