Vertical transport of water in isolated convective clouds in the interior western United States as observed using airborne in-situ measurements

Abstract

Redistribution of water by convection is important to the regional and global energy balance, but the characteristics of vertical water transport in convective clouds at different heights are not well understood. In this study, the vertical transport of water in continental isolated convective clouds is investigated using airborne in-situ measurements made in High Plain Cumulus (HiCu) project. The profiles of the mass flux of water vapor and condensed water, and the cloud width and vertical velocity dependency of the relative contribution to the water budget are statistically analyzed. The results show: 1) The probability density functions (PDFs) of the water vapor mass flux were in lognormal distributions and narrowed with height, while the PDFs of the mass flux of condensed water broadened with height from 2 to 8 km. 2) The net flux of vapor decreased significantly with height. Though the flux of condensed water increased with height, the net flux of total water at cloud top was only about 40% of the influx at cloud base. Averagely, about 80% of the observed condensed water at cloud top was in liquid phase. 3) The clouds provided the main contribution to the water vapor flux transit from small-scale at low-levels to medium and large-scale at high-levels. Overall, the clouds in a scale of 1–5 km had the major contribution to the water mass flux. 4) As the clouds developed vertically, stronger drafts accounted for an increasing contribution to the water budget, and most of the upward water transport can be attributed to updraft cores.