Global uncoupled storm-resolving simulations using the ICOsahedral Non-hydrostatic (ICON) model with prescribed sea surface temperature show a double band of precipitation in the Western Pacific, a feature explained by reduced precipitation over the warm pool. Three hypotheses using an energetic framework are advanced to explain the warm pool precipitation bias, and they are related to 1) high-cloud radiative effect, 2) too-frequent or highly efficient precipitating shallow convection, and 3) surface heat fluxes in light near-surface winds. Our results show that increasing surface heat fluxes in light near-surface winds produce more precipitation over the warm pool and a single precipitation band in the Western Pacific. Further improvements were stronger near-surface winds over the Western Pacific and a moister and warmer tropical troposphere, but these improvements were not enough to fully overcome the existing biases. Simulations with an increased high-cloud radiative effect did not affect precipitation over the warm pool, and according to the energetic framework, due to compensation between the radiative effect and both, surface heat fluxes and circulation. Moreover, the representation of shallow convection did not affect warm pool precipitation. Thus, our results show the importance of the feedback between winds, surface heat fluxes, and convection for a correct representation of the oceanic tropical rainbelt structure in regions of weak sea surface temperature gradient as the warm pool.

We use atmospheric profiles from ERA5, JRA55 and MERRA2 between 1993 and 2023 to estimate Earth’s global clear-sky longwave feedback strength on the seasonal and interannual timescale. Differences in the relationship of relative humidity with skin temperature prior to 2008 lead to interannual feedback strengths between 1.34 W m−2 K−1 (JRA55) and 1.89 W m−2 K−1 (MERRA2). Restricting the analysis to the last 16 years yields more consistent interannual estimates of 2.05 W m−2 K−1 on average, which is larger than the overall seasonal estimate of 1.91 W m−2 K−1. The mid-tropospheric drying causing this difference suggest a substantial influence of ENSO variability on the interannual timescale. This indicates a long-term feedback strength smaller than 2.0 W m−2 K−1, which is already at the lower end of previous estimates; emphasizing the importance of accurate long-term RH measurements to reliably project Earth’s clear-sky feedback strength