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Sensitivity of Middle Atmospheric Analyses to the Representation of Gravity-Wave Drag in the DAO's Data Assimilation SystemThe damping of mesoscale gravity waves has important effects on the global circulation, structure, and composition of the atmosphere. A number of assimilation and forecast experiments have been conducted to examine the sensitivity of meteorological analyses and forecasts to the representation of gravity wave impacts in a data assimilation system (DAS). The experiments were conducted with the Finite-Volume (FV) DAS developed at NASA's Data Assimilation Office (DAO), The main purpose of this research is to determine the optimal combination of wave number, phase speed, wavelength, etc. for representing gravity-wave drag (GWD) in FVDAS. The GWD included in FVDAS includes a spectrum of waves, as would be forced by topography and transient motions (e.g., convection) in the troposphere. The sensitivity experiments are performed by modifying several parameters, such as the number of waves allowed, their wavelength, the background stress amplitude, etc. The results show that the assimilated fields are very sensitive to the number of gravity waves represented in the system, especially at high latitudes of the middle and upper stratosphere and mesosphere in winter. The analyzed stratopause temperature varies by up to 10K when the GWD scheme is modified from a multiple-wave scheme (using a stationary wave and waves with phase speeds of 10, 20, 30 and 40 m/s in each direction) to a single, stationary wave. Insight into the reality of the various versions of the GWD can be obtained by examining the "Observation minus Forecast" residuals from the FVDAS.
Document ID
20020067636
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Li, Shuhua
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Chern, Jiundar
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Joiner, Joanna
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Lin, Shian-Jiann
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Pawson, Steven
(NASA Goddard Space Flight Center Greenbelt, MD United States)
daSilva, Arlindo
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Atlas, Robert
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Geophysics
Meeting Information
Meeting: Spring AGU Meeting
Location: Washington, DC
Country: United States
Start Date: May 28, 2002
End Date: May 31, 2002
Sponsors: American Geophysical Union
Funding Number(s)
CONTRACT_GRANT: NCC5-494
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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