In order to assess the effects of ionospheric feedback on different modes of energy transport in the magnetosphere, we investigate an isolated substorm and a steady magnetospheric convection (SMC) event with very similar solar wind drivers. The primary focus is on a comparison between the isolated substorm and the substorm that initiates the SMC. Auroral data from Polar UVI LBHl and LBHs, along with assimilative mapping of the ionosphere electrojet potential patterns are used as inputs to the global ionosphere‐thermosphere model to calculate conductances and Joule heating rates. Results from this study show that the conductances both before and during the events play a large role the ability of the magnetosphere to remain in steady driven state. The substorm that initiates the SMC event shows very different signatures in the ionosphere than isolated substorm; these signatures indicate that there is very weak substorm current wedge, or possibly a pseudo‐breakup.

Using a new method to identify steady magnetospheric convection events (SMCs), a list of more than 2000 SMCs is compiled over the 11 years between 1997 and 2007. The SMCs are then categorized by the fluctuations in their AL. Active SMCs have large fluctuations in AL and therefore a less steady magnetosphere in terms of small‐scale activity. Classic SMCs fall in the middle 50% for AL steadiness and represent the average of the SMCs. Calm SMCs have very little changes in AL and are the steadiest of the three categories. When investigating the solar wind drivers, it is found that the steadiness of the drivers is less important than the strength of the driving. Active SMCs have stronger drivers with the exception of Alfvenic Mach number and solar wind beta. The SYM‐H of the three categories is also investigated for the approximate storm time conditions of the events. Calm SMCs rarely occur during storm time when SYM‐H is less than −50 nT. If an SMC is identified during storm time, then it tends to be a more active event.

We examine the day‐night asymmetry of near‐equatorial low energy (12–100 eV) electron fluxes measured by Cassini from July 1, 2004 through April 1, 2010. This energy range is also known to be associated with interchange injections. The electrons are separated into field‐aligned (0° to 20° and 160° to 180°) pitch angles and trapped (70° to 110°) pitch angles. There is a stronger day‐night asymmetry for the trapped than the field‐aligned electrons, but both show enhanced energy fluxes on the nightside relative to the dayside. The dayside electron fluxes decrease sharply at an L‐shell of 8, while the nightside electrons exhibit a slow decline in to L = 5. Our finding, along with previous research of high energy electrons, shows that this asymmetry is energy independent. This suggests that interchange injections are stronger, and therefore penetrate deeper into the magnetosphere, on the nightside.

We compared simultaneous magnetotail magnetic flux F estimates, (1) based on in situ spacecraft measurements in the tail and solar wind (FT) with (2) the polar cap magnetic flux, estimated from global auroral images (using proton-induced or electron-induced emissions, Fp or Fe, respectively). Simultaneous Fp and Fe estimates gave the correlation coefficient CC=0.74, indicating that these measures are not absolutely precise. Regression analysis of FT versus Fe and Fp gave CC values 0.73 and 0.50, correspondingly. FT values, containing closed magnetic flux, are systematically higher than Fp and Fe by 20–30%. Motivated by diverse results, published by different groups, we reanalyzed the F dependence on the dayside merging electric field Em for different dynamical states. The linear regression F(Em) for substorm onsets shows a large slope ∼0.07–0.12GWb/(mV/m) for all Fp, Fe and FT, confirming the loading–unloading substorm scheme. For SMC intervals this slope is only 0.03 GWb/(mV/m).

Since the days of Pioneer 11 and the Voyager missions, electrons have shown an unexplained peak in the data at approximately 7.5 Saturn radii (RS). To investigate this peak, we examine near‐equatorial electron energy flux data (±10°) from the Cassini Plasma Spectrometer Electron Spectrometer from 1 July 2004 through 10 August 2007. When these data are plotted versus L shell, a peak between L = 7.5 and L = 8 appears in the electron data in the 12–100 eV range. We show that this peak is associated with interchange injections. The electrons are separated into trapped (70°–110°) pitch angles and field‐aligned (0°–20° and 160°–180°) pitch angles. The field‐aligned electrons show stronger fluxes than the trapped electrons in the 12–100 eV range during these injections. In SLS3 coordinates, the trapped electrons peak at longitudes between 45° and 240° at 7–8 RS with a smaller peak occurring between 310° and 360° SLS3 longitudes that penetrates to 6–5 RS. The field‐aligned electrons, however, show no SLS3 dependence.

