A Multiscale Numerical Study of Hurricane Andrew (1992). Part I: Explicit Simulation and Verification.

Yubao Liu, Da-Lin Zhang and M.K. Yau

Please click here for a 25-h animation of the simulated radar reflectivity.

Figure 1. Design of (a) model domains and (b) model integration (see Table 1 for more detailed information). Tracks of Hurricane Andrew from the 6 hourly best track analysis (OBS, "o") by Mayfield et al. (1994) and the model output (CTL, "x") are given in (a), together with the SST field (dashed) at intervals of 0.5 0C. Larger fonts denote the positions of Hurricane Andrew every 12 hours, with the corresponding date and time given.

Figure 2. Time series of the minimum central pressures (P, hPa) and the maximum surface winds (V, m/s) of Hurricane Andrew from the 72-h simulation (PCTL and VCTL) and the corresponding best analysis (POBS and VOBS) by Mayfield (1994). The arrow along the abscissa shows the period of integration for the 6-km mesh.

Figure 3. Comparison of composite soundings between the simulation (up to 100 hPa) and ODWs (released at 400 hPa) in the (a) northwest (NW); (b) northeast (NE); (c) southwest (SW); and (d) southeast (SE) quadrants of Andrew for the period centered at 0000 UTC 23 August 1992.

Figure 4. (a) Visible satellite imagery at 1801 UTC 23 August 1992 and (b) a top view of the model-simulated hydrometeors, as determined by the 0.01 g/kg surfaces for cloud water and ice, rainwater and snow, and graupel, from 54-h simulation (valid at 1800 UTC 23 August 1992). Both panels cover the same area.

Figure 5 (color). (a) Radar reflectivity from the Miami WSR-57 radar at 0830 UTC 24 August 1992 and (b) the simulated reflectivity that is taken from 68-h integration valid at 0800 UTC 24 August 1992. The legend given along the abscissa denotes the intensity of reflectivity in terms of dBZ. The intervals marked on the frame are mesh grids (6 km for the finest mesh; similarly in the rest of figures).

Figure 6 (color). Time evolution of the radar reflectivity at the surface (i.e., sigma = 0.995) from the final 16-h integrations of Hurricane Andrew (i.e., from 2000 UTC 23 to 1200 UTC 24 August 1992).

Figure 7. Comparison of surface streamlines and wind speeds at intervals of 5 m s-1 between (a) the surface composite (adapted from Powell and Houston 1996) and (b) the simulation at landfall of Hurricane Andrew; both are displayed over a similar domain. Curve AA' marks the east coast of Florida in the simulation and the boundary between over land and over water exposures in the analysis.

Figure 8. Comparison of the south-north wind profiles between the aircraft observations (solid, reproduced from Willoughby and Black 1996) and the simulation (dashed) (a) an hour before landfall; (b) at landfall; and (c) an hour after landfall.

Figure 9 (color). Horizontal distribution of the model-simulated radar reflectivity at (a) 200, (b) 500 and (c) 850 hPa, which are taken from 56-h integration, valid at 2000 UTC 23 August 1992.

Figure 10 (color). Vertical cross sections of the simulated radar reflectivity that are taken, respectively, along line AB in Fig. 9c and line CD in Fig. 5b from (a) 56-h; and (b) 68-h integrations, valid at 2000 UTC 23 and 0800 UTC 24 August 1992. Dashed black line denotes the 0 0C isotherm. Each horizontal bar along the abscissa denotes a distance of 50 km and the width of the sections is 415 km.

Figure 11. As in Fig. 10a but for the mixing ratios of (a) cloud water/ice (solid/dashed); (b) rainwater/snow (solid/dashed); and (c) graupel at isopleths of 0.001, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 and 6.4 g kg-1. The simulated radar reflectivity is superposed with gray scales. Thick solid line denotes the distribution of the 0 0C isotherm.

Figure 12. As in Fig. 10a but for the temperature deviation at intervals of 2 0C. Solid (dashed) lines are for positive (negative) values. The simulated radar reflectivity is superposed with gray scales. Thick solid line denotes the distribution of the 0 C isotherm.

Figure 13 (color). (a) As in Fig. 10a but for the equivalent potential temperature, qe, at intervals of 2 K; and (b) a three-dimensional view of thetae = 346 K surface over mesh-C domain. In (a), different qe regions are colored from yellow (warm) to blue (cold) and dashed green lines show the eyewall as defined by the radar reflectivity of 10 dBZ.

Figure 14. As in Fig. 10a but for the simulated soundings (a) at the center (i.e., with the minimum surface pressure); and (b) in the eyewall (about 66 km to the east from the center).

Figure 15. As in Fig. 10a but for (a) tangential winds (Vt, every 5 m s-1); (b) radial winds (Vr, every 5 m/s); (c) model-output vertical velocity (w, every 0.5 m/s); and (d) vertical relative vorticity (zeta, every 0.5 x 10-3 s-1). Solid (dashed) lines are for positive (negative) values.

Figure 16. As in Fig. 9 but for the streamlines (solid) and isotachs (dashed, every 10 m/s) at (a) 200 hPa; (b) 400 hPa; (c) 850 hPa; and (d) 950 hPa. The simulated reflectivity is superposed with gray scales.

Please access Dr. Yubao Liu's homepage for some Vis5D images of the simulated Andrew.

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