CR 11:173-190 (1999)  -  doi:10.3354/cr011173

Empirical-statistical reconstruction of surface marine winds along the western coast of Canada

Manon Faucher1,*, William R. Burrows2, Lionel Pandolfo3

1Département des sciences de la terre, Université du Québec à Montréal, CP 8888, Succ. 'Centre-Ville', Montréal (Québec) H3C 3P8, Canada
2Numerical Prediction Research Division, Meteorological Research Branch, Atmospheric Environment Service, Downsview, Ontario M3H 5T4, Canada
3Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

ABSTRACT: CANFIS, an empirical-statistical technique, is used to reconstruct continuous daily surface marine winds at 6-hourly intervals at 13 Canadian buoy sites along the western coast of Canada for the 40 yr period 1958-1997. CANFIS combines Classification and Regression Trees (CART) and the Neuro-Fuzzy Inference System (NFIS) in a 2-step procedure. CART is a tree-based algorithm used to optimize the process of selecting relevant predictors from a large pool of potential predictors. Using the selected predictors, NFIS builds a model for continuous output of the predictand. In this project we used CANFIS to link large-scale atmospheric predictors with regional wind observations during a learning phase from 1990 to 1995 in order to generate empirical-statistical relationships between the predictors and buoy winds. The large-scale predictors are derived from the NCAR/NCEP 40 yr reanalysis project while the buoy winds come from the Canadian Atmospheric Environment Service buoy network. Validation results with independent buoy wind data show a good performance of CANFIS. The CANFIS winds reproduce the independent buoy winds with greater accuracy than winds reconstructed with a stepwise multivariate linear regression technique. In addition, they are better than the NCEP reanalyzed winds interpolated to the buoy locations. The reconstructed statistical winds recover more than 60% of the observed wind variance during an independent verification period. In particular, correlation coefficients between independent buoy wind time series and CANFIS wind time series vary between 0.61 and 0.98. Our results suggest that CANFIS is a successful downscaling method. It is able to recover a substantial fraction of the variation of surface marine winds, especially along coastal regions where ageostrophic effects are relatively important.

KEY WORDS: Marine wind modelling · Statistical downscaling · Classification and regression trees · Neuro-fuzzy inference system

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