Ž . Atmospheric Research 55 2000 225–255 www.elsevier.comrlocateratmos A bin-microphysics cloud model with high-order, positive-definite advection Alexandre A. Costa a,b, ) , Gerson P. Almeida b , Antonio Jose C. Sampaio b,1 ˆ ´ a Department of Atmospheric Science, Colorado State UniÕersity, Fort Collins, CO, USA b Laboratorio de Fisica de NuÕens e, Departamento de Fısica, UniÕersidade Federal do Ceara, ´ ´ Fortaleza, CE, Brazil Received 30 March 1999; received in revised form 2 June 2000; accepted 7 September 2000 Abstract An axisymmetric, anelastic model of a convective cloud is described. The model comprises prognostic equations for the azimuthal vorticity, the perturbation potential temperature, the perturbation water vapor mixing ratio, 44 categories of cloud condensation nuclei, and 100 categories of liquid-phase hydrometeors. Results from a control simulation show that the model is capable to reproduce realistically the life cycle of a convective cloud including the production of warm rain. A discussion of the role of advection in bin-microphysics models is presented and sensitivity tests were performed regarding the order of advection. The results show that, although the global characteristics of all simulated clouds were similar, significant differences occur with respect to their microstructure, particularly close to the cloud edges, when the order of the advective scheme changes. The conclusion is that intermediate-order advection schemes can indeed be used in cloud-resolving simulations, as far only as the gross characteristics of the cloudrcloud system are being investigated, but not poor, low-order schemes. On the other hand, the sensitivity with respect to the advection suggests that the evaluation of cloud phenomena that occur in fine-scales, such as entrainment and certain microphysical and radiational processes, must require the use of accurate, higher-order schemes. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Bin-microphysics cloud model; Advection; Simulation ) Corresponding author. Tel.: q 55-85-288-9904; fax: q 55-85-288-9903. Ž . E-mail address: alex@fisica.ufc.br A.A. Costa . 1 Current affiliation: Universidade do Vale do Acarau, Sobral, CE, Brazil. 0169-8095r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0169-8095 00 00066-1