# Surface roughness on a aqua-planet simulation **URL:** \ **Category:** OpenIFS\ **Tags:** openifs-surface-boundary, openifs-idealised-configuration, openifs-43r3, openifs-physics-parametrizations\ **Created:** [11 October 2022 15:38 UTC](https://forum.ecmwf.int/t/surface-roughness-on-a-aqua-planet-simulation/12153 "2022-10-11T15:38:32Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Clement\_Bouvier](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/c/5daacb/32.png) [@Clement\_Bouvier](https://forum.ecmwf.int/u/Clement_Bouvier)\ **Post date:** [11 October 2022 15:38 UTC](https://forum.ecmwf.int/t/surface-roughness-on-a-aqua-planet-simulation/12153/1 "2022-10-11T15:38:32Z")
Hello everyone I'm seeking to perform sensitivity experiments where the surface roughness is changed on a aqua-planet simulation (idealise case) without triggering the wave model (LWCOU or LWCOU2W). My first intuition was to look for Charnock parameter in the code. I modify RCHAR in surf/module/suvexc\_mod.F90 and PDEFAULT in ifs/module/surface\_fields\_mix.F90 but without success. Do you know where the surface roughness is initialise for an aqua-planet simulation and where to modify it? Thanks again for your time and help. Best regards, Clément Bouvier ---
**Author:** ![Clement\_Bouvier](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/c/5daacb/32.png) [@Clement\_Bouvier](https://forum.ecmwf.int/u/Clement_Bouvier)\ **Post date:** [20 October 2022 10:17 UTC](https://forum.ecmwf.int/t/surface-roughness-on-a-aqua-planet-simulation/12153/2 "2022-10-20T10:17:54Z")
Hello everyone, I found a solution. I tested viscosity in surf/module/suvexc\_mod.F90 and Charnock in surf/module/vupdz0\_mod.F90. I finally implement a solution in ifs/module/surface\_fields\_mix.F90 to be able to input the surface roughness for my sensitivity experiment. Thank you for your time! Best regards, Clément Bouvier