Geomagnetic activity is usually characterized by magnetic indices. Most indices have long records that allow statistical studies of the causes of activity and of related phenomena. Correlations between indices and possible drivers provide the basis for empirical prediction. Here we examine solar wind control of D", an index that is thought to be linearly proportional to the total energy in the terrestrial ring current. We use linear prediction filtering, a technique in which an autoregressive (AR) filter maps past values of the index to the next value, and a moving average (MA) filter maps current and past values of the solar wind input to the next value of the index. These ARMA filters may be determined from historical records by least square optimization. Nonlinear systems can be approximated in a piecewise fashion by localizing the filter. We do this by using narrow bins of the solar wind electric field; VBs. Our model utilizes 37 years of hourly observations to estimate the coefficients representing the quiet time ring current, the solar wind dynamic pressure, the ring current decay rate, and the rate of ring current injection in a simple differential equation. We find that pressure and decay coefficients are fit by exponential functions of VBs, decreasing as VBs increases, but ring current injection is a linear function of VBs. Integration of our model using observations of the solar wind and analytic fits to the coefficients produces a time series that contains 76% of the variance in the original data. The prediction residuals have a Gaussian distribution with zero mean and rms error of 10.6 nT. PI•t geomagnetic response as a function of stonn phase and amplitude and the solar wind electric field, J. Geophys. Res.,

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The Fermi Bubbles were discovered about a decade ago in the Fermi-LAT data as a double-lobe structure extending up to 55°in Galactic latitudes above and below the Galactic Center. At the moment their origin is still unknown. The H.E.S.S. collaboration is currently performing the first ever survey in TeV gamma rays of the Milky Way inner region: the Inner Galaxy Survey. This survey is intended to achieve the best sensitivity to faint and diffuse emissions in a region of several degrees around the Galactic Centre. It provides an unprecedented sensitivity to dark matter signals, new diffuse emissions, and TeV outflows from the Galactic Centre. Understanding the properties of the Fermi Bubbles at low Galactic latitudes will provide key insights into their origin. We search for TeV emission at the base of the Fermi Bubbles using low-latitude spatial templates. The first results obtained with the 2014-2020 H.E.S.S. observations will be reported.

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