Rotating radiative–convective equilibrium is studied by extracting the column physics of a mesoscale-resolution global atmospheric model that simulates realistic hurricane frequency statistics and then coupling it to rotating hydrostatic dynamics in doubly periodic domains. The parameter study helps in understanding the tropical cyclones simulated in the global model and also provides a reference point for analogous studies with cloud-resolving models. The authors first examine the sensitivity of the equilibrium achieved in a large square domain (2 × 104 km on a side) to sea surface temperature, ambient rotation rate, and surface drag coefficient. In such a large domain, multiple tropical cyclones exist simultaneously. The size and intensity of these tropical cyclones are investigated. The variation of rotating radiative–convective equilibrium with domain size is also studied. As domain size increases, the equilibrium evolves through four regimes: a single tropical depression, an intermittent tropical cyclone with widely varying intensity, a single sustained storm, and finally multiple storms. As SST increases or ambient rotation rate f decreases, the sustained storm regime shifts toward larger domain size. The storm’s natural extent in large domains can be understood from this regime behavior. The radius of maximum surface wind, although only marginally resolved, increases with SST and increases with f for small f when the domain is large enough. These parameter dependencies can be modified or even reversed if the domain is smaller than the storm’s natural extent.

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Studies have indicated that North Pacific sea surface temperature (SST) variability can significantly modulate El Niño–Southern Oscillation (ENSO), but there has been little effort to put extratropical–tropical interactions into the context of historical events. To quantify the role of the North Pacific in pacing the timing and magnitude of observed ENSO, we use a fully coupled climate model to produce an ensemble of North Pacific Ocean–Global Atmosphere (nPOGA) SST pacemaker simulations. In nPOGA, SST anomalies are restored back to observations in the North Pacific (>15°N) but are free to evolve throughout the rest of the globe. We find that the North Pacific SST has significantly influenced observed ENSO variability, accounting for approximately 15% of the total variance in boreal fall and winter. The connection between the North and tropical Pacific arises from two physical pathways: 1) a wind–evaporation–SST (WES) propagating mechanism, and 2) a Gill-like atmospheric response associated with anomalous deep convection in boreal summer and fall, which we refer to as the summer deep convection (SDC) response. The SDC response accounts for 25% of the observed zonal wind variability around the equatorial date line. On an event-by-event basis, nPOGA most closely reproduces the 2014/15 and the 2015/16 El Niños. In particular, we show that the 2015 Pacific meridional mode event increased wind forcing along the equator by 20%, potentially contributing to the extreme nature of the 2015/16 El Niño. Our results illustrate the significant role of extratropical noise in pacing the initiation and magnitude of ENSO events and may improve the predictability of ENSO on seasonal time scales.

Tropical cyclone (TC)‐permitting general circulation model simulations are performed with spherical geometry and uniform thermal forcing, including uniform sea surface temperature (SST) and insolation. The dependence of the TC number and TC intensity on SST is examined in a series of simulations with varied SST. The results are compared to corresponding simulations with doubly periodic f‐plane geometry, rotating radiative convective equilibrium. The turbulent equilibria in simulations with spherical geometry have an inhomogenous distribution of TCs with the density of TCs increasing from low to high latitudes. The preferred region of TC genesis is the subtropics, but genesis shifts poleward and becomes less frequent with increasing SST. Both rotating radiative convective equilibrium and spherical geometry simulations have decreasing TC number and increasing TC intensity as SST is increased.

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A hierarchy of idealized monsoons with increased degrees of complexity is built using an intermediate model with simplified physics and idealized land–sea geometry. This monsoon hierarchy helps formulate a basic understanding about the distribution of the surface equivalent potential temperature θ e, which proves to provide a general guide on the monsoon rainfall. The zonally uniform monsoon in the simplest aquaplanet simulations is explained by a linearized model of the meridional distribution of θ e, which is driven by the seasonally varying solar insolation and damped by both the monsoon overturning circulation and the local negative feedback. The heat capacities of the surface and the atmosphere give rise to an intrinsic time scale that causes the monsoon migration to lag behind the sun and reduces the monsoon extent and intensity. Monsoons with a zonally confined continent can be understood based on the zonally uniform monsoon by considering the ocean influence on the land through the westerly jet advection, which reduces the monsoon extent and induces zonal asymmetry. Monsoon responses to more realistic factors such as land geometry, albedo, and ocean heat flux are consistently predicted by their impacts on the surface θ e distribution. The soil moisture effect, however, does not fully fit into the surface θ e argument and provides additional control on monsoon rainfall by inducing regional circulation and rainfall patterns.