Application of Lightning Data Assimilation to Numerical Forecast of Super Typhoon Haiyan (2013)

Previous observations from World Wide Lightning Location Network(WWLLN) and satellites have shown that typhoon-related lightning data have a potential to improve the forecast of typhoon intensity. The current study was aimed at investigating whether assimilating TC lightning data in numerical models can play such a role. For the case of Super Typhoon Haiyan in 2013, the lightning data assimilation(LDA) was realized in the Weather Research and Forecasting(WRF) model, and the impact of LDA on numerical prediction of Haiyan’s intensity was evaluated.Lightning data from WWLLN were used to adjust the model’s relative humidity(RH) based on the method developed by Dixon et al.(2016). The adjusted RH was output as a pseudo sounding observation, which was then assimilated into the WRF system by using the three-dimensional variational(3DVAR) method in the cycling mode at 1-h intervals. Sensitivity experiments showed that, for Super Typhoon Haiyan(2013), which was characterized by a high proportion of the inner-core(within 100 km from the typhoon center) lightning, assimilation of the inner-core lightning data significantly improved its intensity forecast, while assimilation of the lightning data in the rainbands(100–500 km from the typhoon center) led to no obvious improvement. The improvement became more evident with the increase in LDA cycles, and at least three or four LDA cycles were needed to achieve obvious intensity forecast improvement. Overall, the improvement in the intensity forecast by assimilation of the inner-core lightning data could be maintained for about 48 h. However, it should be noted that the LDA method in this study may have a negative effect when the simulated typhoon is stronger than the observed, since the LDA method cannot suppress the spurious convection.

An evaluation of treatments and survival rates for pancreatic adenocarcinoma through survival analysis with inverse probability of treatment weighting:a population-based study

Objective:This study conducted inverse probability of treatment weighting(IPTW)survival analysis to examine survival in pancreatic adenocarcinoma patients.Methods:In this population-based study,data from the Surveillance,Epidemiology,and End Results program of the United States were analyzed to identify patients diagnosed with adenocarcinoma of the pancreas 2004 to 2014.Differences in survival rates were examined among patients who underwent pancreatectomy alone,radiotherapy alone,and those who had pancreatectomy plus adjuvant radiotherapy.Kaplan-Meier estimates and Cox proportional hazards models with the IPTW were performed to determine the effect of different treatments on overall and cancer-specific survival.This study was approved by the Ethics Review Board of Weifang Medical University.Results:A total of 8191 patients were included,with 3409 taking pancreatectomy only,2865 taking radiotherapy only,and 1917 taking pancreatectomy plus adjuvant radiotherapy.Patients who received surgery plus adjuvant radiotherapy had statistically a higher survival rate than those who received the other 2 treatments.Survival analysis with the IPTW for the 3 different groups showed that the difference in median overall survival time among these patient groups was significant.Conclusion:Using IPTW survival analysis,the present study shows that surgery with adjuvant radiotherapy is significantly associated with improved overall and cancer-specific survival among patients with pancreatic adenocarcinoma.