How is MCIP using X0, Y0, NCOL, NROW?

MCIP
1

Hello,
I’ve a domain centered at NYC with e_sn=53 and e_sn=43 with BTRIM=5, which results in NCOLS=40 and NROWS=30 with BTRIM=5 (this domain is obviously for testing not for production jobs). Running MCIP with X0 = 13, Y0 = 94, NCOLS = 89, NROWS = 104 or X0 = 13, Y0 = 13, NCOLS = 40, NROWS = 30 generates almost identical files (with the obvious exception of WDATE & WTIME). The GRIDDESC reads:

’ ’
‘LAM_040N074W’
2 35.000 45.000 -74.000 -74.000 40.750
’ ’
‘NYC’
‘LAM_040N074W’ -100000.000 -75000.000 5000.000 5000.000 40 30 1
’ ’

The simulations run w/o any issue but I’m a bit confused as some posts mention that the parameters X0, Y0, NCOLS, NROWS are ignored when BTRIM=0, but testing shows the opposite. I was wondering if it could be clarified how MCIP uses the parameters X0, Y0, NCOLS, NROWS.
Thanks.

2

Hello @afernandez ,

to help us better understand your issue, could you please do the following:

  • for each of the cases you tested, state the settings of X0, Y0, NCOLS, NROWS, and BTRIM in the run script, show the GRIDDESC file generated by MCIP, and attach the MCIP run log
  • confirm that for each of your tests, you are either writing outputs to a new directory, or you are deleting all outputs from previous tests if using the same output directory

Thank you.

3

Parameter set-1:

X0=13
Y0=13
NCOLS=40
NROWS=30

BTRIM=5

GRIDDESC

’ ’
‘CoordName’
2 35.000 45.000 -74.000 -74.000 40.750
’ ’
‘NYC’
‘CoordName’ -100000.000 -75000.000 5000.000 5000.000 40 30 1
’ ’

mcip_01.txt (688.7 KB)

4

Parameter set-2:
BTRIM=5
X0=13
Y0=94
NCOLS=89
NROWS=104

GRIDDESC:

’ ’
‘CoordName’
2 35.000 45.000 -74.000 -74.000 40.750
’ ’
‘ALTNYC’
‘CoordName’ -100000.000 -75000.000 5000.000 5000.000 40 30 1
’ ’

mcip_02.txt (688.7 KB)

5

Hi @hogrefe.christian,
Earlier I didn’t see anything out of ordinary in the logs (except that X0 and Y0 are not there), but maybe you notice something that I didn’t. [My only potential explanation would be the environment]
Thanks,
Arturo

6

Hello Arturo,

thank you very much for these additional posts, they helped me better understand your original question (I think). In particular, I didn’t quite know what you meant by “testing shows the opposite” in your original question post when you wrote “some posts mention that the parameters X0, Y0, NCOLS, NROWS are ignored when BTRIM=0, but testing shows the opposite“

I don’t recall which previous posts mentioned that X0, Y0, NCOLS, and NROWS are ignored only in the case when BTRIM=0, but that statement isn’t correct. The correct information is that they are only used if BTRIM = -1, per this documentation in the MCIP run script distributed with the code. Your examples (which use BTRIM = 5) are consistent with this description, as the different settings of X0, Y0, NCOLS, and NROWS do not (and should not) have any impact on the files generated by MCIP for both of your cases.

#-----------------------------------------------------------------------

Define MCIP subset domain.  (Only used if BTRIM = -1.  Otherwise,

the following variables will be set automatically from BTRIM and

size of input meteorology fields.)

X0:     X-coordinate of lower-left corner of full MCIP “X” domain

(including MCIP lateral boundary) based on input MM5 domain.

X0 refers to the east-west dimension.  Minimum value is 1.

Y0:     Y-coordinate of lower-left corner of full MCIP “X” domain

(including MCIP lateral boundary) based on input MM5 domain.

Y0 refers to the north-south dimension.  Minimum value is 1.

NCOLS:  Number of columns in output MCIP domain (excluding MCIP

lateral boundaries).

NROWS:  Number of rows in output MCIP domain (excluding MCIP

lateral boundaries).

#-----------------------------------------------------------------------
1 Like
7

OK, this clarifies the whole situation. As far as the posts, it was yesterday night: one of them is #4796 (where the last answer is a bit misleading as it should probably state that BTRIM needs to be a positive integer or zero instead of just 0); my recollection is that I might have seen other post but don’t recall where exactly (maybe they are in my browsing history).