Observations and Simulations of a Breaking Mountain Wave Associated with an Aircraft Accident Induced by Clear-Air Turbulence


F. M. Ralph, P. J. Neiman, D. Levinson (CIRES), W. D. Hall (NCAR), T. L. Clark (NCAR), A. Marroquin (CIRA), S. G. Benjamin

Introduction

Motivation: Observations of a mountain wave were being made at the same time a cargo jet lost an engine and part of a wing in extreme clear-air turbulence. The data offer a unique opportunity to document the cause of a potentially deadly aircraft accident and the breaking of a mountain wave in the lower stratosphere. Very few observations of mountain wave breaking, which is a key factor influencing the global atmospheric momentum, have been made.

Method: Use a suite of remote sensors to observe both the structure and evolution of a strong mountain wave. Collaborate on the diagnosis of turbulence from an operational numerical model, and on the simulation of the event with a high-resolution (300 m) 3-D numerical model using time-dependent lateral boundary conditions.

Unique conditions: The stratosphere was rich in volcanic aerosols from the Mt. Pinatubo eruptions of June 1991, which extended the vertical range of the lidar.


ETL / Review / Observations and Simulations of a Breaking Mountain Wave Associated with an Aircraft Accident Induced by Clear-Air Turbulence / Figure: Introduction, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, Conclusion