1. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 Space Weather Definition This is a 1 ½ years effort, ending at 4th MCM (December 2004, ESTEC) US National Space Weather Plan definition (USNSWP definition) Conditions on the sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health The MC considered that there were two main problems with the USNSWP definition: The statement that it "can endanger human life or health" which is true under certain (exceptional) circumstances, it is often felt too strong and not at the same level of relevancy than the other effects. The fact that this definition is much oriented toward effects instead of being pure science.

2. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 ● The MC voted to not continue working with the USNSWP definition ● The MC voted to not continue working with the USNSWP definition ● The MC appointed a Terminology Working Group to define constraints for a new SWDf, and try to reach a reasonably SWDf or a reasonable draft. ● The MC appointed a Terminology Working Group to define constraints for a new SWDf, and try to reach a reasonably SWDf or a reasonable draft.

3. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 ● The MC decided to create a Terminology Working Group specifically dedicated to work on SWDf. The members of the group were: Blai Sanahuja (coordinator)MC member François Lefeuvreinvited expert at MC Pavel Hekda MC member Alain Hilgers invited expert at MC Jean Lilensten COST chairman Iwona Stanislawska MC member Yurdanur Tulunay MC member Terminology Working Group

4. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 Important issues identified by the TWG 1. The USNSWP definition is the most widely used so far  the new definition must be compatible with it 2. The USNSWP is criticised for its excessive emphasis on hazardous SW effect on human health  The statement could be softened 3. The USNSWP is criticised for the lack of reference to scientific activities  space weather can be the subject of scientific study but is not a scientific activity per se

5. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 Weather Space Weather ( = phenomena, state, conditions) Meteorology Physics of the Sun – ( = science, scientific) Earth Relation (?) An analysis was made of several different definition of (terrestrial) weather

6. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 List of constraints approved by the TWG Then, the topical group came with a list of 9 constraints for the definition of space weather to solve the aforementioned issues. This list was approved by the MC These constraints addressed the points above, but also the compatibility with weather, solar variability, understandability … A call was open from which 12 definitions were proposed. 5 of the 12 were answering positively at least some of the constraints. This selection was proposed to the whole MC through a tab to fill. Then, we came with 1 proposition:

7. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 ● SWDf8 Space Weather describes the physical processes induced by solar activity that have impact on our terrestrial and space environment, on ground based and space technological systems, and on human activities and health. The main goals of space weather are establishing the scientific basis to understand such phenomena and developing operational tools to predict and forecast them. ● SWDf8 Modified I Conditions induced by solar activity that have impact on our terrestrial and space environment, on ground based and space technological systems, and on human activities and health. The main goals of space weather are establishing the scientific basis to understand such phenomena and developing operational tools to predict and forecast them. US National Space Weather Plan definition (USNSWP definition) Conditions on the sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health

8. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 And then, the whole process collapsed. I really dislike staying on a failure. Not my way. Therefore, can we discuss a bit: Why did we fail? Can we find a way to have something to present at ESWW4 in November? My suggestion: can we converge toward a few number of definitions (i.e. 3) that would have different goals?

9. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007

10. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 ● SWDf1 Space Weather describes physical conditions in the Earth's environment which are ultimately determined by the variable solar activity. ● SWDf2 Space Weather describes physical conditions in the Earth's environment which are ultimately determined by the variable solar activity. Space weather manifests itself through various physical phenomena which are observed in the Earth's environment comprising space and ground. ● SWDf3 Space Weather Research aims at the understanding and quantification of physical processes associated with solar activity which affect the coupled Sun-Earth system in all aspects. ● SWDf4 The goal of space weather research is the establishment of the scientific basis needed to develop the capability to forecast solar activity and its effect on geospace, the biological manifold, and technological systems. ● SWDf5 Space environment changes (essentially electromagnetic and particulates with natural origin) and their related effects (especially on human activities in space and on Earth). Some Space Weather definitions proposed, adapted or that appeared in the process (I)

11. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 ● SWDf6 Space Weather is the physical and phenomenological state of Ecospace, the region where human activities interact with the terrestrial and space environments. Space Meteorology is aimed at the observation, the study and the prediction of Sun- and non-Sun-driven perturbations in Ecospace, which affect both biological and technological systems ● SWDf7 Space Weather is the science of the composition and dynamics of the space environment of the Earth, from its upper atmosphere to the heliosphere. It aims at understanding the mostly solar origin of the space environment and all the interactions inside the space environment predicting and quantifying the energy inputs due to solar activity and cosmic radiations and their impact on the space environment predicting and quantifying the consequences of these variations on the ecospace, defined as the region where human activities interact with the terrestrial and space environments ● SWDf8 Space Weather describes the physical processes induced by solar activity that have impact on our terrestrial and space environment, on ground based and space technological systems, and on human activities and health. The main goals of space weather are establishing the scientific basis to understand such phenomena and developing operational tools to predict and forecast them. Some Space Weather definitions proposed, adapted or that appeared in the process (II)

12. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 ● SWDf9 Sun activity that acts on the biosystem ● SWDf10 The conditions and processes occurring in space which have the potential to affect the near Earth environment. Space Weather processes can include changes in the interplanetary magnetic field, coronal mass ejections from the sun, and disturbances in the Earth's magnetic field. The effects can range from damage to satellites to disruption of power grids on Earth. ● SWDf11 Space Weather describes physical conditions in the Earth's environment which are ultimately determined by the variable solar activity and which may affect human activities in space and on Earth. Space weather activities include: scientific research, operational observations and modeling, forecast and specification services. ● SWDf12 Processes in the solar wind and Earth environment induced by solar variability (variable conditions on the Sun). Particular consideration is given to their impact on space-born and ground-based technological systems and human health. Some Space Weather definitions proposed, adapted or that appeared in the process (III)

13. COST 724:Developing the scientific basis for monitoring, modelling and predicting Space Weather Sofia meeting, May 2007 SWDf  Constrai nt  Df1Df2Df3Df4Df5Df6Df7Df8Df9Df1 0 Df1 1 Df1 2 Df1 3 C1?Yes ?No Yes No?Yes C2No Yes ? NoYes C3No?? ? ? ??? C4No Yes No Yes C5???No?? Yes?? ? C6No Yes ?NoYes No YesNo C7Ye s ? NoYes C8Ye s No Yes ? C9Ye s NoYes ? LengthNoYes NoYesNoYesNoYes