Studying Mesospheric Chemistry Using Ground Based Resonance Lidars at the Arecibo Observatory

Multi-metal observations in conjunction with electron density measurements using ground-based resonance lidars and incoherent scatter radar located at Arecibo, provides an excellent opportunity to investigate the chemistry and dynamics of the mesospheric and the lower thermospheric (MLT) region. Ablation of meteoroids is responsible for the deposition of various metals like sodium, potassium, iron, calcium, etc., in this region. However, there is a lack of mesospheric Ca, which is depleted by about 100 times compared with Na, even though they are equally abundant in the meteoroids. Also, earlier studies have indicated that the ratio of ion to neutral for the case of Ca is higher than Na or Fe. This reflects that the Ca ion lifetimes against neutralization are large compared with their counterparts. Recent Ca ion and neutral data from Arecibo along with electron densities have shown that neutralization times are of the order of few hours, which would be compared with that predicted from an ion-molecule chemistry model for Ca. This work investigates the relation between the ion and the neutral layers along with their dependence on the strength of sporadic-E layer, which are sudden enhancement in the ionization. Apart from the layer studies, such coordinated measurements can shed light on the mechanisms of the formation of sporadic layers.