Rainbands and Secondary Eye Wall Formation as Observed in RAINEX Derek Ortt and Shuyi S. Chen University of Miami-RSMAS

Motivation and Objective To examine the properties of rainbands in Hurricanes Katrina and Rita using RAINEX observations and model simulations To determine the physical processes that may be responsible for the formation of concentric eyewalls and eyewall replacement cycles in Hurricane Rita

Hurricanes Katrina and Rita KatrinaRita

Data and Analysis Method TMI water vapor data with a ¼ degree resolution P-3 GPS dropsonde data with a ½ s resolution (interpolated on to a 25m vertical resolution) from NOAA and NRL aircraft (47 in Katrina and 40 in Rita) G-IV dropsondes interpolated on a 100m resolution (56 in Katrina and 56 in Rita) Dropsondes are composited day by day Model data is from MM5 vortex following simulations with 3 nested domains at 15, 5, and 1.67km resolution Similar analysis methods are used the with the model as with the TMI and aircraft data

Observations

TMI Total Precipitable Water Katrina Rita Black dots represent sample G-IV dropsonde locations

Storm outer environment

Storm outer environment

Sample P3 Dropsonde Locations Katrina Rita Black dots represent sample P3 dropsonde locations along the flight tracks

Sample Dropsonde Locations Red: NRL P-3 dropsondes Black: NOAA P-3 dropsondes G-IV dropsondes are released farther from the center than the drops depicted above. KatrinaRita

Rainband region

P-3 Dropsonde Composites KatrinaRita

Model Simulations

MM5 Total Precipitable Water KatrinaRita

Sample Model Vertical Profile Locations Magenta dots represent model simulated dropsonde locations Katrina Rita

MM5 Composite Vertical Profiles KatrinaRita

KatrinaRita

KatrinaRita

OTHER STORMS

2004 Frances

EWRC

2004 Ivan

NO EWRC

Conceptual Model of Moisture Gradient Affects to Rainbands Weak Gradient Strong Gradient Moist Dry

Conclusions The Rainbands in Rita were more symmetric about the storm than those in Katrina A sharp moisture gradient between the rainbands and surrounding environment was present in Rita, but not Katrina The rainbands in Rita were able to form into a secondary eye wall. A stable outer storm environment favor symmetric rainbands about the center, which may lead to the formation of concentric eyewalls

Aknowledgements Katrina and Rita track graphics courtesy of Unisys Weather TMI data from NRL and remote sensing systems NOAA P-3 and G-IV dropsonde data courtesy of AOML-HRD This work was funded by NSF grant ATM and this presenter has been funded by an AMS and University of Miami Fellowship