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Re: [Orekit Developers] NRL MSISE





On 09/22/2016 10:49 AM, pascal parraud wrote:
Hi Evan,

Le 21/09/2016 à 14:43, Evan Ward a écrit :
Pascal,

Great work with the NRL MSISE atmosphere. I think it adds a significant capability to the library. I do have a couple questions about the implementation.
Thanks, I also think NRLMSISE-00 is a significant addition as this model can compute density down to the ground, unlike most others atmosphere models. By the way, I'm also working on the JB2008 model in order to give more up-to-date capabilities to Orekit for calculating drag force.

The comment on NRLMSISE00InputParameters.getDailyFlux(date) states it returns the flux for the previous day. Does this mean 24 hours prior to the supplied date?
Well, I'm not sure about that (I just copy the comments from the legacy code) and I didn't find in the literature any clear explanation about F10.7 input data, an other issue being how to get 81 days average F10.7 if you need values in the future ?
All information/experience about these data is welcome ...

I looked at the Fortran version, but that didn't have any information beyond what you've reproduced. I guess one could use predicted flux values to compute the 81 day average, but I wouldn't recommend it as using predicted flux values results in degraded orbit predictions. [1]

[1] http://arc.aiaa.org/doi/pdf/10.2514/6.2016-5258


Several classes related to atmospheres changed packages, which is a change to classes that a user would commonly use in a backward incompatible way. Is the next Orekit release going to be 9.0? I think the reorganization is a good thing. I just want to make sure people were not expecting a 8.1 release.
Luc and I were wondering about that, as it looks like a minor change (but backward incompatible, you're right) in a minor release (if we don't add others features). What do you prefer: being strict on release naming rules or being a bit flexible for minor changes ?

When it comes down to it a number is just a number, but I would prefer that if the first number is the same then the new version is a drop in replacement for the previous version.

Best Regards,
Evan


Best Regards,
Evan
Best Regards,
Pascal