Are storm characteristics the same when viewed using merged surface radars or a merged satellite product?

Ayat, H., J.P. Evans, S. Sherwood, and A. Behrangi
Journal of Hydrometeorology, 22(1), 43-62, doi: 10.1175/JHM-D-20-0187.1, 2021.


High-resolution datasets offer the potential to improve our understanding of spatial and temporal precipitation patterns and storm structures. The goal of this study is to evaluate the similarities and differences of object-based storm characteristics as observed using space- or land-based sensors. The Method of Object-based Diagnostic Evaluation (MODE) Time Domain (MTD) is used to identify and track storm objects in two high-resolution merged datasets: the Integrated Multisatellite Retrievals for Global Precipitation Measurement (IMERG) final product V06B and gauge-corrected ground-radar-based Multi-Radar Multi-Sensor (MRMS) quantitative precipitation estimations. Characteristics associated with landfalling hurricanes were also examined as a separate category of storm. The results reveal that IMERG and MRMS agree reasonably well across many object-based storm characteristics. However, there are some discrepancies that are statistically significant. MRMS storms are more concentrated, with smaller areas and higher peak intensities, which implies higher flash flood risks associated with the storms. On the other hand, IMERG storms can travel longer distances with a higher volume of precipitation, which implies higher risk of riverine flooding. Agreement between the datasets is higher for faster-moving hurricanes in terms of the averaged intensity. Finally, MRMS indicates a higher average precipitation intensity during the hurricane’s lifetime. However, in non-hurricanes, the opposite result was observed. This is likely related to MRMS having higher resolution; monitoring the hurricanes from many viewing angles, leading to different signal saturation properties compared to IMERG; and/or the dominance of droplet aggregation effects over evaporation effects at lower altitudes.

Key Figure

Fig. 7. All hurricane composite intensity maps observed by (a) MRMS and (b) IMERG. (c) Composite intensity bias map is the difference of (a) and (b) by taking the MRMS as the reference. (d) The variation of the averaged radial intensity with the distance from the center of all hurricane composite maps for the MRMS/IMERG (orange/blue) line.

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