||3-D wind and DSD can be retrieved using dual polarization Doppler radar data. In addition to warm-rain microphysical processes such as nucleation, condensation, evaporation, coalescence and breakup, advection and sedimentation also lead to variation of DSD. The DSD at two time steps and the 3-D wind between allow a budget analysis of the drop number concentration, separating microphysical and kinematic effects.|
This article analyzes a convective cell observed by NCAR’s SPOL radar when it performed intensive sector scans toward its south during IOP-8 of SoWMEX/TiMREX. The data processing steps include interpolating radar data, calculating the average system speed, correcting the observation time lag, retrieving 3-D wind, retrieving DSD and calculating the budget equation at different stages of the convective cell. The 3-D wind is recovered by the single-Doppler velocity retrieval method of Liou (2007). The DSD is retrieved by the constrained gamma method of Brandes et al. (2003).
The evolution of the convective cell is divided into 3 stages, during which the budget analysis of rain water content in the reflectivity core is as follows. During the intensifying stage, the total derivative of rain water content is positive for all drop sizes, which infers coalescence and condensation are the dominant microphysical processes. During mature stage I, the total derivative is negative for small and big drops but positive for median ones, which infers, besides condensation, coalescence and breakup dominate for small and big drops respectively. During mature stage II, the total derivative is nearly zero for all sizes, which infers opposite microphysical processes are well-matched. During the dissipating stage, the total derivative is negative for all sizes, which results, in doubt, from evaporation due to entrainment of drier air.
||Armijo, L., 1969: A theory for the determination of wind and precipitation velocities with Doppler radars. J. Atmos. Sci., 26, 570-573.|
Atlas, D., and C. W. Ulbrich, 1977: Path- and area-integrated rainfall measurement by microwave attenuation in the 1-3 cm band. J. Appl. Meteor., 16, 1322-1331.
Beard, K. V., 1985: Simple altitude adjustments to raindrop velocities for Doppler radar analysis. J. Atmos. Oceanic Technol., 2, 468-471.
Brandes, E. A., G. Zhang, and J. Vivekanandan, 2002: Experiments in rainfall estimation with a polarimetric radar in a subtropical environment. J. Appl. Meteor., 41, 674-685.
Brandes, E. A., G. Zhang, and J. Vivekanandan, 2003: An evaluation of a drop distribution-based polarimetric radar rainfall estimator. J. Appl. Meteor., 42, 652-660.
Brandes, E. A., G. Zhang, and J. Vivekanandan, 2004: Comparison of polarimetric radar drop size distribution retrieval algorithms. J. Atmos. Oceanic Technol., 21, 584-598.
Gal-Chen, T., 1982: Errors in fixed and moving frame of references: applications for conventional and Doppler radar analysis. J. Atmos. Sci., 39, 2279-2300.
Gorgucci, E., G. Scarchilli, V. Chandrasekar, and V. N. Bringi, 2000: Measurement of mean raindrop shape from polarimetric radar observations. J. Atmos. Sci., 57, 3406-3413.
Gorgucci, E., V. Chandrasekar, V. N. Bringi, and G. Scarchilli, 2002: Estimation of raindrop size distribution parameters from polarimetric radar measurements. J. Atmos. Sci., 59, 2373-2384.
Liou, Y.-C., 1999: Single radar recovery of cross-beam wind components using a modified moving frame of reference technique. J. Atmos. Oceanic Technol., 16, 1003-1016.
Liou, Y.-C., 2002: An explanation of the wind speed underestimation obtained from a least squares type single-Doppler radar velocity retrieval method. J. Appl. Meteor., 41, 811-823.
Liou, Y.-C., 2007: Single-Doppler retrieval of the three-dimensional wind in a deep convective system based on an optimal moving frame of reference. J. Meteor. Soc. Japan, 85, 559-582.
Liou, Y.-C., and I.-S. Luo, 2001: An investigation of the moving-frame single-Doppler wind retrieval technique using Taiwan Area Mesoscale Experiment low-level data. J. Appl. Meteor., 40, 1900-1917.
Marshall, J. S., and W. McK. Palmer, 1948: The distribution of raindrops with size. J. Meteor., 5, 165-166.
Russchenberg, H. W. J., 1993: Doppler polarimetric radar measurements of the gamma drop size distribution of rain. J. Appl. Meteor., 32, 1815-1825.
Seliga, T. A., and V. N. Bringi, 1976: Potential use of radar differential reflectivity measurements at orthogonal polarizations for measuring precipitation. J. Appl. Meteor., 15, 69-76.
Shapiro, A., S. Ellis, and J. Shaw, 1995: Single-Doppler velocity retrievals with Phoenix II data: clear air and microburst wind retrievals in the planetary boundary layer. J. Atmos. Sci., 52, 1265-1287.
Sun, J., D. W. Flicker, and D. K. Lilly, 1991: Recovery of three-dimensional wind and temperature fields from simulated single-Doppler radar data. J. Atmos. Sci., 48, 876-890.
Ulbrich, C. W., 1983: Natural variations in the analytical form of the raindrop size distribution. J. Climate Appl. Meteor., 22, 1764-1775.
Zhang, J., and T. Gal-Chen, 1996: Single-Doppler wind retrieval in the moving frame of reference. J. Atmos. Sci., 53, 2609-2623.
Zhang, G., J. Vivekanandan, and E. Brandes, 2001: A method for estimating rain rate and drop size distribution from polarimetric radar measurements. IEEE Trans. Geosci. Remote Sens., 39, 830-841.
Zrnic, D. S., and A. V. Ryzhkov, 1999: Polarimetry for weather surveillance radars. Bull. Amer. Meteor. Soc., 80, 389-406.