# Tropical Cyclone Winds from WindSat, AMSR2, and SMAP: Comparison with the HWRF Model
## 4 Results
### Overall Results  
Figure 12 shows scatterplots of matchups between the TC-winds and resampled and time-interpolated HWRF for each of the AMSR2, SMAP, and WindSat sensors for passes over 19 storms across all ocean basins between the years of 2017 and 2020. Overall, good agreement can be seen between the satellites and the resampled HWRF wind in terms of bias (\(-0.24\) m/s, \(-0.79\) m/s, and \(-0.43\) m/s for AMSR2, SMAP, and WindSat, respectively), standard deviations (\(3.86\) m/s, \(3.88\) m/s, and \(3.61\) m/s for AMSR2, SMAP, and WindSat, respectively), and correlation coefficient (\(0.85\), \(0.87\), and \(0.87\) for AMSR2, SMAP, and WindSat, respectively) for winds between \(10\) m/s and \(60\) m/s.  
In Figure 13, we show the average satellite-HWRF bias and standard deviations, which were binned vs. the average satellite/HWRF wind in \(2\) m/s wide bins between \(10\)-\(30\) m/s and in \(5\) m/s wide bins from \(30\) m/s upward. This was done to ensure that the bins were sufficiently populated. If there were less than \(50\) matchups in a given bin, it was not included in this figure. The biases between the three sensors and HWRF were, in general, relatively small, falling between \(\sim\)\(0\) m/s and \(-2.5\) m/s for wind speeds between \(10\) and \(40\) m/s before becoming more positive at higher wind speeds. The standard deviations tended to increase approximately linearly as wind speed increased, and leveled off slightly at higher wind speeds. In general, the standard deviation for WindSat was slightly smaller than for SMAP and AMSR2. Overall, Figure 13 indicates good consistency among the three satellite sensors SMAP, AMSR2, and WindSat when all of them are compared to HWRF. This is not too surprising, as the statistical TC wind algorithms for AMSR2 and WindSat were trained with SMAP winds [4].  
Figure 11: Scatterplots of WindSat matchups with interpolated resampled HWRF fields for Hurricane Teddy on 19 September 2020 at 10:08 UTC. (**a**) shows matchups with the HWRF wind field that has been temporally interpolated to the time of the WindSat overpass. (**b**) shows matchups with the HWRF wind field created by first shifting then interpolating the surrounding winds. The dashed red line represents the one-to-one line (i.e., no bias).  
Figure 12: Scatterplots of AMSR-2 (**a**), SMAP (**b**), and WindSat (**c**) winds plotted against HWRF winds that have been temporally interpolated to the time of satellite overpasses for all 19 storms between 2017 and 2020 analyzed in this study. The bias, standard deviation, and correlation coefficient for all wind speed matchups >10 m/s and <60 m/s are given in the top left corner for each plot. The black line represents the average of the binned HWRF vs. satellite winds and the binned satellite vs. HWRF winds. The red dashed line represents the one-to-one line (i.e., no bias). Note that no HWRF data used in this comparison were shifted before interpolation due to the fact that the statistical sample was large.  
Figure 13: Biases (solid lines) and standard deviations (dashed lines) between each of the three sensors and HWRF binned vs. average satellite/HWRF winds. Bins with a width of 2 m/s were used between 10–30 m/s. Bins with a width of 5 m/s were used for average winds >30 m/s. This was done to ensure the bins were sufficiently populated. If there were less than 50 matchups in a given bin, it was not included in this figure. The black dashed line is the zero-bias line.