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<<  time step in CCM3, http://bb.cgd.ucar.edu//viewtopic.php?t=117 >>

PosterannaPostedThu Feb 10, 2005 9:21 am MST, http://bb.cgd.ucar.edu//viewtopic.php?p=336#336
Message: Dear CCM and CAM users,
<br />
<br />I am using the CCM3.6.6. within Paleo-CCSM simulations with continents different from today. With some
<br />continental geometries everything worked fine, but now I tried a new one, and then the atmosphere model
<br />crashes at some point with the error message:
<br />
<br />CUBYDR: Departure point out of bounds: jcen,icount,pgls= 39,  1726,  1728
<br />
<br />which seems to have to do with the length of the time step.
<br />I use the T31 resolution with a time step
<br />
<br />DTIME=1800
<br />
<br />as it should be for this resolution. The problem seems to be solved by just setting the time step to 1200
<br />seconds as is recomended for the T42 resolution. However, then physical parametrizations also change, and I
<br />don't know what I have to expect from that. Can I just change the time step without changing other
<br />parameters?
<br />
<br />It would be nice if I could get some help with that.
<br />
<br />Best regard!
 s,
<br />
<br />Anna
<br />
<br />--------------------------------
<br />Dr. Anna von der Heydt 
<br />Institute for Marine and Atmospheric Research
<br />Utrecht University
<br />The Netherlands

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PosterpontzsongPostedThu Feb 10, 2005 4:40 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=338#338
Message: Hi Anna,
<br />
<br />   Just read your msg, this reply is NOT to address your question (I'm only a beginner of CCSM), but to ask about your "paleo" modeling setting in the CCSM system (including the CCM etc.).   My name is Aaron, and my email is pontzsong at yahoo.com, can you please email me, thanks.
<br />
<br />      Aaron   2/10/05

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

Postertz0616PostedThu Feb 10, 2005 4:14 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=337#337
Message: Thanks for your nice reply.
<br />   The reason why I ask this question is that I want to figure out the
<br />  discrepancy between the low cloud from CAM3 and observation. I found that the simulated low cloud cover from CAM3 is not capable of simulating 
<br /> the observed low cloud center in the eastern Pacific. I am not sure if this 
<br /> discrepancy is mainly caused by the deficiency of Klein and Hartmann (1993) scheme, because the diagnosed cloud cover using this scheme is 
<br />very close to the low cloud cover output directly from CAM3 over the ocean. I don't know how to examine the contribution of two other clouds:
<br /> relative humidity cloud and convective cloud to the low cloud cover in the
<br /> model.
<br />   Do you have a better idea to examine the discrepancy between the low cloud from CAM3 and observation?
<br />   Thanks very much.

------------------------------
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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