The Influence of Dominant Global Climate Phenomena ENSO, NAO, and AO on Climate in Serbia

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Gyles Pearson
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1 European Conference on Applied Climatology September 21, Zurich, Switzerland The Influence of Dominant Global Climate Phenomena ENSO, NAO, and AO on Climate in Serbia Gordana Jovanović, Republic Hydrometeorological Service of Serbia, Belgrade, Kneza Višeslava 66 Irini Reljin, University of Belgrade, School of Electrical Engineering, Branimir Reljin, University of Belgrade, School of Electrical Engineering,

The Influence of ENSO on Climate in Serbia Time series of mean monthly SST for Niňo 3,4 & Serbia 1951-98 3 28 C Sea-surface temperatures of Niňo3,4 region from 1951 to 1998 yr.

2 The Influence of ENSO on Climate in Serbia Time series of mean monthly SST for Niňo 3,4 & Serbia C Sea-surface temperatures of Niňo3,4 region from 1951 to 1998 yr. Warmer than normal El Niňo Average temperature 25.8 C Cooler than normal La Niňa year 3 Temperatures in Serbia from 1951 to 1998 C Average temperature 1.6 C Time series of averaged monthly temperatures in Serbia from 7 representative main meteorological stations year

3 The analyses by the use of FFT Frequency spectra for Niňo 3,4 and Serbia Amplitude FFT spectrum of temperatures in region Nino3, The first harmonic (1 year) The second harmonic (1/2 year) (a) Frequency bin = 1/48 yr -1 Amplitude FFT spectrum of temperatures in the Serbia region The first harmonic (1 year) The second harmonic (1/2 year) (b) Frequency bin = 1/48 yr Niňo 3,4 has particularly enhanced cycles larger than one year - left part of diagram. Teleconnection - simultaneous, recurrent variation of climate elements on large distances.

4 Cross-correlation analyses Temperature spectra of regions Nino3,4 and Serbia Nino 3,4 Serbia year Visual coincidence between these spectra indicates teleconnection of the temperature series Cross-correlation of SSTs of Niňo 3,4 and (1) (2) MTs in Serbia Certain correlation (.157) among the average monthly temperatures in Serbia and in Niňo 3,4 region, with three months delay, has been found. time (months)

5 Fractal and multifractal analyses of series in regions Niňo 3,4 and Europe Fractal processes are repeated in nonperiodic cycles, not predictable, with occurrence of catastrophe sudden and severe changes. Niňo 3,4 and Belgrade diagrams of R/S statistic suggest to fractal nature. Multifractal spectra f( ) The narrowest Niňo 3,4 diagram indicates dominant monofractal nature while Belgrade produces the broadest f( ) spectrum indicating multifractal nature of the process. R/S R/S statistic for temperature anomalies 1 f( ) 1 Niňo3,4 H= Nino34 Tacna Belgrade H= Brest Bourget -1 aggregated time series Belgrade Similarity of diagrams in the middle region might indicate teleconnection.

Serbia is in the area of high EOF values meaning significant NAO influence.

6 NAO Main mode of natural climate variability on Northern Hemisphere during winter The EOF surface pressure chart indicates NAO domination in NH. Great meridional oscillation of air masses. Serbia is in the area of high EOF values meaning significant NAO influence. During December March NAO explains the most of temperature and precipitation variance. NAO index is normalised surface pressure difference between Azores and Island.

The first EOF mode of surface pressure and precipitation indicates to NAO influence There is a resemblance between isolines over wide Atlantic region and in FRY P A L I ] * 46 S O M B O R K I K I N D

7 The first EOF mode of surface pressure and precipitation indicates to NAO influence There is a resemblance between isolines over wide Atlantic region and in FRY P A L I ] * 46 S O M B O R K I K I N D A 46 PA LI] SOM BOR KIKINDA 45 N O V I S A D Z R E N J A N I N V R [ A C B.K A R L O V A C B E O G R A D V.G R A D I S T E 45 NOVI SA D ZRENJA NIN SR.M ITROVICA BEOGRA D VR[ A C L O Z N I C A LOZNICA 44 V A L J E V O Z L A T I B O R P G A S M.P A L A N K A K R A G U J E V A C ] U P R I JA K R A L J E V O K R U [ E V A C C R N I V R H Z A J E ~A R N E G O T I N 44 VA LJEVO PO@EGA ZLA TIBOR SM.PA LA NKA ] UPRIJA KRA LJEVO KRU[ EVA C NEGOTIN P L J E V L J A S J E N I C A K O P A O N I K N I [ SJENICA NI[ 43 L E S K O V A C D I M I T R O V G R A D 43 DIM ITROVGRA D LESKOVA C T I V A T P O D G O R I C A V R A N J E NIK[ I] HERCEGNOVI PODGORICA PE] PRI[ TINA VRA NJE PRIZREN 42 * 42 ULCINJ The first surface pressure EOF mode explains 92,3 % of the variance in winter comparing to % for the whole year. The first EOF precipitation mode explains 58,7 % of the variance (at 32 stations for the period ).

