Studies using all-sky imagers have revealed the presence of various ionospheric irregularities in the night-time mid-latitude F-region. The most prevalent and well known of these are the Medium Scale Traveling Ionospheric Disturbances (MSTIDs) that usually occur when the geomagnetic activity is low, and mid-latitude spread-F plumes that are often observed when the geomagnetic activity is high. The inverse and direct relations between geomagnetic activity (particularly Kp) and the occurrence rate of MSTIDs and midlatitude plumes, respectively, have been observed by several studies using different instruments. In order to understand the underlying causes of these two relations, it is illuminating to better characterize the occurrence of MSTIDs and plumes using multiple magnetospheric state parameters. Here we statistically compare multiple geomagnetic driver and response parameters (such as Kp, AE, Dst, and solar wind parameters) with the occurrence rates of night-time MSTIDs and plumes observed using an all-sky imager at Arecibo Observatory (AO) between 2003 and 2008. The results not only allow us to better distinguish MSTIDs and plumes, but also shed further light on the generation mechanism and electrodynamics of these two different phenomena occurring at night-time in the mid-latitude F-region
