# Which variables can be changed after WRF-CMAQ two way coupled model feedback? **URL:** \ **Category:** WRF-CMAQ\ **Created:** [March 4, 2025, 11:23am UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643 "2025-03-04T11:23:23Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Fortuna](https://avatars.discourse-cdn.com/v4/letter/f/ea666f/32.png) [@Fortuna](https://forum.cmascenter.org/u/Fortuna)\ **Post date:** [March 4, 2025, 11:23am UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643/1 "2025-03-04T11:23:23Z")
Hi all, I would like to know which variables will be changed after coupled model feedback in addition to several variables related to the short-wave radiation flux? Because when I analyzed the temperature, I found that the variable did not be changed before and after the coupling. Liu ---
**Author:** ![slfarrell](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slfarrell](https://forum.cmascenter.org/u/slfarrell)\ **Post date:** [March 4, 2025, 4:09pm UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643/2 "2025-03-04T16:09:15Z")
Hi Liu, Which variables did you change and can you post one of your rsl.out files and then also your run script? -Sara ---
**Author:** ![Fortuna](https://avatars.discourse-cdn.com/v4/letter/f/ea666f/32.png) [@Fortuna](https://forum.cmascenter.org/u/Fortuna)\ **Post date:** [March 5, 2025, 1:53am UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643/3 "2025-03-05T01:53:38Z")
Thanks for your reply. Variables like SWDOWN about the short-wave radiation flux do change because of the feedback, and the 10-meter wind field also changes very slightly. I want to know exactly which variables in the WRF output are affected by the coupled model. [rsl.out.0000.txt](https://forum.cmascenter.org/uploads/short-url/95SX5i8Q6qPlxZrctqE5yeWSCUA.txt) (1.1 MB) [run\_cctm\_WRFCMAQ.csh.txt](https://forum.cmascenter.org/uploads/short-url/p8372f6ykByK8nCuN1s5EHwd4Cf.txt) (52.5 KB) Liu ---
**Author:** ![slfarrell](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slfarrell](https://forum.cmascenter.org/u/slfarrell)\ **Post date:** [March 6, 2025, 3:46pm UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643/4 "2025-03-06T15:46:11Z")
Hi Liu, Are the temperatures not changing at all or just by very little? Which exact temperature variable are you looking at as well? I have a hunch that it may have to do with nudging. I see that you turned off all surface nudging and are only nudging above the PBL. You could try changing your above the PBL nudging strengths to: guv = 0.0001, gt = 0.0001, gq = 0.00001, Here are some helpful papers on nudging: > **[An Observation-Based Investigation of Nudging in WRF for Downscaling Surface...](https://journals.ametsoc.org/view/journals/apme/53/1/jamc-d-13-030.1.xml)** > > Abstract Previous research has demonstrated the ability to use the Weather Research and Forecasting model (WRF) and contemporary dynamical downscaling methods to refine global climate modeling results to a horizontal grid spacing of 36 km.... > **[Does temperature nudging overwhelm aerosol radiative effects in regional...](https://www.sciencedirect.com/science/article/pii/S1352231017300481)** > > Nudging (data assimilation) is used in many regional integrated meteorology-air quality models to reduce biases in simulated climatology. However, in … > **[Examining Interior Grid Nudging Techniques Using Two-Way Nesting in the WRF...](https://journals.ametsoc.org/view/journals/clim/25/8/jcli-d-11-00167.1.xml)** > > Abstract This study evaluates interior nudging techniques using the Weather Research and Forecasting (WRF) model for regional climate modeling over the conterminous United States (CONUS) using a two-way nested configuration. NCEP–Department of Energy... ---
**Author:** ![Fortuna](https://avatars.discourse-cdn.com/v4/letter/f/ea666f/32.png) [@Fortuna](https://forum.cmascenter.org/u/Fortuna)\ **Post date:** [March 7, 2025, 3:16am UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643/5 "2025-03-07T03:16:56Z")
Hi Sara, Thanks for your advice and recommendation.I look at the two variables T2 and T, double checked them and found that the two variables changed a little, about 10^-1 to 10^-2 K, maybe this was the effect of feedback. Also you mentioned nudging, does that mean turning on the surface nudging and reducing the nudging strength above PBL might lead to better feedback results? Because too much nudging strength may mask the effect of feedback changes. ---
**Author:** ![slfarrell](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slfarrell](https://forum.cmascenter.org/u/slfarrell)\ **Post date:** [March 7, 2025, 11:33pm UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643/6 "2025-03-07T23:33:58Z")
Hi Liu, If you turn on the surface nudging you will likely see an even smaller change! We typically turn nudging off below the PBL with the exception of nudging to soil moisture (which can inadvertently nudge the temperatures a little bit). I would say keep the setup that you have just relax the nudging above the PBL to the strengths I recommended above. I’m curious what domain you are using, what episode you are using and what aerosol loadings you see? ---
**Author:** ![Fortuna](https://avatars.discourse-cdn.com/v4/letter/f/ea666f/32.png) [@Fortuna](https://forum.cmascenter.org/u/Fortuna)\ **Post date:** [March 10, 2025, 1:40am UTC](https://forum.cmascenter.org/t/which-variables-can-be-changed-after-wrf-cmaq-two-way-coupled-model-feedback/5643/7 "2025-03-10T01:40:44Z")
Thanks for your suggestion, Sara. I’m currently looking at the effects of SSA and other aerosols on radiation in autumn and winter over East Asia and the Western Pacific, with a spatial resolution of about 27km.