The 30 cm solar radio flux: a new proxy for upper atmosphere specification by Thierry Dudok de Wit and Sean Bruinsma27 Jun 2017, 11:06 UTC
The 10.7 cm solar radio flux is a widely (if not the most widely) used proxy for solar activity. However, other centimetric wavelengths have also been monitored, some routinely and for several decades. Such observations provide unique records of long-term solar variability. We find that the radio flux at 30 cm receives relatively stronger contributions from Bremsstrahlung vs gyro-resonance emissions (as compared to the 10.7 cm flux); as a consequence, it is a better proxy for solar emissions in the less energetic part of the UV spectrum. This is confirmed by reconstructions of satellite drag by means of DTM (Drag Temperature Model), which performs better when the 10.7 cm flux is replaced by the 30 cm flux.
Daily observations of solar microwave emissions have been routinely made since the 1950’s at the Ottawa/Penticton and Toyakawa/Nobeyama observatories. Given their great value for space weather applications and for understanding long-term solar variability, we have recently set up an operational service that collects these daily values (without flare contributions) at 3.2, 8.0, 10.7, 15.0 and 30.0 cm, and performs quality control, such as replacing missing values. These data are then delivered to satellite operators, and can be accessed at https://spaceweather.cls.fr/services/radioflux/
On time scales ...