Advances in Meteorology The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Advances in Boundary-Layer/Air Pollution Meteorology Tue, 26 Jul 2016 07:45:40 +0000 Xiao-Ming Hu, Jianping Huang, Jose D. Fuentes, Renate Forkel, and Ning Zhang Copyright © 2016 Xiao-Ming Hu et al. All rights reserved. Improving the Predictability of Severe Convective Weather Processes by Using Wind Vectors and Potential Temperature Changes: A Case Study of a Severe Thunderstorm Tue, 19 Jul 2016 06:22:20 +0000 Strong, local convective weather events are capable of causing extensive damage, but weather observation systems with limited resolution and radar monitoring can typically provide only a few minutes to hours of prior warning time. This paper presents a comprehensive case study of the cumulative evolution of several characteristic quantities during one extremely severe convective weather process. The research results indicate that the main feature of strong convective weather is the uneven distribution of thermal energy in the atmosphere, and the structure of this heat distribution determines the level of instability in the atmosphere. A vertical “clockwise rolling current” occurs in the wind field structure at the beginning of the process, and this is accompanied by a rapid drop in temperature at the top of the troposphere. When these signs occurred in the case study, radar technology was used to refine the precipitation region and spatial characteristics of the approaching storm. The height and vertical evolution of radar echoes were indicative of the characteristics of the system’s movement through space. Such findings may be useful for improving the forecasting times for strong convective weather. Hao Wang, Gangyi Chen, Huanhuan Lei, Yongqian Wang, and Shunxian Tang Copyright © 2016 Hao Wang et al. All rights reserved. Evaluation of Air Quality Model Performance for Simulating Long-Range Transport and Local Pollution of PM2.5 in Japan Thu, 14 Jul 2016 06:21:57 +0000 The Community Multiscale Air Quality Model (CMAQ) v5.0.2 was applied to PM2.5 simulation in Japan, which is strongly affected by long-range transport (LRT) from anthropogenic sources in the Asian Continent, for one year from April 2010 to March 2011. The model performance for LRT and local pollution (LP) of PM2.5 was evaluated to identify the model processes that need to be improved. CMAQ well simulated temporal and spatial variation patterns of PM2.5 but underestimated the concentration level by 15% on average. The contribution of LRT was estimated from the difference between the baseline simulation case and a zero-emission case for anthropogenic emissions in the continent. The estimated LRT contribution to PM2.5 was 50% on average and generally higher in the western areas of Japan (closer to the continent). Days that were dominantly affected by LRT or LP were determined based on the contribution of LRT to sulfate, which was fairly well simulated and strongly affected by LRT among major PM2.5 components. The underestimation of PM2.5 was larger in LP days (by 26% on average) than LRT days (by 10% on average). Therefore, it is essential to improve local emissions, formation, and loss processes of precursors and PM2.5 in Japan. Hikari Shimadera, Tatsuya Kojima, and Akira Kondo Copyright © 2016 Hikari Shimadera et al. All rights reserved. Evaluation of Relations between Extreme Precipitation and Temperature in Observational Time Series from the Czech Republic Mon, 11 Jul 2016 14:12:10 +0000 The intensity of precipitation extremes is expected to increase as the climate warms and it may cause floods and increase erosion. From the Clausius-Clapeyron relation (CC) it follows that the maximum moisture content of the atmosphere increases by approximately 7% per degree as temperature rises. However, the increases in observed hourly precipitation extremes of approximately two times the CC relation were described recently. This super CC scaling is attributed to the increased prevalence of convective rainfall and decreased prevalence of stratiform rainfall as temperatures increase. We carried out the disaggregation of precipitation into prevailing stratiform and convective component on the observational data from the Czech Republic for 1966–2006. Then, we analyzed trends in characteristics of disaggregated events and assessed correlation of precipitation intensities with daily mean temperature. The results suggest the increasing trend of convective precipitation in summer. The scaling for total rain events is steeper than for the events with prevailing convective component and for the events with prevailing stratiform component. It is a result of mixing of the two storm types. At higher temperature the events with prevailing convective component prevail and vice versa. Marta Martinkova and Martin Hanel Copyright © 2016 Marta Martinkova and Martin Hanel. All rights reserved. A Three-Parameter S-Shaped Function of Flood Return Period and Damage Sun, 10 Jul 2016 12:42:06 +0000 With growing flood risk due to