synopticscale

Synopticscale is a proposed metric for quantifying the characteristic spatial and temporal extent of synoptic-scale phenomena in atmospheric fields. The term combines the concept of synoptic weather patterns, typically depicted on large-scale weather charts, with the idea of a measurable scale. It is not a formal standard, but rather a concept used in methodological discussions about how to characterize large-scale atmospheric features.

In practice, a synopticscale is often represented as a pair of characteristic values, commonly noted as a horizontal length scale (Ls) and a corresponding time scale (Ts). Typical values cited for synoptic features lie roughly in the range of 1000 to 4000 kilometers for Ls and about 2 to 7 days for Ts, though these numbers vary by region, season, and dataset. The goal is to capture the dominant size and persistence of features such as mid-latitude troughs, ridges, cyclones, and fronts.

Measurement approaches for synopticscale include spectral analysis of gridded fields, space-time autocorrelation, and multiresolution methods like wavelets or empirical mode decomposition. By identifying the primary energy-containing scales or decorrelation lengths, researchers estimate Ls and Ts that best describe the synoptic content of a field.

Applications include evaluating climate and weather model outputs, guiding data assimilation techniques, and informing downscaling or forecast verification studies. The concept helps distinguish synoptic features from mesoscale and planetary-scale phenomena and emphasizes the importance of scale-aware interpretation in atmospheric analysis. Because there is no universal standard, the term is used descriptively and may be defined differently across studies.