Adjustment of extreme rainfall statistics accounting for multidecadal climate oscillations

Summary Rainfall extremes exhibit temporal clustering at multi-decadal time scales, most probably as a result of persistence in large scale atmospheric circulation over such time scales. Analysis of a 107-year time series of 10 min rainfall intensities since 1898 at Uccle, Brussels, has shown that the 1960s and the 1990–2000s had a higher frequency and amplitude of high rainfall intensities at various time scales in the range between 10 min and 1 month. These periods are alternated with periods of lower rainfall quantiles, e.g. in the 1970–1980s. The climate oscillations have to be accounted for when calculating extreme rainfall statistics, e.g. IDF relationships and synthetic storms commonly applied on the basis of urban drainage systems design. The importance of this and how this climate oscillation accounting can be done is demonstrated in this paper based on the Uccle rainfall data. Old and new IDF statistics, based on, respectively, shorter and longer rainfall series have been compared. It is shown that recent increases in rainfall statistics should not necessarily be attributed to climate change but may also be due to a different positioning of the periods with available rainfall data in comparison with the climate oscillation high and low periods. Comparison of old IDF statistics based on the period 1967–1993 versus new statistics based on the full period 1898–2007 or the period 1970–2007 covering one climate oscillation cycle, shows 7.5% difference in extreme rainfall quantiles for return periods higher than 1 year. Adjustment with +7.5% is required to remove the bias in the old rainfall design values in comparison with the long-term statistics.

[1]  G. Hegerl,et al.  Human contribution to more-intense precipitation extremes , 2011, Nature.

[2]  Anders Moberg,et al.  Daily dataset of 20th‐century surface air temperature and precipitation series for the European Climate Assessment , 2002 .

[3]  Neville Nicholls,et al.  Trends in extreme daily rainfall and temperature in Southeast Asia and the South Pacific: 1961–1998 , 2001 .

[4]  Gaston R. Demarée,et al.  Le pluviographe centenaire du plateau d'Uccle: son histoire, ses données et ses applications , 2003 .

[5]  Alberto M. Mestas-Nuñez,et al.  The Atlantic Multidecadal Oscillation and its relation to rainfall and river flows in the continental U.S. , 2001 .

[6]  N. Verhoest,et al.  Analysis Of A 105‐year time series of precipitation observed at Uccle, Belgium , 2006 .

[7]  Kevin E. Trenberth,et al.  Signal Versus Noise in the Southern Oscillation , 1984 .

[8]  J. Southon,et al.  Millennial-scale storminess variability in the northeastern United States during the Holocene epoch , 2002, Nature.

[9]  M. Rusticucci,et al.  Trends in Total and Extreme South American Rainfall in 1960–2000 and Links with Sea Surface Temperature , 2006 .

[10]  D. Gong,et al.  Definition of Antarctic Oscillation index , 1999 .

[11]  Andrew Metcalfe,et al.  Non‐stationarity in rainfall and temperature in the Murray Darling Basin , 2011 .

[12]  J. Wallace,et al.  A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production , 1997 .

[13]  Vincent R. Gray.  Climate Change 2007: The Physical Science Basis Summary for Policymakers , 2007 .

[14]  N. Diffenbaugh,et al.  Higher Hydroclimatic Intensity with Global Warming , 2011 .

[15]  Daniel R. Cayan,et al.  ENSO and Hydrologic Extremes in the Western United States , 1999 .

[16]  A. Grimm,et al.  ENSO and Extreme Rainfall Events in South America , 2009 .

[17]  S. George Philander,et al.  Geophysical Interplays. (Book Reviews: El Nino, La Nina, and the Southern Oscillation.) , 1990 .

[18]  A. Gershunov.  ENSO Influence on Intraseasonal Extreme Rainfall and Temperature Frequencies in the Contiguous United States: Implications for Long-Range Predictability , 1998 .

[19]  R A Kerr,et al.  A North Atlantic Climate Pacemaker for the Centuries , 2000, Science.

[20]  J. Olsson,et al.  Climate change impact assessment on urban rainfall extremes and urban drainage: Methods and shortcomings , 2012 .

[21]  Patrick Willems,et al.  Bias correction in hydrologic GPD based extreme value analysis by means of a slowly varying function , 2007 .

[22]  M. Haylock,et al.  Observed coherent changes in climatic extremes during the second half of the twentieth century , 2002 .

[23]  Clint J. Keifer,et al.  Synthetic Storm Pattern for Drainage Design , 1957 .

[24]  David W. J. Thompson,et al.  Interpretation of Recent Southern Hemisphere Climate Change , 2002, Science.

[25]  Jeff Knight,et al.  A signature of persistent natural thermohaline circulation cycles in observed climate , 2005 .

[26]  B. Goswami,et al.  A dipole mode in the tropical Indian Ocean , 1999, Nature.

[27]  David R. Easterling,et al.  Long-Term Trends in Extreme Precipitation Events over the Conterminous United States and Canada , 1999 .

[28]  C. Schreck,et al.  Variability of the recent climate of eastern Africa , 2004 .

[29]  D. Cayan,et al.  Heavy Daily Precipitation Frequency over the Contiguous United States: Sources of Climatic Variability and Seasonal Predictability , 2003 .

[30]  P. Willems,et al.  Trends and multidecadal oscillations in rainfall extremes, based on a more than 100‐year time series of 10 min rainfall intensities at Uccle, Belgium , 2008 .

[31]  Bryson C. Bates,et al.  Characterizing and Modeling Temporal and Spatial Trends in Rainfall Extremes , 2009 .

[32]  J. Hurrell.  Decadal Trends in the North Atlantic Oscillation: Regional Temperatures and Precipitation , 1995, Science.

[33]  P. Willems.  Compound intensity/duration/frequency-relationships of extreme precipitation for two seasons and two storm types , 2000 .

[34]  Mathieu Vrac,et al.  Statistical precipitation downscaling for small-scale hydrological impact investigations of climate change , 2011 .

[35]  John C. Rodda,et al.  Guide to Hydrological Practices , 2011 .