increased urbanization, flood damage assessment and flood risk management must be reconsidered. To demonstrate and assess the new features and trends of flood risk in urbanized areas, a novel S-shaped function of return period and damage is proposed. The function contains three parameters, which are defined as the maximum flood damage , critical return period , and integrated loss coefficient . A basic framework for flood damage assessment was established to evaluate flood damage in the Taihu Basin under various scenarios. The simulation results were used to construct the flood functions. The study results show that the flood model based on the Gompertz function agrees well with the mutability of flood damage in the highly urbanized basin when the flood scale exceeds the defense capability. The function can be utilized for timely and effective flood damage assessment and prediction. It can describe the impacts of socioeconomic development, urbanization degree, and flood control capability improvements well. The turning points of the function curve can be used as gradation criteria for rational strategy development associated with flood hazards. Chaochao Li, Xiaotao Cheng, Na Li, Zhongmin Liang, Yanyan Wang, and Song Han Copyright © 2016 Chaochao Li et al. All rights reserved. Hydrological Hazards in a Changing Environment: Early Warning, Forecasting, and Impact Assessment Sun, 10 Jul 2016 08:36:10 +0000 Slavisa Trajkovic, Ozgur Kisi, Momcilo Markus, Hossein Tabari, Milan Gocic, and Shahaboddin Shamshirband Copyright © 2016 Slavisa Trajkovic et al. All rights reserved. The Implication of Climate Signal for Precipitation in the Heihe River Basin, Northwest China Mon, 04 Jul 2016 10:11:38 +0000 This paper studies the stochastic dynamic variability of precipitation, for the upper, middle, and lower reaches of the Heihe River basin in Northwest China, by employing Mann-Kendall statistic, Pettitt test, and wavelet transform methods. The possible associations with three prominent climatic patterns, El Niño-Southern Oscillation (ENSO), Artic Oscillation (AO), and Indian Ocean Dipole (IOD), are examined by using multiscale wavelet coherence method. No significant trend is identified for the interannual precipitation variability. However, about 2-year significant variability is detected for the lower reach of the Heihe River basin, and this dominating precipitation variability is essentially depicted by AO. The possible influences of ENSO are exerted on long-term timescale, 8–16 years. The obtained knowledge is helpful for the predications of extreme hydroclimatological events and better reservoir operations for regional water resources. Fei Wang and Jun Niu Copyright © 2016 Fei Wang and Jun Niu. All rights reserved. Reconstruction of Typhoon Structure Using 3-Dimensional Doppler Radar Radial Velocity Data with the Multigrid Analysis: A Case Study in an Idealized Simulation Context Thu, 30 Jun 2016 13:24:43 +0000 Extracting multiple-scale observational information is critical for accurately reconstructing the structure of mesoscale circulation systems such as typhoon. The Space and Time Mesoscale Analysis System (STMAS) with multigrid data assimilation developed in Earth System Research Laboratory (ESRL) in National Oceanic and Atmospheric Administration (NOAA) has addressed this issue. Previous studies have shown the capability of STMAS to retrieve multiscale information in 2-dimensional Doppler radar radial velocity observations. This study explores the application of 3-dimensional (3D) Doppler radar radial velocities with STMAS for reconstructing a 3D typhoon structure. As for the first step, here, we use an idealized simulation framework. A two-scale simulated “typhoon” field is constructed and referred to as “truth,” from which randomly distributed conventional wind data and 3D Doppler radar radial wind data are generated. These data are used to reconstruct the synthetic 3D “typhoon” structure by the STMAS and the traditional 3D variational (3D-Var) analysis. The degree by which the “truth” 3D typhoon structure is recovered is an assessment of the impact of the data type or analysis scheme being evaluated. We also examine the effects of weak constraint and strong constraint on STMAS analyses. Results show that while the STMAS is superior to the traditional 3D-Var for reconstructing the 3D typhoon structure, the strong constraint STMAS can produce better analyses on both horizontal and vertical velocities. Hongli Fu, Xinrong Wu, Wei Li, Yuanfu Xie, Guijun Han, and Shaoqing Zhang Copyright © 2016 Hongli Fu et al. All rights reserved. Estimating the Surface Air Temperature by Remote Sensing in Northwest China Using an Improved Advection-Energy Balance for Air Temperature Model Wed, 29 Jun 2016 10:53:30 +0000 To estimate the surface air temperature by remote sensing, the advection-energy balance for the surface air temperature (ADEBAT) model is developed which assumes the surface air temperature is driven by the local driving force and the advective driving