Analysis of a non-developing tropical circulation system during the Tropical Cyclone Structure (TCS08) field experiment

Abstract

The objective of this research is to analyze the non-developing Tropical Circulation System (TCS025) utilizing data collected during the Tropical Cyclone Structure 2008 (TCS-08) and The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaigns (T-PARC). Aircraft dropwindsondes, special ELDORA radar observations, and analyzed ECMWF model fields are used to define the three-dimensional structure at key times during the lifecycle of TCS025. Two TCS025-related Mesoscale Convective Systems (MCSs) were examined with observations from Air Force WC-130J and Navy Research Lab P-3 flights. On 28 August 2008, dropwindsonde and ELDORA wind fields identified a cyclonic circulation associated with an MCS (MCS-G). However, the upper-level and lower-level circulations were disconnected around the 850 hPa level. The upper-level circulation propagated southward with the MCS-G convection while the lower-level circulation progressed poleward. On 29 August, 2008, dropwindsonde and ELDORA wind fields identified a broad cyclonic circulation associated with another MCS (MCS-H). However, the center of circulation was northwest of MCS-H convection. It appears mid- and upper-level circulations associated with the MCS convection propagated southward with the convection while the low-level cyclonic circulation, under influence of the low-level background flow, progressed poleward. Without continued vertical coupling, TCS025 did not become a tropical depression.