Skip to content

CLP

Seminar

Development of wavelet methodology for weather Data Assimilation

Fournier, A (UCAR)
Friday 17 September 2010, 11:00-12:00

Seminar Room 2, Newton Institute Gatehouse

Abstract

This work aims at improved computation of covariances and of multiscale structures such as clouds, in the Weather Research and Forecasting (WRF) data-assimilation (WRFDA) system, in particular the horizontal factor of the control-variable transform used to optimize the forecast initialization. Better representation can be achieved in the horizontal transform by wavelet-compression techniques that have been proven in many other applications.

In this work, two past obstacles to effective incorporation of wavelets in limited-area models such as WRF are resolved: isometric-injective (i.e., energy preserving, left-invertible) wavelets avoid boundary-condition assumptions at any scale; and these wavelets can be applied to non-dyadic data lengths. A summary technical description of these improved wavelets and their implementation into WRFDA is presented. By retaining only a diagonal background-covariance matrix in wavelet space, appropriate heterogeneity is obtained for the model-space covariances.

A second wavelet application is to partition observation error into a part due to poor representation (e.g., too-coarse resolution), and a residual, using a novel criterion in wavelet space. Other methods to construct inhomogeneous anisotropic covariance models are cited, and other potential technical improvements are discussed.

Presentation

[pdf ]

Video

The video for this talk should appear here if JavaScript is enabled.
If it doesn't, something may have gone wrong with our embedded player.
We'll get it fixed as soon as possible.

Back to top ∧