force. The local driving force produces a local surface air temperature whereas the advective driving force changes it by adding an exotic air temperature. An advection factor is defined to measure the quantity of the exotic air brought by the advection. Since the is determined by the advection, this paper improves it to a regional scale by using the Inverse Distance Weighting (IDW) method whereas the original ADEBAT model uses a constant of for a block of area. Results retrieved by the improved ADEBAT (IADEBAT) model are evaluated and comparison was made with the in situ measurements, with an (correlation coefficient) of 0.77, an RMSE (Root Mean Square Error) of 0.31 K, and a MAE (Mean Absolute Error) of 0.24 K. The evaluation shows that the IADEBAT model has higher accuracy than the original ADEBAT model. Evaluations together with a -test of the MAD (Mean Absolute Deviation) reveal that the IADEBAT model has a significant improvement. Suhua Liu, Hongbo Su, Renhua Zhang, Jing Tian, and Weizhen Wang Copyright © 2016 Suhua Liu et al. All rights reserved. Evapotranspiration Trend and Its Relationship with Precipitation over the Loess Plateau during the Last Three Decades Wed, 29 Jun 2016 05:50:39 +0000 There have been few studies conducted on the changes in actual ET over the Loess Plateau, due to the lack of reliable ET data. Based on ET data simulated by the Community Land Model, the present study analyzed the changes in ET over the Loess Plateau. The results showed the domain-average ET to have decreased in the past 31 years, at a rate of 0.78 mm year−1. ET fluctuated much more strongly in the 1990s than in the 1980s and 2000s, and, apart from in autumn, ET decreased in all seasons. In particular, ET in summer comprised about half of the annual ET trend and had the sharpest trend, dominating the interannual decline. ET also decreased more sharply in the semiarid than semihumid regions. The declining trend of ET was attributed to declining precipitation and air humidity. Locally, the ET trend was closely related to local mean annual precipitation: in areas with precipitation less than 400 mm, ET showed a decreasing trend; in areas with precipitation larger than 600 mm, ET showed an increasing trend; and in areas with precipitation in the range of 400–600 mm could be classified as a transitional zone. Zesu Yang, Qiang Zhang, and Xiaocui Hao Copyright © 2016 Zesu Yang et al. All rights reserved. Standardized Water Budget Index and Validation in Drought Estimation of Haihe River Basin, North China Tue, 28 Jun 2016 15:42:49 +0000 The physical-based drought indices such as the self-calibrated Palmer Drought Severity Index (sc-PDSI) with the fixed time scale is inadequate for the multiscalar drought assessment, and the multiscalar drought indices including Standardized Precipitation Index (SPI), Reconnaissance Drought Index (RDI), and Standardized Precipitation Evapotranspiration Index (SPEI) based on the meteorological factors are lack of physical mechanism and cannot depict the actual water budget. To fill this gap, the Standardized Water Budget Index (SWBI) is constructed based on the difference between areal precipitation and actual evapotranspiration (AET), which can describe the actual water budget but also assess the drought at multiple time scales. Then, sc-PDSI was taken as the reference drought index to compare with multiscalar drought indices at different time scale in Haihe River basin. The result shows that SWBI correlates better with sc-PDSI and the RMSE of SWBI is less than other multiscalar drought indices. In addition, all of drought indices show a decreasing trend in Haihe River Basin, possibly due to the decreasing precipitation from 1961 to 2010. The decreasing trends of SWBI were significant and consistent at all the time scales, while the decreasing trends of other multiscalar drought indices are insignificant at time scale less than 3 months. Shaohua Liu, Denghua Yan, Hao Wang, Chuanzhe Li, Baisha Weng, and Tianling Qin Copyright © 2016 Shaohua Liu et al. All rights reserved. Advances in Remote Sensing and Modeling of Terrestrial Hydrometeorological Processes and Extremes Mon, 27 Jun 2016 09:05:39 +0000 Ke Zhang, Jingfeng Wang, Iftekhar Ahmed, and Prasanna H. Gowda Copyright © 2016 Ke Zhang et al. All rights reserved. Detecting Variation Trends of Temperature and Precipitation for the Dadu River Basin, China Thu, 23 Jun 2016 12:12:30 +0000 This study analyzes the variation trends of temperature and precipitation in the Dadu River Basin of China based on observed records from fourteen meteorological stations. The magnitude of trends was estimated using Sen’s linear method while its statistical significance was evaluated using Mann-Kendall’s test. The results of analysis depict increase change from northwest to southeast of annual temperature and precipitation in space. In temporal scale, the annual temperature showed significant increase trend and the annual precipitation showed increase trend. For extreme indices, the trends for