8 Obvious NAO influence on pressure and precipitation field in Serbia and Montenegro NAO index Pressure anomalies Godine 1. Precipitation anomalies 8. NAO index * Godine Time series ( winter) of average monthly values of NAO index and pressure anomalies (at 13 stations) in reference to normal in Serbia and Montenegro. Time series ( winter) of average monthly values of precipitation anomalies (at 32 stations) and NAO index (x1) in relation to normal.

9 Cross-correlation between time series of NAO index and temperature and precipitation.7 Crosscorr NAOInd-BGDTemp, , Dec-March.1 Crosscorr NAOI-Niksic-Rain, , Dec-March Cross-correlation between NAO index and temperature in Belgrade. Max value is,64 (DJFM). Cross-correlation between NAO index and precipitation in Nikšić. Min value is -,53 (DJFM).

10 TRENDS Precipitation trends were much lower since 198 in winter when AO and NAO positive phase were the most active. There was an increase of precipitation for both periods during the year in most of country except on a few stations in the far east. High positive precipitation trends were obtained for Vojvodina which are in agreement with high positive temperature trends for the same period Annual trend Winter trend Annual trend Winter trend BEOGRAD Y =.7x y = -.7x y = 1.1x + 67 y =.8x NIS Y =.1x y = -.5x y = 3.4x y =.2x NOVI SAD Y = 2.8x y = -.3x y = 5.2x y =.6x + 16 SJENICA y = 3.6x y = 1.x y = 8.4x y = 2.8x ZAJECAR y = -3.1x y = -.8x y = -.2x y = -1.x + 139

11 Fractal and Multifractal analyses of SLP time series winter (DJFM) Belgrade YU mod 1 Gibraltar Iceland Azores Azores, Iceland, Gibraltar, Belgrade and first EOF mode in Serbia and Montenegro *Series have no fractal nature since Hurst index is about.5, that indicate to random walk processes. * But, all series are multifractal with relatively narrow spectras f( ). * Belgrade spectra is identical with the First EOF mode of SLP in FRY, as expected. * Iceland has the broadest spectra i.e. most significant MF nature. Azores is following. * Both spectras have two roughnesses that could point to additive processes. * Azores as well as Iceland have maximum spectras when <1 indicating to more intensive oscillations and higher average values.

12 Arctic oscillation (AO) is NAO complement AO is an alternate view of NAO, described as a seesaw pattern in which pressure fluctuates between positive and negative phases at polar and middle latitudes. Wallace (24) argued that NAO is a part of AO since AO involves atmospheric circulation in lower stratosphere during winter up through 6 to 3 miles above surface. Arctic oscillation might be of importance for global warming and of significant impact on climate variability. AO and NAO represent the same teleconnection mode of climate variability for NH since there are no meaningful distinctions between them and their consequences. Their time series are very similar.

13 Daily precipitation in Serbia and NAO, AO index Station name min AO minnao 1 Beograd Dimitrovgrad Gradiste Kikinda Kragujevac Kraljevo Nis Novi Sad Sjenica Sombor Smed.Palan Zajecar A new evidence of NAO and AO influences on climate in Serbia are proved by the cross-correlation between daily NAO and AO index and daily precipitation at 12 stations for the winter period Three to four times higher correlation coefficients for AO (.44 in Kikinda) than for NAO are calculated for Serbian region. It seems that AO phenomenon has stronger impact than NAO. These results should be compared with similar results from other regions.

14 CONCLUSIONS The analyses of time series of SST in Nino 3,4 and Serbia temperatures in frequency domain (FFT) and time domain (crosscorrelation) has been done. The teleconnection among the average monthly temperatures in Serbia and in Niňo 3,4 region, with three months delay, has been proved. The fractal analyses confirm similarity between shapes of the R/S diagrams while multifractal spectra of temperature series suggest teleconnection. SST in Niňo 3,4 has fractal nature. By comparing the observed data from the stations in (former) Yugoslavia with the NAO indices, through several linear and nonlinear methods of analysis, the significant influence of the NAO to the climate is approved (considering pressure, precipitation and temperature regime).

15 CONCLUSIONS contd. The first SLP EOF mode that explains 92,3 % of the variance in winter also indicates to the NAO influence. Cross-correlation between time series of NAO index and temperature is.63 in Belgrade and -.54 in Niksic for precipitation during summer. Precipitation trends were much lower since 198 in winter when AO and NAO positive phase were the most active, as expected. SLP time series for Azores, Iceland, Gibraltar, Belgrade and first EOF mode in Serbia and Montenegro have multifractal nature. The dependence of daily precipitation with AO is higher than with NAO indicies. Three to four times higher correlation coefficients for AO (.44 in Kikinda) than for NAO in Serbian region. It seems that AO phenomenon has stronger teleconnection impact than NAO, but to be more reliable, these results should be compared with similar results from other regions.

The Impact of Teleconnection on Pressure, Temperature and Precipitation in Serbia

International Journal of Remote Sensing Applications Volume 3 Issue 4, December 2013 doi: 10.14355/ijrsa.2013.0304.03 www.ijrsa.org The Impact of Teleconnection on Pressure, Temperature and Precipitation