Fig. 3. The relationship between the (observable) bias in warm rain fraction and the (emergent) rapid adjustment under scale factor and effective radius threshold tuning strategies.
The relationship between warm rain fraction (fwarm) and normalized rapid adjustment (Fℒ/FNd) is multivalued, which presents an apparent obstacle to an observational constraint. Distinguishing between rain (solid line), which responds strongly to the Qaut scale factor tuning but weakly to the re threshold tuning, and drizzle (dashed line), with the opposite responses, breaks the degeneracy and removes the obstacle to formulating an observational constraint.