[an error occurred while processing this directive]

  <p><img style="float:left" src="/images/research/themes.jpg" alt="themes" /></p>

  <p>&nbsp;<br />&nbsp;<br />&nbsp;<br />&nbsp;<br />&nbsp;<br /></p>

  <table width="60%" border="0" cellspacing="0" cellpadding="0">
  <tr><td>

  <h2>low cloud effects</h2>
  <span style="color:#337799"><b>From</b> <a href="mailto:bstevens@atmos.ucla.edu">
  Bjorn Stevens</a></span><br />
  <span style="color:#337799"><b>Date</b> February 26, 2007</span><p></p>
  Dear All,<p></p>
  attached is our lowcloud effects white paper, adapted to reflect our<br />
  decisions and discussions in Princeville.    The changes from the previous<br />
  version include an explicit reference to aerosol effects in our goal and<br />
  an outline of the proposed tactics.  Please look it over as I hope to post<br />
  a final version by the end of the week.<p></p>
  Bjorn<br />
  <a href="cloud_effects.pdf">cloud_effects.pdf</a><p></p>

  <br /><hr /><p></p>

  <span style="color:#337799"><b>From</b> <a href="mailto:Kiran.Alapaty@science.doe.gov">
  Kiran Alapaty</a></span><br />
  <span style="color:#337799"><b>Date</b> February 26, 2007</span><p></p>
  Bjorn, thanks for sharing it. As you know, some of the science issues are<br />
  very relevant to the ARM science program and I look forward for<br />
  innovative proposals from the team (ARM RFP/solicitation is out and is<br />
  available at grants.gov). Regarding white paper, here are my comments.<br />
  Best, Kiran<p></p>
  1. My past research experience is that nonlocal mixing schemes (PBL)<br />
  (e.g. Blackadar type) help the simulation of shallow convection better<br />
  and possibly deep convection compared to K-schemes (for summer). Thus,<br />
  it's worth testing such schemes in a GCM. For that my belief, I have<br />
  recently developed a new closure formulation for Blackadar-type pbl<br />
  schemes &amp; tested it out for its performance. Works very well. Soon, I<br />
  will implement it in the SCAM (1-D CAM). I believe that it will<br />
  out-perform the existing pbl scheme in CAM and helps to improve shallow<br />
  convection simulations.<p></p> 
  2. Regarding conservative interpolation schemes, Piotr Smolarkiewicz at<br />
  NCAR has done very good work on advection-equivalent interpolation (AEI)<br />
  schemes (probably you may be aware of that work). I have published a<br />
  small note comparing geometrical interpolation and AEI schemes (see<br />
  http://ams.allenpress.com/archive/1520-0493/126/1/pdf/i1520-0493-126-1-2<br />
  43.pdf ) of course, i am talking about linear fields.<p></p>
  3. I am inclined to solicit development of a methodology that physically<br />
  couples convective pbl, shallow, and/or deep convection processes. I am<br />
  making myself a crude attempt to develop one such thing for GCMs. <p></p>

  <br /><hr /><p></p>

  <span style="color:#337799"><b>From</b> <a href="mailto:Steve.Ghan@pnl.gov">
  Steve Ghan</a></span><br />
  <span style="color:#337799"><b>Date</b> February 26, 2007</span><p></p>
  Bjorn:<p></p>
  I wasn't able to attend the CMMAP meeting, so here I'd like to describe<br />
  our plans because I think they fit in nicely with the goals of the low<br />
  cloud CCMAP group.<p></p>
  We are putting aerosol indirect effects into SAM and then the MMF, but we<br />
  recognize that the present simulation of low clouds in the MMF is poor. So<br />
  Vince Larson is putting his turbulence scheme into SAM. I believe he is<br />
  testing it for DYCOMS-II first. His scheme is ideally suited to<br />
  cloud-resolving models, because the time step requirements are comparable.<br />
  We will then add droplet number to the microphysics, and use Vince's Latin<br />
  hypercube technique to treat subgrid microphysics. This approach to aerosol<br />
  indirect effects might not be as accurate as LES, but it will be much<br />
  faster. Our plan is to use the MMF to estimate aerosol indirect effects (we<br />
  have a separate plan for deep convective clouds).<p></p>
  So please add Vince and me to your list of collaborators.<p></p>
  -Steve Ghan
 
  <br /><hr />

  </td></tr></table>

[an error occurred while processing this directive]

</body>

</html>