This paper examines the usefulness of the non-stationary generalized extreme value (GEV) distribution in modelling extreme rainfall. We modelled the annual maxima of daily (AMP1) and 2-day (AMP2) rainfall data observed during the summer rainy season, dating up to 2007 in 28 stations in South Korea. We fitted the GEV distribution to the data for each location. The location parameter of the GEV distribution was formulated as a function of time to explore the temporal trends in maximum precipitation over the course of climatic change and to predict future behaviours. We found evidence of non-stationarity in the form of increasing trends for six stations from AMP1 and for five stations from AMP2. This trend is consistent with the results from a regional climate model derived by the A1B emission forcing of IPCC AR4. The stationary Gumbel distribution provided a good fit to the AMP1 data for 18 stations and to the AMP2 data for 15 stations. We quantified the changes in extreme rainfall for each station; the return levels and their 95% confidence intervals for various return periods are provided.

ObjectiveTo analyze association between urodynamic study (UDS) parameters and renal function in spinal cord injured (SCI) patients with neurogenic detrusor overactivity.MethodsPatients with a suprasacral SCI, who underwent UDS and radioisotope renogram at least twice between January 1, 2006 and January 31, 2013, were included. UDS (cystometric capacity, reflex volume, compliance, and maximal detrusor pressure) and radioisotope renogram (total effective renal plasma flow [ERPF] of both kidneys) data were collected. The following were conducted to reanalyze any association between reflex volume and ERPF: initial and follow-up results of consecutive evaluations were compared; a mixed-model regression analysis to account for clustered data was conducted to evaluate the association between UDS parameters and ERPF; and finally, a mixed-model analysis type 3 test with data pairs, of which the first evaluation showed involuntary detrusor contraction.ResultsA total of 150 patients underwent 390 evaluations which were arranged into 240 pairs of consecutive evaluations, of which 171 had first evaluations with observed involuntary detrusor contraction. The following results were obtained: cystometric capacity was significantly larger and maximal detrusor pressure was significantly lower on follow-up; on univariate analysis, reflex volume and maximal detrusor pressure were significant, and multivariate analysis using these two parameters showed that maximal detrusor pressure is significantly associated with total ERPF; and no significant differences were observed.ConclusionMaximal detrusor pressure should be closely monitored in the urologic management of neurogenic detrusor overactivity in SCI patients. The results also may serve as a reference for regular UDS follow-up.

Attempts to assess the changes between the observed (or historical) and future projected daily rainfall extremes for 59 stations throughout Korea have been made with descriptive statistics and extreme value analysis. For the comparison, three different periods and four different data sets are considered: observation and historical data from 1976 to 2005 (period 0), simulation from 2021 to 2050 (period 1) and from 2066 to 2095 (period 2). The historical and projected rainfalls are obtained from RCP 4.5 and RCP 8.5 scenarios, which are based on a regional climate model HadGEM3‐RA. For the comparison of extreme values, the 20‐ and 50‐year return levels and the return period estimates are obtained by using the best one between two extreme value distributions, the method of L‐moments and the regional frequency analysis. From the descriptive statistics, we find that the numbers of heavy rainfall events will increase in the future. The total precipitation is projected to remain unchanged or slightly increased, compared to the observation. From the extreme value analysis, we realize that a 1‐in‐20 year and a 1‐in‐50 year annual maximum daily precipitation will likely become a 1‐in‐10 year and a 1‐in‐16 year event, respectively, when compared to the observation (a 1‐in‐5 year and a 1‐in‐7 year event, compared to the historical data), by the end of the 21st century. But this finding is based on only one simulation model, which confines the confidence of the result and suggests an ensemble approach based on multiple models to get more reliable result.

Projections of changes in extreme climate are sometimes predicted by multimodel ensemble methods that combine forecasts from individual simulation models using weighted averaging. One method to assign weight to each model is the Bayesian model averaging (BMA) in which posterior probability is used. For the cases of extreme climate, the generalized extreme value distribution (GEVD) is typically used. We applied the approach of GEV-embedded BMA to a series of 35 years of the annual maximum daily precipitation data (both historical data and data gathered from simulation experiments for future periods) over the Korean peninsula as simulated by the models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Simulation data under two Representative Concentration Pathway (RCP) scenarios, namely RCP4.5 and RCP8.5, were used. Observed data and 17 CMIP5 models for 12 gird cells in Korea have been examined to predict future changes in precipitation extremes. A simple regional frequency analysis of pooling observations from three stations in each cell was employed to reduce the estimation variance and local fluctuations. A bias correction technique using the regression-type transfer function was applied to these simulation data. Return levels spanning over 20 and 50 years, as well as the return periods relative to the reference years , were estimated for two future periods, namely Period 1 (2021-2050) and Period 2 (2066-2095). From these analyses, relative increase observed in the spatially averaged 20-year (50-year) return level was approximately 23% (16%) and 45% (36%) in the RCP4.5 and RCP8.5 experiments, respectively, by the end of the 21st century. We concluded that extreme rainfalls will likely occur two times and four times more frequently in the RCP4.5 and RCP8.5 scenarios, respectively, as compared to in the reference years by the end of the 21st century. K E Y W O R D Sclimatic change, global climate model, heavy rainfall, multimodel simulation, Taylor diagram, weighted averaging