MAPL Seminar: Joint Seminar by Chris Thorncroft and Jason Dunion

State University of New York at Albany / University of Miami, NOAA HRD

Tropical Cyclone variability in the East Atlantic

Chris D. Thorncroft, State University of New York at Albany

While tropical cyclogenesis can occur over a wide area of the tropical Atlantic, a significant number occur just downstream of the West African coastline. This suggests that the continental processes that impact the nature of African easterly waves and their associated mesoscale convective weather systems are important for creating favorable environments for tropical cyclogenesis. These processes will be briefly reviewed. This talk will also emphasize phenomena that can influence intraseasonal variability of tropical cyclogenesis in this region including the MJO and Convectively Coupled Kelvin waves.

 

Diurnal Pulsing of Tropical Cyclones: An Overlooked Yet Fundamental TC Process?

Jason P. Dunion, University of Miami, NOAA HRD

New GOES infrared satellite imagery has been developed to continuously monitor changes in the cloud top convective structure of tropical cyclones. This satellite imagery has also revealed a curious diurnal pulsing pattern that may represent an unrealized, yet fundamental process of mature tropical cyclones. The new satellite imagery reveals “cool rings” in the infrared that begin forming in the storm’s inner core at sunset each day. Similar to ripples that form after a pebble is thrown into a pond, the cool ring, or pulse, continues to move away from the storm overnight, reaching areas several hundred kilometers from the storm center by the following afternoon. There appear to be significant structural changes and disruptions to a storm as this pulse moves out from the inner core each day and the timing/propagation of these "cool rings" also appear to be remarkably predictable. Plans for the 2012 Atlantic hurricane season include using the new experimental real-time GOES imagery to monitor these diurnal pulses and guide aircraft sampling of their structure and evolution. Discussion will include:

 

  • Examples of recent and historical tropical cyclones exhibiting diurnal pulsing
  • Diurnal pulse characteristics, hypothesized triggers, and potential predictability
  • Preliminary findings from a NOAA G-IV jet that sampled diurnal pulsing in 2011 Hurricane Katia
  • Possible implications for high altitude aircraft penetrating tropical cyclone diurnal pulses
  • Diurnal pulsing sampling strategies for the 2012 Atlantic Hurricane season