Climate models often face challenges in accurately simulating the daily precipitation cycle

over tropical land, particularly in the Amazon. One contributing factor may be the

incomplete representation of the diurnal evolution of shallow cumulus (ShCu) clouds. This

study seeks to enhance understanding of the diurnal progression of ShCu clouds—from

formation to maturation and dissipation—over the central Amazon (CAMZ). Using

observational data from the Green Ocean Amazon 2014 (GoAmazon) campaign and large-

eddy simulation (LES) modeling, we investigated the diurnal cycle of ShCu clouds. Our

results reveal a well-defined cycle, with cloud formation between 10-11 LT, maturity from

13-15 LT, and dissipation by 17-18 LT. The vertical extent of the liquid water mixing ratio,

and the intensity of updraft mass flux were closely associated with increases in turbulent

kinetic energy (TKE), enhanced buoyancy flux within the cloud layer, and reduced large-

scale subsidence. We further analyzed the diurnal cycles of convective available potential

energy (CAPE), convective inhibition (CIN), the Bowen ratio (BR), and vertically integrated

TKE in the mixed layer (ITKE-ML), exploring their relationships with cloud base mass flux

(Mb) and cloud depth across six ShCu cases. ITKE-ML and Mb exhibited similar diurnal

trends, peaking around 14-15 LT. However, no consistent relationships were found between

CAPE (or BR) and Mb. Similarly, comparisons of cloud depth with CAPE, BR, ITKE-ML,

CIN, and Mb showed no clear relationships. Smaller ShCu clouds were sometimes linked to

higher CAPE and lower CIN. It is important to emphasize that these findings are preliminary

and based on a limited sample of ShCu cases. Further research is necessary, involving an

expanded dataset and more detailed analyses of the TKE budget and synoptic conditions.

These efforts will offer a more comprehensive understanding of the factors influencing ShCu

clouds vertical development.