Implementation and demonstration of the CLM lake model in the NOAA Unified Forecasting System (UFS)

A 1D lake model was implemented into the NOAA Unified Forecast System and its regional model, the Rapid Refresh Forecast System (RRFS). The CLM (Community Land Model) lake model was tested in an experimental version of the RRFS (RRFS version 1). Our experimental control is RRFS with a global sea-surface temperature field and no lake model. This was compared to RRFS with the CLM 1D lake model initialized with cycled lake temperatures. The RRFS with the CLM 1D lake model shows improved 2-m temperature and 2-m dewpoint forecasts over the control. These tests were carried out for both winter and summer periods. The use of the CLM 1D lake model and lake temperature initialization via cycling had previously been found to be effective for the NOAA HRRR model version 4. Its application to RRFS is now confirmed to also be able to improve surface predictions in the vicinity of the lakes.