The steady-state assumption is less severe for single-Doppler wind retrievals, but more assumptions about the unresolved components of the flow are required. In addition to the presence of an airborne Doppler radar with fore–aft capability or multiple radars with sufficient range and geometry around the TC, a steady-state assumption during the Doppler radar observation period is required to synthesize the wind fields into one snapshot in time.
While multiple-Doppler retrievals are generally superior for deriving three-dimensional winds, measurements from two or more radars are not generally available and are often not simultaneous. Therefore, wind retrieval techniques are required in order to identify the convective and kinematic structure of TCs from either single- or multiple-Doppler observations. Future improvements to the asymmetric flow assumptions in single-Doppler analysis and steady-state assumptions in pseudo-dual-Doppler analysis are required to reconcile differences in retrieved tropical cyclone structure.ĭoppler radar can provide high-resolution wind measurements within tropical cyclones (TCs), but the measurement is limited to the projection of the wind along the radial direction of the radar beam.
The strengths and weaknesses of each technique for studying tropical cyclone structure are discussed and suggest that complementary information can be retrieved from both single- and dual-Doppler retrievals. Fourier decomposition of asymmetric kinematic and convective structure shows more discrepancies due to spatial and temporal aliasing in the retrievals. A comparison between the two techniques shows that the axisymmetric tangential winds are generally comparable between the two techniques, and the improved GVTD technique improves the accuracy of the retrieval.
#Max track doppler full
A spline-based variational wind retrieval technique called SAMURAI can retrieve the full three-dimensional wind field from airborne radar fore–aft pseudo-dual-Doppler scanning, but it has been shown to have errors due to temporal aliasing from the nonsimultaneous Doppler measurements. An improved technique that mitigates errors due to storm motion is derived in this study, although some spatial aliasing remains due to limited information content from the single-Doppler measurements. The generalized velocity track display (GVTD) technique can retrieve a subset of the wind field from a single ground-based Doppler radar under the assumption of nearly axisymmetric rotational wind, but it has been shown to have errors from the aliasing of unresolved wind components. Hurricane Matthew (2016) was observed by the ground-based polarimetric Next Generation Weather Radar (NEXRAD) in Miami (KAMX) and the National Oceanic and Atmospheric Administration WP-3D (NOAA P-3) airborne tail Doppler radar near the coast of the southeastern United States for several hours, providing a novel opportunity to evaluate and compare single- and multiple-Doppler wind retrieval techniques for tropical cyclone flows.
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