CGD Special Seminar Series-Evaluating a New Mountain Wave Paramterization for CESM-J. Bacmeister

Title: Evaluating a New Mountain Wave Parameterization for CESM

Speaker:  Julio Bacmeister

Date:  Wednesday, 6 February 2019

Time:  11 am - 12 pm

*Refreshments at 10:45*

Location:  Mesa Lab, Main Seminar Room, ML-132

Abstract:  An updated parameterization of mountain wave drag for CAM/CESM is described and then evaluated using several approaches. The updated scheme incorporates a new specification of wave forcing and orientation derived from observed characteristics of topography, as well as a representation of nonlinear near-surface drag processes, e.g., form drag, that were missing in the previous scheme. The performance of the updated scheme is initially evaluated using standard climate model diagnostics from long simulations. Diagnostics based on tendencies in nudging and data assimilation experiments are also examined. Finally, direct comparisons of parameterized mountain waves with satellite data, balloon data and with high resolution numerical simulations are made.

These various diagnostics of parameterization behavior provide consistent “messages” in some cases and conflicting messages in others. In general, in the troposphere all diagnostics agree that more parameterized drag is an improvement. However, in the lower stratosphere and above standard climate diagnostics, and some observations, indicate that larger parameterized mountain wave forcing is needed, while nudging experiments suggest the opposite. This talk will attempt to explain these conflicting assessments, as well as to suggest future wave drag parameterizations that perform better across all time and space scales.


Room Number: 

Type of event:

Will this event be webcast to the public by NCAR|UCAR?: 
Yes - ML-Main Seminar Room -
Announcement Timing: 
Tuesday, February 5, 2019 to Wednesday, February 6, 2019
Calendar Timing: 
Wednesday, February 6, 2019 - 11:00am to 12:00pm

Posted by Tracy Baker at ext. 1366,

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