**6. Effects of the volcano eruptions**

10 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

**Figure 5.** Time variations in the annual values of AOD and in the flux of direct solar radiation for the Sun's height 30°: (a) multiyear variations in the annual values of AOD for three stations (Krasnodar (1), Chita (2), and Okhotsk (3)) and (b) multiyear variations in the annual values of AOD and in the annual mean of direct solar radiation flux at the Sun's height 30° for the two stations with the maximum and minimum means of AOD. For both graphs, the period under analysis is 1976– 2010. Krasnodar(*1*  corresponds to AOD and 3corresponds to direct radiation), Solyanka ( *2* corresponds to AOD and *4* 

(b)

(a)

corresponds to direct radiation)

## **6.1. Influence of the volcano eruptionson AOD**

Fig. 7 gives a "long" (45 years) series of annual means of AOD for the Ust' Vym station (62.2°N, 50.4°E), which demonstrates a characteristic multiyear trend of variations in the annual values of AOD and its response to stratospheric disturbances. The four powerful volcanic episodes— Agung ( 8°S, 116°E, 1963), Fuego (14°N, 91°W, 1974), El Chichon (17°N, 93°W, 1982), and Pinatubo (15°N, 120°W, 1991)—are clearly pronounced and quantitatively estimated. In particular, the maximum effect observed a year after the eruptions is 100% (in deviations from the multiyear norm); throughout the year, its attenuation occurs with the dissipation and transformation of the stratospheric aerosol layer. A decrease in the AOD values for 1995–2006 is also clearly manifested. Such a character of multiyear variations in the annual values of AOD is characteristic of most stations and is, to a great extent, determined by the four powerful volcanic eruptions in the latter half of the 20th century, because seasonal and local disturbances caused by the effects of tropospheric aerosol, when annually averaged, become leveled and have almost no influence on the distribution of the multiyear values of AOD.

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 13

ΔТ2%=100\*(Ti-Tm)/Tm ΔТ2= (Ti-Tm)/σ El Chichon Pinatubo El Chichon Pinatubo

T (1976-2005) **/** Tstab (1976-2005)

North of EPR 20 32 1.9 3.0 Central part of EPR 18 30 1.8 3.1 Southof EPR 14 20 1.8 2.6 Ural 26 23 2.6 2.3 West Siberia 19 35 1.7 3.1 North–east of APR 19 35 1.7 3.2 Central part of APR 19 27 2.0 2.8 Southof EPR 22 38 1.8 3.0 Far East of the Russia 15 36 1.5 3.4 **Table 2.** Anomalies of the mean month values of the Т during post volcanic period after the eruptions

Month 1 2 3 4 5 6 7 8 9 10 11 12 Year North of EPR 1,03 1,03 1,04 1,03 1,03 1,02 1,02 1,03 1,02 1,04 1,03 Central part ofEPR 1,04 1,05 1,04 1,04 1,03 1,02 1,02 1,02 1,01 1,02 1,02 1,05 1,03 Southof EPR 1,04 1,04 1,03 1,03 1,02 1,02 1,01 1,01 1,01 1,01 1,03 1,04 1,02 Ural 1,05 1,06 1,06 1,04 1,03 1,03 1,02 1,02 1,03 1,02 1,05 1,05 1,04 West Siberia 1,03 1,05 1,04 1,03 1,04 1,03 1,02 1,03 1,04 1,03 1,02 1,02 1,03 North–east ofAPR 1,07 1,07 1,04 1,03 1,03 1,03 1,03 1,02 1,02 1,03 1,05 1,07 1,04 Central part ofAPR 1,04 1,02 1,02 1,02 1,02 0,98 0,98 1,02 1,01 1,00 1,06 1,04 1,02 Southof EPR 1,06 1,04 1,04 1,04 1,03 1,02 1,02 1,02 1,02 1,02 1,03 1,03 1,03 Far East of the Russia 1,06 1,05 1,04 1,03 1,02 1,02 1,01 1,01 1,01 1,02 1,03 1,05 1,03

