Total Heating Characteristics of the ISCCP Tropical and Subtropical Cloud Regimes
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AbstractComposite profiles of the apparent heat source Q1 and moisture sink Q2 are calculated for the International Satellite Cloud Climatology Project (ISCCP) cloud regimes (or weather states) using sounding observations from 10 field campaigns comprising both tropical and subtropical domains. Distinct heating profiles were determined for each ISCCP cloud regime, ranging from strong, upper-tropospheric heating for mesoscale convective systems (WS1) to integrated cooling for populations typically associated with marine stratus and stratocumulus clouds (WS5, WS6, and WS7). Despite being primarily associated with thin cirrus, the corresponding regime (WS4) has heating maxima in the lower and midtroposphere due to the presence of underlying clouds. Regime-averaged Q2 profiles showed similar transitions with strong drying observed for deep convection and low-level moistening for marine boundary layer clouds. The derived profiles were generally similar over land and ocean with the notable exception of the fair-weather cumulus regime (WS8). Additional midlevel moistening was identified for several weather states over land, suggesting enhanced detrainment and more frequent congestus clouds compared to oceanic domains.A control simulation using the Community Atmosphere Model, version 4 (CAM4), was similar to the large-scale patterns of diabatic heating at low levels produced by the ISCCP composites. Differences were more pronounced at middle and upper levels and are largely attributed to the uncertainty in the heating profiles for the cumulus regime (WS8). Low-level heating anomalies were calculated for each phase of the MaddenJulian oscillation (MJO) and they precede upper-tropospheric heating from deep convection by 34 phases. Implications for future research using ISCCP heating reconstructions are also discussed.