temperature are more consistent in the region compared to precipitation. This paper has practical meanings for an effective management of climate risk and provides a foundation for further study of hydrological situation in this river basin. Ying Wu, Wensheng Wang, and Guoqing Wang Copyright © 2016 Ying Wu et al. All rights reserved. Heat-Wave Events in Spain: Air Mass Analysis and Impacts on 7Be Concentrations Wed, 22 Jun 2016 08:40:46 +0000 The present paper describes and characterizes the air mass circulation during the heat-wave events registered during the period 2005–2014 over Spain, paying special attention to the role of the Saharan circulations. Backward trajectories at 500, 1500, and 3000 m in Seville (south), Madrid (centre), and Bilbao (north) during the thirteen heat-wave events identified are analysed. Finally, the impact of the heat-wave events and of each advection pattern on 7Be activity concentrations is also analysed. The heat-wave events are characterized roughly by western, southern, and nearby advections, with a higher frequency of the first two types. The analysis shows an increase of African air masses with height, presenting a different spatial impact over Spain, with a decreasing occurrence and a decrease in the simultaneous occurrence percentage from south to north. On average, the 7Be activity concentrations during these events show an increase of concentrations in central (21%) and southern (18%) areas and a decrease in northern (13%) Spain. This increase is not associated with Saharan air masses but instead with the arrival of distant westerly air masses. M. A. Hernández-Ceballos, E. Brattich, and G. Cinelli Copyright © 2016 M. A. Hernández-Ceballos et al. All rights reserved. Attenuation Correction Effects in Rainfall Estimation at X-Band Dual-Polarization Radar: Evaluation with a Dense Rain Gauge Network Mon, 20 Jun 2016 12:05:34 +0000 The effects of attenuation correction in rainfall estimation with X-band dual-polarization radar were investigated with a dense rain gauge network. The calibration bias in reflectivity () was corrected using a self-consistency principle. The attenuation correction of and the differential reflectivity () were performed by a path integration method. After attenuation correction, and were significantly improved, and their scatter plots matched well with the theoretical relationship between and . The comparisons between the radar rainfall estimation and the rain gauge rainfall were investigated using the bulk statistics with different temporal accumulations and spatial averages. The bias significantly improves from 70% to 0% with . However, the improvement with was relatively small, from 3% to 1%. This indicated that rainfall estimation using a polarimetric variable was more robust at attenuation than was a single polarimetric variable method. The bias did not show improvement in comparisons between the temporal accumulations or the spatial averages in either rainfall estimation method. However, the random error improved from 68% to 25% with different temporal accumulations or spatial averages. This result indicates that temporal accumulation or spatial average (aggregation) is important to reduce random error. Young-A Oh, DaeHyung Lee, Sung-Hwa Jung, Kyung-Yeub Nam, and GyuWon Lee Copyright © 2016 Young-A Oh et al. All rights reserved. A Method to Assess Localized Impact of Better Floodplain Topography on Flood Risk Prediction Sun, 19 Jun 2016 06:58:25 +0000 Many studies have highlighted the need for a higher accuracy global digital elevation model (DEM), mainly in river floodplains and deltas and along coastlines. In this paper, we present a method to infer the impact of a better DEM on applications and science using the Lower Zambezi basin as a use case. We propose an analysis based on a targeted observation algorithm to evaluate potential data acquisition subregions in terms of their impact on the prediction of flood risk over the entire study area. Consequently, it becomes trivial to rank these subregions in terms of their contribution to the overall accuracy of flood prediction. The improvement from better topography data may be expressed in terms of economic output and population affected, providing a multifaceted assessment of the value of acquiring better elevation data. Our results highlight the notion that having higher resolution measurements would improve our current large-scale flood inundation prediction capabilities in the Lower Zambezi by at least 30% and significantly reduce the number of people affected as well as the economic loss associated with high magnitude flooding. We believe this procedure to be simple enough to be applied to other regions where high quality topographic and hydrodynamic data are currently unavailable. Guy J.-P. Schumann and Konstantinos M. Andreadis Copyright © 2016 Guy J.