**8. Changes in integral and aerosol atmospheric turbidity in Trans-Baikal and Central Siberia**

The turbidity factor T and atmospheric aerosol optical thickness AOD for the wavelength 0.55 μ is used in this section as atmospheric transparency characteristics. The series T and AOT were analyzed for the 1976–2010 years for the stations presented in Fig.11.

From Fig. 12, 13 and Table 5 it is evident that AOD and T have the apparent seasonal dependence: maximal values of the aerosol turbidity are observed in spring (mean excess above the year ones is 25%), maximal values of the integral turbidity are observed in summer (mean excess above the year ones is 10%). At the same time the structure of the spatial distribution is similar in April and in July as for AOD so for T. The sources, formed AOD and T spatial distribution: prevailing air circulations, bearing of the aerosol and water vapor rich air masses (and vice versa), "constant" local aerosol sources, antropogenic or natural (for example, the forest or peat fires).

From Fig. 14, 15 it is evident that in July it is exist the constant district in Trans-Baikal region with high AOD (may be the fires); in April a structure of the AOD field is formed by the air masses arriving from the south directions. But in April a structure of the T is not so apparent. In Fig.16 the variation of the month averaged values of FQ - fires quantity (aircraft data) and factor of integral turbidity T are showed. It is observed that FQ have seasonal variations with the maximum value in May, at the same time maximum for T is observed in July. We can also see the growth of T, connected with the El Chichon eruption in 1982 - 1983 years. In Fig.17 the wavelet spectra of the fire quantity ( FQ) and factor of integral turbidity (T) series demonstrate the oscillations by 12 moths period ( in both series) up to 1982-83 years (1982 y. - volcano eruption). Then the oscillations by 6 - 3 month periods are exist in the FQ series, which are connected with the variations of the FQ - fire quantity. Colorbar represents normalized variances.

In Fig.18 the variation of the month averaged values of fires quantity FQ (aircraft data) and factor of integral turbidity T are showed during 1992 -2009 years. It is also observed that the FQ have seasonal variations with the maximum value in May, at the same time maximum for T is observed in July. We can also see the decrease of T, connected with the Pinatubo eruption during 1992-1993 years. In Fig.19 the wavelet spectra of the fire quantity ( FQ) and factor of integral turbidity (T) series demonstrate the oscillations by 12 moths period ( in both series) from 1997 year up to 2005 year ( in FQ series) and up to 2006 year ( in T series) . Then the oscillations by 7- 3 monhs are exist in the FQ series, which may be also connected with the variations of the fire quantity. Colorbar represents normalized variances.

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 19

**Figure 11.** Layout of 17 actinometric stations whose data were analyzed in this section to investigate

**Figure 12.** Spatialdistribution of AOD in Trans-Baikal and Central Siberia region of Russia for the year and season AOD values:year,April,July and October values(from the top to the

bottom), averaging period 1976-2010 years (14 stations).

integral and aerosol atmospheric turbidity variability in Trans-Baikal and Central Siberia.

18 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

**Figure 10.** Spatial distribution of mean values of the turbidity factor *T* for June, July, and August in 1994 – 2009 years (top part) and in summer 2010 year (lower part).

**Figure 10.** Spatial distribution of mean values of the turbidity factor *T* for June, July, and August in

1994 – 2009 years (top part) and in summer 2010 year (lower part).

**Figure 11.** Layout of 17 actinometric stations whose data were analyzed in this section to investigate integral and aerosol atmospheric turbidity variability in Trans-Baikal and Central Siberia.

**Figure 12.** Spatialdistribution of AOD in Trans-Baikal and Central Siberia region of Russia for the year and season AOD values:year,April,July and October values(from the top to the bottom), averaging period 1976-2010 years (14 stations).

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 21

**Figure 14.** Spatial distribution of AOD in Trans-Baikal and Central Siberia region of RF for the July

(top) and April (bottom) values, averaging period 1976-2010 years, 17 stations.

