Various of Decompositions on a fluid field

misc., misc., 2025

Time-mean decomposition, high-low frequency decomposition, Helmholtz decomposition,… everything you’ll need to analyze a fluid field!

This page is under construction…

Time-mean decomposition

30-day running mean

Seasonal mean

Calendar-date mean

High-low frequency decomposition

Lanczos Filtering

When we need to separate fast-evovling field (such as synoptic cyclones) from (quasi-)stationary fields (such as slowly varying Rossby Waves), we could either do a FFT and cutoff at a 5-day of temporal frequency, or we can use a Lanczos filter that is even faster on large datasets.

Method: See this link

Helmholtz decomposition

When we need to decompose a 2D wind field into rotating part (div-free) and a irrotational part (straining only, curl-free), we could use a helmholtz decomposition.