# BCON m3conc from CCTM outputs **URL:** \ **Category:** CMAQ\ **Created:** [September 14, 2018, 1:36pm UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299 "2018-09-14T13:36:05Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![ernesto.pinoc](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/ernesto.pinoc/32/43_2.png) [@ernesto.pinoc](https://forum.cmascenter.org/u/ernesto.pinoc)\ **Post date:** [September 14, 2018, 1:36pm UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/1 "2018-09-14T13:36:05Z")
Hello: I did a run in CCTM for 15 days. Now I want to continue for 16 days to complete 1 month (January) and I was wondering if I have to use the same BCON file as used for the first run, or instead, I could use a bcon file but using module m3conc. I reviewed the bcon script and the input required is a file called CCTM\_d1bCONC.d1b. I was looking for it in the output file and I did not find it. Could you please help me to understand what file is required? Thanks for your time ---
**Author:** ![cgnolte](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/cgnolte/32/53_2.png) [@cgnolte](https://forum.cmascenter.org/u/cgnolte)\ **Post date:** [September 18, 2018, 12:31am UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/2 "2018-09-18T00:31:32Z")
Ernesto, I am unsure as to exactly what you are trying to do. I assume you used some kind of static profile boundary condition for the 15-day run. While you do not have to use the same BCON file for the second half of the month, it seems to me that is the most reasonable thing to do. Alternatively, if you have some better BCON data, I would use it for the entire month if possible. In order to use your existing CCTM outputs to create boundary conditions for a new run, the new run must be entirely nested within the domain of the original simulation. (Otherwise, how can the simulation you have completed provide data along the boundary?) The time period must be restricted to the period for which you have run the first origination. And most importantly, you need meteorological and emissions input data on your nested grid. ---
**Author:** ![ernesto.pinoc](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/ernesto.pinoc/32/43_2.png) [@ernesto.pinoc](https://forum.cmascenter.org/u/ernesto.pinoc)\ **Post date:** [September 18, 2018, 3:04am UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/3 "2018-09-18T03:04:22Z")
Hello Mr Nolte: First, I would like to apologize with you because I did not expressed my self as I wanted. So, I ´ll try to do righ now. First. I have just one domain (hemispheric domain of 108 km with 180 horizontal cells by 180 v vertical cells. So, I don´t work with nested domains. My question was about when it is used the bcon module using m3conc type. It is just for nested domain or I can use in a single domain? Are this related?? I used profile type in BCON module before during the first 15 days. I ran that period because I have emission from SMOKE in that range of time. Thanks again, Grettings ---
**Author:** ![cgnolte](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/cgnolte/32/53_2.png) [@cgnolte](https://forum.cmascenter.org/u/cgnolte)\ **Post date:** [September 18, 2018, 12:07pm UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/4 "2018-09-18T12:07:03Z")
The description of the BCON program provided [here](https://github.com/USEPA/CMAQ/blob/5.2.1/DOCS/User_Manual/CMAQ_OGD_ch07_programs_libraries.md#bcon) may help. The BCON program creates input files for CMAQ that describe chemical lateral boundary conditions around the boundary (perimeter) of your modeling domain, using the vertical layer structure of your meteorological data. You can either create static (time-independent) files following some assumed vertical profile along the boundaries, or you can take some other time-varying data source, such as output from a coarser scale CTM simulation. In this time-varying mode, BCON creates time-varying (typically hourly, but this is configurable) files of species concentrations along the boundary of your designated modeling domain. ---
**Author:** ![fang63](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/fang63/32/42_2.png) [@fang63](https://forum.cmascenter.org/u/fang63)\ **Post date:** [January 29, 2020, 9:57pm UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/6 "2020-01-29T21:57:16Z")
@cgnolte I have the same question, where is CCTM\_d1bCONC.d1b file (states in bcon run script [https://github.com/USEPA/CMAQ/blob/5.2.1/PREP/bcon/scripts/run\_bcon.csh](https://github.com/USEPA/CMAQ/blob/5.2.1/PREP/bcon/scripts/run_bcon.csh))? I am trying to do a nested run based on a CCTM result. Huan > if ( $BC == m3conc ) then > setenv CTM\_CONC\_1 $CMAQ\_DATA/cctm/CCTM\_d1bCONC.d1b > setenv MET\_CRO\_3D\_CRS > setenv MET\_CRO\_3D\_FIN ---
**Author:** ![cgnolte](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/cgnolte/32/53_2.png) [@cgnolte](https://forum.cmascenter.org/u/cgnolte)\ **Post date:** [January 30, 2020, 1:25am UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/7 "2020-01-30T01:25:02Z")
@fang63, You want to set the CTM\_CONC\_1 variable to point to the CONC output file from your coarse domain. ---
**Author:** ![fang63](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/fang63/32/42_2.png) [@fang63](https://forum.cmascenter.org/u/fang63)\ **Post date:** [January 30, 2020, 1:36am UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/8 "2020-01-30T01:36:59Z")
but the CCTM output files are in netCDF format, and in the script it states .d1b file, which confused me Huan ---
**Author:** ![cgnolte](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/cgnolte/32/53_2.png) [@cgnolte](https://forum.cmascenter.org/u/cgnolte)\ **Post date:** [January 30, 2020, 1:57am UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/9 "2020-01-30T01:57:08Z")
Sorry for the confusion, but that was just a name. The convention that the last part of a filename (after a period, such as .txt, .exe, or whatever) mostly applies to Windows (and, earlier, DOS). Unix and Linux are more flexible. While I believe we have changed most of our scripts so that netCDF files are given a .nc extension, that is for user convenience and comprehensibility. Linux doesn’t care. ---
**Author:** ![fang63](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/fang63/32/42_2.png) [@fang63](https://forum.cmascenter.org/u/fang63)\ **Post date:** [January 30, 2020, 8:04am UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/10 "2020-01-30T08:04:10Z")
So I just change “CCTM\_d1bCONC.d1b” to “CCTM\_CONC\_\*\*\*\*.nc” file? ---
**Author:** ![cgnolte](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.cmascenter.org/cgnolte/32/53_2.png) [@cgnolte](https://forum.cmascenter.org/u/cgnolte)\ **Post date:** [January 30, 2020, 1:16pm UTC](https://forum.cmascenter.org/t/bcon-m3conc-from-cctm-outputs/299/11 "2020-01-30T13:16:50Z")
Use the name of the CONC file on the coarse domain. ``` setenv CTM_CONC_1 ```