**Figure 13.** Spatial distribution of T in Trans-Baikal and Central Siberia region of Russia for the year and season AOD values: year, April, July and October values (from the top to the bottom), averaging period 1976-2010 years (14 stations).


**Table 5.** Multiyear mean values of the T turbidity factors of the atmospheric aerosol optical thickness (AOD) and their variation coefficients (the period of averaging is 1976–2010)

Variations in the Aerosol Optical Depth Above the Russia from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 21

20 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

1976-2010 years (14 stations).

variation

turbidity

variation

**Figure 13.** Spatial distribution of T in Trans-Baikal and Central Siberia region of Russia for the year and season AOD values: year, April, July and October values (from the top to the bottom), averaging period

AOD 0.14 0.19 0.14 0.09

coefficient % 13 16 15 16

coefficient % 36 43 44 66

(AOD) and their variation coefficients (the period of averaging is 1976–2010)

factor T 2.72 2.76 3.02 2.39

**Table 5.** Multiyear mean values of the T turbidity factors of the atmospheric aerosol optical thickness

YEAR APRIL JULY OCTOBER

**Figure 14.** Spatial distribution of AOD in Trans-Baikal and Central Siberia region of RF for the July (top) and April (bottom) values, averaging period 1976-2010 years, 17 stations.

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 23

**Figure 16.** Fire quantity (FQ) (dotted line) and factor of integral turbidity T (firm line) during 1977 -

**Figure 17.** A result of the one-dimensional wavelet transformation of the two signals: fire quantity FQ (top) and factor of integral turbidity T (bottom) during 1977 -1986 years in Trans-Baikal region.

1986 years in Trans-Baikal region.

**Figure 15.** Spatial distribution of T in Trans-Baikal and Central Siberia region of RF for the July (top) and April (bottom) values, averaging period 1976-2010 years, 17 stations.

**Figure 15.** Spatial distribution of T in Trans-Baikal and Central Siberia region of RF for the July (top)

and April (bottom) values, averaging period 1976-2010 years, 17 stations.

**Figure 16.** Fire quantity (FQ) (dotted line) and factor of integral turbidity T (firm line) during 1977 - 1986 years in Trans-Baikal region.

**Figure 17.** A result of the one-dimensional wavelet transformation of the two signals: fire quantity FQ (top) and factor of integral turbidity T (bottom) during 1977 -1986 years in Trans-Baikal region.

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 25

**Figure 20.** A result of the WTC transformation of the two signals: fire quantity FQ and factor of integral turbidity T during 1987- 1986 years (top) and 1992 – 2009 years (bottom) in Trans-Baikal region. Units of the colorbar are wavelet squared coherencies. An arrow, pointing from left to right signifies in-phase, and an arrow, pointing upward means that T series lags FQ series by 90° (phase angle is 270°).

**Figure 21.** A result of the XWT transformation of the two signals: fire quantity FQ and factor of integral turbidity T during 1987- 1986 years (top) and during 1992 – 2009 years (bottom) in Trans-Baikal region. Units of the colorbar are wavelet squared coherencies. An arrow, pointing from left to right signifies inphase, and an arrow, pointing upward means that T series lags FQ series by 90° (phase angle is 270°).

**Figure 18.** Fire quantity FQ (dotted line) and factor of integral turbidity T (firm line) during 1992 - 2009 years in Trans-Baikal region.

**Figure 19.** A result of the one-dimensional wavelet transformation of the two signals: fire quantity FQ (top) and factor of integral turbidity T (bottom) during 1992 - 2009 years in Trans-Baikal region.

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 25

24 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

years in Trans-Baikal region.

200

400

600

fire quantity and T\*100

800

1000

1200

**Figure 18.** Fire quantity FQ (dotted line) and factor of integral turbidity T (firm line) during 1992 - 2009

<sup>1993</sup> <sup>1994</sup> <sup>1995</sup> <sup>1996</sup> <sup>1997</sup> <sup>1998</sup> <sup>1999</sup> <sup>2000</sup> <sup>2001</sup> <sup>2002</sup> <sup>2003</sup> <sup>2004</sup> <sup>2005</sup> <sup>2006</sup> <sup>2007</sup> <sup>2008</sup> <sup>2009</sup> <sup>0</sup>

year

**Figure 19.** A result of the one-dimensional wavelet transformation of the two signals: fire quantity FQ (top) and factor of integral turbidity T (bottom) during 1992 - 2009 years in Trans-Baikal region.

