  Inspired by recent observations suggesting that photospheric magnetic flux
cancellation occurs much more frequently than previously thought, we
analytically estimated the energy released from reconnection driven by
photospheric flux cancellation, and proposed that it can act as a mechanism for
chromospheric and coronal heating (Priest et al., 2018). Using two-dimensional
simulations we validated the analytical estimates and studied the resulting
atmospheric response (Syntelis et al. 2019). In the present work, we set up
three-dimensional resistive MHD simulations of two cancelling polarities in a
stratified atmosphere with a horizontal external field to further validate and
improve upon the analytical estimates. The computational evaluation of the
parameters associated with the energy release are in good qualitative agreement
with the analytical estimates. The computational Poynting energy flux into the
current sheet is in good qualitative agreement with the analytical estimates,
after correcting the analytical expression to better account for the horizontal
extent of the current sheet. The atmospheric response to the cancellation is
the formation of hot ejections, cool ejections, or a combination of both hot
and cool ejections, which can appear with a time difference and/or be spatially
offset, depending on the properties of the cancelling region and the resulting
height of the reconnection. Therefore, during the cancellation, a wide spectrum
of ejections can be formed, which can account for the variety of multi-thermal
ejections associated with Ellerman bombs, UV bursts and IRIS bombs, and also
other ejections associated with small-scale cancelling regions and spicules.
