1. Conceptual Models of Tropical Cyclone Structures
R. A. Houze
University of Washington
(with A. Didlake and D. Hence)
HS3 Science Team Meeting, Moffett Field, California, 9 May, 2013

2. The over-storm GH raises the question: Can HS3 verify conceptual models that have been published?

3. Here are a few that have been published!
OK…then which one?
Here are a few that have been published!

5. We need to see how some of these conceptual models combine to tell a coherent story

6. Let’s look at the inner core features

7. Eyewalls and Rainbands
Freely adapted from Willoughby 1988

8. Rainband composite from TRMM PR Stratified by environment shear Inner
Hence and Houze 2012
Rainband composite from TRMM PR
Stratified by environment shear
Inner
Outer
Recall: how shear computed, how regions defined, what reflectivity statistics were analyzed
Imported
Local

9. Reflectivity CFADs
Hence and Houze 2012

10. Reflectivity Kurtosis
Inner region
Outer region
Hence and Houze 2012

11. Upwind end of a Principal Rainband
Plan view schematic of the upwind end of a mature principal rainband at 2-km altitude, outlined by the 25-dBZ reflectivity contour. Solid and dashed contours indicate regions of positive and negative vertical velocity, respectively. A region of convergence is indicated. The large arrow indicates the main airflow of the mesoscale vortex.
Didlake and Houze 2009

12. Middle Section of a Principal Rainband
Barnes et al. 1983
Powell 1990
Hence and Houze 2008
Didlake and Houze 2009
Updrafts
Downdrafts w
Downdrafts
Updraft seems to have the dynamical character of an eyewall updraft, but highly localized.
Downdrafts not the type the regenerate the updrafts.

13. Middle Section of a Principal Rainband
Fig. 18. Schematic of the convective motions associated with two mature convective cells at different radial distances
from the storm center within the inner core. Reflectivity contours are drawn showing cell 1 at a smaller radius
and cell 2 at a larger radius. The solid arrows represent the overturning secondary circulation within each cell, and the
plus (minus) signs indicate regions of increasing (decreasing) tangential velocity; V1 and V2 represent the tangential
velocity jets in each cell.
The vertical and radial advection of tangential momentum produce the pluses in the lower troposphere—extending higher in the outer region. The inner cell build the tangential wind max at low levels, more like an eyewall development.
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Didlake and Houze 2013a

14. Downwind Section of a Principal Rainband
Enhanced stratiform
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Figure 17. a) Plan view schematic of an organized rainband complex in a mature tropical cyclone. Reflectivity contours (20 dBZ and 35 dBZ) show embedded convective cells that collapse (indicated by dashed contours) and form stratiform precipitation traveling around the storm. The solid arrows represent tangential jets associated with each precipitation feature, with VT indicating the jet within the stratiform sector. The gray line represents the cross section conceptualized in (b). b) Schematic of the dynamics within a stratiform rainband. Reflectivity contours are drawn. storm, and the broad arrows represent mesoscale motions associated with the stratiform rainband. The broad arrows of the descending inflow are gradient, dB/dr. The plus signs indicate regions of increasing tangential velocity by the secondary circulation. The circled region indicates the tangential jet, VT. Latent cooling and latent heating occur in the indicated regions.
Didlake and Houze 2013b

15. How can HS3 flights confirm or reject conceptua models based on TRMM radar and airborne Doppler observations?
Locate major rainbands in GH data
Determine if their structures conform to the patterns seen in TRMM data
Locate downwind stratiform zones
Look for the cross-band mesoscale over turning in HIWRAP & other remote sensor data
Use dropsondes to determine the rainband momentum budgets
Do the results look like the conceptual model?

16. Question for discussion?
Can AV-1 flight patterns achieve the objective of understanding rainband dynamics?

17. End
This research is supported by NASA grant NNX12AJ82G and NSF grant ATM