Notation for smaller and bigger time intervals in a time series

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In a time series, I am trying to illustrate a situation where I have two types of events:

  • some occurring at a shorter interval from each other, that corresponds to events happening at time $t$
  • some occuring at a longer interval from each other, that corresponds to rarer events happening at time $T$

both types of events' recurrence have no relations to each other (e.g. unlike seconds accumulate to minutes).

My solution is the following if I want to sum between two longer intervals:

$$d_{T+1} = \sum_{t = t >^1 T}^{ t <^1 T+1} ...$$

$d_{T+1}$ being anything that has to be estimated.

I want to express the next $t$ right after $T$ and the last $t$ just before $T+1$ in a compact form. This is what my little 1 tries to indicate. I feel like it is a similar idea to floor and ceiling ($⌈x⌉$ and $⌊x⌋$), except that they refer to integers.

Is there a better way to do this?