Month 1 2 3 4 5 6 7 8 9 10 11 12 Year North of EPR 1,11 1,10 1,10 1,08 1,07 1,07 1,06 1,06 1,06 1,14 1,07 Central part of EPR 1,06 1,07 1,08 1,09 1,10 1,08 1,08 1,07 1,06 1,02 1,09 1,10 1,07 Southof EPR 1,10 1,09 1,06 1,07 1,05 1,04 1,03 1,02 1,03 1,04 1,10 1,14 1,06 Ural 1,08 1,12 1,14 1,11 1,09 1,08 1,07 1,08 1,14 1,08 1,07 1,08 1,06 West Siberia 1,05 1,10 1,11 1,09 1,11 1,10 1,08 1,06 1,08 1,13 1,07 1,08 1,08 North–east of APR 1,03 1,13 1,11 1,08 1,09 1,08 1,08 1,07 1,09 1,11 1,13 1,02 1,09 Central part of APR 1,08 1,07 1,08 1,09 1,10 1,08 1,08 1,07 1,06 1,05 1,13 1,11 1,06 Southof EPR 1,09 1,08 1,09 1,10 1,08 1,05 1,05 1,05 1,05 1,04 1,06 1,06 1,07 Far East of the Russia 1,12 1,11 1,09 1,06 1,06 1,07 1,06 1,03 1,04 1,04 1,08 1,12 1,07 **Table 3.** Estimation of the volcano contribution into the multiyearmean values of the factor turbidity and aerosol optical depth during 1976 - 2005 years period; EPR -- the European Part of Russia; APR --

AOD (1976-2005) /AODstab.(1976-2005)

Region

of El Chichon and Pinatubo.

theAsian Part of Russia.

**Figure 7.** Example of multiyear variations in the annual means of AOD (red) and their deviations from the averaged (blue),

d *=*100%\*(AODi - AODm) / AODm.

## **6.2. Influence of the volcano eruptions on the turbidity factor (T)**

From the data of 80 observation stations over the Russia the special analysis of the turbidity factor (T) have been fulfilled: time variations during 1976-2010 y.y. and during 1994-2010 y.y. have been estimated. For the 9 regions over all Russia territory long-term trends for the characteristics of the integral atmospheric transparency have described. For all regions during 1976-2010 y.y. negative Т and AODvariations tendencies exist; during 1994-2010 y.y. negative Т2 иАОТ variations tendencies remain at the same level as during 1994-2009 y.y. practically for all Russia regions. So, for the most part of Russia territory the conditions of the relatively high atmospheric transparency (in 1994-2010 y.y. – 17 years) remain as well as the atmospheric transparency increase within this 17 years time interval remain. Comparatively stable, longterm and intensive variations (increase) take place in postvolcanic periods: 1) for El Chichon eruption (1982 year, April) – from the last 1982 year to October of 1983 year; 2) for Pinatubo (1991 year, June) – from the September of 1991 year to July of 1993 year. Anomalies of the mean month values of the Т2 during these "post volcanic" period after the eruptions of El Chichon and Pinatubo are presented in Table 2.

Estimations of the volcano contribution into the multiyear mean values (for the months and year) of the factor turbidity and aerosol optical depth during 1976 – 2005 years period and durings the so called "stable" 1976-2005 years period (without 1982, 1983, 1991,1992, 1993 years) are pointed in Table 3. It is obvious that effects, connected with eruptions lead to increase of the multiyear mean values equal 3% (from 1% - to 7%) for Tand equal 7% (from 2% - to 12%) for AOD.

Variations in the Aerosol Optical Depth Above the Russia from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 13


12 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

the averaged (blue),

2% - to 12%) for AOD.

**Figure 7.** Example of multiyear variations in the annual means of AOD (red) and their deviations from

d *=*100%\*(AODi - AODm) / AODm.

