Top-10 Papers of 2007

Here is one more post in this set of three with my lists of top papers from past years of JGR Space Physics. Here is the list for 2007; so, ~10 year-old papers. As a final reminder, these citation counts listed below were taken from Web of Science on December 30, 2017.

The list of Top-10 Most Cited Papers published in 2007 in JGR Space Physics:

  1. Summers, D., et al., Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 2. Evaluation for VLF chorus, ELF hiss, and electromagnetic ion cyclotron waves, 310 citations
  2. Zhang, J., et al., Solar and interplanetary sources of major geomagnetic storms (Dst <= -100 nT) during 1996-2005, 267 citations (note: has a correction)
  3. Newell, P. T., et al., A nearly universal solar wind-magnetosphere coupling function inferred from 10 magnetospheric state variables, 232 citations
  4. Li, W., et al., Dynamic evolution of energetic outer zone electrons due to wave-particle interactions during storms, 214 citations
  5. Summers, D., Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 1. Theory, 183 citations
  6. Lei, J., Comparison of COSMIC ionospheric measurements with ground-based observations and model predictions: Preliminary results, 167 citations
  7. Vadas, S. L., Horizontal and vertical propagation and dissipation of gravity waves in the thermosphere from lower atmospheric and thermospheric sources, 146 citations
  8. Meredith, N. P., et al., Slot region electron loss timescales due to plasmaspheric hiss and lightning-generated whistlers, 128 citations
  9. Omura, Y., et al., Relativistic turning acceleration of resonant electrons by coherent whistler mode waves in a dipole magnetic field, 118 citations
  10. Fejer, B. G., et al., Equatorial ionospheric electric fields during the November 2004 magnetic storm, 117 citations

For this crew, let’s suggest Totally Awesome stickers:


These are, like last time, from Zazzle.

Again, all of these papers have an average of over 10 citations per year. That’s high for any annual count of any paper in our field, but to sustain it for 10 years, that’s truly phenomenal. These papers, and their authors, deserve special acknowledgment. Congratulations on writing such highly-cited papers!

An interesting thing to point out is the one-two punch of the Summers et al. papers, both making it into this top-10 list. Paper #1 derives the formulas for the timescale analysis of several different combinations of plasma wave and energetic electron characteristics and then Paper #2 applies the specific wave properties for several magnetospheric plasma waves of particular relevance to the radiation belts. Danny and crew had a very good year!

Counting the research topics, I see one solar-heliospheric paper, one techniques paper (the “Paper #1: theory” one just discussed), one solar wind-magnetosphere coupling function study, three ionosphere-thermosphere papers, and 4 on radiation belt results. No planetary space environment papers made the top-10 list, but all of the other major disciplines within the journal scope are there.


Top-10 Papers of 2012

I’d like to continue with my lists of top papers from past years of JGR Space Physics. Here is the list for 2012. Again, the citation information used to generate this list was taken from Web of Science on December 30, 2017.

The list of Top-10 Most Cited Papers published in 2012 in JGR Space Physics:

  1. Meredith et al., Global model of lower band and upper band chorus from multiple satellite observations, 95 citations
  2. Usanova et al., THEMIS observations of electromagnetic ion cyclotron wave occurrence: Dependence on AE, SYMH, and solar wind dynamic pressure, 89 citations
  3. Min et al., Global distribution of EMIC waves derived from THEMIS observations, 89 observations
  4. Gjerloev, J. W., The SuperMAG data processing technique, 86 citations
  5. Schrijver, C. J., et al., Estimating the frequency of extremely energetic solar events, based on solar, stellar, lunar, and terrestrial records, 68 citations
  6. Jin, H., et al., Response of migrating tides to the stratospheric sudden warming in 2009 and their effects on the ionosphere studied by a whole atmosphere-ionosphere model GAIA with COSMIC and TIMED/SABER observations, 66 citations
  7. Jia, X., et al., Magnetospheric configuration and dynamics of Saturn’s magnetosphere: A global MHD simulation, 62 citations
  8. Dwyer, J. R., The relativistic feedback discharge model of terrestrial gamma ray flashes, 61 citations
  9. Fu, H. S., et al., Pitch angle distribution of suprathermal electrons behind dipolarization fronts: A statistics overview, 56 citations
  10. Park, J., et al., Effect of sudden stratospheric warming on lunar tidal modulation of the equatorial electrojet, 54 citations

You should go get yourself a Super! sticker:




Remember, all of these papers are only ~5 years old, so these citation numbers indicate a healthy rate of more than 10 per year since publication. That’s very high for our field.

