GLOBALGEODETICOBSERVING
SYSTEM
GGOS Focus Area 4: Geodetic Space Weather Research
12Chair: Michael Schmidt , Vice-Chair: Klaus Börger
1 Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM), Munich, Germany, Contact: mg.schmidt@tum.de
2 German Space Situational Awareness Centre (GSSAC), Uedem, Germany

Introduction• Space weather is a very up-to-date and interdisciplinary field of research.
• It describes physical processes in space mainly caused by the Sun’s radiation of energy.
• The are multiple manifestations of space weather, e.g. (1) the variations of the Earth magnetic field, (2) thepolar lights in the northern and southern hemisphere, (3) the variations of the ionosphere and thermosphere(due to coupled processes), (4) the solar wind, (5) the interplanetary magnetic field, and (6) the electriccurrents.
• The most extreme known space weather event happened at September 1, 1859 – the Carrington storm.
• Prominent recent events are the Halloween storm at October 28 – 30, 2003, the Bastille Day Event at July
14, 2000 or the St. Patrick’s storm at March 17, 2015.
• The strength of these events, their impacts on modern society and the possibility of much stronger future
events have brought several countries such as US, UK, Japan, Canada and China to recognize the necessity– of studying these impacts scientifically,– of developing protection strategies and procedures and– to establish space weather data centers and space weather services.

Figure 1: Space-geodetic observation techniquesin the context of satellite missions monitoring
solar events.

Geodetic Monitoring of the Ionosphere and theThermosphere• Figure 1 gives an overview about the space-geodetic observation techniques which provide
valuable information about the state of the ionosphere.
• Satellite Geodesy has to deal with the thermosphere, since thermospheric drag is the mostimportant force acting on Low-Earth Orbiting (LEO) satellites and objects in the re-entry stage.
• Figure 2 illustrates symbolically the coupled processes between magnetosphere, ionosphere andthermosphere.
• Geodesy has a long history and large experience in developing and using sophisticated analysis
techniques and modelling approaches.
Figure 2: Events effecting different parts of theatmosphere including the coupling processes from thelower to the upper atmosphere.

Conclusion: Space Weather is a geodetic topic as well!

Consequences

Objectives of Focus Area 4

Geodetic space weather research must bebased on

Joint Study Groups (JSG) related
to the Focus Area 4

The main objectives are:

For the realization of the objectives at least 2
new GGOS JSGs have to be installed:• the use and combination of all spacegeodetic observation techniques,• geodetic methods for real-time modelling and• forecast approaches.
Assimilation strategies must be developed toconsider additional information such as Sunobservations.
Consequently, geodetic space weather
research comprises the basic ideas of GGOS.

• improvement of positioning andnavigation by developing high-precisionand high-resolution models of the electrondensity,• improvement of precise orbit
determination (satellites and space debris)by developing high-precision and highresolution thermospheric drag models..

Image courtesy of the Earth Sciences and Remote Sensing Unit, NASA Johnson Space Center• JSG 1: Electron density modelling of theionosphere including space weather effects
from the combination of space-geodetic
measurement techniques.
• JSG 2: Improvement of thermospheremodels including physics-based realisationsof coupled thermosphere-ionosphereprocesses, in particular for applications toLEO precise orbit determination (POD).