Relation of long-term dynamics of atmospheric circulation - PowerPoint PPT Presentation

Relation of long-term dynamics of atmospheric circulation parameters, in terms of cyclones, to surface air temperature over Siberia Podnebesnykh N.V., Ippolitov I.I. Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences (IMCES SB RAS), Tomsk, Russia ¡

Relationship of long-term dynamics of atmospheric circulation parameters, in terms of cyclones, with surface air temperature over Siberia has been investigated.

The territory of the study ¡ The region bounded by the coordinates 50-70°N, 60-110°E

Initial data Data analysis was carried out using surface synoptic maps (0, 6, 12, 18 UTC) for the period of 1976-2011. To calculate the temperature fields daily observational at 169 stations located in the selected area were used (data, ftp://ftp.cdc.noaa) for 1976-2011.

Interannual variability of surface air temperature (a) and numbers of cyclones (b) over Siberia for the period 1976-2011 Average annual trend of surface air temperature is 0,29°C/10 years over the whole period 1976-2011. Positive temperature trend is observed throughout the year, except January, November and December. Figure shows air temperature which is in antiphase with the progress of the number of cyclones, except last few years. ¡

Number of cyclones moved with different motion path over Siberia for the period 1976-2011 40 22 38 W 20 N 36 34 18 32 16 30 14 28 26 12 24 10 22 20 8 18 6 16 14 4 12 2 10 8 0 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 32 In the periods of rising surface air temperature 30 S ¡ 28 over Siberia southern cyclones dominated, and 26 24 in the period of its decrease - northern 22 cyclones. During the period 2003-2011 of 20 18 sustained growth in surface air temperature 16 14 increase of zonal circulation is observed. 12 10 8 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 Trend of western cyclones number is negative (-0.1/10 years), for northern cyclones and southern cyclones it is positive (1.4/10 years and 0.3/10 years, correspondingly).

Interannual variability numbers of cyclones over Siberia for the period 1976-2011 The total number of cyclones was 1704 over the period. The average annual number of cyclones is 47. The seasonal variation of the number of cyclones has pronounced with maximum in the spring (May), and minimum in summer (July).

Interannual variability the average pressure in the center of the cyclone over Siberia for the period 1976-2011 Its value varies from 997.4 hPa to 1006.0 hPa, the average pressure in the center of the cyclone is 1001.2 hPa. By the end of the period the pressure in the center of cyclones has slightly reduced. As for interannual pressure in the cyclones during the second half of the period it is less than that in the first half. Thus, we can suggest that in the second half cyclones became deeper.

Thank you for your attention ¡