Constraints on MTZ Water Content From Joint Inversion of Diurnal Variations and Magnetospheric Signals

Electrical conductivity of mantle minerals is highly sensitive to water content, so estimates this physical parameter based on long-period electromagnetic induction data can help constrain hydration. Reliable constraints require model with sufficient resolution at relevant depths, as well a comprehensive uncertainty analysis. In global study, we combine from the primarily ionospheric diurnal variation and longer-period magnetospheric ring current bands. Joint inversion these two sources allows significantly improved vertical radial variations, especially in transition zone (MTZ). We then evaluate how uncertainties resulting model, thermal models, laboratory results affect content estimates, focusing MTZ. Our analysis suggests that best explained by dry MTZ pyrolitic composition. Considering uncertainties, an upper bound average 0.3 wt.% water.