S. Lovejoy et al., Atmospheric complexity or scale by scale simplicity?

Geophysical Research Letters, 36, L01801; doi: 10.1029/2008GL035863

Editors' Highlight

Atmosphere driven by cascades, an aid to numerical weather prediction

Numerical weather forecasting typically involves complex and nonlinear calculations, although many have theorized that there must be a simpler way to model terrestrial weather. To help search for this way, Lovejoy et al. (2009) hypothesized whether simplicity can be reached through seeing weather dynamics as cascade processes in which large structures modulate smaller ones and the process repeats to smaller and smaller scales, generating extremely variable fractal structures. The authors analyzed data from 1000 orbits of the Tropical Rainfall Measuring Mission satellite and found that shortwave and longwave radiance and reflective properties planet-wide follow predictions of cascade models with good agreement from planet scales down to 10 km. Because radiances and atmospheric dynamics are strongly coupled, the authors concluded that weather can be accurately modeled as a cascade process.

Atmospheric complexity or scale by scale simplicity?

Atmospheric complexity or scale by scale simplicity?

S. Lovejoy (Physics, McGill University, Montreal, Quebec, Canada), D. Schertzer (CEREVE, Université Paris Est, Marne-la Vallée France), V. Allaire (Physics, McGill University, Montreal, Quebec, Canada), T. Bourgeois (CEREVE, Université Paris Est, Marne-la Vallée France), S. King, J. Pinel, and J. Stolle (Physics, McGill University, Montreal, Quebec, Canada)

Abstract

Is the numerical integration of nonlinear partial differential equations the only way to tackle atmospheric complexity? Or do cascade dynamics repeating scale after scale lead to simplicity? Using 1000 orbits of TRMM satellite radiances from 11 bands in the short wave (visible, infra red) long wave (passive microwave) and radar regions and 8.8 to 20,000 km in scale, we find that the radiance gradients follow the predictions of cascade theories to within about ±0.5%, ±1.25%, ±5.9% for the short waves, long waves and reflectivities respectively and with outer scales varying between ≈5,000 to ≈32,000 km. Since the radiances and dynamics are strongly coupled, we conclude that weather can be accurately modeled as a cascade process.

(Received 30 August 2008; accepted 10 November 2008; published 1 January 2009.)

Citation: Lovejoy, S., D. Schertzer, V. Allaire, T. Bourgeois, S. King, J. Pinel, and J. Stolle (2009), Atmospheric complexity or scale by scale simplicity?, Geophys. Res. Lett., 36, L01801, doi:10.1029/2008GL035863.

Link to abstract: http://www.agu.org/pubs/crossref/2009/2008GL035863.shtml