In a previous post I looked at yearly cohorts of JGR-ES papers, and the mean number of citations that papers from each yearly cohort accrues through time as the papers age. In this post I will look at something slightly different — what is the age distribution of cited JGR-ES articles in a given year? Put another way, if we had all the citations that JGR-ES papers racked up in a single year, say 2007, what fraction of are citations to JGR-ES papers published in 2003? or 2004? or 2005? The idea for this plot came from Clark and Hanson (2017).
Each line on this plot represents all citations to JGR-ES articles in a given year. For instance, the dark blue curve represents all citations to JGR-ES articles in the year 2010. The big spike in the dark blue curve means that, in 2010, 27% of all citations to JGR-ES articles were specifically focused on JGR-ES articles from 3 years prior (i.e., 2007). Notice that the orange curve (2011 citations) has a peak at 4 years prior (i.e., 2007 as well). As we march forward in time, that peak in citations moves back, and always represents the 2007 cohort of JGR-ES papers.
So what happened in 2007? Looking further in the citation data, there is a rotating group of ~10 papers from 2007 that are all highly cited. In additional a single paper (Schoof, 2007) is highly cited every year after its publication. This group of papers from 2007 accounted for 10% – 30% of all citations that JGR-ES received from 2010-2016.