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A total solar eclipse occurred on 20 March 2015, with a totality path passing mostly above the North Atlantic Ocean, which resulted in a partial solar eclipse over Belgium and large parts of Europe. In anticipation of this event, a dedicated observational campaign was set up at the Belgian Solar-Terrestrial Centre of Excellence (STCE). The objective was to perform high-quality observations of the eclipse and the associated effects on the geospace environment by utilising the advanced space-and ground-based instrumentation available to the STCE in order to further our understanding of these effects, particularly on the ionosphere. The study highlights the crucial importance of taking into account the eclipse geometry when analysing the ionospheric behaviour during eclipses and interpreting the eclipse effects. A detailed review of the eclipse geometry proves that considering the actual obscuration level and solar zenith angle at ionospheric heights is much more important for the analysis than at the commonly referenced Earth's surface or at the plasmaspheric heights. The eclipse occurred during the recovery phase of a strong geomagnetic storm which certainly had an impact on (some of) the ionospheric characteristics and perhaps caused the omission of some ''low-profile'' effects. However, the analysis of the ionosonde measurements, carried out at unprecedented high rates during the eclipse, suggests the occurrence of travelling ionospheric disturbances (TIDs). Also, the high temporal and spatial resolution measurements proved very important in revealing and estimating some finer details of the delay in the ionospheric reaction and the ionospheric disturbances.

A series o f five trifluoroacetophenones and five phenyl trifluoromethyl carbinols have been synthesized and their ionizatio~i constants iri water measured. T h e y are t h e unsubstituted , p-methoxy, p-methyl, ni-bromo, and ?la-nitro I n connection with a n i~ivestigation of the mechanism of the permanganate osidatioli of alcohols (1) we have examined a series of trifluoromethyl carbinols (2). These were chosen because their e n l~a~~c e c l acidity permittee1 measurements to be made of the concentratio11 of the allioxicle ion believed to be the iiltermediate in the oxidation mechanism. The trifluoromethyl carbinols ant1 the ketones from which they are preparecl are interesting compounds in their own right because of their acidities, the hydrates of the latter being of similar strength to phenols. \lie woi~lcl lilie to report herein the synthesis of a series of substituted phenyl trifluoromethyl alcollols anel ketones and the determination I of their acidities. E X P E R I i L I E N T A L Reagentsa,a,a-Trifli~~roa~eto~~l~e~~~~~e \\as obtained from Columbia Organic Chemicals and was fractioilally distilled before use. All other reagents used were of reagent grade. 12-Methyl-a,a,a-frifluoroaceto$heno~zcp-Tolylmagnesiuin bromide was preparecl in the usual way from $-broiiiotoluene (31.7 g, 0.203 mole) and an equivalent a~n o u n t of magnesium. Trifluoroacetic acicl (7.5 g, 0.066 mole) clissolved in ether was aclclecl dropwise with vigorous stirring over a periocl of 2 hours a t room temperature. After refluxing for 1 hour the reaction ~t i i x t~~r e was poul-ccl onto a 10% s~~l p h u r i c acid -ice mixture and extracted several times with ether. The ether extracts were dried a~~d distilled and a clear fraction boiling a t 69' a t 13 mm was obtained; yield, 30-50%, nh5 = 1.4'710 (lit., nAO = 1.4693 (3)) ; 2,4-dinitrophenylhydrazone, 1n.p. [133][134][135][136] 57.4; H , 3.7; F, 30.3. Fou~lcl: C, 57.8; H , 3.9; I:, 26.8. This compouncl has been synthesizecl previously using a different procedure (3). rn-Brorno-a,a,a-tri~uoroacet0~~1zenoneT o a Carius tube of approximately 100 ml volume was acldecl a,a,a-trifluoroacctophenone (20 g, 0.115 mole), anhydrous ferric chloride (0.1 g), anel bromine (9 ml, 0.168 mole). The mixtul-e \\?as cooled in liquid nitrogen, the tube was sealed and then heated in a furnace for 6 days a t 1:20°.After reaction the liquid was extracted with aqueous sodiunl bromide and then fractionally clistillecl giving a small amount of unreacted lietone, a solid residue, and a clear liquid, b.p. 83.5' a t 12 mln, ng= 1.5030; yield, 50y0. Calc. for

Forecasting the strength of the sunspot cycle is highly important for many space weather applications. Our previous studies have shown the importance of sunspot number variability in the declining phase of the current 11-year sunspot cycle to predict the strength of the next cycle when the minimum of the current cycle has been observed. In this study we continue this approach and show that we can remove the limitation of having to know the minimum epoch of the current cycle, and that we can already provide a forecast of the following cycle strength in the early stage of the declining phase of the current cycle. We introduce a method to reliably calculate sunspot number second differences (SNSD) in order to quantify the short-term variations of sunspot activity. We demonstrate a steady relationship between the SNSD dynamics in the early stage of the declining phase of a given cycle and the strength of the following sunspot cycle. This finding may bear physical implications on the underlying dynamo at work. From this relation, a relevant indicator is constructed that distinguishes whether the next cycle will be stronger or weaker compared to the current one. We demonstrate that within 24-31 months after reaching the maximum of the cycle, it can be decided with high probability (0.96) whether the next cycle will be weaker or stronger. We predict that sunspot cycle 25 will be weaker than the current cycle 24.