Rain and cloud Organization in the Trades using ObseRvations and models

Our climate fundamentally depends on the abundance and behaviour of its smallest clouds: shallow trade cumulus clouds.

Their response to climate change is a major uncertainty in climate projections, with the most pressing but least understood question being: What is the role of mesoscale convective organization in trade cumulus feedbacks? Rain affects convective organization through its re-evaporation, which triggers downdrafts and cold pools.

Cold pools can create large ‘cloud holes’ surrounded by cloud arcs.

But how the size and lifetime of cold pools link to the initial rain evaporation and downdrafts, and how they influence cloud cover and thus the radiative budget is unclear.

Critical reasons for these knowledge gaps are a lack of rain process observations and the fascinating range of scales involved.ROTOЯ is driven by the opportunity for ground-breaking advances in observing, simulating, and understanding organized precipitating shallow convection to elucidate the role of rain and cold pools for climate.

My goal is to answer three questions: (i) What is the impact of evaporation, downdrafts, and cold pools on the trade-wind layer equilibrium state? (ii) Under what conditions do cold pools organize or disorganize shallow convection? (iii) Do cold pools increase or decrease total cloud cover in the trades?

To answer these questions, I will create a unique multi-year dataset of rain evaporation, downdrafts and cold pools by applying new remote sensing retrieval techniques to existing trade cumulus observations.

Combined with cutting-edge numerical simulations using super-droplet microphysics, the project promises to fundamentally improve our understanding of how organized shallow clouds may change with warming and the implications this has for the hydrological cycle.

ROTOЯ is a unique opportunity for me to focus my broad expertise in observing and modeling clouds to answer three critical questions of tropical meteorology and climate science.