# CMAQ memory problem

**URL:** <https://forum.cmascenter.org/t/cmaq-memory-problem/4486>\
**Category:** CMAQ\
**Created:** [October 16, 2023, 6:37pm UTC](https://forum.cmascenter.org/t/cmaq-memory-problem/4486 "2023-10-16T18:37:47Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![lizadams](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@lizadams](https://forum.cmascenter.org/u/lizadams)\
**Post date:** [October 16, 2023, 8:17pm UTC](https://forum.cmascenter.org/t/cmaq-memory-problem/4486/2 "2023-10-16T20:17:29Z")

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This is likely the [netcdf4 memory leak](https://forum.cmascenter.org/t/why-disabling-netcdf4/3866) issue. The solution is to convert EQUATES netcdf4 files to netcdf3-classic files using [nccopy](https://www.unidata.ucar.edu/software/netcdf/workshops/2011/utilities/Nccopy.html).

Please see:  
[Example instruction to convert EQUATES input data from nc4 to nc3](https://forum.cmascenter.org/t/equates-memory-leak-issue/4250)  
This ncopy conversion requires using the netCDF version built to support netCDF-4 compression.

Then [use the I/O API and netCDF libraries that were built to disable netCDF-4 compression](./configure --prefix=$cwd/…/netcdf --disable-netcdf-4 --disable-dap) to run CMAQ using the netcdf3-classic input files.

To manage multiple versions of netCDF builds, please consider building and using custom [Environment Modules](https://researchcomputing.princeton.edu/support/knowledge-base/custom-modules).

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