Substantial Reductions in Cloud Cover and Moisture Transport by Dynamic Plant Responses

Abstract

Cumulus clouds make a significant contribution to the Earth's energy balance and hydrological cycle and are a major source of uncertainty in climate projections. Reducing uncertainty by expanding our understanding of the processes that drive cumulus convection is vital to the accurate identification of future global and regional climate impacts. Here we adopt an interdisciplinary approach that integrates interrelated scales from plant physiology to atmospheric turbulence. Our explicit simulations mimic the land‐atmosphere approach implemented in current numerical weather prediction, and global climate models enable us to conclude that neglecting local plant dynamic responses leads to misrepresentations in the cloud cover and midtropospheric moisture convection of up to 21% and 56%, respectively. Our approach offers insights into the key role played by the active vegetation on atmospheric convective mixing that has recently been identified as the source of half of the variance in global warming projections (i.e., equilibrium climate sensitivity).

Interactions Between the Amazonian Rainforest and Cumuli Clouds: A Large‐Eddy Simulation, High‐Resolution ECMWF, and Observational Intercomparison Study

“…Based on an additional DALES experiment that imposed radiative transparent clouds, we conclude that the adequate distribution of the energy at the canopy top impacts relevant cloud characteristics such as cloud cover and liquid water path. In agreement with previous work (Sikma & Vilà-Guerau de Arellano, 2019), the absence of coupling leads to an intensification of the diurnal cycle of shallow cumuli. The inclusion of other processes such as more complex microphysics or three-dimensional radiation might play a role in invigorating the shallow convection, which suggests that the vertical domain of the numerical experiments will need to be extended to allow the vertical growth of clouds.…”

Impact of Future Warming and Enhanced [CO2] on the Vegetation‐Cloud Interaction

“…Our simulations have been designed to understand the sensitivity of plant-atmosphere-cloud interactions on elevations in CO 2 and temperature and complement to our previous research for current atmospheric conditions on the cloud-plant forcing (Sikma et al, 2017) and subsequent plant-clouds feedback (Sikma & Vilà-Guerau de Arellano, 2019). Our control case has been designed based on observations and represents a typical West-European early-autumn day with cumulus development over 90% covered moist C3 grassland (10% bare soil).…”

“…Moist convection and cloud development are strongly affected by surface characteristics (Rieck et al, 2014;Sikma & Vilà-Guerau de Arellano, 2019). Incoming solar radiation is redistributed in soil heat and turbulent energy fluxes based on the soil moisture content, vegetation activity and characteristics, and surface roughness.…”

Terrestrial evaporation and global climate: lessons from Northland, a planet with a hemispheric continent

“…The atmosphere uses moist dynamics, but does not represent clouds. While cloud responses to land surface properties and their changes can play an important role in determining impacts on surface climate (Cho et al 2018;Sikma and Vilà-Guerau de Arellano 2019;Laguë et al 2019;Kim et al 2020), cloud responses to climate perturbations are also a large source of uncertainty (Stocker et al 2013;Zelinka et al 2017). Our idealized modeling framework avoids uncertainties associated with cloud responses to climate perturbations, at the cost of not capturing any cloud interaction effects.…”