Effect on long term climatology and trends

Figure 7 shows mean wind speed and standard deviation valid at 20 m for January, both corrected (Figs. 7a,c) and the difference of corrected minus uncorrected (Figs. 7b,d). In this calculation all quality controlled COADS data from 1945 to 1989 were used, correcting all estimated wind speeds according to eq. (6). Consistent with previous studies, corrected mean speeds exceed uncorrected mean speeds by about 0.5 m/s in parts of the North Atlantic, with smaller differences in the North Pacific. The corrected standard deviation (Figs. 7c,d) is reduced in the extra-tropics, with a more pronounced reduction ( 0.3 m/s) in the North Atlantic ocean. The corrected standard deviation is generally increased in the tropics with magnitudes around 0.1 m/s in the eastern tropical Atlantic and Pacific oceans. Similar calculations for the month of July show that the correction to the wind speed (not shown) is positive and greater than that for January, primarily due to the lower wind speed in July. Consistent with the findings of Cardone et al. (1990), we note a reduction in the wind speed's temporal linear trend for most of the globe due to our scientific Beaufort scale correction (not shown). This artificial upward trend in wind speed can adversely impact studies of long term variability of the ocean-atmosphere climate system.