Time lag is about 3 months. An important open issue is that IMF observations contain gaps. For some days, there is no IMF data at all, so some fallback strategy must be devised. Since the rotation measure is determined by both electron density and the magnetic field strength, Ionosphere needs to know the Earth magnetic field. The data is downloaded from the receiver directly at the observing station.
Time lag is anywhere from a few days to a couple of weeks.
Ephemeris data for the GPS sattelites. 24 hours' worth of ephemeris, typically at 15-min sampling, is about 160 Kb. The data seems to be available for the asking at various data centers, but, unlike the other data sets mentioned here, not made publicly accessible in a standard format. Data size is negligible. Geophysical data, TGD clearly fits into the Global Data Proposal.