Observatory of Environmental Safety Resource Center, Research Park. St.Petersburg. Russia.

Transcription

1 Correct atmospheric optics modelling: Theory and Experiment Irina Melnikova Observatory of Environmental Safety Resource Center, Research Park St.Petersburg State University St.Petersburg. Russia. 1

2 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 2

3 Optical parameters Optical thickness of the clear atmosphere : τ = τ a.sc + τ a.ab ab + τ R + τ m.ab. τ a.sc the optical thickness of aerosol scattering. τ a.ab ab - the optical thickness of aerosol absorption. τ R - the optical thickness of molecular scattering. τ m.ab - the optical thickness of molecular absorption; Cloud optical thickness τ Single scattering albedo: for clear atmosphere ω = (τ a.sc + τ R )/τ ; For cloudy atmosphere ω = (τ + τ a.sc + τ R )/( τ + τ ) ; The phase function asymmetry parameter: g=. for clear atmosphere and g=.85 for cloud atmosphere; The ground albedo A s 3

4 1..9 y = 7E-5x Ground albedo y = -9E-7x 2 +.1x WATER SAND SNOW Wavelength. nm y = 3E-7x 2 -.x 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 ) 4

5 Data of the SPSU RC lidar is used for aerosol optical thickness modelling Elastic channels Aerosol lidar Raman channels Multiwavelength lidar Polarization filter 355 nm Doppler (wind) lidar Tunable titan-sapphier lasers (at the mobile complex) 5

6 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

7 Stationary lidar system

8 Aerosol lidar 164 nm - 4 mj 532 nm - 16 mj 355 nm - 1 mj Doppler (wind) lidar for wind velocity and direction profile Pulse repetition rate 1kHz 8

9 signal Lidar 38 Screenshot of the received Lidar signal _Anlg 2 355_PhCt 3 355_De_Anlg 4 355_De_PhCt 5 532_Anlg 6 532_PhCt 7 387_Anlg 8 387_PhCt 9 68_Anlg 1 68_PhCt _Anlg 12 48_PhCt E+ 2E+3 4E+3 6E+3 Distance [m] 8E+3 1E+4 1.2E+4 1.4E+4 9

10 Lidar sounding above St. Petersburg city The extinction coefficient above St. Petersburg 25 March 213. The vertical profile till 4 km and 25 km during 1 hour λ=532 nm The maximum of hat pollution at.7 km, disappeared during 45 min (15:3-16:15) α(z).56km -1 The stratosphere aerosol Yunge layer at 17-22km α(z).15km -1 Total optical thickness is τ =.735 1

11 Mol scatt VALUES OF OPTICAL PARAMETERS OF THE CLEAR ATMOSPHERE λ. µm τ Rel(z=) Aer τ a scatt. τ a abs..25 Aer I τ a scatt τ a abs.1 Aer III τ a scatt.7 τ a abs I ω III I III τ

12 Clear atmosphere 2. Optical thickness.6 Single scattering co-albedo Optical thickness Sing gle scattering co-albedo Wavelength. µm A-1 A-2 A-3 Thin lines optical thickness of scattering Thick lines optical thickness of absorption Wavelength. µm A A1 A3 A2 Spectral dependence of the single scattering co-albedo for 4 aerosol models 12

13 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 Том p ) 13

14 Experimental values of the aerosol optical thickness in St.Petersburg and suburbs Wavelength. nm Experiment St. Petersburg city. Lidar sounding The Ladoga Lake Airborne observations Peterhoff city. Ground observations

15 Calculation of radiative characteristics Clear atmosphere. Radiative divergence Radiative div vergence. Wcm -2 µm Aerosol Аs= Wavelength. µm A= A=.5 Simulation and airborne observation of radiative divergence for models of Aerosol and 1 15

16 Clear atmosphere. Radiative divergence (continuation) Radiat tive divergence. Wcm -2 µm Aerosol Wavelength. µm А=, 8 Kara-Kum , 7 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 p.) 16

17 CLOUD 1 τ = 5 and 1 for all wavelength. added to the scattering optical thickness of the clear atmosphere CLOUD 2 2-layer atmosphere : cloud 1 (in layer -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 τ (λ) - Spectral dependent optical thickness 17

18 OPTICAL PARAMETERS OF THE CLOUD-1 MODEL I II III I II III I II III I II III λ. µm τ Σ (τ =1) CLOUD ω (τ =1) CLOUD τ Σ (τ =5) CLOUD 1 ω (τ =5) CLOUD

