A proposal to improve the CIRA '86 model in the equatorial region: the ddMSIS model

The paper intends to draw the attention of future authors of the planned CIRA model to two effects discovered by us previously. They should be taken into account both in the description of the total density and in the physical connection between the magnetosphere and the neutral upper atmosphere. The first is the nighttime density maximum – even in geomagnetically quiet periods – which is probably connected with compressional heating due to global winds originating from the subsolar point. The second is the dependence of the total density residuals (with respect to the CIRA ''86 model values) on <f>Dst</f>, which might be the consequence of heating by particles precipitating from the ring current [Nabl. ISZ, vol. 24 (1986) pp. 121–127]. This effect hints at an additional magnetospheric heating (besides the well-known auroral heating in the main phase of geomagnetic storms) which acts during the recovery phase of the storms as well with a maximum near the equator. The equatorial source may be connected with ions, neutralized by charge exchange (Energetic Neutral Atoms, ENA), precipitating from the ring current and having a velocity vector directed towards the Earth. A new multiplicating function to the CIRA ''86 model (ddMSIS model) describes both additional heating effects. [Copyright &y& Elsevier]