Correct atmospheric optics modelling: Theory and Experiment

Irina MelnikovaObservatory

of Environmental Safety

Resource Center, Research Park

St.Petersburg State University

St.Petersburg. Russia. irina.melnikova@pobox.spbu.ru

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Objectives:

1. Constructing the simple optical model of homogeneous atmosphere

2. Solution of the direct problem of atmospheric optics with operative varying optical parameters for elucidating the interaction between key atmospheric parameters and radiative characteristics

3. The solution of the direct problem is calculation of radiation characteristics (radiant heat. radiation balance at the tropopause level)

4. Comparison with the results of airborne measurements

3

Optical parameters

• Optical thickness of the clear atmosphere :

= a.sc + a.ab + R + m.ab .

a.sc – the optical thickness of aerosol scattering.

a.ab - the optical thickness of aerosol absorption. R- the optical thickness of molecular scattering.m.ab - the optical thickness of molecular absorption;

• Cloud optical thickness 0

• Single scattering albedo: for clear atmosphere

= (a.sc + R)/ ;

• For cloudy atmosphere = (0 + a.sc + R)/( + 0) ;

• The phase function asymmetry parameter:

g=0.0 for clear atmosphere and g=0.85 for cloud atmosphere;

• The ground albedo As

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300 400 500 600 700 800 900 10000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

f(x) = 7.47049029078755E-05 x + 0.889947870065316

f(x) = − 9.085957323764E-07 x² + 0.001810412314957 x − 0.456068551075826

f(x) = 2.797136383811E-07 x² − 0.000473367439686 x + 0.216573864906913

WATERPolynomial (WATER)SANDPolynomial (SAND)SNOW

Wavelength. nm

Gro

un

d a

lbed

o

Spectral dependence of the ground albedo of different surfaces from observational data processing

(C.A. Varotsos. I.N. Melnikova. A.P. Cracknell. C. Tzanis. A.V. Vasilyev. New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations. Atmospheric Chemistry and Physics. v. 13. pp. 16211-16245)

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Multiwavelength lidar  Multiwavelength lidar 

Raman

channelsRaman

channels

Aerosol lidarAerosol lidar

Doppler (wind) lidar

Doppler (wind) lidar

Tunable titan-sapphier lasers  

(at the mobile complex)

Tunable titan-sapphier lasers  

(at the mobile complex)

Polarization filter 355 nmPolarization filter 355 nm

Elastic channelsElastic

channels

Data of the SPSU RC lidar is used for aerosol optical thickness modelling

Stationary lidar system:

• A Doppler lidar for measuring the wind speed and direction up to 12 km height

• An aerosol lidar for measuring the atmospheric

aerosol parameters up to 25 km height

1. Provide regular monitoring the dynamics of an atmospheric pollution above the big city center. 2. Retrieving atmospheric dust parameters: size, extinction coefficient, backscattering coefficient, real and imagine parts of the refractive index, and content

Stationary lidar system

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Aerosol lidar1064 nm - 400 mJ532 nm - 160 mJ355 nm - 100 mJ

Doppler (wind) lidar for wind velocity and direction profilePulse repetition rate 10kHz

1 | 355_Anlg2 | 355_PhCt3 | 355_De_Anlg4 | 355_De_PhCt5 | 532_Anlg6 | 532_PhCt7 | 387_Anlg8 | 387_PhCt9 | 608_Anlg10 | 608_PhCt11 | 1064_Anlg12 | 408_PhCt

Distance [m]1.4E+041.2E+041E+048E+036E+034E+032E+030E+00

Lida

r sig

nal

78

7674

727068

6664

6260

585654

5250

484644

4240

3836

343230

2826

242220

1816

1412

1086

42

0

Screenshot of the received Lidar signal 31.10.2013

9

10

The extinction coefficient above St. Petersburg 25 March 2013.

