Comparison of water budget between AMMA and TWP-ICE clouds

Description

Two field campaigns, AMMA (the African Monsoon Multidisciplinary Analysis) and TWP-ICE (Tropical Warm Pool-International Cloud Experiment), took place in 2006 near Niamey, Niger, and Darwin, Australia, providing extensive observations of mesoscale convective systems (MCSs) near a tropical coast and a desert, respectively. Under the constraint of their observations, three-dimensional cloud-resolving model simulations are carried out in the paper to replicate the basic characteristic of the observed MCSs. All of the modeled MCSs exhibit a clear structure with deep convective clouds accompanied by stratiform clouds and farther anvil clouds. In contrast to TWP-ICE ones, AMMA MCSs with a scale of ~400 km have been duplicated successfully.

These modeled AMMA and TWP-ICE MCSs offer an opportunity to understand the structure and mechanism of MCSs, with their water budget that is represented in terms of horizontal water fluxes between convective, stratiform, and anvil cloud regions; vertical water fluxes between warm, mixed-phased and icy cloud layers; and water source/sink due to microphysical processes. The comparison in water budget between AMMA and TWP-ICE MCSs suggests that TWP-ICE convective clouds are stronger while the AMMA mesoscale ascent outside convective clouds is stronger. This result is consistent with the observed difference in convective and stratiform clouds between the two climatological regimes where the two campaigns resided. In addition, case comparison suggests that strong vertical wind shear in the upper troposphere brings about wide anvil clouds in TWP-ICE and high ice crystal concentration is one of the factors that contribute to large AMMA MCSs.