-P. Schumann and Konstantinos M. Andreadis. All rights reserved. Hydrometeorology and Hydroclimate Sun, 19 Jun 2016 06:13:55 +0000 Christophe Cudennec, Alexander Gelfan, Liliang Ren, and Mohamed Slimani Copyright © 2016 Christophe Cudennec et al. All rights reserved. A Multimethod Approach towards Assessing Urban Flood Patterns and Its Associated Vulnerabilities in Singapore Thu, 16 Jun 2016 12:29:48 +0000 We investigated flooding patterns in the urbanised city-state of Singapore through a multimethod approach combining station precipitation data with archival newspaper and governmental records; changes in flash floods frequencies or reported impacts of floods towards Singapore society were documented. We subsequently discussed potential flooding impacts in the context of urban vulnerability, based on future urbanisation and forecasted precipitation projections for Singapore. We find that, despite effective flood management, (i) significant increases in reported flash flood frequency occurred in contemporary (post-2000) relative to preceding (1984–1999) periods, (ii) these flash floods coincide with more localised, “patchy” storm events, (iii) storms in recent years are also more intense and frequent, and (iv) floods result in low human casualties but have high economic costs via insurance damage claims. We assess that Singapore presently has low vulnerability to floods vis-à-vis other regional cities largely due to holistic flood management via consistent and successful infrastructural development, widespread flood monitoring, and effective advisory platforms. We conclude, however, that future vulnerabilities may increase from stresses arising from physical exposure to climate change and from demographic sensitivity via rapid population growth. Anticipating these changes is potentially useful in maintaining the high resilience of Singapore towards this hydrometeorological hazard. Winston T. L. Chow, Brendan D. Cheong, and Beatrice H. Ho Copyright © 2016 Winston T. L. Chow et al. All rights reserved. Improving the Distributed Hydrological Model Performance in Upper Huai River Basin: Using Streamflow Observations to Update the Basin States via the Ensemble Kalman Filter Thu, 16 Jun 2016 10:00:45 +0000 This study investigates the capability of improving the distributed hydrological model performance by assimilating the streamflow observations. Incorrectly estimated model states will lead to discrepancies between the observed and estimated streamflow. Consequently, streamflow observations can be used to update the model states, and the improved model states will eventually benefit the streamflow predictions. This study tests this concept in upper Huai River basin. We assimilate the streamflow observations sequentially into the Soil and Water Assessment Tool (SWAT) using the ensemble Kalman filter (EnKF) to update the model states. Both synthetic experiments and real data application are used to demonstrate the benefit of this data assimilation scheme. The experiment shows that assimilating the streamflow observations at interior sites significantly improves the streamflow predictions for the whole basin. Assimilating the catchment outlet streamflow improves the streamflow predictions near the catchment outlet. In real data case, the estimated streamflow at the catchment outlet is significantly improved by assimilating the in situ streamflow measurements at interior gauges. Assimilating the in situ catchment outlet streamflow also improves the streamflow prediction of one interior location on the main reach. This may demonstrate that updating model states using streamflow observations can constrain the flux estimates in distributed hydrological modeling. Yongwei Liu, Wen Wang, Yiming Hu, and Wei Cui Copyright © 2016 Yongwei Liu et al. All rights reserved. Variability in Dust Observed over China Using A-Train CALIOP Instrument Thu, 16 Jun 2016 08:54:04 +0000 Patterns of dust aerosol variation over China are analyzed using A-Train CALIOP and precipitation, soil moisture, and vegetation coverage datasets during the period of 2007 and 2014. Spatially, dust is mostly prominent over northwestern China, with the highest and most widespread dust activities being in Taklimakan Desert. Dust is generally distributed across the atmosphere up to 5 km altitude, with a peak of DAFOD around 3 km. The dust layer has a significant geographical and seasonal drifting, with higher altitude in spring and summer and dust source regions (between 3 km and 5 km). Additionally, single dust layer is more often observed in a vertical column. Temporally, high amounts of dust aerosol (C-DAFOD as high as 0.08) experienced in spring subsequently continuous decrease until the spring of next year. The correlation coefficients between the latitude averaged column integrated dust aerosol feature optical depth (C-DAFOD) and precipitation, soil moisture, and vegetation coverage are −0.65, −0.81, and −0.77, respectively. The correlation coefficients of seasonal mean C-DAFOD with the three factors are −0.15, −0.67, and −0.35, respectively. The analysis showed dust and the other three factors are negatively correlated. Overall, dust over China shows considerable