Repatriation operation in South Australia during the COVID-19 pandemic: initial planning and preparedness.

ABSTRACT: With COVID-19 affecting millions of people around the globe, quarantine of international arrivals is a critical public health measure to prevent further disease transmission in local populations. This measure has also been applied in the repatriation of citizens, undertaken by several countries as an ethical obligation and legal responsibility. This article describes the process of planning and preparing for the repatriation operation in South Australia during the COVID-19 pandemic. Interagency collaboration, development of a COVID-19 testing and quarantining protocol, implementing infection prevention and control, and building a specialised health care delivery model were essential aspects of the repatriation operational planning, with a focus on maintaining dignity and wellbeing of the passengers as well as on effective prevention of COVID-19 transmission. From April 2020 to mid-February 2021, more than 14,000 international arrivals travellers have been repatriated under the South Australian repatriation operations. This paper has implications to inform ongoing repatriation efforts in Australia and overseas in a pandemic situation.

Investigation of the Middle Corona with SWAP and a Data-Driven Non-Potential Coronal Magnetic Field Model.

The large field-of-view of the Sun Watcher using Active Pixel System detector and Image Processing (SWAP) instrument onboard the PRoject for Onboard Autonomy 2 (PROBA2) spacecraft provides a unique opportunity to study extended coronal structures observed in the EUV in conjunction with global coronal magnetic field simulations. A global non-potential magnetic field model is used to simulate the evolution of the global corona from 1 September 2014 to 31 March 2015, driven by newly emerging bipolar active regions determined from Helioseismic and Magnetic Imager (HMI) magnetograms. We compare the large-scale structure of the simulated magnetic field with structures seen off-limb in SWAP EUV observations. In particular, we investigate how successful the model is in reproducing regions of closed and open structures, the scale of structures, and compare the evolution of a coronal fan observed over several rotations. The model is found to accurately reproduce observed large-scale, off-limb structures. When discrepancies do arise they mainly occur off the east solar limb due to active regions emerging on the far side of the Sun, which cannot be incorporated into the model until they are observed on the Earth-facing side. When such "late" active region emergences are incorporated into the model, we find that the simulated corona self-corrects within a few days, so that simulated structures off the west limb more closely match what is observed. Where the model is less successful, we consider how this may be addressed, through model developments or additional observational products. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11207-020-01668-2) contains supplementary material, which is available to authorized users.

Global Non-Potential Magnetic Models of the Solar Corona During the March 2015 Eclipse.

Seven different models are applied to the same problem of simulating the Sun's coronal magnetic field during the solar eclipse on 2015 March 20. All of the models are non-potential, allowing for free magnetic energy, but the associated electric currents are developed in significantly different ways. This is not a direct comparison of the coronal modelling techniques, in that the different models also use different photospheric boundary conditions, reflecting the range of approaches currently used in the community. Despite the significant differences, the results show broad agreement in the overall magnetic topology. Among those models with significant volume currents in much of the corona, there is general agreement that the ratio of total to potential magnetic energy should be approximately 1.4. However, there are significant differences in the electric current distributions; while static extrapolations are best able to reproduce active regions, they are unable to recover sheared magnetic fields in filament channels using currently available vector magnetogram data. By contrast, time-evolving simulations can recover the filament channel fields at the expense of not matching the observed vector magnetic fields within active regions. We suggest that, at present, the best approach may be a hybrid model using static extrapolations but with additional energization informed by simplified evolution models. This is demonstrated by one of the models.

Giant convection cells found on the Sun.

Heat is transported through the outermost 30% of the Sun's interior by overturning convective motions. These motions are evident at the Sun's surface in the form of two characteristic cellular structures: granules and supergranules (~1000 and ~30,000 kilometers across, respectively). The existence of much larger cells has been suggested by both theory and observation for more than 45 years. We found evidence for giant cellular flows that persist for months by tracking the motions of supergranules. As expected from the effects of the Sun's rotation, the flows in these cells are clockwise around high pressure in the north and counterclockwise in the south and transport angular momentum toward the equator, maintaining the Sun's rapid equatorial rotation.