Evaluation of Tianji and ECMWF high-resolution precipitation forecasts for extreme rainfall event in Henan in July 2021

The extreme rainfall event of July 17 to 22, 2021 in Henan Province, China, led to severe urban waterlogging and flood disasters. This study investigated the performance of high-resolution weather forecasts in predicting this extreme event and the feasibility of weather forecast-based hydrological forecasts. To achieve this goal, high-resolution precipitation forecasts from the Tianji weather system and the forecast system of the European Centre for Medium-Range Weather Forecasts (ECMWF) were evaluated with the spatial verification metrics of structure, amplitude, and location. The results showed that Tianji weather forecasts accurately predicted the amplitude of 12-h accumulated precipitation with a lead time of 12 h. The location and structure of the rainfall areas in Tianji forecasts were closer to the observations than ECMWF forecasts. Tianji hourly precipitation forecasts were also more accurate than ECMWF hourly forecasts, especially at lead times shorter than 8 h. The precipitation forecasts were used as the inputs to a hydrological model to evaluate their hydrological applications. The results showed that the runoff forecasts driven by Tianji weather forecasts could effectively predict the extreme flood event. The runoff forecasts driven by Tianji forecasts were more accurate than those driven by ECMWF forecasts in terms of amplitude and location. This study demonstrates that high-resolution weather forecasts and corresponding hydrological forecasts can provide valuable information in advance for disaster warnings and leave time for people to act on the event. The results encourage further hydrological applications of high-resolution weather forecasts, such as Tianji weather forecasts, in the future.

The Gravity Environment of Zhouqu Debris Flow of August 2010 and Its Implication for Future Recurrence

This study investigates the geological background of the August 7-8, 2010 Zhouqu debris flows in the northwestern Chinese province of Gansu, and possible future occurrence of such hazards in the peri-Tibetan Plateau (TP) regions. Debris flows are a more predictable type of landslide because of its strong correlation with extreme precipitation. However, two factors affecting the frequency and magnitude of debris flows: very fine scale precipitation and degree of fracture of bedrock, both defy direct observations. Annual mean Net Primary production (NPP) is used as a surrogate for regional precipitation with patchiness filtered out, and gravity satellite measured regional mass changes as an indication of bedrock cracking, through the groundwater as the nexus.?The GRACE measurements indicate a region (to the north east of TP) of persistent mass gain (started well before the 2008 Wenchuan earthquake), likely due to increased groundwater percolation. While in the neighboring agricultural region further to the north east, there are signal of decreased fossil water reservoir. The imposed stress fields by large scale increase/decrease groundwater may contribute to future geological instability of this region. Zhouqu locates right on the saddle of the gravity field anomaly. The region surrounding the Bay of Bangle (to the southeast of TP) has a similar situation. To investigate future changes in extreme precipitation, the other key player for debris flows, the “pseudo-climate change” experiments of a weather model forced by climate model provided perturbations on the thermal fields are performed and endangered locations are identified. In the future warmer climate, extreme precipitation will be more severe and debris will be more frequent and severe.

SPECT/CT同机融合显像和CT在估测口腔恶性肿瘤侵犯下颌骨范围的应用价值(英文)

Objective: The aim of our study was to compare the value of computed tomography (CT) and 99mTc-methylene-diphosphonate (MDP) SPECT (single photon emission computed tomography)/CT fusion imaging in determining the extent of mandibular invasion by malignant tumor of the oral cavity. Methods: This study had local ethical committee approval, and all patients gave written informed consent. Fifty-three patients were revealed mandibular invasion by malignant tumor of the oral cavity underwent CT and SPECT/CT. The patients were divided into two groups: group A (invasion-periphery-type) and group B (invasion-center-type). Two radiologists assessed the CT images and two nuclear medicine physicians separately assessed the SPECT/CT images in consensus and without knowledge of the results of other imaging tests. The extent of bone involvement suggested with an imaging modality was compared with pathological findings in the surgical specimen. Results: With pathological findings as the standard of reference, Group A: The extent of mandibular invasion by malignant tumor under-went SPECT/CT was 1.02 ± 0.20 cm larger than that underwent pathological findings. And the extent of mandibular invasion underwent CT was 1.42 ± 0.35 cm smaller than that underwent pathological examination. There were significant difference among the three methods (P < 0.01). Group B: The extent of mandibular invasion by malignant tumor underwent SPECT/CT was 1.3 ± 0.39 cm larger than that underwent pathological examination. The extent of mandibular invasion underwent CT was 2.55 ± 1.44 cm smaller than that underwent pathological findings. There were significant difference among the three methods (P < 0.01). The extent of mandibular invasion underwent SPECT/CT was the extent which surgeon must excise to get clear margins. Conclusion: SPECT/CT fusion imaging has significant clinical value in determining the extent of mandibular invasion by malignant tumor of oral cavity.

