Question

Hi guys!

I am just starting to use GPSTk for TEC calculations and I came across a question for which I do not have an answer and which I would like to let at your consideration:

The line of sight determination of TEC for a satellite-receiver pair leads directly to values of TEC that are primarily associated with the coordinates of the Ionospheric Pierce Points.

How are these coordinates (e.g.,longitude) converted to local time so as to allow a plot of TEC versus local time? Is there any particular assumption in doing this conversion or it is an exact conversion? My thanks,

Manuel Silva

-- ManuelSilva - 25 Oct 2010

Answer

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Dear Manuel, Conversion from longitude to local time is straight forward, and is given by LT = LONG / (15 deg/hr) + UT The important thing to remember is that this is local time, not standard time (i.e. the time in your time zone).

I hope this helps.

-- TrevorGarner - 25 Oct 2010

Dear Trevor, Thank you very much for your help. Does that mean that the value of vertical TEC determined for a specific GPS epoch and longitude is expected to become the value of vertical TEC at the ionosphere pierce point just above the receiver station after the time given by LONG/(15 deg/hr). If so, isn't this equivalent to assume that the ionosphere is static with respect to the Sun-Earth line?

Manuel

-- ManuelSilva - 27 Oct 2010