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<<  parameterization of cloud in CAM3, http://bb.cgd.ucar.edu//viewtopic.php?t=115 >>

PosterpjrPostedFri Feb 11, 2005 3:52 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=340#340
Message: There are definite meteorlogical reasons for the problems with the
<br />stratus in the eastern subtropical oceans. These have been document
<br />in studies (which never made print) by Bjorn Stevens, Chris Bretherton,
<br />and a variety of people here at NCAR. Some of the problems are 
<br />associated with the vertical resolution in the PBL (too low), and with the
<br />rate of subsidence (too high), and with the formulation for the boundary layer itself (doesnt use moisture in the formulation), and with the
<br />formulation for the clouds.  It is a very difficult problem, and the more
<br />people looking at it the better. We are hoping that some of these
<br />issues can be significantly improved in the next generation model (post-cam3) which will have substantial changes to all the items mentioned above.
<br />
<br />In answer to your question, you can turn on a couple of fields that will help you understand the issues. These are a variable called CLDST (whic!
 h contains the clouds predicted by the K/L relationship) and CONCLD or CNVCLD (or both) which contain information about the convective clouds. The difference between the field called CLOUD and these two fields tell you what the relative humidity contribution is.
<br />
<br />Phil

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Postertz0616PostedFri Feb 11, 2005 9:56 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=344#344
Message: Dear phil,
<br />   
<br />   Thanks your valuable suggestions. I learn a lot from you.
<br />  I still have 3 small questions.
<br />
<br />1) I am not sure if in each model vertical layer, the  field called CLOUD 
<br />  is equal to max (Cc,Ccir,Cst).  
<br />  Here Cc, Ccir, Cst is the relative humidity cloud, convective cloud and
<br />  stratus cloud.
<br />
<br />2) Why the variable called CLDST (which contains the clouds predicted by the K/L relationship) has 26 layers in the vertical? Becuase according to
<br />the formulation of Klein and Hartmann (1993),
<br />  that is, Cst=min{1.,max}
<br />I only can get 2-D variable Cst, which is independent of the vertical layers?
<br />
<br />3) I look at the output from CAM3  /JMCCAA/csm/eul64x128_d50amip/
<br />but I can not find the variable CLDST (which contains the clouds predicted by the K/L relationship) and CNVCLD.
<br />  I don't where to get these variables, or I have to run the model by myself to turn on !
 the output for these variables.
<br />
<br />   Thanks very much,
<br />   tao

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