Project Title and Principal Investigator(s)

1. THORPEX-Pacific Asian Regional Campaign (T-PARC)NSF Funded Projects Background Project Title and Principal Investigator(s) Scientific Objectives Field Experiment Requirements Extratropical Transition of Tropical Cyclones over the Western North Pacific: Physical Characteristics, Downstream Impacts, and Predictability Patrick A. Harr and Russell L. Elsberry Naval Postgraduate School, Monterey, CA Chris Velden University of Wisconsin, Madison, WI • The ET of a TC over the western North Pacific often results in a high-amplitude, Rossby-wave response that extends across the North Pacific • During the primary TC season over the western North Pacific, the forcing of the midlatitude circulations during an ET event is often related to high-impact weather events over western North America. • Downstream development from an ET event is often associated with reduced predictability. • Increase understanding of the occurrence, amplitude, and extent of the downstream response to an extratropical transition (ET) event and the dependence on the interaction between the decaying tropical cyclone (TC) and the midlatitude flow into which it is moving • Define the relative roles of the decaying tropical cyclone characteristics and the midlatitude flow characteristics in downstream development during an ET event • Assess the impact on predictability of downstream development due to improved representation of the structural characteristics of an ET event • Utilize a combination of observation platforms to examine the structural features associated with ET events, which include a large region of warm frontogenesis, warm advection and ridge building downstream of the decaying TC, and TC outflow interactions with the midlatitude jet. • Collect in situ observations together with satellite observations to produce a merged data set for calibration/validation of satellite-based estimates of key structural characteristics during ET and the impact on downstream development.