# NEMOv5.0 field\_definition required altough not used (ice suppresion on child grid) **URL:** \ **Category:** Uncategorized\ **Tags:** XIOS, AGRIF\ **Created:** [16 January 2025 08:38 UTC](https://nemo-ocean.discourse.group/t/nemov5-0-field-definition-required-altough-not-used-ice-suppresion-on-child-grid/824 "2025-01-16T08:38:20Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Franziska](https://avatars.discourse-cdn.com/v4/letter/f/8797f3/32.png) [@Franziska](https://nemo-ocean.discourse.group/u/Franziska)\ **Post date:** [16 January 2025 08:38 UTC](https://nemo-ocean.discourse.group/t/nemov5-0-field-definition-required-altough-not-used-ice-suppresion-on-child-grid/824/1 "2025-01-16T08:38:20Z")
Hi! I’m running a nested configuration (OCE ICE NST) with an ice-free nest region and consequently run the ice model only on the parent grid (namelist\_cfg: nn\_ice = 2) and suppress the ice model on the child grid (1\_namelist\_cfg: nn\_ice=0). Although not required, I also need to specify field\_def\_nemo-ice.xml in the child-context (1\_context\_nemo.xml). Otherwise the model fails, already while initialising the partent grid. It seems to be due to some modifications to reduce memory load, by explicitely only allocating/defining variables if used. The accoring error message hinting at this is: `In file "object_factory_impl.hpp", function "static std::shared_ptr xios::CObjectFactory::GetObject(const std::__cxx11::basic_string, std::allocator> &) [with U = xios::CField]", line 78 -> [id = dvpn_mlt, U = field] object was not found.` with `dvpn_mlt` defined in icethd\_pnd.F90 but only if “iom\_used”. While it doesn’t hurt to have this additional line in the context file, it’s counter intuitive and took me quite a while to figure out the reason for the failure. Fixing this for future releases would be great. Best regards, Franziska