Dear All,

I am trying to export daily average value for water temperature. I used fixed time step - 1 second.

To obtain daily average water temperature, I exported hourly data and then calculated daily value from there, but If I export 30 min frequency and calculate daily average, the number would be different. So I am wondering whether EFDC model internally track parameter value in each time step and allow user to export daily average values.

Thanks for your inputs,

Hailiang

Hello Hailiang,shen wrote:I am trying to export daily average value for water temperature. I used fixed time step - 1 second.

You can view the plot of the data you want to export the water temperature. Then on the series window you can press "ALT-S" which would display the line statistics by time blocks. This means you can choose either 1 hour , 1 day , even 1 month. The data would be the average and it would also display other statistical parameters such as minimum, maximum, standard deviation etc.

I hope this helps.

John

Thanks John, I get what you mean.

My duration of reference period is 24 hours. If i set “Writes per Ref. Period” to 1, that will export the value at midnight of each day.

If I set it to 24, it will export hourly data.

The statistic (ALT + S) calculated is based on these exported data. In other words, if i set it to 48 hours, that will be 30 min frequency in output data. The statistics would be different.

What is a normal way if asked to give daily average data?

Thanks

Hailiang

Hello Hailiang,

I think the data would be different if you choose different reference period. But I think the data averaged with most number of data would be more representative. So, I think if you are interested to show the daily data then I think you might want to make your reference period to 24 hours or more. If you have only one reference period then you will miss the details and that single number would be unrepresentative. However, if you have more number of data then it would be more relevant and more representative. It also depends what type of data you want to present.

Thanks

John