New schemes to perturb sea‐surface temperature and soil moisture content in <scp>MOGREPS</scp>

Abstract

Abstract This article investigates two schemes that perturb sea‐surface temperatures ( SST s) and soil moisture content ( SMC ) in the Met Office Global and Regional Ensemble Prediction System ( MOGREPS ), to address a known deficiency of a lack of ensemble spread near the surface. Results from a two‐month‐long trial during the Northern Hemisphere summer show positive benefits from these schemes. These include a decrease in the spread deficit of surface temperature and improved probabilistic verification scores. SST perturbations exhibit a stronger impact than SMC perturbations but, when combined, the increased spread from the two schemes is cumulative. A regional ensemble system driven by the global ensemble members largely reflects the same changes seen in the global ensemble but cycling fields, like SMC , between successive regional forecasts does show some benefit.