Figure 17.

The growth of helicity studies in solar physics over my career, measured by the annual number of refereed (blue) and total (green) research publications in the NASA ADS database as of the time of writing whose abstracts contain the words solar and helicity. Contributions to this figure of which I am most proud are: latitude variation of the helicity of photospheric magnetic fields of active regions (Pevtsov, Canfield, and Metcalf, 1995); evidence that magnetic flux emerges already carrying current (Leka et al., 1996); AGU Conference on magnetic helicity in space and laboratory plasmas (Brown, Canfield, and Pevtsov, 1999); relation between sigmoidal morphology and eruptive solar activity (Canfield, Hudson, and McKenzie, 1999); properties of interplanetary magnetic clouds and geomagnetic storms associated with eruptions of coronal sigmoids (Leamon, Canfield, and Pevtsov, 2002); predictions of energy and helicity in large eruptive flares (Kazachenko et al., 2012).