| 22 May 2026
A global kilometre-scale tropical cyclone inner-core vector wind field dataset from CYGNSS observations
Abstract. Tropical cyclone (TC) inner-core vector wind fields are essential for intensity forecasting, storm surge prediction, and structural climatology. The Cyclone Global Navigation Satellite System (CYGNSS) constellation provides dense temporal sampling and L-band precipitation-penetrating capability over the tropical belt, but its sparse, scalar wind speed retrievals have not been fully assimilated to produce kilometre-scale TC inner-core vector wind fields with global multi-basin coverage. This paper presents the QiFeng-CYGNSS dataset, which combines CYGNSS observations with a physics-guided score-based diffusion assimilation framework to reconstruct spatially complete 10 m vector wind fields from sparse scalar wind speed observations. The dataset covers 249 TCs across six active global basins during January 2020–September 2022, providing 1.5 km resolution vector wind fields at every IBTrACS reporting time with available CYGNSS coverage (4955 snapshots in total), accompanied by observation metadata and pixel-level ensemble uncertainty estimates for 138 major-hurricane snapshots. Independent validation against spaceborne C-band synthetic aperture radar, airborne Tail Doppler Radar, and GPS dropsondes indicates that the reconstructions represent TC inner-core structures at kilometre scales, reducing the absolute Vmax bias relative to ERA5 and CCMP by ~79% and ~75%, respectively, on the full sample. The dataset is freely available from Zenodo at https://doi.org/10.5281/zenodo.20046109 (Han et al., 2026b).
This is a potentially useful dataset as surface winds in tropical cyclones are difficult to observe with the both the scarcity, quality and spatial coverage of those observations.  I have my reservations about the reconstruction of the inner core wind fields and would like to see some additional validation.  I also have a few comments that pertain to the introduction of this being the only option around, and some issues that need to be clarified.
Verification: Two of the difficulties in reconstructing the two-dimensional wind field in tropical cyclones whether via parametric models or data fitting methods are the proper estimation of asymmetries and of the radius of maximum wind. To make this dataset more useful and provide users with confidence that these data can be used for a particular task, errors and uncertainties related to the vortex asymmetries and the location of the radius of maximum wind should be included in the write up. You can see issues related to the rmw in figure 1 and figure 2. The former shows RMW of 34 km while the aircraft based estimate is closer to 17-19 km. In figure 2 the observed by SAR rmw values are 15, 37 and 37 km, from left to right.Â
I suggest 1) providing errors and uncertainties as a function of radius either normalized by RMW or not, 2) provide statistics about the quality of the location of the radius of maximum wind, and 3) provide some estimate of the quality of the wavenumber 1 asymmetries also as a function of radius (possibly done in a motion relative framework). Â
Missing acknowledgement of like datasets:  NESDIS has a km-scale tropical cyclone surface wind analysis that provides 3-hourly estimates of surface vector winds. The original method was documented in this paper.Â
 Knaff, J. A., M. DeMaria, D. A. Molenar, C. R. Sampson, and M. G. Seybold, 2011: An automated, objective, multi-satellite platform tropical cyclone surface wind analysis. J. of Applied Meteorology and Climatology. 50(10), 2149-2166. doi: 10.1175/2011JAMC2673.1.
And real-time estimate available from this website with the data being available from NOAA CLASS.Â
https://www.ospo.noaa.gov/products/ocean/tropical/mtcswa/
https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C01683
Clarification: IBTRaCS is an amalgamation of best track dataset from many agencies including Warning Centers and WMO RSMCs.  Could you clarify which best tracks from IBTRaCs are being used.  If NHC and JTWC are indeed used as I suspect can you provide the references to those best tracks. NHC's reference is https://doi.org/10.1175/MWR-D-12-00254.1 and JTWC reference (very recent) is https://www.metoc.navy.mil/jtwc/products/best-tracks/JTWC_TC_Best_Tracks_NRL_Report.pdf.  Both reports discuss uncertainties associated with intensity and structure.  This information probably should be part of your write up.
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