The vertical profile till 4 km and 25 km during 1 hour =532 nm

The maximum of hat pollution at 0.7 km, disappeared during 45 min (15:30 - 16:15) (z)0.056km-1

The stratosphere aerosol–Yunge layer at 17-22km (z)0.015km-1

Total optical thickness is = 0.0735

Lidar sounding above St. Petersburg city

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VALUES OF OPTICAL PARAMETERS OF THE CLEAR ATMOSPHERE

. m 0.30 0.40 0.50 0.60 0.70 0.80 0.90Mol scatt 

Rel (z=0) 1.222

0.364

0.14 0.067

0.036

0.021

0.013

Aer 0

a scatt

a abs

0.00.0

0.00.0

0.00.0

0.00.0

0.00.0

0.00.0

0.00.0

Aer I a scatt

a abs

0.250.01

0.180.01

0.160.01

0.140.01

0.130.01

0.120.01

0.120.01

Aer III

a scatt

a abs

0.70.4

0.50.4

0.50.4

0.50.4

0.40.4

0.30.4

0.30.4

0IIII

0

0.26184

0.29876

0.33328

1.00.9819

50.6835

4

1.00.9677

40.6153

9

0.91781

0.93243

0.58757

1.00.9431

80.5215

3

1.00.9337

80.4452

2

1.00.9300

70.4389

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0IIII

4.6674.9275.767

0.3640.5541.264

0.140.3101.040

0.0720.2220.965

0.0360.1760.836

0.0210.1510.721

0.0130.1430.713

Clear atmosphere

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0.3 0.5 0.7 0.90.0

0.4

0.8

1.2

1.6

2.0Optical thickness

A-1 A-2 A-3

Wavelength. mm

Op

tic

al t

hic

kn

es

s

0.3 0.4 0.5 0.6 0.7 0.8 0.90.00

0.10

0.20

0.30

0.40

0.50

0.60 Single scattering co-albedo

A0 A1 A3 A2

Wavelength. mm

Sin

gle

s

ca

tte

rin

g

co

-alb

ed

o

Thin lines –optical thickness of scattering

Thick lines –optical thickness of absorption

Spectral dependence of the single

scattering co-albedo for 4 aerosol

models

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Clear atmosphere. Lidar sounding

Dynamics of the variation of aerosol extinction from lidar observation in SPSU (Donchenko V.K.. Samulenkov D.A.. Melnikova I.N.. Boreysho A.S.. Chugreev A.V. Laser systems of the St.Petersburg State University Resources Center. Possibilities. Problems Statement and the First Results. The contemporary problems of the Earth remote sensing form the Space. Moscow. 2013. Том 10. № 3. p 122-134)

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Wavelength. nmExperiment

355 532 700

St. Petersburg city.

Lidar sounding

0.136 0.842  

The Ladoga Lake

Airborne observations

0.01 0.06 0.15

Peterhoff city.Ground

observations

0.03 0.07 0.09

Experimental values of the aerosol optical thickness in St.Petersburg and suburbs

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Calculation of radiative characteristicsClear atmosphere. Radiative divergence

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00

5

10

15

20

25

Aerosol 0 Аs=0. 0.5. 0.9

A=0Wavelength. mm

Rad

iati

ve d

iverg

en

ce. W

cm

-2

mm

-1

Simulation and airborne observation of radiative divergence for models of Aerosol 0 and 1

16

0.2 0.4 0.6 0.8 10

10

20

30 Aerosol 3

А=0, 80 Kara-Kum 12.10.1983, 70

Wavelength. mm

Radi

ative

di

verg

ence

. W c

m-2

mm

-1

Clear atmosphere. Radiative divergence (continuation)

Simulation (Aerosol 3) and airborne observation of radiative divergence after the sand storm (Melnikova I.. Vasilyev A. Short-wave solar radiation in the Earth atmosphere. Calculation. Observation. Interpretation. Springer-Verlag. Heidelberg. 2004. 350 p.)

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• CLOUD 1 0= 5 and 10 for all wavelength. added to the scattering

optical thickness of the clear atmosphere

• CLOUD 2 2-layer atmosphere : cloud 1 (in layer 0-1 km) + clear layer above the cloud

The partly scattered light falls to cloud top and cloud spherical albedo is assumed as ground albedo for above -cloud layer• CLOUD 3

0 () - Spectral dependent optical thickness

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. m 0.30 0.4 0.5 0.6 0.7 0.8 0.90IIIIII 

(0=10)

CLOUD 1

14.66714.92715.07815.767

10.36410.55410.68011.264 

10.14010.31010.43011.040 

10.11710.28710.42711.037 

10.03610.17610.29610.836 

10.02110.15110.26110.721 

10.01310.14310.25310.713

0IIIIII

0 (0=10)

CLOUD 1 

0.765120.768540.768870.75614

10.999050.996260.96449

10.999030.996170.96377

0.996050.992220.989450.95742

10.999020.996120.96309

10.999020.996100.96269

10.999010.996100.96266

OPTICAL PARAMETERS OF THE CLOUD-1 MODEL

0IIIIII 

(0=5)