19 I II III OPTICAL PARAMETERS IN THE CLEAR ABOVE-CLOUD LAYER (P Z=1 λ, µm τ Σ =1KM) III I II III ω

20 OPTICAL PARAMETERS OF THE CLOUD-3 MODEL λ, µm τ scattτ Rel τ (z>) scatt τ Σ τ Σ I II III I II III ω

21 14 12 Cloudy atmosphere 12 Optical thickness 1 Optical thickness for Cloud 1 (red) Cloud 3 (lila) Optical thickness Op ptical thickness Wavelength. µm А А1 А2 А Wavelength, µm Optical thickness of Cloud-1 model (τ =1) (upper group of curves) and above-cloud atmosphere (lower group of curves) for 4 Aerosol models А Cl1 А3 Cl1 А3-CL3 Optical thickness of Cloud-1 and Cloud 3 models 21

22 Single scattering co-albedo Cloudy atmosphere (continuation) Single scattering co-albedo Single scattering co-albedo for 4 aerosol models and Cloud-1 model with optical thickness 5 and 1 and.2 experimental data from Wavelength. µm TAU=1,A TAU=1,A1 TAU=1,A2 TAU=1,A3 3: 1 Apr : 5 Oct : 5 Dec : 1 Oct : 3 May : : : : 12 July : 4 Aug 1974 NASA (T) TAU=5,A TAU=5,A1 TAU=5,A2 (Melnikova I. Vasilyev A. Short-wave solar radiation in the Earth atmosphere. Calculation. Observation. Interpretation. Springer-Verlag. Heidelberg p.) 22

23 Cloudy atmosphere. Radiative divergence Radiative di ivergence. Wcm -2 µm CLOUD 1. 2; Aerosol 1 A= Wavelength. µm Aerosol 2 Cloud 1, 6 Ladoga, 24,9,1972, 63 Cloud 2, A=, 6 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 p.) 23

24 Cloudy atmosphere. Radiative divergence (continuation) Radiative divergence. W cm -2 mm CLOUD 1. Aerosol 1. 3; A=..9 Simulation for Aerosol 1 and 3). Cloud 1 model and results of airborne observations of radiative divergence after the sand storm (Sakhara dust) above the Atlantic Ocean and in clean atmosphere above the Ladoga Lake Wavelength. µm Aerosol 2, A=,9, 6 GATE, 4,8,1974, 15 GATE, 12,7,1974, 15 Ladoga, , snow, 5 Aerosol 3, A=,9, 6 (Melnikova I.. Vasilyev A. Short-wave solar radiation in the Earth atmosphere. Calculation Observation. Interpretation. Springer-Verlag. Heidelberg p.) 24

25 1..9 Cloudy atmosphere. Relative radiative divergence. Cloud - 3 model Relat tive radiative divergence. r.u Wavelength. µm GATE GATE Black Sea, Azov Sea Aer 1, A=, Div, 2 Aer 3, A=, Div, 2 Aer 2, A=, Div, 2 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 p.) 25

26 Local instantaneous radiative forcing (variations of the net flux at the troposphere top) Clear atmosphere (1-F ) forsing Aerosol Cloud 1 (Smoothed cloud) (1-F ) forsing forsing Aerosol cloud Cloud 2 (2-layer atmosphere) (1-F ) forsing forsing Aerosol cloud Aer= W/m Aer= W/m Aer= W/m Aer= W/m f aeros =[(1-F ) Aer - (1-F )]F f = cloud [(1-F ) clear -(1-F )]F 26

27 Estimating the heating rate of the atmospheric layer in the shortwave range S λ = 1 J/(s m 2 ) - the solar constant in shortwave range (.3 1. µm); r = 1 kg/m 3 - the air density at the level 8 mb; C p = 15 J/(kg deg) - the specific heat of the dry air in clear atmosphere C p = 1952 J/(kg deg) - the specific heat of water vapor at constant pressure; dt dt S rc dr dz C p = 4218 J/(kg deg) - the specific heat of liquid water at C; The average value C p = 2392 J/(kg deg) in clouds. Model CLEAR p = λ p dt/dt. dt. degree / day CLOUD A S.9.9 Aerosol Aerosol

28 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 28 forecast of global environmental changes

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