[OpenMadrigal-developers] F10.7 Multiday average proposal

[Shunrong Zhang]

I think Fbar definition is somewhat universally adopted. If we change 
the definition as described, the Fbar for the last 40 days will actually 
repeat the true Fbar values from 80 days before to 40 days before. 
Today's Fbar will be the true value for 41 days back. As there is a 
28-day (not 41 days!) periodicity in the sloar flux, there might be some 
problems.
There might be also a big jump in the time series.

In my opinion, there are two options:  (1) when data are not available 
for the Fbar calculation, use the data for 28 (or so) days back. (2) 
invent a new F107 index, for example, Fdbar, that always give F107 
averages in the past 81 days. But we'll need to change our codes for 
calling MSIS model so that when Fbar isn't available we use Fdbar.
I think option (2) is better.

Shunrong

Bill Rideout wrote:
> Phil Erickson has suggested we modify out definition of the F10.7 
> Multiday average (FBAR).  Right now this is an 81 day average, where 
> the 81 days the center day, 40 days in the past, and 40 days in the 
> future.  The problem with this definition is that this parameter is 
> never available for any day less than 40 days in the past.  For 
> example, since MSIS uses FBAR as an input, this means that MSIS also 
> cannot be run for any day less than 40 days in the past.
> Phil has suggested that for any day less than 40 days in the past, we 
> calculate FBAR as an average over the most recent 81 days.  From the 
> Madrigal point-of-view, this means that every time we reload 
> geophysical data, the FBAR values for the latest 40 days might change 
> slightly.  At present, FBAR is not loaded into Madrigal for days less 
> than 40 days ago.
>
> We would document this FBAR definition on the Madrigal help pages.  
> Any thoughts?
>
> Bill Rideout
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-- 

_____________________________________________________________
 Shunrong Zhang  (shunrong at haystack.mit.edu)
 http://www.haystack.mit.edu/~shunrong/
 MIT Haystack Observatory, Route 40, Westford, MA 01886, USA
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