Plasma ion data from the Cassini Plasma Spectrometer (CAPS) are examined for all orbits from October 25, 2004 through Dec. 26, 2007. To eliminate effects of incomplete angular coverage, data are only used from the CAPS anode that is closest to viewing into the corotational flow and within 20° of that flow. The data are plotted in the SKR‐based SLS3 longitude system. The result is a cam‐shaped distribution in radial distance and SLS3 that has an outer lobe extending beyond 20 RS at SLS3 longitudes in the range ∼270° − 50°. The western edge of this outer lobe maps to the inner extent of a previously observed spiral pattern of periodic ion enhancements, which had the magnetic signature of plasmoids at distances >35 Rs. The plasma cam and the plasmoid spiral emanating from it are responsible for plasma periodicities observed at radial distances beyond ∼15 Rs in Saturn's magnetosphere.

There are many similarities and differences in the solar wind drivers during three of the main modes of convection in the magnetosphere (isolated substorms, global sawtooth oscillations, and steady magnetospheric convection (SMC) events, which we term here balanced reconnection intervals (BRI)). Thus, this investigation utilizes statistical analysis to compare the solar wind and interplanetary magnetic field (IMF) drivers and their steadiness (standard deviation divided by the mean) during these three different event types. By including the steadiness of the drivers, the importance of magnitude, sign, and stability of the drivers for the different modes can be investigated. A series of histograms with each mode plotted over top of 6 years of background is used to measure the deviation of the mode drivers from the nominal data, and also allows for a comparison between each event type. We found that the magnitude and direction of B-z are the dominate driver for substorms, while BRIs and sawteeth require both magnitude and steadiness of certain drivers to occur. Both BRIs and sawteeth show similar steadiness in their drivers, while the magnitude of the drivers is much stronger for the sawtooth oscillations. Also included in this study are the substorms that initiate BRIs. The solar wind and IMF drivers for the initiating substorms are similar to drivers for BRIs; thus initiating substorms of BRIs are different from isolated substorms and may play a role in preconditioning the magnetosphere for BRIs.

During steady magnetospheric convection (SMC) events the magnetosphere is active, yet there are no data signatures of a large scale reconfiguration, such as a substorm. While this definition has been used for years it fails to elucidate the true physics that is occurring within the magnetosphere, which is that the dayside merging rate and the nightside reconnection rate balance. Thus, it is suggested that these events be renamed Balanced Reconnection Intervals (BRIs). This paper investigates four diverse BRI events that support the idea that new name for these events is needed. The 3–4 February 1998 event falls well into the classic definition of an SMC set forth by Sergeev et al. (1996), while the other challenge some previous notions about SMCs. The 15 February 1998 event fails to end with a substorm expansion and concludes as the magnetospheric activity slowly quiets. The third event, 22–23 December 2000, begins with a slow build up of magnetospheric activity, thus there is no initiating substorm expansion. The last event, 17 February 1998, is more active (larger AE, AL and cross polar cap potential) than previously studied SMCs. It also has more small scale activity than the other events studied here.

Abstract. Using Polar UVI LBHl and IMAGE FUV WIC data, we have compared the auroral signatures and polar cap open flux for isolated substorms, sawteeth oscillations, and steady magnetospheric convection (SMC) events. First, a case study of each event type is performed, comparing auroral signatures and open magnetic fluxes to one another. The latitude location of the auroral oval is similar during isolated substorms and SMC events. The auroral intensity during SMC events is similar to that observed during the expansion phase of an isolated substorm. Examination of an individual sawtooth shows that the auroral intensity is much greater than the SMC or isolated substorm events and the auroral oval is displaced equatorward making a larger polar cap. The temporal variations observed during the individual sawtooth are similar to that observed during the isolated substorm, and while the change in polar cap flux measured during the sawtooth is larger, the percent change in flux is similar to that measured during the isolated substorm. These results are confirmed by a statistical analysis of events within these three classes. The results show that the auroral oval measured during individual sawteeth contains a polar cap with, on average, 150% more magnetic flux than the oval measured during isolated substorms or during SMC events. However, both isolated substorms and sawteeth show a 30% decrease in polar cap magnetic flux during the dipolarization (expansion) phase.