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| Astronomy & Geophysics 48 (2) 2.07 | | |||||
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From Giles Harrison and colleagues The article in the February A&G by Henrik Svensmark draws attention to the importance of understanding clouds in the climate system, and discusses the possibility of external cloud forcing by cosmic rays on a range of timescales extending to geological time. Uncertainty associated with clouds in the climate system has led to enormous growth in cloud physics research in recent years and the role of atmospheric electricity in solar variability and cloud processes is known to be an under-explored area ripe for further study (Gray et al. 2005, Harrison and Shine 1999, Carslaw et al. 2002). The behaviour and effects of atmospheric ions are not new topics in atmospheric physics, however. Studies extend as far back as the work of Rutherford and C T R Wilson (whose work on simulating ion-droplet processes ultimately led to a Nobel Prize for the cloud chamber). The cosmic-ray link between weather, clouds and solar variability was originally postulated in detail by Dickinson (1975), expanding on a suggestion made by Ney (1959). Empirical findings linking cosmic-ray decreases with clouds were made by Pudovkin in the 1990s (Pudovkin and Veretenenko 1997). Ion-assisted production of particles has also been extensively studied in chamber experiments, although experimental difficulties have restricted the range of parameters considered. One motivation for studying ion-assisted particle formation was its relevance to the nuclear industry, in estimating effects of atmospheric releases of radioactivity. At least one study (Vohra et al. 1969) demonstrated ultra-fine particle production from ions in the laboratory, at ion production rates typically found in the lower atmosphere. The results from the Copenhagen group represent a further incremental step, but it should be noted that their original conclusions in the Proceedings A paper (Svensmark et al. 2006) were, unlike the A&G piece, written in cautious terms. For example, on the basis of the A&G article alone, it could appear that the electron catalysis mechanism – an entirely new idea and barely experimentally investigated – should be regarded as active throughout the entire atmosphere for all time. We prefer to wait for further results, ideally obtained in the atmosphere and included in atmospheric models, before making such an extrapolation. Only by detailed independent corroboration and extension to the atmosphere can general conclusions be drawn from the preliminary experimental work in Copenhagen. There is a real possibility that fundamental new knowledge can be obtained through the international and interdisciplinary CLOUD experiment being developed at CERN, in which UK scientists have played a substantial role from the outset. References Gray L J et al. 2005 The Influence of Solar Changes on the Earth's Climate Hadley Centre Technical Note 62, Met Office. Harrison R G and Shine K P 1999 A review of recent studies of the influence of solar changes on the Earth's climate Hadley Centre Technical Note 6, Met Office. Carslaw K S et al. 2002 Science 298 5599 1732 –1737. Dickinson R E 1975 Bull. Am. Meteorol. Soc. 56 1240. Ney E P 1959 Nature 183 451 –452. Pudovkin M I and Veretenenko S V 1997 J. Atmos. Terr. Phys. 59 141739 –1746. Vohra K G et al. 1969 Role of natural ionisation in the formation of condensation nuclei in the atmospheric air Planetary Electrodynamics eds Coroniti S C, Hughes J Henrik Svensmark et al. 2006 Experimental evidence for the role of ions in particle nucleation under atmospheric conditions Proc. Roy. Soc. London A 463 2078 385 –396, DOI: 10.1098/rspa.2006.1773. Giles Harrison11Giles Harrison, Dept of Meteorology, University of Reading; Robert Bingham, Karen Aplin, Barry Kellett, Space Science and Technology Dept, Rutherford Appleton Laboratory; Ken Carslaw, Institute for Atmospheric Science, University of Leeds; Joanna Haigh, Space and Atmospheric Physics, Imperial College. |
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From David Clarke
Its purpose was to give the Junior Membership a voice and for participants to describe their research from the perspective of a student approaching the time of thesis writing or of a young post-doc. I do remember one proposal for a talk was “Nice work if you can get it”, but this was abandoned, not at my suggestion, and replaced by a more scientific topic. Eight people put their names forward and presented papers. On checking the current Membership List, I have been able to trace three of the participants who have graduated to full membership of the RAS and who continue working in posts within astronomy. A fourth person also pursues astronomy at a professional level. It is encouraging to see that 50% of the presenters have had continued interest and a strong drive to succeed in the subject and have got a piece of the “nice work”. References The Observatory 1984 104 211 –216. David Clarke11Dr David Clarke, Dept of Physics & Astronomy, The University, Glasgow G12 8QQ. |
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From Frank Pijpers Following Michael Merrifield's comment on my paper on performance metrics in the February issue of A&G, it is indeed embarrassing for me, as it must be annoying to Dr Pearce, to have predated his paper by a decade. It is a mistake which neither I nor the A&G editor spotted when reading the proofs. Given that there is only one reference in the paper, getting it wrong both in the text and in the reference list is inexcusable. The second problem lies with the 11 000+ publications. I should instead have stated that there was at least one author with 1100+ entries. I am aware that the surname Smith would not have been unique. In fact the person with the most bibliographic entries in ADS is, I think, B G Marsden with at the moment 6169 entries and as far as I know this does refer to a single person. At the date when I extracted the data from the ADS there were in fact 25 such entries (excluding et al. entries) but I admit I am not completely certain that each of those names is indeed a unique entry. Those numbers are extracted by computer from a list without detailed checks. Also, the actual number of researchers in this group could be larger since sometimes in the lists that I used, the same person would appear several times: for instance with two or only one initial, or with a full first name and an initial etc. This distributes the publications of a single person over several ADS entries. The specific point that I am attempting to make is that there is a large range, although admittedly not quite as large as the number appears to make out. For the subsequent analysis, however, I did restrict my searches to names that I could identify uniquely, and to refereed papers, as opposed to bibliographic entries. In each case I did that search explicitly through the ADS interface rather than use an automatic extraction from a list. The plots are therefore in accordance with the text. Evidently I can only wholeheartedly agree that any metric is only as good as the data from which it is generated, and repeat what I also state in the paper: I do not think there is a single metric that ought to be used for all researchers in astronomy. I would hope that this at least is supported by the paper. Frank Pijpers11Frank P Pijpers, Imperial College London. |
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From Mike Merrifield My letter was intended to be read as somewhat tongue-in-cheek, so I hope you did not take my criticisms personally. It did, I think, underline what is a real issue with metric-based systems, though: the quality of the data has to be more reliable than that which we customarily use. I also entirely agree with you that one cannot define a scientist's contribution in a one-dimensional space. Brian Marsden, whom you mentioned, is an interesting case in point: as director of the Minor Planet Center, he has put out a huge number of publications, but his h-index is 24, which is unexceptional for someone nearing the end of his career. Mike Merrifield11Prof. Michael Merrifield, University of Nottingham. |
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I noted according to the announcement poster, part of the 8 December 2006 session was given to “The First RAS Young Astronomers Meeting”. In fact, the claim of being the “first” is not exactly correct. Following an idea proposed by myself at a Council Meeting in Durham – remember the adage “never suggest anything unless you are prepared to take it on yourself”– I organized an RAS Junior Members' Day which was duly held on 10 February 1984.