CLOUD 1

9.6679.927

10.07810.767

5.3645.5545.6806.264 

5.1405.3105.4306.040 

5.1175.2875.4276.037 

5.0365.1765.2965.836 

5.0215.1515.2615.721 

5.0135.1435.2535.713 

0IIIIII

0 (0=5)

CLOUD 1 

0.643630.651960.654200.64289

10.998200.992960.93614

10.998120.992630.93378

0.992180.984870.979730.92215

10.998070.992450.93146

10.998060.992400.93008

10.9980

60.9924

00.9300

8

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, m 0.30 0.4 0.5 0.6 0.7 0.8 0.9

0IIIIII

4.5454.8054.9565.645

0.3280.5180.6441.228

0.130.3000.4201.030

0.1100.2150.3650.965

0.0320.1720.2920.832

0.0190.1490.2590.719

0.0120.1420.2520.712

0IIIIII

00.242020.280970.296810.31887

10.980700.937890.67427

10.966670.904760.61165

0.545460.930230.849320.58031

10.941860.863010.51923

10.932890.845560.44367

10.929580.841270.43820

OPTICAL PARAMETERS IN THE CLEAR ABOVE-CLOUD LAYER (PZ=1KM)

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, m 0.30 0.40 0.50 0.60 0.70 0.80 0.90

scatt 058 25 16 12 10 10 10

 Rel scatt

(z>0)1.222 0.364 0.140 0.067 0.036 0.021 0.013

0IIIIII

62.66762.80562.95663.645

25.36425.51825.64426.228

16.14016.30016.42017.030

12.07212.21012.35012.96

10.03610.17210.29210.832

10.02110.14910.25910.719

10.01310.14210.25210.712

0IIIIII

0

0.9450270.9449880.9446440.939590

10.9996080.9984400.984749

10.999390.997560.97651

0.999590.999180.996760.96914

10.999020.996110.96307

10.999020.996100.96268

10.999010.996100.96266

OPTICAL PARAMETERS OF THE CLOUD-3 MODEL

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0.2 0.4 0.6 0.8 10

2

4

6

8

10

12

14Optical thickness

А0 А1 А2Wavelength. mm

Opti

cal t

hick

ness

Cloudy atmosphere

Optical thickness of Cloud-1 model (0=10) (upper group of curves) and above-cloud atmosphere (lower group of curves) for 4 Aerosol models

Optical thickness of Cloud-1 and Cloud 3 models

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

20

40

60

80

100

120

Optical thickness for Cloud 1 (red) Cloud 3 (lila)

А0 Cl1 А3 Cl1

Wavelength, mmO

pti

cal

thic

kn

ess

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0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14 Single scattering co-albedo

TAU=10,A0 TAU=10,A1TAU=10,A2 TAU=10,A33: 10 Apr.1971 4: 05 Oct.1972 5: 05 Dec.1972 9: 01 Oct.1972 11: 30 May 1976 6: 24.09.1972 7: 20.04.1985 8: 12.04.1996 1: 12 July 1974 2: 04 Aug 1974NASA 13.09.2000 (T) TAU=5,A0TAU=5,A1 TAU=5,A2TAU=5,A3

Wavelength. mm

Sing

le s

catt

erin

g c

o-al

bedo Single scattering co-albedo

for 4 aerosol models and

Cloud-1 model with optical

thickness 5 and 10

and

experimental data from

(Melnikova I. Vasilyev A.Short-wave solar radiation in the Earth atmosphere. Calculation. Observation. Interpretation. Springer-Verlag. Heidelberg. 2004.

350 p.)

Cloudy atmosphere (continuation)

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Cloudy atmosphere. Radiative divergence

0.25 0.35 0.45 0.55 0.65 0.75 0.85 0.950

2

4

6

8

10

12

14

16

CLOUD 1. 2; Aerosol 1 A=0

Aerosol 2 Cloud 1, 60Ladoga, 24,09,1972, 63Cloud 2, A=0, 60

Wavelength. mm

Radi

ative

di

verg

ence

. W c

m-2

mm

-1

Simulation for Aerosol 1. Cloud 1 (red) and 2 (green) models and results of airborne observation of the radiative divergence above the Ladoga Lake

(Melnikova I.. Vasilyev A. Short-wave solar radiation in the Earth atmosphere. Calculation. Observation. Interpretation. Springer-Verlag. Heidelberg. 2004. 350 p.)

