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New understanding of the solar eclipse effects on geospace: The 21 August 2017 Solar Eclipse

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Last updated:
25 September 2017
A solar eclipse generates dramatic changes throughout the Earth's geospace due to the fast reduction and recovery of solar EUV irradiation. It modifies local and global energetics, dynamics, and the ionospheric ionization supply, leading to substantial changes in the coupled magnetosphere-ionosphere-thermosphere-mesosphere (geospace) system. It is an idealized "active experiment" to explore the impulse-response dynamics of geospace and to address some of the fundamental scientific questions in geospace. The 21 August 2017 solar eclipse provides an unprecedented opportunity for this because of the large amount of observational data obtained during the eclipse with recent major advances in sensitivity, spatial/temporal resolution, and global coverage of measurements, as well as the development of sophisticated geospace modeling tools. This special issue aims at quantifying the new understanding of the solar eclipse effects on geospace. This new understanding includes, but not limited to, global ionospheric and thermospheric changes, responses of neutral composition, temperature, and winds, traveling ionospheric disturbances, geomagnetic and electric field disturbances, localized and meso-scale structures,  lower ionospheric changes and associated impacts on VLF/LF/HF radio propagation.

Editors’ Highlights from Cassini Mission

Last updated:
15 September 2017

NASA/JPL/Space Science Institute

After two decades of incredible exploration, the Cassini Mission to Saturn finished on September 15, 2017. The Cassini spacecraft has beamed back images and vast amounts of data, first from its flybys of Earth, Venus and Jupiter, then from 13 years spent circulating the ringed planet and its moons, as well as insights from landing the Huygens probe on the surface of Titan, the largest moon. According to NASA, 3948 science papers have been published as a result of the mission. A search for papers in AGU journals with Cassini mentioned in the abstract published since the mission started in 1997 generated more than 750 results across 6 different journals. We are very proud that AGU has played a significant role in publishing some of the important findings from the mission. We invited some of the editors to reflect on papers published in their journals and how they have contributed to our scientific understanding. Read their comments here; the papers they chose to highlight are included in this collection.

First results from NASA's Magnetospheric Multiscale (MMS) Mission

Last updated:
11 October 2016
The Magnetospheric Multiscale (MMS) mission has been performing particle and electromagnetic field measurements in the near-Earth environment since its launch in March 2015. Thanks to data with unprecedented time resolution on four identical spacecraft in a close tetrahedron configuration (down to 10 km), MMS science goals are to probe and understand the electron-scale physics involved in the magnetic reconnection process. This collection provides a selection of key results obtained during the first phase of the mission at the dayside magnetopause. It includes new observations of the geometry and variability of the reconnection process, the detailed dynamics of particles, fields and waves in the vicinity of the reconnection region, the observation of small-scale signatures at current sheets formed in the magnetosheath, in Kevlin-Helmholtz vortices, or flux transfer events, as well as other small-scale features which are by-products of magnetic reconnection or not. These results open a new window for our understanding of magnetic reconnection in space, with direct and numerous implications for astrophysical and laboratory plasmas.

ESA's Swarm Mission, One Year in Space

Last updated:
18 June 2015
This special collection includes a series of papers that present the very first results from ESA's Earth Observation satellite mission, launched on November 22, 2013. This mission, which comprises three satellites at low Earth polar orbits, with two spacecraft flying side-by-side at low altitude (about 460km), and one flying at a slightly higher altitude (510km), provides high-precision and high-resolution measurements of the strength, direction and variation of the magnetic field, complemented by precise navigation, accelerometer and electric field measurements. These, and the constellation configuration, make it possible to separate and model the various sources of the geomagnetic field and investigate the in situ behavior of the ionosphere. This series of papers present the mission, some of its innovating instruments and the very first results and conclusions that could already be derived from the first year of Swarm in space.

Early Results from the Van Allen Probes

28 March 2014
"The Van Allen Probes mission (formerly known as the Radiation Belt Storm Probes mission, renamed on Nov. 9, 2012) is part of NASA’s Living With a Star Geospace program to explore fundamental processes that operate throughout the solar system, in particular those that generate hazardous space weather effects near the Earth and phenomena that could affect solar system exploration.

The Van Allen Probes helps us understand the sun’s influence on the Earth and near-Earth space by studying the planet’s radiation belts on various scales of space and time.
This special collection reports early results from the Van Allen Probes mission. 

Dynamics Explorer Results

1 September 1982
The Dynamics Explorer (DE) program is the latest of a number of NASA scientific missions directed toward understanding the Earth's environment. DE is particularly concerned with how the energy conveyed both by the solar wind and ultraviolet radiation interacts with the magnetosphere, ionosphere, and thermosphere and is both lost, and coupled through those regions to the lower atmosphere.

The Scifer Experiment

1 July 1996


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Featured Special Collection

A Census of Atmospheric Variability from Seconds to Decades 

The atmosphere varies naturally on all length scales from millimeters to thousands of kilometers, and on all time scales from seconds to decades and longer.  This special collection of Geophysical Research Letters synthesizes and summarizes that variability through a phenomenological census.  The collection brings together some of the most influential and definitive papers to have been published in this journal in recent years.  The topics covered include turbulence on time scales of seconds and minutes, gravity waves on time scales of hours, weather systems on time scales of days, atmospheric blocking on time scales of weeks, the Madden–Julian Oscillation on time scales of months, the Quasi-Biennial Oscillation and El Niño–Southern Oscillation on time scales of years, and the North Atlantic, Arctic, Antarctic, Pacific Decadal, and Atlantic Multi-decadal Oscillations on time scales of decades.  The collection is accompanied by a Commentary article, which provides an authoritative, concise, and accessible point of reference for the most important modes of atmospheric variability.

A Census of Atmospheric Variability from Seconds to Decades