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The Cassini spacecraft Ultraviolet Imaging Spectrograph (UVIS) obtained observations of Jupiter's auroral emissions in [H.sub.2] band systems and H Lyman-[alpha] from day 275 of 2000 (October 1), to day 81 of 2001 (March 22). Much of the globally integrated auroral variability measured with UVIS can be explained simply in terms of the rotation of Jupiter's main auroral arcs with the planet. These arcs were also imaged by the Space Telescope Imaging Spectrograph (STIS) on Hubble Space Telescope (HST). However, several brightening events were seen by UVIS in which the global auroral output increased by a factor of 2-4. These events persisted over a number of hours and in one case can clearly be tied to a large solar coronal mass ejection event. The auroral UV emissions from these bursts also correspond to hectometric radio emission (0.5-16 MHz) increases reported by the Galileo Plasma Wave Spectrometer (PWS) and Cassini Radio and Plasma Wave Spectrometer (RPWS) experiments. In general, the hectometric radio data vary differently with longitude than the UV data because of radio wave beaming effects. The 2 largest events in the UVIS data were on 2000 day 280 (October 6) and on 2000 days 325-326 (November 20-21). The global brightening events on November 20-21 are compared with corresponding data on the interplanetary magnetic field, solar wind conditions, and energetic particle environment. ACE (Advanced Composition Explorer) solar wind data was numerically propagated from the Earth to Jupiter with an MHD code and compared to the observed event. A second class of brief auroral brightening events seen in HST (and probably UVIS) data that last for ~2 min is associated with auroral flares inside the main auroral ovals. On January 8, 2001, from 18:45-19:35 UT UVIS [H.sub.2] band emissions from the north polar region varied quasiperiodically. The varying emissions, probably due to auroral flares inside the main auroral oval, are correlated with low-frequency quasiperiodic radio bursts in the 0.6-5 kHz Galileo PWS data. Keywords: Auroras; Jupiter; Solar wind; Ultraviolet

Abstract: In this paper we analyze a pre-shock event that we observed in the foot region of the quasi-parallel bow shock (BS) that the Cassini spacecraft crossed on 30 January 2001, at about 1030UT. Before crossing the BS, the incoming solar wind first decelerated, and then the bulk velocity both of the proton and α components increased, the flow accelerated and decelerated, heated and cooled several times. We characterize the plasma in the foot using the data measured by the magnetometer, the radio and plasma wave science (RPWS) instrument, and the Cassini plasma spectrometer (CAPS) being carried onboard the Cassini spacecraft, and analyze the observations. We argue that the velocity and temperature changes can be caused by firehose instabilities excited by ions reflected from the shock. We investigate another possibility, shocklet formation, to account for the observed features, but conclude that this explanation seems to be less likely. In the foot we also identified both backstreaming electrons and ions and electrostatic waves in the 100–1000Hz range very likely excited by the backstreaming electrons. [Copyright &y& Elsevier]

• We examine the emissions impact of battery storage across sensitivities and regions. • Existing studies focus on dispatch; we show how investment effects drive emissions. • Emissions impacts of storage vary based on policy and market assumptions. • Storage emissions reductions are more likely when wind and solar are lower cost. Battery storage technologies have attracted attention from policymakers for their potential to reduce electric sector emissions by enabling greater wind and solar penetration. Yet existing studies indicate that adding energy storage actually increases emissions. The difference may be explained by the absence in the previous literature of "investment effects" – changes in deployment of other generation technologies after storage is deployed. Our paper tests this hypothesis by evaluating battery-storage-induced emissions changes using a model that accounts for both long-run investment and dispatch effects simultaneously across regions in the United States, which can be used to separate the relative magnitudes of these two effects. Model results indicate that the investment effect dominates the dispatch effect under a range of sensitivities. We find that emissions may increase or decrease with battery storage, depending on policy and market assumptions, with reductions more likely in environments where wind and solar are more economically competitive relative to natural-gas-fired generation. These results suggest that existing studies that only account for operational impacts likely underestimate potential emissions changes from battery storage deployment. [ABSTRACT FROM AUTHOR]

Abstract: Observations by several instruments onboard the Cassini spacecraft revealed the existence of heavy hydrocarbon and nitrile species with masses of several thousand atomic mass units in the ionosphere of Titan. These very large molecules are in fact aerosols. The goal of this paper is to compute the concentrations of the charged aerosols in the upper atmosphere (950–1200km) of Titan. The charging of these aerosols has been studied using the charge balance equations, where positive ions, negative ions, electrons, neutral and charged aerosols are included. Number concentrations of charged aerosols are compared with those observed by the Cassini instruments. The present work estimates the aerosol mass density as 1–10kg/m3, which is within the predicted range. The results show that the aerosols must be smaller than 10nm in order to have reasonable agreement with observations by the Cassini Plasma Spectrometer. [Copyright &y& Elsevier]

Abstract: Data from the Cassini plasma spectrometer (CAPS) electron spectrometer (ELS) have been found to be contaminated with an energy-independent background count rate which has been associated with radiation sources on Cassini. In this paper we describe this background radiation and quantitatively assess its impact on numerically integrated electron moments. The general properties of such a background and its effects on numerical moments are derived. The properties of the ELS background are described and a model for the background presented. A model to generate synthetic ELS spectra is presented and used to evaluate the density and temperature of pure noise and then extended to include ambient distributions. It is shown that the presence of noise produces a saturation of the electron density and temperature at quasi-constant values when the instrument is at background, but that these noise level moments are dependent on the floating spacecraft potential and the orientation of the ELS instrument with respect to the spacecraft. When the ambient distribution has a poor signal-to-noise ratio (SNR) the noise determines the density and temperature; however, as the SNR increases (increasing primarily with density) the density and temperature tend to those of the ambient distribution. It is also shown that these noise effects produce highly artificial density–temperature inverse correlations. A method to subtract this noise is presented and shown to correct for the presence of the noise. Simulated error estimates for the density and temperature are also presented. The analysis described in this paper not only applies to weak background noise, but also to more significant penetrating backgrounds such as those in radiation belt regions of planetary magnetospheres. [Copyright &y& Elsevier]