The previous two-dimensional simple adjoint method for retrieving horizontal wind field from a time sequence of single-Doppler scans of reflectivity and/or radial velocity is further developed into a new method to retrieve both horizontal and vertical winds at high temporal and spatial resolutions. This new method performs two steps. First, the horizontal wind field is retrieved on the conical surface at each tilt (elevation angle) of radar scan. Second, the vertical velocity field is retrieved in a vertical cross-section along the radar beam with the horizontal velocity given from the first step. The method is applied to phased array radar (PAR) rapid scans of the storm winds and reflectivity in a strong microburst event and is shown to be able to retrieve the three-dimensional wind field around a targeted downdraft within the storm that subsequently produced a damaging microburst. The method is computationally very efficient and can be used for real-time applications with PAR rapid scans. 1. Introduction Updrafts and downdrafts are the essential components of storms. Their strengths often determine the type and evolution stage of storms. Quickly detecting updrafts and downdrafts and estimating their strengths in storm wind fields will make timely and accurate assessments of hazardous weather conditions. It is thus desirable to develop an efficient method to retrieve both the horizontal and vertical winds, including updrafts and downdrafts, in real time from phased array radar (PAR) rapid scans of storms. A key advantage of PAR over Weather Surveillance Radar 1988-Doppler (WSR-88D) is the capability to rapidly and adaptively scan storms. With its agile electronic beam steering, the PAR scan strategy can be optimized on particular weather phenomena with the volume scan time reduced from minutes to seconds (Zrnic et al. [1], Torres et al. [2]). High spatial and temporal resolution volumetric radar data are often necessary to resolve very fine echo structures, their transient developments, and movements inside storms (Heinselman et al. [3]). Previous research also indicates that the retrieval errors can be reduced if the reflectivity and radial-velocity fields are sampled more frequently (Qiu and Xu [4], Shapiro et al. [5]). Since Doppler radar observations are limited mainly to reflectivity and radial-component velocity (along the radar beam) and there is no direct measurement of the remaining two wind components perpendicular to the radar beam, a two-dimensional simple adjoint (2D-SA) method was developed by Qiu and Xu [6] to retrieve the horizontal
References
[1]
D. S. Zrnic, J. F. Kimpel, D. E. Forsyth et al., “Agile-beam phased array radar for weather observations,” Bulletin of the American Meteorological Society, vol. 88, no. 11, pp. 1753–1766, 2007.
[2]
S. Torres, P. Heinselman, R. Adams et al., “ADAPTS implementation: can we exploit phased-array radar's electronic beam steering capabilities to reduce update times?” in Proceedings of the 28th Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology, American Meteorological Society, New Orleans, La, USA, 2012.
[3]
P. L. Heinselman, D. L. Priegnitz, K. L. Manross, T. M. Smith, and R. W. Adams, “Rapid sampling of severe storms by the national weather radar testbed phased array radar,” Weather and Forecasting, vol. 23, no. 5, pp. 808–824, 2008.
[4]
C. Qiu and Q. Xu, “Least squares retrieval of microburst winds from single-Doppler radar data,” Monthly Weather Review, vol. 124, no. 6, pp. 1132–1144, 1996.
[5]
A. Shapiro, P. Robinson, J. Wurman, and J. Gao, “Single-Doppler velocity retrieval with rapid-scan radar,” Journal of Atmospheric and Oceanic Technology, vol. 20, no. 12, pp. 1758–1775, 2003.
[6]
C. Qiu and Q. Xu, “A simple adjoint method of wind analysis for single-Doppler data,” Journal of Atmospheric and Oceanic Technology, vol. 9, no. 5, pp. 588–598, 1992.
[7]
Q. Xu, C. Qiu, H. Gu, and J. Yu, “Simple adjoint retrievals of microburst winds from single-Doppler radar data,” Monthly Weather Review, vol. 123, no. 6, pp. 1822–1833, 1995.
[8]
Q. Xu, H. Gu, and C. Qiu, “Simple adjoint retrievals of wet-microburst winds and gust-front winds from single-Doppler radar data,” Journal of Applied Meteorology, vol. 40, no. 8, pp. 1485–1499, 2001.
[9]
Q. Xu, H. Gu, and S. Yang, “Simple adjoint method for three-dimensional wind retrievals from single-Doppler radar,” Quarterly Journal of the Royal Meteorological Society, vol. 127, no. 573, pp. 1053–1067, 2001.
[10]
J. Sun and A. Crook, “Wind and thermodynamic retrieval from single-Doppler measurements of a gust front observed during Phoenix II,” Monthly Weather Review, vol. 122, no. 6, pp. 1075–1091, 1994.
[11]
Q. Xu, K. Nai, L. Wei, P. Zhang, Q. Zhao, and P. R. Harasti, “A real-time radar wind data quality control and analysis system for nowcast application,” in Proceedings of the International Symposium on Nowcasting and Very Short Range Forecasting (WSN '09), WMO, Whistler, Canada, 2009, http://www.nowcasting2009.ca/images/stories/Presentations/WSN09_Presentations.htm.
[12]
Q. Xu, “Representations of inverse covariances by differential operators,” Advances in Atmospheric Sciences, vol. 22, no. 2, pp. 181–198, 2005.
[13]
R. J. Purser, W. S. Wu, D. F. Parrish, and N. M. Roberts, “Numerical aspects of the application of recursive filters to variational statistical analysis—part I: spatially homogeneous and isotropic Gaussian covariances,” Monthly Weather Review, vol. 131, no. 8, pp. 1524–1535, 2003.
[14]
R. J. Purser, W. Wu, D. F. Parrish, and N. M. Roberts, “Numerical aspects of the application of recursive filters to variational statistical analysis—part II: spatially inhomogeneous and anisotropic general covariances,” Monthly Weather Review, vol. 131, no. 8, pp. 1536–1548, 2003.
[15]
Q. Xu, L. Wei, W. Gu, J. Gong, and Q. Zhao, “A 3.5-dimensional variational method for Doppler radar data assimilation and its application to phased-array radar observations,” Advances in Meteorology, vol. 2010, Article ID 797265, 14 pages, 2010.
[16]
E. Kessler, “On the distribution and continuity of water substance in atmospheric circulation,” Meteorological Monographs, vol. 10, no. 32, p. 84, 1969.
[17]
Q. Xu and C. Qiu, “Adjoint-method retrievals of low-altitude wind fields from single-Doppler reflectivity and radial-wind data,” Journal of Atmospheric and Oceanic Technology, vol. 12, no. 5, pp. 1111–1119, 1995.
[18]
Q. Xu, C. Qiu, and J. Yu, “Adjoint-method retrievals of low-altitude wind fields from single-Doppler reflectivity measured during Phoenix II,” Journal of Atmospheric and Oceanic Technology, vol. 11, no. 2, pp. 275–288, 1994.
