For the unfamiliar, 'Eulerian' and 'Lagrangian' are basically just names for two different frames of reference. Eulerian sampling is like dotting the countrysi

For the unfamiliar, 'Eulerian' and 'Lagrangian' are basically just names for two different frames of reference. Eulerian sampling is like dotting the countryside with weather stations. Your measurement data shows the weather at each of those fixed points over time and from that you can understand what was happening. Lagrangian sampling is like sending up weather balloons. Your measurement data shows the weather around the balloons as they float along with the wind. That will give you all the same information, but from a different perspective. The Eulerian perspective for weather makes it easier to understand what's happening at a specific location, but harder to understand what's happening to a specific particle of air. The Lagrangian perspective is the opposite. There is an explanation of this in the paper, but IMO, it's a little more difficult to follow than the classic weather analogy. Just wanted to demystify the name a bit.