Question about computing the H density at 500 km in jr1971.jl

[penghl]

• Detail: In the paper, An analytic model for upper atmosphere densities based upon Jacchia's 1970 models, the fomular for computing the H density at 500km utilizes T∞ as shown below. However, in line 490 of file jr1971.jl, T500 is used instead to calculate the H density.
  

Could you kindly clarify why such a difference exists? Understanding the reasoning behind this would greatly help in resolving the confusion and ensuring accurate implementation. Thank you for your time and support!

[ronisbr]

Hi @penghl !

This is probably a bug! Thanks, I will investigate but it seems you are right.

[ronisbr]

I will need to perform more tests. Using your equation, the error above 500 km compared to GMAT was higher. I need to remember why I used this new version.

[penghl]

Thank you, @ronisbr. I appreciate you taking the time to test and share your findings.

[penghl]

Hi @ronisbr!
I've found that the formula in the jr1971.jl file likely originates from the report titled "Revised Static Models of the Thermosphere and Exosphere with Empirical Temperature Profiles" on page 9.
Therefore, using T_500 to calculate the H density at 500km is right.

And the header description in jr1971.jl currently cites "New Static Models of the Thermosphere and Exosphere with Empirical Temperature Profiles".

[ronisbr]

Awesome! Thanks! I will update the comment.