Extended Data Fig. 2: Winds of weak TCs derived from drifter current measurements based on typhoon wind field model of Batts.

a, The difference of spatial averages between the theoretical wind fields and composite wind fields for each five-consecutive-year period from 1991 to 2020. The length of the error bar for each period is twice the standard deviation divided by the square root of the effective number of observations during that period (i.e., twice the standard error of the mean). The effective number of observations is approximated as the number of observations that are separated by at least 500 km in distance or at least 10 days in time. b, The theoretical and composite wind fields for each five-consecutive-year period during 1991–2020, and differences between the two winds (theoretical winds minus composite winds). c, The composite wind fields for the periods of 1991–2005 and 2006–2020, and change of the wind fields between the two periods (2006–2020 minus 1991–2005).