Research ArticleCLIMATE CHANGE

Record Balkan floods of 2014 linked to planetary wave resonance

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Science Advances  15 Apr 2016:
Vol. 2, no. 4, e1501428
DOI: 10.1126/sciadv.1501428
  • Fig. 1 Daily precipitation averaged over the BHSC region during the first half of 2014, showing clusters of heavy rainfall in April and around 3 May (dark blue), before the record-breaking rainfall events associated with cyclone Yvette (14 May; dark blue).

    Horizontal lines indicate monthly means for April and May 2014 (dashed) and their climatology (dotted).

  • Fig. 2 Accumulated rainfall (blue colors) over southeastern Europe from 13 to 16 May 2014 (in millimeters) and the position of cyclone Yvette tracked by its lowest core pressures (red line).

    Large red dots represent the position at 12:00 a.m. with the date labeled, and small red dots indicate positions at 6:00 a.m., 12:00 p.m., and 6:00 p.m.

  • Fig. 3 Increased heavy rainfall days over the BHSC region during spring.

    (A) Daily rainfall distribution for days in MAMJ (dots) plus linear regressions of the mean, median, and the 95th and 99th quantile for 1950–2014. (B) Linear trend of different quantiles in daily rainfall during spring showing strong and significant trends in the upper tail. (C) Number of days exceeding the 95th and 99th rainfall percentile during spring in the BHSC region.

  • Fig. 4 Upper-level hemispheric circulation in May 2014.

    (A) Total wind field (in meters per second) at 300 mb over the Northern Hemisphere mid-latitudes on 13 May (daily mean). Color displays the magnitude of the flow, and arrows indicate direction. (B) Meridional component of the wind speed (in meters per second) averaged from 6 to 20 May 2014, revealing a quasi-stationary wave 6 pattern. (C) Spectral contributions of different wave numbers to the meridional wind field averaged from 35°N to 60°N and from 6 to 20 May 2014. (D) Latitudinal distribution of the square of the stationary wave number given by (l2a2 + k2), which gives the location of possible turning points for any given k indicated on the right vertical axis. It shows that a waveguide for wave number 6 forms from 34°N to 40°N (dashed lines). The vertical dashed black lines indicate the latitudinal positions of the turning points for wave number 6 as given by the crossing of the horizontal dashed black lines with the right y axis.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/4/e1501428/DC1

    Amplitude calculation

    fig. S1. Daily precipitation totals (in millimeters) for several days of May 2014.

    fig. S2. Anomalies for mean volumetric soil water layers (soil moisture) in April and May 2014.

    fig. S3. Spring (MAMJ) Goddard Institute for Space Studies surface temperature anomalies over the region extending from 12°E to 28°E and from 32°N to 46°N showing that warming in this region has been about 1°C since 1950.

    References (3840)

  • Supplementary Materials

    This PDF file includes:

    • Amplitude calculation
    • fig. S1. Daily precipitation totals (in millimeters) for several days of May 2014.
    • fig. S2. Anomalies for mean volumetric soil water layers (soil moisture) in April
      and May 2014.
    • fig. S3. Spring (MAMJ) Goddard Institute for Space Studies surface temperature
      anomalies over the region extending from 12°E to 28°E and from 32°N to 46°N
      showing that warming in this region has been about 1°C since 1950.
    • References (38–40)

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