Sensitivity of different physics schemes using WRF model in Typhoon Damrey (2017) over the Indochina region

To reduce the tropical cyclone impact of lives and economics, the precise forecast of the event is required. The typhoon Damrey (2017), which caused ravaging of the strong wind, heavy precipitation, flash flood and storm surge over the Indochina region, was simulated by Weather Research and forecasting (WRF) model. The simulated duration was 8 days starting from 31 October 2017 00 00 UTC to 8 November 2017 00 00 UTC. The NCEP 6-hour global FNL (final analysis) data at 1-degree resolution is provided for initial condition. The WRF model was run in a single domain of 20 km horizontal resolution bounded 0 to 20 N and 96°E to 124°E. The different physics schemes, which are the microphysics schemes, the planetary boundary layer schemes and cumulus parameterization schemes, were emphasized to examine the suitable schemes in tropical cyclone simulation over the Indochina region. To evaluate the reliability of the simulation of tropical cyclone, the track-position is correlated with the Japan Meteorological Agency (JMA) observation. The results show that the typhoon simulation forced by Belts-Millers-Janjic cumulus, WSM6 microphysics was suitable for simulating of typhoon Damrey.

Numerical modeling and validating waves generated by typhoons in the East Vietnam Sea using satellite data

Calculating waves generated by typhoons is one of the most important tasks for wave forecasting at a stormy region like the East Vietnam Sea. It is, however, difficult to access the accuracy of calculated wave heights due to the lack of observed data. An approach of combining numerical models and satellite data has been widely used. In this study, we used the WAVEWATCH III model to stimulate wave fields caused by three strong typhoons: Damrey (2005), Ketsana (2009) and Haiyan (2013), then compared significant wave heights with the merged satellite observations. The results show that the BIAS values are small and negative, indicating that the wave heights from the model are lower than those from satellites in all cases. In contrast, the RMSE values of the three cases are considerably different but are still below 1 m. Finally, the average correlation coefficient is highest in typhoon Damrey (r = 0.94) whereas in typhoon Ketsana and Haiyan, r = 0.84 and r = 0.87, respectively. In conclusion, the study suggests that the WAVEWATCH III model has good performance for typhoon wave calculations and can be useful for wave forecasting in the East Vietnam Sea.

Some features of marine dynamics caused by damrey typhoon (11/2017) and its impacts on coral reef in Ninh Van waters, Khanh Hoa province

Typhoon Damrey (Vietnamese name is Typhoon No.12 in 2017) landed in South Phu Yen - North Khanh Hoa provinces in the morning of 4th Nov 2017 causing severe damage to people, material and serious consequences on the social and economy of the region (especially Khanh Hoa Province). So far, there have been no published papers and reports on the results of analysis of observing and monitoring data, calculations on marine dynamics as well as their impact on some marine ecosystems. Based on the results of coral reef survey in the study area before and after storm as well as hydrodynamic model results, the paper presents some results of data analysis of monitoring water level, calculations of wave field, currents caused by Damrey Typhoon in coastal waters of Khanh Hoa Province. On that basis, there have initial comments on the impact of storm on the coral reef of this region for management, forecasting and mitigation of local natural disaster damage in the future.

Ensemble prediction with OpenIFS

<div>Probabilistic forecasts provide information on how predictions of the atmospheric evolution may differ from the best guess solution provided by a deterministic forecast. Ensemble prediction systems generate this information through assessing uncertainties in both the model initial state and the model itself. In order to open up ensemble prediction research for a wider research community, we have recreated all 50+1 operational ECMWF ensemble initial states for OpenIFS. The data set covers one year (December 2016 to November 2017) twice a day. A range of model resolutions are provided to cover different research needs (TL159, TL399 and TL639). The probabilistic skill of OpenIFS ensembles using these initial states is showcased. A case study of typhoon Damrey, which severely affected Vietnam in 2017, will also be presented.</div>