Transpolar convection and magnetospheric ring current relations: real
time applications of the Polar Cap (PC) indices
Abstract
The relations between transpolar plasma convection intensities recorded
by the Polar Cap (PC) indices and magnetospheric ring current
intensities recorded by the asymmetric ASY-H indices and the symmetric
Dst and SYM-H indices are examined. The present work believed to be the
first of its kind examines the validity of previously derived relations
between polar cap and ring current indices when used in real time
applications. Polar cap (PC) indices are here derived in simulated
real-time versions by using past data only from -40 days up to current
time in the construction of the quiet reference levels (QDCs) for the
magnetic data. From analyses spanning a decade (2009-2018), equivalent
ASY-H index values were derived from a linear relation with simulated
real-time PCN (North) and PCS (South) indices combined to form the
non-negative PCC indices. For cases of strong magnetic storms
(Dst(peak)<-100 nT, the equivalent ASY-H indices were found to
agree well with reported (real) ASY-H index values. The simulated
real-time PCC indices, furthermore, have been used in a PC-based source
function to derive equivalent values of the total ring current indices
Dst (or SYM-H) up to one hour ahead of time. With integration of the
source function throughout a decade (2009-2018) with no attachment to
reported Dst values, the simulated real-time equivalent Dst indices
displayed close agreement with real Dst index values. The applied method
could be used without modifications to generate PC index values and
derived ASY-H and Dst (or SYM-H) index values in real-time space weather
applications.