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0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00

10

20

30

40

50

60CLOUD 1. Aerosol 1. 3; A=0. 0.9

Aerosol 2, A=0,9, 60GATE, 04,08,1974, 15GATE, 12,07,1974, 15Ladoga, 20.04.1985, snow, 50Aerosol 3, A=0,9, 60

Wavelength. mm

Ra

dia

tiv

e

div

erg

en

ce

. W c

m-2

mm

-1Cloudy atmosphere. Radiative divergence (continuation)

Simulation for Aerosol 1 and 3). Cloud 1 model and results ofairborne observations of radiative divergence after the sand storm (Sakhara dust) above the Atlantic Ocean and in clean atmosphere above the Ladoga Lake

(Melnikova I.. Vasilyev A. Short-wave solar radiation in the Earth atmosphere. Calculation. Observation. Interpretation. Springer-Verlag. Heidelberg. 2004. 350 p.)

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0.3 0.5 0.7 0.90.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

GATE 12.07.1974 GATE 04.08.1974 Black Sea, 10.04.1971Azov Sea 05.10.1972 Aer 1, A=0, Div, 20 Aer 3, A=0, Div, 20Aer 2, A=0, Div, 20

Wavelength. mm

Re

lativ

e r

ad

iativ

e d

ive

rge

nce

. r.

u..

Simulation (Aerosol 1.2 and 3) for Cloud 3 model and airborne observation of relative radiative divergence in cloudy atmosphere

(Melnikova I.. Vasilyev A. Short-wave solar radiation in the Earth atmosphere. Calculation. Observation. Interpretation. Springer-Verlag. Heidelberg. 2004. 350 p.)

Cloudy atmosphere. Relative radiative divergence. Cloud - 3 model

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  Clear atmosphere

Cloud 1 (Smoothed cloud)

Cloud 2(2-layer atmosphere)

  (1-F)

forsing Aerosol

(1-F) forsing Aerosol

forsing

cloud

(1-F) forsing Aerosol

forsing cloud

Aer=0W/m2

0.761 

0.0 0.4843 

0.0 -0.2767-50.152

0.7743 

0.0 

+0.0133+2.41

Aer=1W/m2

0.7586

-0.0024 -0.435

0.4831

-0.0012-0.2175

-0.2755-49.93

0.534 -0.2403-43.55

-0.2246-40.71

Aer=2W/m2

0.768

+0.0065+1.178

0.492 

+0.0077+1.396

-0.2755-49.93

0.5804 

-0.1949-35.14

-0.1835-33.26

Aer=3W/m2

0.863 

0.1021+18.5

0.6788 

+0.1945+35.25

-0.1843-33.40

0.8219 

+0.0476+8.628

-0.0412-7.468

Local instantaneous radiative forcing (variations of the net flux at the troposphere top)

faeros=[(1-F)Aer 0 - (1-F)]F0

fcloud= [(1-F)clear -(1-F)]F0

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Estimating the heating rate of the atmospheric layer

in the shortwave range

S = 1000 J/(s m2) - the solar constant in shortwave range (0.3–1.0 m);

r = 1 kg/m3 - the air density at the level 800 mb;

Cp = 1005 J/(kg deg) - the specific heat of the dry air in clear atmosphere

Cp = 1952 J/(kg deg) - the specific heat of water vapor at constant pressure;

Cp = 4218 J/(kg deg) - the specific heat of liquid water at 0 C;

The average value Cp = 2392 J/(kg deg) in clouds.

dzdR

rC

S

dtdT

pp

Model dT/dt. degree / day

CLEAR CLOUD

AS 0 0.9 0 0.9Aerosol 1 2.7 3.0 2.7 2.9Aerosol 3 12.3 24.5 5.6 8.3

CONCLUSIONS:

1.Lidar sounding in the Research Park of SPSU provides the construction of adequate optical models of the atmosphere

2.The simplest optical model provides suitable results of radiative characteristics calculation that shows an acceptable accordance with airborne observation

3.These model allows clearly demonstrate influence of chosen optical parameter on radiative characteristics.

4.The presence of aerosols in the atmosphere greatly affects the optical and radiative properties of clouds

5.Even the simple models confirm that simulation of the atmosphere optical and radiative characteristics should accurate account for atmospheric pollution and correct forecast of global environmental changes

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