I see one planetary study, one heliospheric, one techniques paper, three ionosphere-thermosphere related, and 4 magnetospheric physics focused papers in the list. So, the studies are distributed across all major themes of the journal’s scope.

That the top 3 are about plasma waves in the magnetosphere is probably not a coincidence; with the launch and commissioning of the Van Allen Probes in late 2012, this topic has become a central focus of the community since then. So, a stating-the-obvious take-away point from these examples: when there will be a flood of papers on a particular topic from a new spaceflight mission, it is perhaps useful to get a pre-mission paper published just before the prime mission phase.

Top-10 Papers of 2015

It’s been suggested to me that I should occasionally use this space to list the “top papers” in JGR Space Physics. I did this once but that was a while ago. As 2017 came to a close (on December 30, to be specific), I surfed to Web Of Science and downloaded the citation information with the “publication name” search term “Journal of Geophysical Research Space Physics.” I did this for papers published in a few selected years: 2015, 2012, and 2007; so, 2, 5, and 10 year-old papers. The 2015 papers will be skewed a bit due to the proportionately large age difference from January 2015 to December 2015, but this is a year included in the Journal Impact Factor, so I thought I’d include it here. Also, not all of the 2017 citations to papers are included in WoS yet, especially from papers published late in the year. Still, these citation values are fairly complete and can provide insight into top papers in these years.

Yeah, this is how I spend my Saturday evenings. Don’t worry about me, though, it didn’t take that long.

I’ll spend a few posts here in January analyzing these citation reports. I won’t go into too much detail, as I know that there is a detailed manuscript on this topic in works. Top 10 lists are good to share, though, as are some basic stats on citations for these specific years.

For this first post, here is the list of Top-10 Most Cited Papers published in 2015 in JGR Space Physics:

  1. Kurth et al, Electron densities inferred from plasma wave spectra obtained by the Waves instrument on Van Allen Probes, 79 citations
  2. Livadiotis, Introduction to the special section on Origins and Properties of Kappa Distributions: Statistical Background and Properties of Kappa Distributions in Space Plasmas, 53 citations
  3. Astafyeva et al., Ionospheric response to the 2015 St. Patrick’s Day storm: A global multi-instrument overview, 50 citations
  4. Saikin et al., The occurrence and wave properties of H+-, He+-, and O+-band EMIC waves observed by the Van Allen Probes, 43 citations
  5. Jaynes et al., Source and seed populations for relativistic electrons: Their roles in radiation belt changes, 39 citations
  6. Li et al., Statistical properties of plasmaspheric hiss derived from Van Allen Probes data and their effects on radiation belt electron dynamics, 35 citations
  7. Saur et al., The search for a subsurface ocean in Ganymede with Hubble Space Telescope observations of its auroral ovals, 33 citations
  8. Engebretson et al., Van Allen probes, NOAA, GOES and ground observations of an intense EMIC wave event extending over 12 h in magnetic local time, 32 citations
  9. Li et al., Upper limit on the inner radiation belt MeV electron intensity, 31 citations
  10. Ni et al., Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales, 29 citations

These authors all get a gold star for writing a highly-cited paper:


If you need more gold stars, you can buy them for yourself here, where I got the image.

I am not sure if there are any lessons to learn from this list, but it is fun to share it and commend these authors on a job well done. Here are a couple of other tidbits about the list.

