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We propose that the flux-rope $\Omega$ loop that emerges to become anybipolar magnetic region (BMR) is made by a convection cell of the$\Omega$-loop's size from initially-horizontal magnetic field ingested throughthe cell's bottom. This idea is based on (1) observed characteristics of BMRsof all spans ($\sim$ 1000 km to $\sim$ 200,000 km), (2) a well-known simulationof the production of a BMR by a supergranule-size convection cell fromhorizontal field placed at cell bottom, and (3) a well-known convection-zonesimulation. From the observations and simulations, we (1) infer that thestrength of the field ingested by the biggest convection cells (giant cells) tomake the biggest BMR $\Omega$ loops is $\sim$ 10$^3$ G, (2) plausibly explainwhy the span and flux of the biggest observed BMRs are $\sim$ 200,000 km and$\sim$ 10$^{22}$ Mx, (3) suggest how giant cells might also make "failed-BMR"$\Omega$ loops that populate the upper convection zone with horizontal field,from which smaller convection cells make BMR $\Omega$ loops of their size, (4)suggest why sunspots observed in a sunspot cycle's declining phase tend toviolate the hemispheric helicity rule, and (5) support a previously-proposedamended Babcock scenario for the sunspot cycle's dynamo process. Because theproposed convection-based heuristic model for making a sunspot-BMR $\Omega$loop avoids having $\sim$ 10$^5$ G field in the initial flux rope at the bottomof the convection zone, it is an appealing alternative to the presentmagnetic-buoyancy-based standard scenario and warrants testing byhigh-enough-resolution giant-cell magnetoconvection simulations.

On Making Magnetic-Flux-Rope $\Omega$ Loops for Solar Bipolar Magnetic Regions of All Sizes by Convection Cells