1. Deanna Hence, Stacy Brodzik and Robert Houze University of Washington Introduction Methodology TCSP Storms RAINEX Storms Combined TCSP + RAINEX Storms Acknowledgements We would like to thank Ulrike Romatschke for invaluable assistance in processing this data. TRMM and PMM Grant NAG5-13654 and NNX07AD59G NASA ESS Grant NNX06AF17H RAINEX National Science Foundation Grant ATM-0432623 Summary and Future Work CFAD analysis illustrates the differences in precipitation structure as a function of radius for four major Gulf hurricanes. The precipitation in the innermost ring was mostly uniform and intense, with evidence of occasional deep convective towers. The precipitation was more shallow and stratiform in the middle radii and deeper and more convective at the farthest radii. Further CFAD analysis shows little variation in structure from quadrant to quadrant. This symmetry is consistent with the low shear environments of all four storms. The CFAD analysis provides a statistical dataset of storm precipitation structure for comparing with high-resolution numerical models For future work, some planned groupings for CFAD generation to expand study to all tropical cyclone basins for all years of TRMM mission (1998-present) include: · Storm strength (categories 1-5 on the Saffir-Simpson Scale) · Basin (N. Atlantic, NW Pacific, etc.) · Latitude (I.e. 10º-15º, 15º-20º, etc.) · Analyze sheared storms by quadrants Contour Frequency by Altitude Diagrams (CFADS, Yuter and Houze (1995) ) generated by radius annulus, quadrant, as well as radius and quadrant for each storm overpass. Annulus rings are based on the eye diameter (R e ) reported by the National Hurricane Center: Radius 1 (green) = R e + 25km, Radius 2 (yellow) is 2R1, Radius 3 (orange) is 3R1, and Radius 4 (red) is 4R1. Radius 5 is everything outside of Radius 4. Quadrants (white) are determined counter-clockwise from the storm motion vector. Cross-section taken along black line PMM Science Team Meeting, Atlanta, GA, 7 May 2007 Vertical Structure of TCSP and RAINEX Hurricanes as seen by the TRMM PR Schematic of typical rain pattern as seen by radar, according to Willoughby (1988) Outer eyewall Inner eyewall eye Secondary bands Principle band Variation in echo tops from ring to ring is robust result for all 4 storms. CFADS that are normalized by height (bottom panels) better emphasize convective/stratiform differences. Broad spectrum aloft (esp. Ring 5) indicates more convective; narrow spectrum (Ring 3) indicates stratiform. Ring 1 CFAD defies traditional classifications of “convective” (like radius 5) and “stratiform” (like radius 3). Its sharp central distribution suggests eyewall slantwise convection has a uniform intense core, but the outliers indicate occasional embedded deep convective towers. CFADS generated by quadrant (not shown) suggest symmetric structure for all storms in this study, consistent with low shear environments of these storms. Non-normalized CFADS for combined Dennis, Emily, Katrina, and Rita overpasses Ring 1Ring 3Ring 5 CFADS for combined Dennis, Emily, Katrina, and Rita overpasses normalized by height Ring 1 Ring 3Ring 5 The rain pattern of a tropical cyclone consists of eyewalls and rainbands arranged in patterns like that shown below. Interactions of eyewalls and rainbands may affect storm intensity changes, but relatively little information exists on the statistics of the vertical structure of these features. To better document these vertical structures, we compile statistics of the TRMM PR data as a function of distance from storm center. CFADS for all Hurricane Dennis overpasses Ring 1Ring 3Ring 5 CFADS for all Hurricane Emily overpasses Ring 3Ring 1Ring 5 180.4 Distance (km)  TRMM PR Vertical Slice 12 4 8 16 Height (km) 0 0.045.190.2135.3 48.6 43.2 37.8 32.4 27.0 21.6 16.2 10.8 5.4 dBZ eye TRMM PR Reflectivity at 03:36 on 28 August 2005 79° W 51 45 39 33 27 21 dBZ 15 9 3 8081908988878685848382 RR LR 25 24 LF RF 28°N 26 27 Storm motion Radial variation of CFADs for RAINEX storms is generally similar to that seen in TCSP storms—seems to be a very robust result. Hurricane Katrina has deepest convective tower occurrences of all storms. Inner radii precipitation features of RAINEX storms appear to be more intense than corresponding radii in TCSP storms. Transitional radii (Radius 2 and 4, not shown) show mixture of features of surrounding radii for all storms. Ring 1Ring 3Ring 5 CFADS for all Hurricane Katrina overpasses Ring 1Ring 3Ring 5 CFADS for all Hurricane Rita overpasses Precipitation within Ring 1 (eyewall region). Intense but generally uniform structure (tight gradients) associated with slantwise convection. Deep, variable outliers suggest some deep convective towers in the eyewall region. Precipitation within the middle regions (Ring 3) has shallower (~10 km) heights & more uniform precipitation with well-defined brightband, indicative of stratiform precipitation. Characterizes rainbands outside but near eyewall. Precipitation in furthest regions are highly variable (broad distribution). Suggests more purely convective precipitation well outside inner-core region.