# S5P\_L2\_CH4, ERROR: cannot keep non-existent variable CH4\_column\_number\_density\_avk
**URL:** https://forum.atmospherictoolbox.org/t/s5p-l2-ch4-error-cannot-keep-non-existent-variable-ch4-column-number-density-avk/519
**Category:** HARP
**Tags:** sentinel-5p
**Created:** [June 3, 2022, 11:15pm UTC](https://forum.atmospherictoolbox.org/t/s5p-l2-ch4-error-cannot-keep-non-existent-variable-ch4-column-number-density-avk/519 "2022-06-03T23:15:46Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@aggiedude](https://forum.atmospherictoolbox.org/u/aggiedude)
#### Post date: [June 3, 2022, 11:15pm UTC](https://forum.atmospherictoolbox.org/t/s5p-l2-ch4-error-cannot-keep-non-existent-variable-ch4-column-number-density-avk/519/1 "2022-06-03T23:15:46Z")
Trying to convert some S5P\_L2\_CH4 data to L3 and I am getting this error:
ERROR: cannot keep non-existent variable CH4\_column\_number\_density\_avk
when I run this command:
harpconvert --format hdf5 --hdf5-compression 5 -o ch4=bias\_corrected -a ‘CH4\_column\_volume\_mixing\_ratio\_dry\_air\_validity\>50; derive(datetime\_stop {time}); bin\_spatial(3601, -90, 0.05, 7201, -180, 0.05);squash(time, (latitude\_bounds,longitude\_bounds));derive(latitude {latitude});derive(longitude {longitude}); keep(datetime\_start, latitude, longitude, dry\_air\_column\_number\_density, CH4\_column\_volume\_mixing\_ratio\_dry\_air, CH4\_column\_number\_density\_avk)’
Any ideas on what I am getting wrong?
---
### Author:  [@aggiedude](https://forum.atmospherictoolbox.org/u/aggiedude)
#### Post date: [June 6, 2022, 9:23pm UTC](https://forum.atmospherictoolbox.org/t/s5p-l2-ch4-error-cannot-keep-non-existent-variable-ch4-column-number-density-avk/519/2 "2022-06-06T21:23:25Z")
> [@aggiedude](#):
>
> CH4\_column\_number\_density\_avk
nevermind…
According to this post,
> [@Keep averaging kernel variables](https://forum.atmospherictoolbox.org/t/keep-averaging-kernel-variables/447):
>
> Hello, I would like to compare S5P HCHO with model simulated results. For comparing simulated and observed results, I need averaging kernel. So I tried converting L2 tropospheric\_HCHO\_column\_number\_density\_avk variable into L3 grid by following code. However, running this code raised error. I also tried running this code without specifying variables in keep() parameter, but resulting L3 files do not contain tropospheric\_HCHO\_column\_number\_density\_avk variable. Is there a…
cant regrid averaging kernel variables