Bias Correction and Ensemble Projections of Temperature Changes over Ten Subregions in CORDEX East Asia

Regional climate models(RCMs)participating in the Coordinated Regional Downscaling Experiment(CORDEX)have been widely used for providing detailed climate change information for specific regions under different emissions scenarios.This study assesses the effects of three common bias correction methods and two multi-model averaging methods in calibrating historical(1980−2005)temperature simulations over East Asia.Future(2006−49)temperature trends under the Representative Concentration Pathway(RCP)4.5 and 8.5 scenarios are projected based on the optimal bias correction and ensemble averaging method.Results show the following:(1)The driving global climate model and RCMs can capture the spatial pattern of annual average temperature but with cold biases over most regions,especially in the Tibetan Plateau region.(2)All bias correction methods can significantly reduce the simulation biases.The quantile mapping method outperforms other bias correction methods in all RCMs,with a maximum relative decrease in root-mean-square error for five RCMs reaching 59.8%(HadGEM3-RA),63.2%(MM5),51.3%(RegCM),80.7%(YSU-RCM)and 62.0%(WRF).(3)The Bayesian model averaging(BMA)method outperforms the simple multi-model averaging(SMA)method in narrowing the uncertainty of bias-corrected results.For the spatial correlation coefficient,the improvement rate of the BMA method ranges from 2%to 31%over the 10 subregions,when compared with individual RCMs.(4)For temperature projections,the warming is significant,ranging from 1.2°C to 3.5°C across the whole domain under the RCP8.5 scenario.(5)The quantile mapping method reduces the uncertainty over all subregions by between 66%and 94%.

中国高质量天然径流量估算

国家社会经济的可持续发展与可用淡水资源量关系密切.我国人口众多,水资源供需矛盾较突出.现有的天然河川径流资料缺失率较高,参考站点密度不足,在年际和季节变化尺度上存在较大偏差,难以客观揭示大尺度河川径流变化的自然规律.本研究基于VIC(The Variable Infiltration Capacity)分布式水文模型,结合参数不确定分析、流向校正和统计后处理方法,建立了一套长时序、多站点、高质量的天然河川径流资料.全国330个水文站分别约有83%和56%水文站的NSE值、KGE值大于0.70,该天然径流数据集可以为变化环境下水文过程模拟与水资源综合管理提供重要基础数据与科学服务.

An Objective Approach to Generating Multi-Physics Ensemble Precipitation Forecasts Based on the WRF Model

Selecting proper parameterization scheme combinations for a particular application is of great interest to the Weather Research and Forecasting(WRF)model users.This study aims to develop an objective method for identifying a set of scheme combinations to form a multi-physics ensemble suitable for short-range precipitation forecasting in the Greater Beijing area.The ensemble is created by using statistical techniques and some heuristics.An initial sample of 90 scheme combinations was first generated by using Latin hypercube sampling(LHS).Then,after several rounds of screening,a final ensemble of 40 combinations were chosen.The ensemble forecasts generated for both the training and verification cases using these combinations were evaluated based on several verification metrics,including threat score(TS),Brier score(BS),relative operating characteristics(ROC),and ranked probability score(RPS).The results show that TS of the final ensemble improved by 9%-33%over that of the initial ensemble.The reliability was improved for rain≤10 mm day^-1,but decreased slightly for rain>10 mm day^-1 due to insufficient samples.The resolution remained about the same.The final ensemble forecasts were better than that generated from randomly sampled scheme combinations.These results suggest that the proposed approach is an effective way to select a multi-physics ensemble for generating accurate and reliable forecasts.

Numerical Investigation and Uncertainty Analysis of Eastern China's Large-Scale Urbanization Effect on Regional Climate

Eastern China has experienced rapid urbanization during the past four decades,and it is necessary to understand the impacts of the urbanization on the regional climate.Previous simulations with either regional climate models(RCMs)or general circulation models have produced inconsistent and statistically non-significant urbanization effects on precipitation during the East Asian summer monsoon.In the studies with RCMs,reanalysis data were used as the lateral boundary conditions(LBCs)for both urban and non-urban experiments.Since the same LBCs may limit the urbanization effect,in this study,the Weather Research and Forecasting(WRF)model nested within the Global Forecast System(GFS),both of which were coupled with an urban canopy model,were used to explore the urbanization effect over eastern China.The WRF’s LBCs in the runs with/without urbanization were provided by the corresponding GFS runs with/without urbanization.The results showed a significant decrease in precipitation over North China,mainly due to a marked decrease in evaporation and the divergence induced by the reduced latent heating in the mid and upper atmosphere,from the experiment with urbanization.Meanwhile,to the north and south of the large-scale urbanization areas,especially to the south of the Yangtze River,precipitation increased significantly due to largescale urbanization-induced circulation change.With the same LBCs for the WRF runs with/without urbanization,the urbanization effects were limited only to urban and nearby areas;no significant change was found to the south of the Yangtze River,since the same LBCs hampered the effects of urbanization on large-scale circulation.In addition,this study demonstrated that the urban fraction may be a key factor that affects the intensity of the urbanization effect within the urban areas.