Kevin Cronin
Feb. 8, 2022
8:37 a.m. PST

Beginning Interval and how observations are averaged

This is assuming you will be comparing hourly averaged observations against the forecasts. We are trying to understand what beginning interval means.
How do you conduct your hourly average of the observations?
1. Center average around the hour. So if its 12Z: 11:30Z-12:30Z.
2. Every observations in the hour. So if its 12Z: 12:00Z-12:59Z

-Thanks for your help so far you have been very helpful.
1 Reply

Leland Boeman
Feb. 8, 2022
9:56 a.m. PST
Hi Kevin,

When calculating observation averages in the SFA, there are a few things to account for. Each forecast and observation has it's own "interval label", "value type" and "interval length". For the competition, each forecast and observation will have a "value type" of "interval mean", that is each data point represents the average value over a period of "interval_length".

"Interval label" describes which side of a given interval the data is labelled for. If an observation has a interval length of 1 minute and interval label of "beginning" then for example the 12:00Z data point contains data for 12:00:00-12:00:59. Similarly, an interval label of "ending" means that the 12:00Z data point contains data for 11:59:01-12:00:00.

When averaging for analysis, we average the observation to conform to the interval conventions of the forecast.

For example, consider a 1-hour interval, "beginning" labelled forecast. The 12:00Z data point would be for data that occurs between 12:00:00Z and 12:59:59Z.

To obtain an average 12Z observation to compare against this forecast, we will use an average of the 1-minute observations from 12:00Z-12:59Z. If the observation were to have an interval label of "ending" we would use the 1-minute observations from 12:01Z-13:00Z.

Hopefully that helps. Let me know if you have any further questions.
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