The truly surprising one on this list, at least to me, is #2: the special section preface.  Over 50 citations to a preface in just under 3 years is, well, amazing. If you have a look at it, though, then you will quickly realize that it is a tutorial on the topic of Kappa distributions in space plasmas, with 82 references to papers published in a wide range of years, from 1862 to 2014. It’s really a topical review.

Also, 6 of the 10 are about the Earth’s radiation belts or plasma waves relevant to this particle population. This is not surprising given that, in 2015, NASA’s Van Allen Probes mission was just finishing its prime mission phase, with a full scan of local time of data available for analysis. The continued success of this mission’s data set for scientific discovery has propelled radiation belt papers to the top of this list. The top-cited paper (Kurth et al) is not included in this count of 6 but is related to the topic, being a study of the thermal plasma density in Earth’s inner magnetosphere from this same mission. Because the thermal plasma density is a critical controlling factor for plasma waves and wave-particle interactions, it should probably be added to the count, making it 7 of 10. It was a good year for radiation belt papers.

More On Plain Language Summaries

For over a year now, AGU has been including the option of a Plain Language Summary with manuscript submissions to any of its journals. This can be about as long as a regular Abstract to your paper, but should be written so that those outside of space physics can understand it. From the AGU text requirements page, the definition goes like this:

“The plain language summary should be written for a broad audience. It should be free of jargon, acronyms, equations and any technical information that would be unknown to the general public. The purpose is to explain the study to the public. A good summary should state the general problem, what was done, and the result.”

This description should be ingrained in all of us, not just those submitting papers in the near future but also anyone reviewing a manuscript for JGR Space Physics or another AGU journal. Yes, if you are asked to review a paper and it has a Plain Language Summary, then please read it and comment on its quality. This should be considered as an essential part of the review process, just like assessing the Key Points and keywords that the authors have provided for the paper.

AGU now has more information about these Plain Language Summaries to help you write a good one. For me, this advice about creating a Plain Language Summary comes down to the final bullet point: take the time to do it right. This is not something that you should crank out during the GEMS submission process. That not only will just be an initial draft of what it could be but also won’t be vetted by your coauthors. Their name is on the paper too, and the Plain Language Summary is published with the paper, right below the official Abstract, so you should definitely include your coauthors in its creation. Please do not just change a few words from your regular Abstract, but instead write it from scratch and edit it to make it appealing to a nonspecialist audience.

Here is the nice graphic from that webpage, by @JoannaScience:


She did a cartoon for one of my Editors’ Vox articles. This graphic above pretty much sums up how space physics Abstracts are understood by non-space-physicists. Our niche of AGU has to work especially hard at communicating our work to the public; learning how to write a good Plain Language Summary is an excellent start.

AGU has put together a page with some really good Plain Language Summaries. Have a look to see the kind of summary that resonates.

For now, this paragraph is optional, and I have been told that roughly 20% of manuscript submissions include a Plain Language Summary. Writing a good Plain Language Summary, however, greatly increases the chances of your paper being highlighted by AGU in some way. AGU HQ staff read every Plain Language Summary for all accepted papers across all AGU journals. If they come across a good one. At 20%, this is about 5 summaries per day. When they come across a really good one, the paper will, at the very least, receive a social media highlight. They might work with the journal Editor that handled the paper to create an Editors’ Highlight for the paper. Or, it might even be the initial nugget of a Research Spotlight or Editors’ Vox article about the paper. The point is that the paper could be elevated to receive a highlight regardless of what the reviewers and editor thought about its highlight worthiness. If you write a good highlight, then your paper will have an increased chance of receiving special highlight attention from AGU.

While I have not seen stats on whether the various highlighting that AGU does for papers results in more citations, I have seen the stats on page views and full-text downloads, and the link is clear and extremely favorable. Traffic towards the paper is typically greatly enhanced with a highlight. So, it is in your best interest to spend some time on the Plain Language Summary.



Comparing the Impact of Journals

Yesterday the JGR Space Physics editors had their quarterly telecon and we talked a bit about the new Journal Impact Factor (JIF) that was just released. We want the journal to be very high quality but we do not want to be metrics manipulators. We agreed to monitor it for the next few years.

