Linear Evolution of Error Covariances in a Quasigeostrophic Model

Snyder, Chris; Hamill, Thomas M.; Trier, Stanley B.
January 2003
Monthly Weather Review;Jan2003, Vol. 131 Issue 1, p189
Academic Journal
The characteristics of forecast-error covariances, which are of central interest in both data assimilation and ensemble forecasting, are poorly known. This paper considers the linear dynamics of these covariances and examines their evolution from (nearly) homogeneous and isotropic initial conditions in a turbulent quasigeostrophic flow qualitatively similar to that of the midlatitude troposphere. The experiments use ensembles of 100 solutions to estimate the error covariances. The error covariances evolve on a timescale of O(1 day), comparable to the advective timescale of the reference flow. This timescale also defines an initial period over which the errors develop characteristic features that are insensitive to the chosen initial statistics. These include 1) scales comparable to those of the reference flow, 2) potential vorticity (PV) concentrated where the gradient of the reference-flow PV is large, particularly at the surface and tropopause, and 3) little structure in the interior of the troposphere. In the error covariances, these characteristics are manifest as a strong spatial correlation between the PV variance and the magnitude of the reference-flow PV gradient and as a pronounced enhancement of the error correlations along reference-flow PV contours. The dynamical processes that result in such structure are also explored; the key is the advection of reference-flow PV by the error velocity, rather than the passive advection of the errors by the reference flow.


Related Articles

  • Antarctic Satellite Meteorology: Applications for Weather Forecasting. Lazzara, Matthew A.; Keller, Linda M.; Stearns, Charles R.; Thom, Jonathan E.; Weidner, George A. // Monthly Weather Review;Feb2003, Vol. 131 Issue 2, p371 

    For over 30 years, weather forecasting for the Antarctic continent and adjacent Southern Ocean has relied on weather satellites. Significant advancements in forecasting skill have come via the weather satellite. The advent of the high-resolution picture transmission (HRPT) system in the 1980s...

  • Improving Short-Term Numerical Weather Prediction in the California Coastal Zone by Dynamic Initialization of the Marine Boundary Layer. Leidner, S. Mark; Stauffer, David R.; Seaman, Nelson L. // Monthly Weather Review;Feb2001, Vol. 129 Issue 2, p275 

    Presents a study on how to improve the warm season short-term mesoscale numerical predictions of California coastal zone meteorology. Description of the mesoscale modelling system; Design of the experiment; Meteorology of the northeast Pacific.

  • The Sensitivity of Precipitation to Circulation Details. Part II: Mesoscale Modeling. Roebber, Paul J.; Reuter, Gerhard W. // Monthly Weather Review;Jan2002, Vol. 130 Issue 1, p3 

    A base case and the best time-coherent, regional analog to that case, identified in Part I, were analyzed to determine the precise mechanisms responsible for the differences in precipitation amounts. This analysis was conducted using two modeling approaches. A model dataset that provides time...

  • Variational Assimilation of GOME Total-Column Ozone Satellite Data in a 2D Latitude-Longitude... Eskes, H. J.; Piters, A. J. M. // Journal of the Atmospheric Sciences;10/15/99, Vol. 56 Issue 20, p3560 

    Presents information on a study which described a data-assimilation method to derive synoptic ozone fields from total-column ozone satellite measurements. Importance of data assimilation in numerical weather prediction; Methodology; Conclusion.

  • Dynamics of storm tracks: A linear instability perspective. Lee, Woo-Jin; Mak, Mankin // Journal of the Atmospheric Sciences;3/15/95, Vol. 52 Issue 6, p697 

    Investigates the different manifestations of atmospheric instability in a realistic setting. Northern Hemispheric flow in the winter on 1982/83; Instability properties of time-mean flow; Examination of the normal modes; Classification of unstable normal modes; Differentiation of local unstable...

  • Optimal Prediction of Forecast Error Covariances through Singular Vectors. Ehrendorfer, Martin; Tribbia, Joseph J. // Journal of the Atmospheric Sciences;1/1/97, Vol. 54 Issue 2, p286 

    Presents a study of the optimal prediction of forecast error covariances through singular vectors (SV), or optimal perturbations. Methods of study; The SV method for a Lorenz system and for a barotropic model; Orthogonal transformation of covariance structure; Conclusions and discussion.

  • Weather Impacts, Forecasts, and Policy: An Integrated Perspective. Pielke Jr., Roger; Carbone, R. E. // Bulletin of the American Meteorological Society;Mar2002, Vol. 83 Issue 3, p393 

    Society invests considerable resources into the science and technology of weather services. In order to effectively assess the market for weather services, and thus properly scale the level of resources that, for example, the U.S. Congress or a company ought to devote to serving this market,...

  • THE INDO-U.S. WORKSHOP ON WEATHER AND CLIMATE MODELING. Singh, S. V.; Basu, S. // Bulletin of the American Meteorological Society;Jan2003, Vol. 84 Issue 1, p97 

    A workshop on Weather and Climate Modelling, held in New Delhi (7–9 February 2002), India, under the aegis of the Indo–U.S. Science and Technology Forum brought together scientists involved in weather and climate modeling from both India and the United States. The National Centre...

  • Storm sleuths track West Coast torrents. Spotts, Peter N. // Christian Science Monitor;12/26/97, Vol. 90 Issue 22, p3 

    Reports on the efforts of meteorologists on the West Coast of the United States to more accurately forecast the rapidly changing weather which can occur. The hope for more detailed short-range rainfall estimates; Why understanding low-level jets is key to forecasting rainfall patterns;...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics