The Canadian Meteorological Centre (CMC) global analyses (1991-1996): An evaluation by comparison with the ECMWF and NCEP analyses

An evaluation of the analyses of the large-scale global circulation produce d by the Canadian Meteorological Centre (CMC) is undertaken by intercompari ng them to the corresponding analyses of two independent analysis centres: the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Nati onal Centers for Environmental Prediction (NCEP; formerly the National Mete orological Center). The evaluation is done by constructing the mean of the analyses from the th ree centres and then computing the deviations of the analyses from each of the three centres from the mean. Results are presented for January and July over a sc-year period for the moisture field, the mass field and the wind field. The results suggest that the CMC analyses, like those from the other two ce ntres, have strengths and weaknesses and do not stand out as being consiste ntly better or worse than the other two. In general, the analyses agree wel l in mid-latitudes and northern polar regions and exhibit poor agreement in the tropics and southern polar regions. The results also indicate that dat a assimilation systems continue to have great difficulty in analysing the m oisture field.