In this study, the effect of assimilating Himawari-8 (HIMA-8) atmospheric motion vectors (AMVs) on forecast errors in East Asia is evaluated using observation system experiments based on the Weather Research and Forecasting Model and three-dimensional variational data assimilation system. The experimental period is from 1 August to 30 September 2015, during which both HIMA-8 and Multifunctional Transport Satellite-2 (MTSAT-2) AMVs exist. The energy-norm forecast error based on the analysis of each experiment as reference was reduced more by replacing MTSAT-2 AMVs with HIMA-8 AMVs than by adding HIMA-8 AMVs to the MTSAT-2 AMVs. When the HIMA-8 AMVs replaced or were added to MTSAT-2 AMVs, the observation impact was reduced, which implies the analysis–forecast system was improved by assimilating HIMA-8 AMVs. The root-mean-square error (RMSE) of the 500-hPa geopotential height forecasts based on the analysis of each experiment decreases more effectively when the region lacking in upper-air wind observations is reduced by assimilating both MTSAT-2 and HIMA-8 AMVs. When the upper-air radiosonde (SOUND) observations are used as reference, assimilating more HIMA-8 AMVs decreases the forecast error. Based on various measures, the assimilation of HIMA-8 AMVs has a positive effect on the reduction of forecast errors. The effects on the energy-norm forecast error and the RMSE based on SOUND observations are greater when HIMA-8 AMVs replaced MTSAT-2 AMVs. However, the effects on the RMSE of the 500-hPa geopotential height forecasts are greater when both HIMA-8 and MTSAT-2 AMVs were assimilated, which implies potential benefits of assimilating AMVs from several satellites for forecasts over East Asia depending on the choice of measurement.

In this study, the performance of wind forecasts over Svalbard, located between the Arctic Ocean and the Norwegian Sea, was evaluated using the Polar Weather Research and Forecasting (PWRF) model and three-dimensional variational data assimilation (DA) system. The forecasts of the analysis-forecast cycling experiment using the PWRF 3DVAR were compared with those of the cold start experiment using reanalysis as the initial condition. Three strong wind cases that occurred during January and February 2011-2012 were selected, where polar lows were generated on the east coast of Greenland and generated a wind speed above 20 m s −1 in Svalbard. The wind speed forecasts for both cycling and cold start experiments were similar to the highest 10minute average wind speed for the last 1 hour (HAW). The average root mean square error (RMSE) of the forecasts in the cold start experiment from HAW was 3.78 m s −1 for three cases and was greater than that in the cycling experiment. The forecast performance in the cycling experiment was comparable to, or even better than, that in the cold start experiment, which implies that the cycling system with DA is more useful than the cold start system in forecasting polar weather to support research activities.

Tracheobronchial disruption is one of the most severe injuries caused by blunt chest trauma. It may cause airway obstruction and resulting life-threatening respiratory deficiency. However, the clinical presentations are variable and frequently difficult to diagnose. We report a case of a previously healthy 16-year-old man with complete right main bronchial transection sustained after a vehicular accident, who had progressive dyspnea, subcutaneous emphysema in the neck and anterior chest wall, and bilateral tension pneumothorax. Prompt chest tube drainage for suspected bilateral tension pneumothorax and a tracheal intubation were performed. Shortly after the positive pressure ventilation, severe subcutaneous emphysema developed and he was at risk for developing shock. Additional chest tubes were inserted. An emergency bronchoscopy showed rupture of the right main bronchus. After changing to a double lumen endotracheal tube, the patient’s condition improved. A surgical closure was performed and postoperative bronchoscopy showed good repair. The patient was discharged without complications.