<div dir="ltr"><div class="gmail_default" style="font-family:trebuchet ms,sans-serif">Hi Doug,<br><br></div><div class="gmail_default" style="font-family:trebuchet ms,sans-serif">I'm not too knowledgeable in this but have some literature which might be of relevance. Please have a look at the attached files.<br><br></div><div class="gmail_default" style="font-family:trebuchet ms,sans-serif">Cheers,<br><br></div><div class="gmail_default" style="font-family:trebuchet ms,sans-serif">Tabish<br></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature"><div dir="ltr"><div><div><font size="1"><span style="font-family:tahoma,sans-serif">Tabish U Ansari<br></span></font></div><font size="1"><span style="font-family:tahoma,sans-serif">PhD student, Lancaster Environment Center<br></span></font></div><font size="1"><span style="font-family:tahoma,sans-serif">Lancaster Univeristy<br> <span>Bailrigg</span>, <span>Lancaster</span>, <br><span>LA1 4YW</span>, <span>United Kingdom</span></span></font><br></div></div></div>
<br><div class="gmail_quote">On 25 February 2016 at 13:59, Douglas Lowe <span dir="ltr"><<a href="mailto:Douglas.Lowe@manchester.ac.uk" target="_blank">Douglas.Lowe@manchester.ac.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi all,<br>
<br>
I'm running WRF-Chem with a nest of 3 domains, with the settings listed below. I'd like to be<br>
able to split this across as many processes as possible in order to speed things up (currently<br>
I'm only managing 3x real time, which isn't very good when running multiday simulations).<br>
Unfortunately I am finding that WRF hangs when calling the photolysis driver for my 2nd domain<br>
(which is the smallest of the domains) if I use too many processors.<br>
<br>
The (relevant) model domain settings are:<br>
max_dom = 3,<br>
e_we = 134, 81, 91,<br>
e_sn = 146, 81, 91,<br>
e_vert = 41, 41, 41,<br>
num_metgrid_levels = 38,<br>
dx = 15000,3000,1000,<br>
dy = 15000,3000,1000,<br>
<br>
WRF will run when I split over upto 168 processes (7 nodes on the ARCHER supercomputer),<br>
but wont work if I split over 192 (or more) processes (8 nodes on ARCHER).<br>
<br>
Looking at the log messages I *think* that WRF is splitting each domain into the same<br>
number of patches, and sending one patch from each domain to a single process for<br>
analysis. However, this means that I am limited by the smallest domain as to how many<br>
patches I can split a domain into before we end up with patches which are dwarved by<br>
the halos around them.<br>
<br>
Would it not make more sense to be able to split each domain into different numbers<br>
of patches (so that each patch is of a similar size, regardless of which domain it is from) and<br>
send one patch from one domain to a single process (or, perhaps, send more patches from the<br>
outer domains to a single process, if needed for balancing computational demands)? And<br>
is there anyway for me to do this with WRF?<br>
<br>
Thanks,<br>
Doug<br>
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</blockquote></div><br></div>