Response of Monsoon Rainfall to Changes in the Latitude of the Equatorward Coastline of a Zonally Symmetric Continent

Abstract Recent studies have shown that the rapid onset of monsoon can be interpreted as a switch in tropical circulation, which occur even absence land–sea contrast, from dynamical regime controlled by eddy momentum fluxes to more directly energetic constraints. Here we investigate how one aspect continental geometry, is, position equatorward coastal boundary, influences such transitions. Experiments are conducted with an aquaplanet model slab ocean, different zonally symmetric continents prescribed Northern Hemisphere poleward southern boundaries at various latitudes, “land” having mixed layer depth two orders magnitude smaller than ocean. For extending simulated features migration convergence zone over continent, similar what is seen observed monsoons. boundaries, main precipitation remains moving gradually into summer hemisphere. We show land latitudes prevents displacement subtropics maximum lower-level moist static energy and, it, establishment overturning circulation subtropical transition rapidly angular momentum–conserving regime.