18th Conference on Weather and Forecasting, 14th Conference on Numerical Weather Prediction, and Ninth Conference on Mesoscale Processes

Wednesday, 1 August 2001: 2:00 PM
observations and numerical simulations of tropopause PV trough filamentation and "Cut-Off" Low development over the North Pacific Ocean
Melvyn A. Shapiro, NOAA/OAR/ETL, Boulder, CO; and F. Zhang, C. S. Velden, D. Parrish, and Z. Toth
During the period 3-7 February, a dramatic example of anticyclonic Rossby-wave breaking occurred over the North Pacific ocean in association with Rossby-wave energy propagation (downstream development) from extratropical to tropical latitudes. The NOAA/G-4 weather reconnaissance aircraft took measurements throughout the life cycle of this event by deploying high-spatial resolution (50 km) GPS dropwindsondes on three consecutive days The G-4 flights were tasked from Honolulu Hawaii in corrdination with the NOAA/NCEP Winter-Storm Reconnaissance Program. Onboard ozone measurements documented the intrusion of ozone-laded stratospheric air as the upper PV anomaly narrowed from its initial wave-like structure culminating in the formation of a tropopause-based cut off cyclone vertically coupled to the lower-tropospheric warm-core seclusion of the Kona Low. Hourly multi-spectral visible, infrared, and water-vapor cloud and water vapor-drift winds and images provide a temporally and spatially continuous documentation of the Kona low life cycle. Total columnar ozone measurements from geostationary and polar orbiting satellites provided a surrogate visualization of the evolution of lower-stratospheric PV wave breaking, filamentation, and tropopause based cut-off cyclone development. A high-resolution numerical simulation with the NCAR/Penn. State multi-scale prediction model provides a realistic replication of the observed event and is used to carry out dynamical and physical process diagnostics of the role of tropopaue-based PV evolution and tropospheric sensible and latent heating.

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