1026 Dual-polarization radar rainfall estimation over warm tropical oceans

Wednesday, 25 January 2017
4E (Washington State Convention Center )
Elizabeth J. Thompson, APL/Univ. of Washington, Seattle, WA; and S. A. Rutledge, B. Dolan, and M. Thurai

The impacts of Tropical Warm Pool rain variability on the dual-polarization radar variables and their utility for rainfall estimation in this key climate region are investigated. A 1.5-year W. Pacific disdrometer dataset provided high resolution rain rate (R) and drop size distribution (DSD) parameters to simulate radar variables (Zh, Zdr, Kdp) at X, C, and S band. A previous study using the same dataset found that tropical, maritime convection is composed of more numerous, higher liquid water content DSD, with smaller median drop diameter for a given R, compared to stratiform rain. This resulted in lower Zdr for a given Zh, and lower Zdr for a given Kdp in maritime convection compared to stratiform rain. In contrast, intense continental convective rain made up of fewer, but larger rain drops can exhibit very high Zdr for a given Zh. Despite high liquid water content, Kdp, Zdr, and Zh ranges were also lower in maritime convection compared to continental convection. New equations relating Kdp(z), R(z, ζdr), R(Kdp), and R(Kdp, ζdr) at X, C, and S band were developed to account for this tropical, oceanic and C/S DSD variability. The new polarimetric R equations outperformed z-only methods individually and in optimization algorithms. Polarimetric radar equations were demonstrated to be more resilient to convective/stratiform and global DSD variability than z-only equations.
- Indicates paper has been withdrawn from meeting
- Indicates an Award Winner