<div dir="ltr"><div><div><div>Dear Colleagues,<br><br></div><span><span>the IAGA meeting will be in Cape Town, South Africa  from 27 August  to 1
                            September
                            2017. </span></span>The IAGA abstract submission <b>deadline is on 12 March 2017.</b><br><span><span><br>We want to bring to your attention an across discipline session A39 “<b>Developing
                              and Using Realistic
                              External Source Models for imaging global
                              deep Earth conductivity
                              with Satellite and Ground-based Data”. </b>Please
                            consider submitting an abstract. The session description is attached below.<br><br></span></span></div><span><span>Sincerely,<br></span></span></div><span><span>The conveners </span></span><span><span style="color:black">(Gary Egbert, Astrid
                            Maute, Patrick Alken, Nils Olsen)<br></span></span><div><div><span><span><br>=============================================================<br></span></span><div><div><span><p style="text-align:justify;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span style="color:black">A39 - Developing and
                            Using Realistic
                            External Source Models for Imaging global
                            deep Earth conductivity
                            with Satellite and Ground-based Data (DIV VI
                            – DIV II – DIV
                            V)</span><br></p>
                        
                        <p style="margin:0in 0in 15pt;text-align:justify;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span style="color:black">Recent developments in
                            EM induction
                            modeling and inversion, together with new
                            global geomagnetic
                            datasets (e.g., from the SWARM mission),
                            present exciting new
                            opportunities for imaging three-dimensional
                            electrical conductivity
                            variations in the mantle. Results from these
                            studies may ultimately
                            provide important new constraints on the
                            composition (e.g., water
                            content), physical state, and geodynamics of
                            the deep Earth.
                            Probably the greatest obstacle to success in
                            this endeavor is the
                            need to accurately characterize the
                            spatially complex external
                            source fields, which must be disentangled
                            from the induced internal
                            fields to image mantle conductivity
                            reliably. Observations of the
                            time-varying magnetic fields remain sparse,
                            making a direct
                            empirical separation very challenging. One
                            promising approach is to
                            make use of physics-based numerical models
                            of ionospheric and
                            magnetospheric current systems. These are
                            becoming increasingly
                            sophisticated, and may provide additional
                            constraints on source
                            geometries, and enable significant advances
                            in realistic modeling
                            of external sources. This symposium seeks to
                            bring the induction
                            and external source communities together, to
                            explore progress on
                            combining ground- and satellite-based
                            geomagnetic observations with
                            numerical models for improved separation,
                            characterization and
                            modeling of external source current systems
                            in the ionosphere and
                            magnetosphere.</span></p>
                        <p style="margin:0in 0in 15pt;text-align:justify;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;box-sizing:border-box"><span style="color:black">Contributions on
                            improving source models
                            for mantle induction studies are sought,
                            along with novel uses of
                            satellite and ground based data to validate
                            or improve models for
                            external source studies. We also welcome
                            contributions on other
                            aspects of global-scale studies of mantle
                            electrical conductivity,
                            including theoretical or methodological
                            developments, and results
                            based on analysis of data from ongoing or
                            past satellite magnetic
                            missions, as well as ground based arrays.</span></p></span></div></div></div></div></div>