[gradsusr] GRADS control file for CMAQ output (PDEF)

[Tan, Haochen]

Hi Irena,

Here's my understanding of latref and lonref based on the CTL for NARR data from this website<https://psl.noaa.gov/data/narr/format.html>.

The latref and lonref in your ctl file can be your first grid point from left bottom so that you can set iref and jref as 1 and 1. In the NARR example, their left bottom grid is 1 in lat and -145 in lon.

Hope this helps!

Haochen


________________________________
From: gradsusr <gradsusr-bounces at gradsusr.org> on behalf of Irena Ivanova <iivanov at gmu.edu>
Sent: Thursday, May 4, 2023 16:44
To: gradsusr at gradsusr.org <gradsusr at gradsusr.org>
Subject: [gradsusr] GRADS control file for CMAQ output (PDEF)

Hi,

I need help with the GRADS control file for Lambert Conformal projection.

I understand I need to define the grid using PDEF:

* PDEF isize jsize LCC latref lonref iref jref Struelat Ntruelat slon dx dy
*Example:       PDEF 103 69 lccr 30 -88 51.5 34.5 20 40 -88 90000 90000
*Args:
*isize  The size of the native grid in the x direction
*jsize  The size of the native grid in the y direction
*latref reference latitude
*lonref reference longitude (in degrees, E is positive, W is negative)
*iref   i of ref point
*jref   j of ref point
*Struelat       S true lat
*Ntruelat       N true lat
*slon   standard longitude
*dx     grid X increment in meters
*dy     grid Y increment in meters

Here is my PDEF line but not sure what to specify for latref=? lonref=? and not sure if the other arguments are correct:
pdef 442 265 lcc  ???  ???  1    1    33       45       -97.   12000    12000

Here is an example lat-lon grid that covers CONUS domain (for GRADS to interpolate onto)
xdef  1000 linear   192. 0.1169081
ydef 500 linear   20.   0.1169081


Here are the global attributes of the CMAQ-Offline output. I can provide the data file upon request.


// global attributes:
                :IOAPI_VERSION = "ioapi-3.2: $Id: init3.F90 185 2020-08-28 16:49:45Z co" ;
                :EXEC_ID = "CMAQ_CCTMv531_sma8_20230412_212323_441724109                                    " ;
                :FTYPE = 1 ;
                :CDATE = 2023102 ;
                :CTIME = 212328 ;
                :WDATE = 2023102 ;
                :WTIME = 212328 ;
                :SDATE = 2019209 ;
                :STIME = 0 ;
                :TSTEP = 10000 ;
                :NTHIK = 1 ;
                :NCOLS = 442 ;
                :NROWS = 265 ;
                :NLAYS = 35 ;
                :NVARS = 226 ;
                :GDTYP = 2 ;
                :P_ALP = 33. ;
                :P_BET = 45. ;
                :P_GAM = -97. ;
                :XCENT = -97. ;
                :YCENT = 40. ;
                :XORIG = -2508000. ;
                :YORIG = -1716000. ;
                :XCELL = 12000. ;
                :YCELL = 12000. ;
                :VGTYP = -9999 ;
                :VGTOP = 0.999f ;
                :VGLVLS = 1.f, 0.995253f, 0.990479f, 0.985679f, 0.980781f, 0.975782f, 0.970684f, 0.960187f, 0.954689f, 0.936895f, 0.930397f, 0.908404f, 0.888811f, 0.862914f, 0.829314f, 0.786714f, 0.735314f, 0.645814f, 0.614214f, 0.582114f, 0.549714f, 0.511711f, 0.484394f, 0.451894f, 0.419694f, 0.388094f, 0.356994f, 0.326694f, 0.297694f, 0.270694f, 0.245894f, 0.223694f, 0.203594f, 0.154394f, 0.127094f, 0.f ;
                :GDNAM = "AQF5X           " ;
                :UPNAM = "OPACONC         " ;
                :VAR-LIST = "NO2             NO              O               O3 ...


Help much appreciated!

Irena
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