Effect of Sea Surface Temperature Errors on Snowfall in WRF: A Case Study of a Heavy Snowfall Event in Korea in December 2012


We examined the sensitivity of simulated snowfall to prescribed sea surface temperature (SST) data using the Weather Research and Forecasting (WRF) model and the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) SST dataset for the Korean Peninsula. The OSTIA data were initially compared with in situ buoy measurements from three coastal sites in the Yellow Sea and was shown to be in good agreement with the in situ data with root mean square errors of 0.14 - 0.17 K for the daily mean values. Next, we conducted several WRF simulations, including a baseline simulation with the OSTIA data and sensitivity simulations with a temporally and spatially varying SST. The simulations were run for the Yellow Sea during December 2012 when a severe snowfall occurred in Korea. The baseline model generally captured the observed spatial and temporal variations of snowfall, surface air temperature and surface pressure in Korea. The sensitivity simulations with an increased and decreased SST resulted in a variation of +0.8/-0.7 K for the surface air temperature, ±0.6 hPa for the surface pressure, and ±0.3 m s-1 for the surface wind speed, in relation to the baseline simulation. The SST deviation affected the precipitation variability with changes of ±9% for snowfall and ±18% for rainfall, indicating considerable model sensitivity to SST perturbations. The change in the meteorological variables of the upper layer induced by the SST perturbations showed a symmetrical structure with respect to warmer and colder SST. Nevertheless, ice represented a nonlinear combination of the results at the low and mid-levels.

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