The topic of metric reliability is on the minds of many journal editors. Martyn Clark, the Editor in Chief of AGU’s journal Water Resources Research, just published an Editorial entitled, “The citation impact of hydrology journals,” coauthored by Brooks Hanson, AGU’s Director of Publications. It analyzes several metrics for 6 hydrology-related peer-reviewed journals for the past ~20 years. It’s a very nice examination of journal metrics for a geophysics field. I encourage you to read it.

Let me summarize the key findings. They show that all of the journals have the same temporal trend in their metrics, with the JIF steadily rising, in general, for all hydrology journals over the last 15 years. They also see significant variability in the JIF of smaller journals (i.e., those that publish < 200 articles per year) as a few highly-cited papers skew the JIF upwards for a year or two, quantified by resampling the articles to create a uncertainty spread on the metric. All of the journals had Lost Papers with zero citations and Super Papers with >100 citations. They find hydrology papers taking a relatively long time to “mature” and reach full influence on the field, a similar trend as in space physics, as evidenced by most citations occurring after the 2-year window of the JIF (compare their Figures 6 and 7 with a similar plot for JGR Space Physics here). The main finding of the article is that journal metrics, in particular the JIF, are temporally variable, have relatively large spreads of uncertainty, and are not representative of the influence of a specific paper on its research field.

The JIF is reported to 4 significant digits, but this Editorial clearly demonstrates that this level of precision is overkill. Here is a plot of the spread of JIF values for 3 of the journals:


JHM is the smaller of these 3 and the uncertainty in its JIF is > 0.5. The other two journals publish 500-800 articles per year, so their uncertainties are lower, but they are still several tenths of a point.

They bring up a fantastic point that I want to repeat here: citations to a paper do not necessarily measure the quality of the paper, but rather represent the utility of the paper. Citations show that others are building on the findings of the paper but the number of citations does not capture the robustness of the analysis within the paper. I don’t think that we have a good measure for that yet.

If you look at the Acknowledgments, Jennifer Satten at Wiley provided the bibliometrics data for this article. She has given me much of the same information for the field of space physics. I could work up a similar article for our discipline. It’s on my to-do list. Maybe I will, or perhaps I’ll just show some plots in this blog as I make them.

JGR’s 2016 Impact Factor

Clarviate Analytics, the new company name for the part of Thomson Reuters that makes the Journal Citation Reports, just released the 2016 Journal Impact Factors. As expected, they separated the sections of JGR into different journals, giving each one its own JIF. And the value for JGR Space Physics is … wait for it … 2.7.


            As I wrote back in January his is what I was expecting. Actually a little higher, which is nice. While this is a big drop from last year’s “all sections of JGR” value of 3.3. The JGR Space Physics JIF score is the lowest of the JGR family, just below JGR Oceans (at 2.9) and a full point below JGR Planets (at 3.7).

I am not that concerned about it. I gave several reasons for this back in January, especially the fact that we have a near linear growth in the average citations per paper for the first decade after publication. That is, the average citations per 10-year-old paper is right at 30. On average, we cite each paper ~3 times per year, every year, for a long time after publication. Here’s the graph I showed in January supporting this:


This is not the only good news about the longevity of JGR Space Physics papers: the cited half life is over 10 years (the maximum that Clarviate Analytics posts, “>10.0”). So, on average, a 10-year-old paper has yet to reach half of its total citations over its lifetime. This means that the average JGR Space Physics paper will eventually reach a total citation count of over 60.

Another bright spot: our Immediacy Index is 0.71, which is second among the JGR family. This is the number of citations in the year 2016 to papers published in the year 2016. For reference, a quick scan over the last 5 years of values reveals that only one AGU journal, Reviews of Geophysics, has an Immediacy Index over one (it jumps between 1 and 3, with its 2016 value being 2.3). I have not analyzed whether this is from a few papers getting many citations or a broad spectrum of papers getting a few, but either way, I’d say that we’re doing pretty well at reading the new literature. Way to go!

