Cloud and Precipitation in Low-Latitude Extratropical Cyclones Conditionally Sorted on CYGNSS Surface Latent and Sensible Heat Fluxes

Extratropical cyclones are the primary cause of midlatitude winds, precipitation, and clouds. Surface latent and sensible heat fluxes from the ocean impact cyclone intensity, but their role in moisture transport leading to cloud and precipitation is still under investigation. While numerical simulations can help establish such links, evaluating and constraining these simulations require observations. To this end, satellite-based observations of cloud and precipitation in low-latitude extratropical cyclones are examined for four distinct classifications based on the Cyclone Global Navigation Satellite System (CYGNSS) latent and sensible heat fluxes, averaged in the post-cold-frontal or warm-sector areas of the cyclones. Using a cyclone compositing approach, contrasts in cloud and precipitation in strong- versus weak-surface-flux conditions are examined. In the post-cold-frontal region, stronger latent or sensible heat fluxes are associated with lower precipitation rates and higher cloud opacity, indicating more vigorous shallow convection. However, larger sensible heat flux cases display larger cloud fraction, while larger latent heat flux cases exhibit lower cloud fraction, which could indicate differing cloud morphologies. In the comma region of the cyclones, clouds and precipitation depend on both cyclone strength and moisture availability. Consistent with this, larger cloud amount and precipitation are found for strong fluxes in the post-cold-frontal region, and weak or negative sensible heat fluxes, indicative of poleward warm advection, in the warm sector. The strong regional differences in the surface heat flux-cloud and precipitation relationships highlight the need for further investigation into moisture supply and transport in cyclones, while providing guidance for future work.