On the reliability of spatially disaggregated global ensemble rainfall forecasts

Ensemble rainfall forecasts are of high interest for decision making, as they provide an explicit and dynamic assessment of the uncertainty in the forecast. However, for hydrological forecasting, their low resolution currently limits their use to large watersheds. To bridge this gap, various implementations of a spatial statistical downscaling method were compared, bringing Environment Canada's global ensemble rainfall forecasts from a 100 × 70‐km resolution down to 6 × 4‐km while increasing each pixel's rainfall variance and preserving its original mean. This was applied for nine consecutive days of summer 2009 with strong rain events over Quebec City, Canada. For comparison purposes, simpler methods were also implemented such as the bilinear interpolation, which disaggregates global forecasts without modifying their variance.

[1]  W. W. Peterson,et al.  The theory of signal detectability , 1954, Trans. IRE Prof. Group Inf. Theory.

[2]  Robert E. Wernikoff,et al.  A theory of signals , 1958 .

[3]  R. L. Winkler,et al.  Scoring Rules for Continuous Probability Distributions , 1976 .

[4]  Praveen Kumar,et al.  A multicomponent decomposition of spatial rainfall fields: 1. Segregation of large‐ and small‐scale features using wavelet transforms , 1993 .

[5]  Praveen Kumar,et al.  A multicomponent decomposition of spatial rainfall fields: 2. Self‐similarity in fluctuations , 1993 .

[6]  Murugesu Sivapalan,et al.  Scale issues in hydrological modelling: A review , 1995 .

[7]  E. Foufoula‐Georgiou,et al.  Model for multiscale disaggregation of spatial rainfall based on coupling meteorological and scaling descriptions , 1996 .

[8]  E. Foufoula‐Georgiou,et al.  Linkage of scaling and thermodynamic parameters of rainfall: Results from midlatitude mesoscale convective systems , 1996 .

[9]  T. Wigley,et al.  Downscaling general circulation model output: a review of methods and limitations , 1997 .

[10]  E. Foufoula‐Georgiou,et al.  Subgrid‐scale rainfall variability and its effects on atmospheric and surface variable predictions , 1997 .

[11]  R. Buizza.  Potential Forecast Skill of Ensemble Prediction and Spread and Skill Distributions of the ECMWF Ensemble Prediction System , 1997 .

[12]  T. Hamill,et al.  Evaluation of Eta-RSM Ensemble Probabilistic Precipitation Forecasts , 1998 .

[13]  D. Wilks,et al.  The weather generation game: a review of stochastic weather models , 1999 .

[14]  Chong-Yu Xu,et al.  Climate Change and Hydrologic Models: A Review of Existing Gaps and Recent Research Developments , 1999 .

[15]  Ye Hong,et al.  Separation of Convective and Stratiform Precipitation Using Microwave Brightness Temperature , 1999 .

[16]  Chong-yu Xu.  From GCMs to river flow: a review of downscaling methods and hydrologic modelling approaches , 1999 .

[17]  Efi Foufoula-Georgiou,et al.  A space-time downscaling model for rainfall , 1999 .

[18]  R. Deidda.  Rainfall downscaling in a space‐time multifractal framework , 2000 .

[19]  T. Hamill.  Interpretation of Rank Histograms for Verifying Ensemble Forecasts , 2001 .

[20]  D. Stensrud,et al.  Evaluation of a Short-Range Multimodel Ensemble System , 2001 .

[21]  Roberto Buizza,et al.  Accuracy and Potential Economic Value of Categorical and Probabilistic Forecasts of Discrete Events , 2001 .

[22]  Kenneth R. Mylne.  Decision‐making from probability forecasts based on forecast value , 2002 .

[23]  S. Ray.  Evaluation and calibration , 2002 .

[24]  A spatial disaggregation procedure for precipitation , 2002 .

[25]  Nicola Rebora,et al.  A comparison of stochastic models for spatial rainfall downscaling , 2003 .

[26]  R. Buizza,et al.  A Comparison of the ECMWF, MSC, and NCEP Global Ensemble Prediction Systems , 2005 .

[27]  R. Buizza,et al.  Flood forecasting using medium-range probabilistic weather prediction , 2005 .

[28]  U. Damrath,et al.  Probabilistic precipitation forecasts from a deterministic model: a pragmatic approach , 2005 .

[29]  Taha B. M. J. Ouarda,et al.  Méthodes de désagrégation appliquées aux Modèles du Climat Global Atmosphère-Océan (MCGAO) , 2007 .

[30]  Nicola Rebora,et al.  RainFARM: Rainfall Downscaling by a Filtered Autoregressive Model , 2006 .

[31]  E. Roulin,et al.  Skill and relative economic value of medium-range hydrological ensemble predictions , 2006 .

[32]  Zbynek Sokol,et al.  A radar-based verification of precipitation forecast for local convective storms , 2007 .

[33]  Hayley J. Fowler,et al.  Linking climate change modelling to impacts studies: recent advances in downscaling techniques for hydrological modelling , 2007 .

[34]  G. Lindström,et al.  Evaluation and calibration of operational hydrological ensemble forecasts in Sweden , 2008 .

[35]  D. Maraun,et al.  Precipitation downscaling under climate change: Recent developments to bridge the gap between dynamical models and the end user , 2010 .