Extended Data Fig. 8: Sensitivity tests examining dependences of modeled overcooling on tropical cyclone track density, translation speed, and intensity.

a, Category 1 tropical cyclones (TCs) track density captured by drifter observations in the Western North Pacific TC main development region (black box), denoted by dividing number of TCs in each 5°×5° by total number of TCs. b-f, Same as (a), but simulated by the models. g, Inner-core sea surface temperature (SST) cooling induced by slow (blue, < 5 m s⁻¹) and fast (green, > 5 m s⁻¹) Category 1 TCs observed by drifters and simulated by models. The inner-core cooling by Drifter, Model-Ensemble, CMCC-CM2, CNRM-CM6-1, ECMWF-IFS, and HadGEM3-GC31 is calculated from 53, 1245, 834, 171, 53, and 187 samples for slow-moving TCs and 67, 1156, 692, 166, 96, and 202 samples for fast-moving TCs. h, Inner-core cooling induced by tropical depression (TD), tropical storm (TS), Category 1–4 (C1–4) from drifters (red) and the CNRM-CM6-1 high-resolution model (blue). The maximum TC intensity simulated by the model is C4. The inner-core cooling induced by TD, TS, C1, C2, C3, C4, and C5 TCs is calculated from 402, 265, 120, 91, 59, 121, and 45 drifter samples and 7154, 2616, 337, 92, 58, 6, and 0 model samples. 6 samples under C4 TCs for the model are plotted using black circles. In (g, h), bars and error bars indicate mean inner-core cooling and corresponding 95% confidence intervals. Models simulate reasonably well the track density of Category 1 TC observed. Under the same TC attributes, modeled overcooling is produced. The overcooling consistently occurs across TCs from tropical depression to Category 4. Basemaps in a−f generated using M_Map v1.4 (www.eoas.ubc.ca/~rich/map.html).