Mesoscale and Convective Structure of a Hurricane Rainband Barnes, G. M., E. J. Zipser, D. Jorgensen, and F. Marks, Jr., 1983: J. Atmos. Sci., 40, 2125-2137.

Mesoscale and Convective Structure of a Hurricane Rainband Barnes, G. M., E. J. Zipser, D. Jorgensen, and F. Marks, Jr., 1983: J. Atmos. Sci., 40, Introduction History Gentry(1964), Simpson(1965), Willoughby(1982), Leary and Houze(1979) Fitzjarrald and Grastang(1981), Zipser(1981) Objectives Structure, motion, mesoscale airflow, convection and the barrier in the rainband Sampling strategy Flight pattern, aircraft sensors 1. Flying twice at a given altitude. 2. Each flight leg was 60KM. 3. A total of 26 legs were flown at the levels: 150, 600, 1500, 2400, 3000, 4800 and 6400 m. 4. The experiment was made form GMT on 7 September Aircraft instrumentation includes an inertial navigation system, partial measuring system, the Johnson- Williams liquid water sensor, two Rosemount temperature sensors, an experimental CO2 radiometer, a dew point hygrometer, and aircraft pressure/height sensors. General weather situation 1. The Hurricane Floyd is asymmetric, and is moving northeast at 4.7 (m/s). 2. Aircraft penetrations of the eye estimate the central pressure to be 975 (mb). The Hurricane Floyd in a visible picture at 1300 GMT. Results Radar structure and definitions of rainband. Kinematic fields Thermodynamic fields D-value the height of a given pressure surface minus the height of the same surface in a reference atmosphere. Reflective levels are 25, 30, 35, and 38 dBz. The domain size is 240 km 240 km. Altitude is 1.5 km, derived between 1155 and 1347 GMT. a (a) GMT b (b) GMT d (d) GMT c (c) GMT Results Radar structure and definitions of rainband. Kinematic fields Thermodynamic fields D-value the height of a given pressure surface minus the height of the same surface in a reference atmosphere. The composite field of relative normal velocity component ( ). Divergence associated with the rainband. LHL -- L + H Results Radar structure and definitions of rainband. Kinematic fields Thermodynamic fields D-value the height of a given pressure surface minus the height of the same surface in a reference atmosphere. The e fields associated with the rainband. The change in e with height as one travels from outside to inside the rainband. Skew T-log P diagram Results Radar structure and definitions of rainband. Kinematic fields Thermodynamic fields D-value the height of a given pressure surface minus the height of the same surface in a reference atmosphere. The composite D-value for 150, 2400 and 6400m. Discussion Estimates of mesoscale vertical motion. Subgrid-scale fluxes Hypothesized motions in the rainband. Mesoscale vertical velocity field derived from Divergence diagram. ? ? Discussion Estimates of mesoscale vertical motion. Subgrid-scale fluxes Hypothesized motions in the rainband. Vertical velocity measured. 1504: : : : : :32 (feg11) 1546: :47 (feg12) (a)Histograms of drafts as a function of radial distance. (b)Reflectivity cells as a function of radial distance. Discussion Estimates of mesoscale vertical motion. Subgrid-scale fluxes Hypothesized motions in the rainband. A schematic of the rainband in r, z coordinates Rainband in x, y coordinates. Conclusions A partial mesoscale barrier to the inflow is associate with rainband. Reflectivity observations show that band has both a stratiform and convective structure. A weak mesoscale high pressure area is nearly coincident with the rainband near the surface.