Sensitivity of MM5 and WRF mesoscale model predictions of surface winds in a typhoon to planetary boundary layer parameterizations

Abstract

Sea surface winds and coastal winds, which have a significant influence on the ocean environment, are very difficult to predict. Although most planetary boundary layer (PBL) parameterizations have demonstrated the capability to represent many meteorological phenomena, little attention has been paid to the precise prediction of winds at the lowest PBL level. In this study, the ability to simulate sea winds of two widely used mesoscale models, fifth-generation mesoscale model (MM5) and weather research and forecasting model (WRF), were compared. In addition, PBL sensitivity experiments were performed using Medium-Range Forecasts (MRF), Eta, Blackadar, Yonsei University (YSU), and Mellor-Yamada-Janjic (MYJ) during Typhoon Ewiniar in 2006 to investigate the optimal PBL parameterizations for predicting sea winds accurately. The horizontal distributions of winds were analyzed to discover the spatial features. The time-series analysis of wind speed from five sensitivity experimental cases was compared by correlation analysis with surface observations. For the verification of sea surface winds, QuikSCAT satellite 10-m daily mean wind data were used in root-mean-square error (RMSE) and bias error (BE) analysis. The MRF PBL using MM5 produced relatively smaller wind speeds, whereas YSU and MYJ using WRF produced relatively greater wind speeds. The hourly surface observations revealed increasingly strong winds after 0300 UTC, July 10, with most of the experiments reproducing observations reliably. YSU and MYJ using WRF showed the best agreements with observations. However, MRF using MM5 demonstrated underestimated winds. The conclusions from the correlation analysis and the RMSE and BE analysis were compatible with the above-mentioned results. However, some shortcomings were identified in the improvements of wind prediction. The data assimilation of topographical data and asynoptic observations along coast lines and satellite data in sparsely observed ocean areas should make it possible to improve the accuracy of sea surface wind predictions.

Sensitivity of the WRF model to PBL parametrisations and nesting techniques: evaluation of wind storms over complex terrain

“…Hence, the number of vertical levels has been set to 40 in every domain. This number is similar to the number in the recent literature, which ranges between 30 and 46 (Miguez-Macho et al, 2004;Lo et al, 2008;Kwun et al, 2009;Santos-Alamillos et al, 2013;Etienne et al, 2013). The vertical resolution ensures that several eta levels lie below the PBL height at any time.…”

“…It employs an Eulerian mass-coordinate solver with a nonhydrostatic approach, and a terrain-following eta-coordinate system in the vertical. It is a state-of-the-art mesoscale model used in a variety of studies also for hindcast simulations (Kwun et al, 2009;Jiménez et al, 2010Awan et al, 2011;García-Díez et al, 2013;Jiménez and Dudhia, 2013;Santos-Alamillos et al, 2013;Menendez et al, 2014, among others). A first decision in regional climate modelling concerns the selection of the domain to be simulated.…”

“…The PBL plays a major role in simulating surface winds (Stensrud, 2007;Kwun et al, 2009;Santos-Alamillos et al, 2013;Menendez et al, 2014). Nowadays, there are many different approximations to account for the relevant subgrid processes that lead to different PBL formations.…”

“…More recently, García-Díez et al (2013) focused on the role of different PBL schemes. Other studies have investigated the role of the PBL schemes in the ability to simulate the surface wind of typhoons (Kwun et al, 2009) along the coast of the Mediterranean Sea (Menendez et al, 2014) or in southern Spain (Santos-Alamillos et al, 2013). Recently, García-Díez et al (2015) investigated the added value of dynamical downscaling compared to the driving data set, and found that over the Iberian Peninsula, 9 km resolved simulations are barely able to add value compared to the driving data set.…”

Atmospheric boundary layer characteristics over the Pearl River Delta, China, during the summer of 2006: measurement and model results

“…The vertical structure and spatial and temporal variability of the ABL are very important for numerical weather prediction (NWP). Many studies have demonstrated that many meteorological characteristics of the ABL can be represented by the MM5 and WRF mesoscale models (Kwun et al, 2009;Zhu, 2008;Miao et al, 2009). Furthermore, an accurate depiction of the meteorological conditions within the ABL is also important for air pollution modeling.…”