spatial, temporal, and vertical variations. Hui Xu, Fengjie Zheng, and Wenhao Zhang Copyright © 2016 Hui Xu et al. All rights reserved. Spatial and Temporal Variability of Sea Surface Temperature in Eastern Marginal Seas of China Wed, 15 Jun 2016 12:37:29 +0000 Spatial mean value evolution, long-term mean pattern, and seasonal as well as interannual variability of sea surface temperature (SST) in Eastern Marginal Seas of China (EMSC) are reanalyzed based on thirty years’ NOAA optimum interpolation (OI) 1/4 degrees’ daily SST data. Temporal evolution of the spatial mean value shows a very marked annual cycle and a weak warming tendency (0.03437°C/year). Spatial distribution of the long-term mean value shows some more fine spatial structure of SST compared to previous studies. Over 90% of the temporal variability can be explained by the annual harmonic whose amplitude is one order larger than that of the semiannual harmonic. In addition, the annual harmonic amplitude distribution is consistent with that of the value of standard deviation. In order to investigate the interannual variation of SST, the EMSC SST interannual index was constructed. Based on wavelet analysis, a significant peak around 3.3 years was found in the EMSC SST interannual index. Further analysis demonstrated that the interannual variability of SST is linked with El Niño-Southern Oscillation (ENSO) teleconnection, through which anomalous surface heat flux warms or cools the EMSC during El Niño or La Niña events. Renhao Wu, Jianmin Lin, and Bo Li Copyright © 2016 Renhao Wu et al. All rights reserved. The Impacts of Different PBL Schemes on the Simulation of PM2.5 during Severe Haze Episodes in the Jing-Jin-Ji Region and Its Surroundings in China Tue, 07 Jun 2016 10:57:32 +0000 In this study, three schemes [Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), and Bougeault-Lacarrère (Boulac)] were employed in the Weather Research and Forecasting/Chemistry (WRF-Chem) model to simulate the severe haze that occurred in February 2014 in the Jing-Jin-Ji region and its surroundings. The PM2.5 concentration simulated using the three schemes, together with the meteorological factors closely related to PM2.5 (wind speed, local vertical diffusivity, and PBL height), was evaluated through comparison with observations. The results indicated that the eastern plain cities produced better simulation results than the western cities, and the cities under the eastern root of Taihang Mountain produced the worst results in simulating high PM2.5 concentration in haze. All three schemes simulated very similar variation trends of the surface PM2.5 concentration compared with observations. The diurnal variations of simulated surface PM2.5 were not as reasonable as their reflection of daily averaged variation. The simulated concentrations of surface PM2.5 using the YSU, MYJ, and Boulac schemes all showed large negative errors during daytime in polluted days due to their inefficient descriptions of local atmospheric stability or diffusion processes in haze. The lower ability of PBL schemes in distinguishing the diffusion between haze and clean days in the complex topography areas in China is an important problem for PM2.5 forecasting, which is worthy of being studied in detail. Tian Li, Hong Wang, Tianliang Zhao, Min Xue, Yaqiang Wang, Huizheng Che, and Chao Jiang Copyright © 2016 Tian Li et al. All rights reserved. Influence of Hydrological Model Selection on Simulation of Moderate and Extreme Flow Events: A Case Study of the Blue Nile Basin Tue, 31 May 2016 16:05:49 +0000 Five hydrological models were applied based on data from the Blue Nile Basin. Optimal parameters of each model were obtained by automatic calibration. Model performance was tested under both moderate and extreme flow conditions. Extreme events for the model performance evaluation were extracted based on seven criteria. Apart from graphical techniques, there were nine statistical “goodness-of-fit” metrics used to judge the model performance. It was found that whereas the influence of model selection may be minimal in the simulation of normal flow events, it can lead to large under- and/or overestimations of extreme events. Besides, the selection of the best model for extreme events may be influenced by the choice of the statistical “goodness-of-fit” measures as well as the criteria for extraction of high and low flows. It was noted that the use of overall water-balance-based objective function not only is suitable for moderate flow conditions but also influences the models to perform better for high flows than low flows. Thus, the choice of a particular model is recommended to be made on a case by case basis with respect to the objectives of the modeling as well as the results from evaluation of the intermodel differences. Charles Onyutha Copyright © 2016 Charles Onyutha. All rights reserved. Mesoscale Spatial Variability of Linear Trend of Precipitation Statistics in Korean Peninsula Tue, 31 May 2016 09:09:19 +0000 This study analyzed