tokens: a simple threshold of 450 km s −1 . It is clear that in general, inverted HMF is much more similar to slow wind than fast wind. Indeed, inverted HMF is distinct from fast uninverted HMF in all parameters except α :p. The CDFs of Fe:O for inverted and fast uninverted HMF are clearly separated in the upper part of the distribution, despite the fairly modest β ′ value. Inverted HMF is nevertheless distinct from slow wind in terms of the HMF properties, which is weaker and increasingly inclined the radial direction. 4. Discussion and Conclusions Inverted HMF occurs in short bursts and preferentially in slow, dense solar wind. It generally exhibits lower HMF intensity and increased inclination to the radial direction compared to the solar wind as a whole. We have further shown that inverted HMF is similar to slow solar wind in terms of elemental composition and oxygen, carbon, and iron ion charge states, suggesting common coronal source conditions. Inverted HMF is strongly differentiated from fast uninverted HMF in all parameters except the elemental composition measures and iron ion charge-states. Specifically, inverted HMF is weakly differentiated from fast uninverted HMF in terms of Fe:O abundance ratios, but there is little difference in the α :p abundance ratio, as is often the case with the slow wind in general (Fu et al. 2017 ). It is possible that gradients in elemental abundance are produced in the corona, but that differential streaming of heavy ions relative to the bulk (proton) solar wind (Berger et al. 2011 ; Alterman et al. 2018 ) is able to traverse the short inverted HMF intervals and remove this signature by 1 au (though this should equally wash out the carbon and oxygen charge-state signatures). It may be possible to identify any such compositional signatures using observations from close to the Sun, discussed below, or focusing only on the longer-lived HMF inversions, though this prohibits statistical analysis. Interpretation of ion charge states in terms of coronal temperature is not straightforward, with coronal electron density, temperature, and plasma velocities all contributing to the observed in situ values (Zhao et al. 2014 ). But in general, elevated oxygen and carbon charge states are produced by increased temperatures in the lower corona, whereas elevated iron charge states are more likely to result from heating through the extended corona (Song et al. 2016 ). Thus inverted HMF is associated with increased heating in the lower corona, which suggests that the material was released from hot coronal loops. This is consistent with previous results that show an association between inverted HMF and closed coronal loops in dipolar and unipolar coronal streamers (Owens et al. 2013 ). Hot coronal material on closed coronal loops can be released by interchange reconnection (Crooker Owens 2011 ) with an open magnetic flux tube. This could be initiated by either random foot-point motions or more large-scale convection of open
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