How Well Does the ERA5 Reanalysis Capture the Extreme Climate Events Over China? Part II: Extreme Temperature

The fifth-generation atmospheric reanalysis of the European Center for Medium-Range Weather Forecasts (ERA5) is the latest reanalysis product. However, the reliability of ERA5 to capture extreme temperatures is still unclear over China. Hence, based on conventional meteorological station data, a new criterion (DISO) was used to validate the ERA5 capturing extreme temperature indices derived from the Expert Team on Climate Change Detection and Indices (ETCCDI) across the six subregions of China on different timescales. The conclusions are as follows: the original daily temperatures (mean temperature, maximum temperature, and minimum temperature) can be well reproduced by ERA5 reanalysis over China. ERA5 tends to exhibit more misdetection for the duration of extreme temperature events than extreme temperature intensity and frequency. In addition, ERA5 performed best in the summer and worst in the winter, respectively. The trend of absolute indices (e.g., TXx and TNx), percentile-based indices (e.g., TX90p, TX10p, TN90p, and TN10p), and duration indices (e.g., WSDI, CSDI, and GSL) can be captured by ERA5, but ERA5 failed to capture the tendency of the diurnal temperature range (DTR) over China. Spatially, ERA5 performs well in southeastern China. However, it remains challenging to accurately recreate the extreme temperature events in the Tibetan Plateau. The elevation difference between the station and ERA5 grid point contributes to the main bias of reanalysis temperatures. The accuracy of ERA5 decreases with the increase in elevation discrepancy

How Well Does the ERA5 Reanalysis Capture the Extreme Climate Events Over China? Part I: Extreme Precipitation

ERA5 is the fifth-generation atmospheric reanalysis of the European Center for Medium-Range Weather Forecasts, with high spatiotemporal resolution and global coverage. However, the reliability of ERA5 for simulating extreme precipitation events is still unclear over China. In this study, 12 extreme precipitation indices and a comprehensive quantitative distance between indices of simulation and observation were used to evaluate ERA5 precipitation from three fundamental aspects: intensity, frequency, and duration. The geomorphological regionalization method was used to divide the subregions of China. The results showed that the ability of ERA5 to simulate annual total precipitation was better than that of daily precipitation. For the intensity indices, ERA5 performs well for simulating the PRCPTOT (annual total wet days precipitation) over China. ERA5 performs better on RX5day (max 5-days precipitation amount) and R95p (very wet days), especially in eastern China, than on RX1day (max 1-day precipitation amount) and R99p (extremely wet days). For the frequency indices, the ability of the ERA5 simulation increased as the amount of precipitation increased, except for northwestern China. However, the ability of ERA5 to simulate R50 mm (number of extreme heavy precipitation days) decreased. For the duration indices, ERA5 was better at simulating drought events than wet events in eastern China. Our results highlight the need for ERA5 to enhance the simulation of trend changes in extreme precipitation events

Gradient estimates for the conductivity problems

We establish both upper and lower bounds of the gradient estimates for solutions to the perfect conductivity problem in the case where perfect (stiff) conductors are closely spaced inside an open bounded domain. These results give the optimal blow-up rates of the stress for conductors with arbitrary shape and in all dimensions. While for solutions to the insulated conductivity problem we also obtain an upper bound of the gradient estimates.Ph.D.Includes bibliographical references (p. 69-71)

Is the Development of China’s Financial Inclusion Sustainable? Evidence from a Perspective of Balance

Balance plays an important role in the sustainable development of China’s financial inclusion. First, this paper reports the entropy weight method used to construct a financial inclusion index (FII) and measure the level of development of financial inclusion in China’s regions. Second, the concept of the Gini coefficient of financial inclusion is proposed and the structural balance of China’s financial inclusion is shown, as calculated by using this Gini coefficient. Third, we report the use of a dynamic shift-share model to further discuss the development balance of the financial inclusion of China’s regions. The results show that there is an imbalance in the development of financial inclusion in China’s regions. For 2006–2016, the Gini coefficient and the structural balance of China’s financial inclusion show a significant downward trend. The gap of the financial inclusion development between regions is narrowing and the structure of China’s financial inclusion tends to be reasonable. The penetration dimension is at a structural disadvantage. Availability and usage dimension are at a structural advantage, which can effectively promote the development of China’s financial inclusion. In the future, the government should establish a more balanced financial inclusion development mechanism, making full use of structural advantages of the availability and usage of financial services to promote the sustainable development of China’s financial inclusion