Comparison of photometer and global MHD determination of the open‐closed field line boundary

Abstract

We compare open‐closed field line boundary positions from the BATS‐R‐US Global MHD model and CANOPUS photometer measurements of red‐line emissions. We choose intervals of steady interplanetary and ionospheric conditions in order to adhere to the “steady‐state” picture that we are trying to address. Nine intervals are chosen that correspond to stable IMF and auroral conditions that can be simulated with the MHD model. We find that on average, the steady‐state BATS‐R‐US MHD model provides an excellent estimate of the open‐closed field line boundary proxy as determined by the red‐line auroral emissions. Typical errors between the model calculations of the open‐closed field line boundary and the observations are within the inherent error in using the red‐line emissions.