Relation between the solar wind dynamic pressure at Voyager 2 and the energetic particle events at Voyager 1

Starting in 2001, Voyager 1 observed three events characterized by enhanced fluxes of energetic particles. These events suggest that Voyager 1 made a close approach to, or a crossing of, the termination shock. Although the plasma experiment on Voyager 1 is not providing useful data, plasma data from Voyager 2 may shed light on the plasma conditions at Voyager 1. Before the first particle event, Voyagers 1 and 2 see similar particle signatures. Voyager 2 pressure and energetic particle flux profiles have similar structure. The merged interaction regions (MIRs) observed at Voyager 2 have counterparts in the Voyager 1 data. We propagate solar wind data from Voyager 2 to Voyager 1 and show that at the predicted MIR arrival times, there is always a response in the Voyager 1 particle data. These effects vary, from an increase in particle flux to a rapid turnoff of the particle event. We discuss the observed energetic particle effects and how the MIRs produce them

The Challenge of Machine Learning in Space Weather Nowcasting and Forecasting

The numerous recent breakthroughs in machine learning (ML) make imperative to carefully ponder how the scientific community can benefit from a technology that, although not necessarily new, is today living its golden age. This Grand Challenge review paper is focused on the present and future role of machine learning in space weather. The purpose is twofold. On one hand, we will discuss previous works that use ML for space weather forecasting, focusing in particular on the few areas that have seen most activity: the forecasting of geomagnetic indices, of relativistic electrons at geosynchronous orbits, of solar flares occurrence, of coronal mass ejection propagation time, and of solar wind speed. On the other hand, this paper serves as a gentle introduction to the field of machine learning tailored to the space weather community and as a pointer to a number of open challenges that we believe the community should undertake in the next decade. The recurring themes throughout the review are the need to shift our forecasting paradigm to a probabilistic approach focused on the reliable assessment of uncertainties, and the combination of physics-based and machine learning approaches, known as gray-box.Comment: under revie

Correlation of solar wind features observed from well=separated spacecraft

International audienc

Correlation of solar wind features observed from well=separated spacecraft

International audienc

Correlation of solar wind features observed from well=separated spacecraft

International audienc

The Geostationary Earth Radiation Budget Project

This paper reports on a new satellite sensor, the Geostationary Earth Radiation Budget (GERB) experiment. GERB is designed to make the first measurements of the Earth's radiation budget from geostationary orbit. Measurements at high absolute accuracy of the reflected sunlight from the Earth, and the thermal radiation emitted by the Earth are made every 15 min, with a spatial resolution at the subsatellite point of 44.6 km (north–south) by 39.3 km (east–west). With knowledge of the incoming solar constant, this gives the primary forcing and response components of the top-of-atmosphere radiation. The first GERB instrument is an instrument of opportunity on Meteosat-8, a new spin-stabilized spacecraft platform also carrying the Spinning Enhanced Visible and Infrared (SEVIRI) sensor, which is currently positioned over the equator at 3.5°W. This overview of the project includes a description of the instrument design and its preflight and in-flight calibration. An evaluation of the instrument performance after its first year in orbit, including comparisons with data from the Clouds and the Earth's Radiant Energy System (CERES) satellite sensors and with output from numerical models, are also presented. After a brief summary of the data processing system and data products, some of the scientific studies that are being undertaken using these early data are described. This marks the beginning of a decade or more of observations from GERB, as subsequent models will fly on each of the four Meteosat Second Generation satellites