@Article{HernándezPardoMorMacHarLeb:2020:DrSiDi,
               author = "Hern{\'a}ndez Pardo, Lianet and Morrison, H. and Machado, Luiz 
                         Augusto Toledo and Harrington, J. Y. and Lebo, Z. J.",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {National 
                         Center for Atmospheric Research} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Pennsylvania State University} 
                         and {University of Wyoming}",
                title = "Drop size distribution broadening mechanisms in a bin microphysics 
                         Eulerian model",
              journal = "Journal of the Atmospheric Sciences",
                 year = "2020",
               volume = "77",
               number = "9",
                pages = "3249--3273",
             abstract = "n this study, processes that broaden drop size distributions 
                         (DSDs) in Eulerian models with two-moment bin microphysics are 
                         analyzed. Numerous tests are performed to isolate the effects of 
                         different physical mechanisms that broaden DSDs in two- and 
                         three-dimensional Weather Research and Forecasting Model 
                         simulations of an idealized ice-free cumulus cloud. Sensitivity of 
                         these effects to modifying horizontal and vertical model grid 
                         spacings is also examined. As expected, collision-coalescence is a 
                         key process broadening the modeled DSDs. In-cloud droplet 
                         activation also contributes substantially to DSD broadening, 
                         whereas evaporation has only a minor effect and sedimentation has 
                         little effect. Cloud dilution (mixing of cloud-free and cloudy 
                         air) also broadens the DSDs considerably, whether or not it is 
                         accompanied by evaporation. This mechanism involves the reduction 
                         of droplet concentration from dilution along the cloud's lateral 
                         edges, leading to locally high supersaturation and enhanced drop 
                         growth when this air is subsequently lifted in the updraft. DSD 
                         broadening ensues when the DSDs are mixed with those from the 
                         cloud core. Decreasing the horizontal and vertical model grid 
                         spacings from 100 to 30 m has limited impact on the DSDs. However, 
                         when these physical broadening mechanisms (in-cloud activation, 
                         collision-coalescence, dilution, etc.) are turned off, there is a 
                         reduction of DSD width by up to;20%-50% when the vertical grid 
                         spacing is decreased from 100 to 30 m, consistent with effects of 
                         artificial broadening from vertical numerical diffusion. 
                         Nonetheless, this artificial numerical broadening appears to be 
                         relatively unimportant overall for DSD broadening when physically 
                         based broadening mechanisms in the model are included for this 
                         cumulus case.",
                  doi = "10.1175/JAS-D-20-0099.1",
                  url = "http://dx.doi.org/10.1175/JAS-D-20-0099.1",
                 issn = "0022-4928",
             language = "en",
        urlaccessdate = "28 abr. 2024"
}