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<DIV><FONT face=Arial size=2><SPAN
class=194425509-26032009>Hello!</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=194425509-26032009></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=194425509-26032009>in our institution,
in order to speed up some operational tasks, we are starting to work with
regional subsets of global 0.5-GFS GRIB2 files as inital/boundary conditions for
WRF (we are using "small_grib" option of wgrib2 to generate our regional subset)
as you can observe in the attached document</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=194425509-26032009></SPAN></FONT> </DIV>
<DIV><SPAN class=194425509-26032009><FONT face=Arial size=2>We have found some
significant differences in WRF results due to use of those regional files
instead of global files<SPAN class=865342413-01042009> (as it can be seen in
this document: </SPAN> </FONT><A
href="http://www.meteogalicia.es/galego/modelos/numerico/edu/dif_grib2.pdf"><FONT
face=Arial
size=2>http://www.meteogalicia.es/galego/modelos/numerico/edu/dif_grib2.pdf</FONT></A><FONT
face=Arial><FONT size=2>)<SPAN class=865342413-01042009>. Differences grow up to
2 degrees in 2m-temperature or 2 m/s in 10m-winds at the end of the simulation
(84/96 hour forecast).</SPAN></FONT></FONT></SPAN></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=194425509-26032009></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=194425509-26032009>We've contacted with
people at NCEP related to grib2 processing, and they said that this is normal,
wgrib2 just "generates" some truncation errors, and th<SPAN
class=865342413-01042009>at those</SPAN> differences in WRF results are
similar to those obtained using the same initial conditions in differente
machines/compilers.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=194425509-26032009></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=194425509-26032009>Even though, it
seems that the differences are really important (non-negligible)... does anyone
has faced with this kind of problem? any suggestions?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=194425509-26032009></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=194425509-26032009>Thanks in
advance!</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=194425509-26032009></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=194425509-26032009>Eduardo
Penabad</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=194425509-26032009>MeteoGalicia. NWP
Department</SPAN></FONT></DIV></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><A
href="http://www.meteogalicia.es/galego/modelos/numerico/edu/dif_grib2.pdf"></A></FONT> </DIV>
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