Our field of space physics has a particular way of citing publications. Some papers get immediate attention resulting in citations within the first year but most papers take a while to be absorbed by the community and achieve their full impact on the field. In the long run, JGR Space Physics papers are highly cited.

AGU’s Commentary Collections

A Commentary is an AGU paper type that offers a perspective on a recent result, controversy, or special event in particular field. JGR Space Physics published 15 Commentaries in 2016, most of them as part of the special section on Unsolved Problems in Magnetospheric Physics. These short articles are meant to spur discussion, action, and hopefully eventual resolution regarding the chosen topic. In JGR Space Physics, they are too new to understand and quantify their influence. Other journals have published Commentaries for many years, and the anecdotal evidence is good enough that AGU is encouraging all journals to publish more of these.

To better highlight and promote the existence of these papers, AGU has assembled several new special collections that gather these Commentaries for easy discovery. The link is on all journal websites, under the Special Collections pull-down menu:


On this page are links to the Commentaries in each AGU discipline, including Space Weather and Space Physics. There are Commentaries here from a few different journals. Because papers cannot be in two special sections in the Wiley paper management system, instead of listing all of the UPMP Commentaries, there is simply a link to that special section’s webpage.

Happy reading!


Want Some Salt With That Metric?

I’ve become a fan of the Scholarly Kitchen. It’s a multi-author blog produced by the Society for Scholarly Publishing. They have daily posts about academic publishing across a wide range of topics, including some useful categories for JGR Space Physics readers, like peer review, discovery and access, and a category simply called academia.


While at the AGU EiC meeting this week, a link to a just-posted Scholarly Kitchen article was circulated on the trustworthiness of journal metrics. The author rates the various journal metrics according to their completeness, transparency, and veracity. She uses a clever scale…the “grains of salt” with which you should take each of the metrics. It goes well with my recent posts on metrics.

And the winner is…CrossRef, which only requires a pinch of salt. ISI and Scopus should be taken with a cup of salt, Download Statistics with a bathtub of salt, and Google Scholar and Research Gate with a classroom full of salt. Yeah, she really doesn’t like Google Scholar for scholarly metrics.

The author is Angela Cochran, who is the Journals Director for the American Society of Civil Engineers and a Past-President of the Council of Science Editors. She knows what she’s talking about on this subject.

I like one of the comments on the article about defining a new SI unit for skepticism, the pinch. A cup of salt is then a kilopinch, a bathtub a megapinch, and a classroom is a gigapinch. Clever.

CrossRef is what is used by Wiley for the “Cited By” link on each paper for all AGU journals, including JGR Space Physics. Here’s a recent example article with a healthy number in the “cited by” tab. When a publisher prepares a paper for production, they check the references for compliance with the database of known scholarly literature. Once published and online, that paper’s link is sent to CrossRef, which resolves the reference tags against its vast database, ensuring that the citation from the new paper is counted in the “cited by” list for each cited reference in it. The system is fast and the linkages are automatically made. CrossRef is a non-profit organization to which nearly all publishers contribute and subscribe, meaning that the database is as robust as possible and yet focused only on scholarly content.

CrossRef does not take the next step of generating an Impact Factor or CiteScore, which are proprietary creations of Thomson Reuters and Elsevier, respectively. What you get with CrossRef is a near-instantaneous update of the “cited by” number and paper listing at the Wiley site for your papers in AGU journals, and you can trust that it is the most accurate count of citations to your paper from other scholarly publications. That’s okay with me. We need to be dishing out kilopinches (or more) of salt with those other metrics, anyway.

Impact Factor Just For JGR-Space Physics

This coming year, I am told that Thomson Reuters will release section-specific Journal Impact Factors for JGR. I want to give the community a heads-up on where we stand.

If your institution has a subscription to Thomson Reuter’s Web of Science, then it is not a difficult to do a search for “Journal of Geophysical Research Space Physics” in the “Publication Name” field for specific years (one at a time) and get the citation numbers for a Journal Impact Factor specific for JGR-Space Physics.