From the data of 80 observation stations over the Russia the special analysis of the turbidity factor (T) have been fulfilled: time variations during 1976-2010 y.y. and during 1994-2010 y.y. have been estimated. For the 9 regions over all Russia territory long-term trends for the characteristics of the integral atmospheric transparency have described. For all regions during 1976-2010 y.y. negative Т and AODvariations tendencies exist; during 1994-2010 y.y. negative Т2 иАОТ variations tendencies remain at the same level as during 1994-2009 y.y. practically for all Russia regions. So, for the most part of Russia territory the conditions of the relatively high atmospheric transparency (in 1994-2010 y.y. – 17 years) remain as well as the atmospheric transparency increase within this 17 years time interval remain. Comparatively stable, longterm and intensive variations (increase) take place in postvolcanic periods: 1) for El Chichon eruption (1982 year, April) – from the last 1982 year to October of 1983 year; 2) for Pinatubo (1991 year, June) – from the September of 1991 year to July of 1993 year. Anomalies of the mean month values of the Т2 during these "post volcanic" period after the eruptions of El Chichon and Pinatubo are presented in Table 2.

Estimations of the volcano contribution into the multiyear mean values (for the months and year) of the factor turbidity and aerosol optical depth during 1976 – 2005 years period and durings the so called "stable" 1976-2005 years period (without 1982, 1983, 1991,1992, 1993 years) are pointed in Table 3. It is obvious that effects, connected with eruptions lead to increase of the multiyear mean values equal 3% (from 1% - to 7%) for Tand equal 7% (from

**6.2. Influence of the volcano eruptions on the turbidity factor (T)** 

**Table 2.** Anomalies of the mean month values of the Т during post volcanic period after the eruptions of El Chichon and Pinatubo.


**Table 3.** Estimation of the volcano contribution into the multiyearmean values of the factor turbidity and aerosol optical depth during 1976 - 2005 years period; EPR -- the European Part of Russia; APR - theAsian Part of Russia.

The examples of the long-term time variations for Tand AOD in the differentRussia regions:North,Central part and South of theEuropean Part of the Russia andRussianFar East are presented in Fig. 8.

Variations in the Aerosol Optical Depth Above the Russia

from the Data Obtained at the Russian Actinometric Network in 1976–2010 Years 15

The events of summer 2010 (abnormal heat and forest and peat fires) evidently changed both the average values of air turbidity and the character of its spatial variations. Therefore, our estimates are of interest in the analysis (All Russia Meeting, 2010) of the situation on the European Part of Russia (EPR) in summer 2010. Fig. 9 presents the coordinates of solar radiometry stations on the EPR (Luts'ko et al., 2001); data from it were used in this work. The long-term annual average (over a "post-volcanic" period of 1994–2009 years) values *Т*postfor summer months and the corresponding monthly values *Т*2010for 2010 are given in Table 4, along with the monthly average maxima of *Т*and the relative difference (%) *D* = (*Т*2010 – *Т*post)/*Т*post. As it is seen, the average July and August *Т*in 2010 and in the "postvolcanic" period differ by –6% and +4%, respectively (the differences *D* vary from – 28% to +11% of the average value for a certain station in June and from – 22% to +25% in July). The value of *D* = (*Т*2010 – *Т*post)/*T*postis 14% in August (for the region) and varies from –

**Figure 9.** Layout of 18 actinometric stations on the EPR whose data will be analyzed in this section.

Spatial variations in Тare shown in Fig. 10. To interpolate the data of the stations to the whole region under study , we also used features of the MATLAB package, i.e., the option for creating a homogeneous grid for the EPR region under study, the option of bilinear (horizontal and vertical) interpolation of data from 18 stations to the territory (40°–70° N, 30°–60° E), and the projection of the function Т*=* F(ϕ, λ) (where ϕand λare the longitude and latitude, respectively, for each of the observational points) to the grid. The spatial distribution of the mean Tpost(for June, July, and August) for the "postvolcanic" period corresponds to the results obtained earlier (Plakhina et al., 2009) for the long-term annual average AOD. In this period, Tpostquasi -monotonically decreased from southwest to

11% to +48% for certain stations.

**Figure 8.** Examples of the long-term time variations for T(blue)and AOD (green) in the different Russia regions: South of theEuropean Part of the Russia (1)and North part (2).