**Figure 20.** A result of the WTC transformation of the two signals: fire quantity FQ and factor of integral turbidity T during 1987- 1986 years (top) and 1992 – 2009 years (bottom) in Trans-Baikal region. Units of the colorbar are wavelet squared coherencies. An arrow, pointing from left to right signifies in-phase, and an arrow, pointing upward means that T series lags FQ series by 90° (phase angle is 270°).

**Figure 21.** A result of the XWT transformation of the two signals: fire quantity FQ and factor of integral turbidity T during 1987- 1986 years (top) and during 1992 – 2009 years (bottom) in Trans-Baikal region. Units of the colorbar are wavelet squared coherencies. An arrow, pointing from left to right signifies inphase, and an arrow, pointing upward means that T series lags FQ series by 90° (phase angle is 270°).

## **Notice:**

The continuous WT (wavelet transformation) expands the time series into time frequency space. Cross wavelet transform (XWT) finds regions in time frequency space where the time series show high common power. Wavelet coherence (WTC) finds regions in time frequency space where the two time series co-vary (but does not necessarily have high power); See

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 27

averaged special-time changes (standard deviations from the all year-averaged values of AOD for all stations) are 0.04 and are equal to mean space changes (standard

3. Minimum annual AOD values for European and Asian parts of Russia are, respectively:

4. "Purification" of the atmosphere from aerosol is caused by the absence of large volcanic eruptions and by industrial "calm" conditions during the last decades. The mean AOD for the last 15 years {[AOD (1976-1994 ) – AOD (1995- 2010)] / AOD (1976-2010)}100%=28% is lower than in the preceding 19 years. Negative tendencies are almost similar for remote and urban (as well as for rural) stations; they are less pronounced in the fall than in spring

5. Local effect of the AOD increase due to volcanic eruptions can reach 100%, while the

The study was supported by the Russian Foundation for Basic Research, project № 10-05- 01086. I thank Academician G. S. Golitsyn for helpful remarks; I am helpful to my close colleague Makhotkina E.L. for herhelp in preparing and analysis of the experimental data.

Abakumova, G.; Gorbarenko, E.; Chubarova, N. (2006 ). Estimation of Determination Accuracy of Atmosphere Aerosol Optical Thickness and Moisture Content by Data of Standart Observations on the Base of Comparison with Measurements by Solar Photometer SIMEL, Proc. of the Intern. Symp. of SNG Countries on Atmospheric Radiation MSAR-2006, 27–30 June 2006 (St.-Petersb. Gos. Univ., St.-Petersburg, 2006),

All Russia Meeting on the Status of the Air Basin in Moscow and European Russia under Extreme Weather Conditions in Summer 2010. (2010) http://www.ifaran.ru/

Grinsted, A.; Moore, J.; Jenrejeva, S. (2004). Application of the cross wavelet transform and wavelet coherence to geophysical time series, *Nonlinear Processes Geophys.,* 11, 561-566

Holben, B.; Eck, T.; Slutsker, I. et al. (1998). AERONET: a Federated Instrument Network

and Data Archive for Aerosol Characterization, *Rem. Sens. Envir.*66, 1–16

(or http:www.pol.ac.uk/research/ waveletcoherence/)

deviations of mean AOD over all stations) which are found to be 0.03;

average effects, within our consideration period, are of some percents.

*Oboukhov Institute of Atmospheric Physics, RussianAcademy of Science, Russia* 

0.03 and 0.02;

and summer;

**Author details** 

**Acknowledgement** 

**10. References** 

pp. 43–44

messaging/forum/

Inna Plakhina

(Grinsted et al., 2004; Jevrejeva, 2003)