I just did this and here are the results:


Unofficial JIF for JGR-Space Physics:

Number of items published in 2014:              760

Number of items published in 2013:              711

Cites in 2015 to items published in 2014:      1808

Cites in 2015 to items published in 2013:      2077

My estimate of the 2015 JGR-Space Impact Factor =      3885 / 1471 = 2.64


Hmm. This is well below the JGR-all sections JIF of 3.3 reported by Thomson Reuters. When I do this same search but with “Journal of Geophysical Research *” for the publication name, then I get a value of 3.20. This is close but a bit lower than the Thomson Reuters value. This is expected because I did not remove Editorials, Prefaces, and other items from the list of “papers”, which presumably have few if any citations and which presumably Thomson Reuters removes from the JIF calculation. So, perhaps the JGR-Space Physics value that I just calculated should be up by a tenth or two, but most likely it is still below 3.0.

I gathered the numbers for the 5-year Impact Factor, and for 2015, JGR-Space Physics has 2.76. Better than the 2-year JIF above, as expected because the journal has such a long cited half-life. With the correction to the denominator, this value is approaching 3.0, but again, probably not all the way up to it.

I was a nerd about it and pulled values back to 2002, when JGR went digital. This gives me 2-year JIF scores back to 2004 and 5-year JIF scores back to 2007. With my simple method, there has only been one 2-year JIF for JGR-Space Physics above 3.0, in 2012. The lowest is in 2004, which I calculate to be 1.89, but I am not sure that I trust the citation numbers for 2002; they are noticeably lower than other years and it is the year of the “switch.” So, removing this, then the next lowest year is 2007, with 2.25. Most years are between 2.5 and 2.7.

What does this mean? It means that this is the “level” for the JIF of JGR-Space Physics. Adding in the “Immediacy Index” values (cites in the same year as publication), which are usually between 0.6 and 0.8, and the total number of citations in the first two years of a paper’s life is, on average, between 6 and 6.5.

Note that the number of papers without a citation at all is very low. After 2 years, it is already down to just a few percent. Nearly all papers are cited at least once. In fact, total citations for the average paper increases almost linearly for the first ~8 years or so, as seen here:


I’d say that’s pretty good.

In fact, it is a big reason why I am not afraid of the coming official release of a JIF specific to JGR-Space Physics and its expected value of below 3.0. This journal’s papers have longevity, accumulating citations well past anyone’s journal metric calculations. People have published good papers in this journal, and present-day researchers continue to cite those studies. We take a while to absorb a result and build on it. The JIF is useful as a journal metric, but it is not the whole story.

JIF and CiteScore

This week, Physics Today published an article on the Journal Impact Factor and the new CiteScore index. Both are average citation values within a certain year to papers published in a few preceding years. The main difference between the two are that the JIF uses citations to papers in the prior two years while CiteScore includes citations to papers in the previous three years. The other main difference is that Elsevier, the creator of the new CiteScore index, is making everything about the creation of the values open, while Thomson Reuters only makes the formula and numbers used available to subscribers, and the actual list of citations is kept proprietary.


            As the Physics Today article notes, the values are similar for most journals between the two indices, but some shifting is evident, especially among the top titles. For JGR (all sections combined), the values are almost identical, with the 2015 Impact Factor being 3.32 and the CiteScore being 3.39 (to two significant digits, which I don’t like to do).

Also as noted in the Physics Today article, the similarity in how they are calculated suggests that the complaints about JIF are largely applicable to CiteScore. Okay, it includes another year, but Thomson Reuters already produces a 5-year Impact Factor, so CiteScore splits the difference. Both are susceptible to the size of the “highly cited tail” of the paper distribution in a journal, especially if the number of citable items is relatively small. Also, both are susceptible to manipulation, if publishers were to unethically push authors of new manuscripts into citing papers in their journals.

I find it bewildering that there are ~5% of journals in existence with a CiteScore of zero (as reported in the Physics Today article). This means that there was a year in which there were no citations to any of the articles published in that journal for the prior three years. I have not looked up the names of these journals to look for a trend or commonality but, regardless…wow. Thanks again for reading and citing the papers in JGR Space Physics!