# After using the run\_combine.csh in CMAQ/POST, the new .nc file has the differnt time from the ACONC file

**URL:** https://forum.cmascenter.org/t/after-using-the-run-combine-csh-in-cmaq-post-the-new-nc-file-has-the-differnt-time-from-the-aconc-file/5211
**Category:** CMAQ
**Created:** [September 12, 2024, 5:21am UTC](https://forum.cmascenter.org/t/after-using-the-run-combine-csh-in-cmaq-post-the-new-nc-file-has-the-differnt-time-from-the-aconc-file/5211 "2024-09-12T05:21:41Z")
**Posts on this page:** 4
**Page:** 1

<div class="post-metadata">

### Author: ![hczuo](https://avatars.discourse-cdn.com/v4/letter/h/839c29/32.png) [@hczuo](https://forum.cmascenter.org/u/hczuo)
#### Post date: [September 12, 2024, 5:21am UTC](https://forum.cmascenter.org/t/after-using-the-run-combine-csh-in-cmaq-post-the-new-nc-file-has-the-differnt-time-from-the-aconc-file/5211/1 "2024-09-12T05:21:41Z")

</div>

i want to combine the PM2.5 component into a total varible. so i use the “/home/hczuo/CMAQv5.4/POST/combine/scripts/run\_combine.csh” to finish it . after successfully generate the new ACONC\_combine file, i find the time varibe’s type has changed from the datetime64 to int64. just like this:

 ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/6/64b6031fa511f3d475782535e0c634cab476a3be.png)

---

<div class="post-metadata">

### Author: ![hczuo](https://avatars.discourse-cdn.com/v4/letter/h/839c29/32.png) [@hczuo](https://forum.cmascenter.org/u/hczuo)
#### Post date: [September 12, 2024, 5:23am UTC](https://forum.cmascenter.org/t/after-using-the-run-combine-csh-in-cmaq-post-the-new-nc-file-has-the-differnt-time-from-the-aconc-file/5211/2 "2024-09-12T05:23:59Z")

</div>

![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/4/42680d68c5c3cbdc442804ee2107f8944e193c74.png)  
this is the original aconc file

---

<div class="post-metadata">

### Author: ![barronh](https://avatars.discourse-cdn.com/v4/letter/b/85e7bf/32.png) [@barronh](https://forum.cmascenter.org/u/barronh)
#### Post date: [September 12, 2024, 10:00am UTC](https://forum.cmascenter.org/t/after-using-the-run-combine-csh-in-cmaq-post-the-new-nc-file-has-the-differnt-time-from-the-aconc-file/5211/3 "2024-09-12T10:00:05Z")

</div>

The data type of the underlying file cannot be inferred from a to\_dataframe call of an xarray.Dataset object. NetCDF files cannot carry variables with type “datetime”. At best, they can carry of CF-compliant definition of time that xarray translates to a datetime object… Even so, ACONC files from CMAQ do not carry have datetime variable.

Use `ncdump -h` to get the header information (or m3hdr) of each of these files. That will show the variables that the files actually have and the units that the file has them in.

The file that you call the “original aconc file” looks like it is some custom file, and I would not expect an output from combine to match it.

---

<div class="post-metadata">

### Author: ![hczuo](https://avatars.discourse-cdn.com/v4/letter/h/839c29/32.png) [@hczuo](https://forum.cmascenter.org/u/hczuo)
#### Post date: [September 12, 2024, 3:29pm UTC](https://forum.cmascenter.org/t/after-using-the-run-combine-csh-in-cmaq-post-the-new-nc-file-has-the-differnt-time-from-the-aconc-file/5211/4 "2024-09-12T15:29:29Z")

</div>

thank you so much. I have find out the problem: because of my mistake of using the wrong scripts to convert the TFLAG variable. Thanks again!!!