Parameterization of the Autoconversion Process: Unification and Physics <p> HR: <span class="hr"> 09:30h<br></span> AN: <span class="an"> A41F-05 <a href="../absbook/sm05_A41F.html">[Abstracts]</a><br></span> TI: <span class="ti"> Parameterization of the Autoconversion Process: Unification and Physics <br></span> AU: <span class="au"> * Liu, Y <br></span> EM: <span class="em"> lyg@bnl.gov<br></span> AF: <span class="af"> Brookhaven National Laboratory, Bldg. 815E (75 Rutherford Dr.), Upton, NY 11973-5000 United States <br></span> AU: <span class="au"> Daum, P H<br></span> EM: <span class="em"> phdaum@bnl.gov<br></span> AF: <span class="af"> Brookhaven National Laboratory, Bldg. 815E (75 Rutherford Dr.), Upton, NY 11973-5000 United States <br></span> AU: <span class="au"> McGraw, R L<br></span> EM: <span class="em"> rlm@bnl.gov<br></span> AF: <span class="af"> Brookhaven National Laboratory, Bldg. 815E (75 Rutherford Dr.), Upton, NY 11973-5000 United States <br></span> AB: <span class="ab"> A key process that must be parameterized in atmospheric models of various scales is the autoconversion process whereby large cloud droplets collect small ones and become embryonic raindrops. Accurate parameterization of this process is especially important for studies of the second indirect aerosol effect. In terms of the representation of the threshold behavior of the autoconversion process, existing parameterizations can be classified into either Kessler-type or Sundqvist-type. Kessler-type parameterizations have been developed to explicitly account for cloud droplet number concentration, relative dispersion, and liquid water content, whereas Sundqvist-type parameterizations consider only the liquid water content. In this work, we first put Sundqvist-type parameterizations on the same footing as Kessler-type parameterization by generalizing Sundqvist-type parameterizations to explicitly account for droplet number concentration, relative dispersion, as well as liquid water content. We then show that the more commonly used Kessler-type parameterizations are in fact a special case of the corresponding Sundqvist-type parameterizations, unifying the two types of parameterizations. A new parameterization is further derived theoretically, and is compared to Kessler-type and Sundqvist-type parameterizations. <br></span> DE: <span class="de"> 0305 Aerosols and particles (0345, 4801)<br></span> DE: <span class="de"> 0320 Cloud physics and chemistry<br></span> DE: <span class="de"> 1600 GLOBAL CHANGE (New category)<br></span> DE: <span class="de"> 1836 Hydrologic budget (1655)<br></span> DE: <span class="de"> 3354 Precipitation (1854)<br></span> SC: <span class="sc"> Atmospheric Sciences [A]<br></span> MN: <span class="mn"> 2005 Joint Assembly<br></span></p></body></html>