# Questions about reading emissions file in CMAQv533 **URL:** \ **Category:** CMAQ\ **Tags:** cmaq\ **Created:** [September 7, 2023, 2:59pm UTC](https://forum.cmascenter.org/t/questions-about-reading-emissions-file-in-cmaqv533/4361 "2023-09-07T14:59:45Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![wfy](https://avatars.discourse-cdn.com/v4/letter/w/4af34b/32.png) [@wfy](https://forum.cmascenter.org/u/wfy)\ **Post date:** [September 7, 2023, 2:59pm UTC](https://forum.cmascenter.org/t/questions-about-reading-emissions-file-in-cmaqv533/4361/1 "2023-09-07T14:59:45Z")
Hi, I have a gridded emission file with 23 levels, but when I run CMAQv533 model, it prints “CTM\_EMLAYS | 0 (default)”. The log files show “Number of Emissions Layers is 23”, which is causing confusion. I wondering if I should set CTM\_EMLAYS=23 in the runscript? weather my emission file is valid to read? Thank you for your help. ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/c/c7e872fc1bbe4ef1784fc52743881d8042237708.png) ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/f/f0fd1914bd1de19bce295a15c605d9aacf560305.png) ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [September 7, 2023, 4:22pm UTC](https://forum.cmascenter.org/t/questions-about-reading-emissions-file-in-cmaqv533/4361/2 "2023-09-07T16:22:51Z")
In my recollection, the environment variable CTM\_EMLAYS can be used to instruct the CMAQ inline plume rise calculations to set a maximum layer to which plume rise should be restricted. The default value of 0 indicates that there is no restriction, i.e. the maximum layer to which plumes are allowed to rise is the topmost model layer. The actual plume rise of course is determined by the inline stack parameters and ambient meteorological conditions and would typically result in plume rise much below the top model layers - I believe the option to impose a maximum layer by setting CTM\_EMLAYS was meant to allow users to guard against cases where erroneous stack parameters would lead to unrealistically high plume rise. If CTM\_EMLAYS is specified (in which case the default value of 0 is overridden), it must be set to a value between 4 and the number of layers in the meteorology files, as noted in one of the comments in PT3D\_DEFN.F. ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [September 8, 2023, 11:18am UTC](https://forum.cmascenter.org/t/questions-about-reading-emissions-file-in-cmaqv533/4361/3 "2023-09-08T11:18:26Z")
I should also note that starting in CMAQv5.4, the functionality discussed above is no longer controlled by environment variable CTM\_EMLAYS, but instead by variable `Desid_MaxLays` specified in [CMAQ\_Control\_DESID.nml](https://github.com/USEPA/CMAQ/blob/main/CCTM/src/emis/emis/CMAQ_Control_DESID.nml). ---
**Author:** ![wfy](https://avatars.discourse-cdn.com/v4/letter/w/4af34b/32.png) [@wfy](https://forum.cmascenter.org/u/wfy)\ **Post date:** [September 9, 2023, 3:33am UTC](https://forum.cmascenter.org/t/questions-about-reading-emissions-file-in-cmaqv533/4361/4 "2023-09-09T03:33:24Z")
Oh, I got it. Thanks for the answer!