the spatial variability of the linear trend of the precipitation mean, variance, lag-1 autocorrelation coefficient, and probability of dryness (PD) based on the precipitation data between 1981 and 2015 observed at 65 rain gages located across Korean Peninsula. While the result of the Mann-Kendall test based on the yearly statistics showed no temporal trend at most of the gage locations, the same test based on the 20-yearly statistics showed that statistically significant temporal trend exists at 54% (mean), 60% (variance), 61% (autocorrelation), and 61% (PD) among the total 65 rain gages. In addition, this study produced the map of the linear trend of the precipitation statistics. The map showed a clear regional and seasonal tendency implying that the impact of the climate change varies significantly within Korea. The variogram analysis revealed that the approximate characteristic scale of linear trend of hourly and daily precipitation statistics ranges between 50 km and 200 km and between 100 km and 250 km, respectively. This characteristic scale is significantly smaller than the spatial scale of atmospheric circulation, which suggests that future water resources management plans of Korea should consider this mesoscale variability that otherwise can be missed if it is based only on the GCM simulation results. Jaehyeon Lee, Jaehyun Ahn, Eunsoo Choi, and Dongkyun Kim Copyright © 2016 Jaehyeon Lee et al. All rights reserved. Verification of Forecast Weather Surface Variables over Vietnam Using the National Numerical Weather Prediction System Tue, 31 May 2016 06:49:52 +0000 The national numerical weather prediction system of Vietnam is presented and evaluated. The system is based on three main models, namely, the Japanese Global Spectral Model, the US Global Forecast System, and the US Weather Research and Forecasting (WRF) model. The global forecast products have been received at 0.25- and 0.5-degree horizontal resolution, respectively, and the WRF model has been run locally with 16 km horizontal resolution at the National Center for Hydro-Meteorological Forecasting using lateral conditions from GSM and GFS. The model performance is evaluated by comparing model output against observations of precipitation, wind speed, and temperature at 168 weather stations, with daily data from 2010 to 2014. In general, the global models provide more accurate forecasts than the regional models, probably due to the low horizontal resolution in the regional model. Also, the model performance is poorer for stations with altitudes greater than 500 meters above sea level (masl). For tropical cyclone performance validations, the maximum wind surface forecast from global and regional models is also verified against the best track of Joint Typhoon Warning Center. Finally, the model forecast skill during a recent extreme rain event in northeast Vietnam is evaluated. Tien Du Duc, Lars Robert Hole, Duc Tran Anh, Cuong Hoang Duc, and Thuy Nguyen Ba Copyright © 2016 Tien Du Duc et al. All rights reserved. Probabilistic Dressing of a Storm Surge Prediction in the Adriatic Sea Mon, 30 May 2016 09:42:18 +0000 Providing a reliable, accurate, and fully informative storm surge forecast is of paramount importance for managing the hazards threatening coastal environments. Specifically, a reliable probabilistic forecast is crucial for the management of the movable barriers that are planned to become operational in 2018 for the protection of Venice and its lagoon. However, a probabilistic forecast requires multiple simulations and a considerable computational time, which makes it expensive in real-time applications. This paper describes the ensemble dressing method, a cheap operational flood prediction system that includes information about the uncertainty of the ensemble members by computing it directly from the meteorological input and the local spread distribution, without requiring multiple forecasts. Here, a sophisticated error distribution form is developed, which includes the superposition of the uncertainty caused by inaccuracies of the ensemble prediction system, which depends on surge level and lead time, and the uncertainty of the meteorological forcing, which is described using a combination of cross-basin pressure gradients. The ensemble dressing is validated over a 3-month-long period in the year 2010, during which an exceptional sequence of storm surges occurred. Results demonstrate that this computationally cheap method can provide an acceptably realistic estimate of the uncertainty. R. Mel and P. Lionello Copyright © 2016 R. Mel and P. Lionello. All rights reserved. Attribute Analysis of Aridity Variability in North Xinjiang, China Sun, 29 May 2016 12:58:39 +0000 Identifying the dominant meteorological factors affecting aridity variability can improve our understanding of climate change and its future trend in arid and semiarid regions. This study investigated the spatiotemporal aridity variability in North Xinjiang, China, from 1961 to 2013, based on the UNESCO aridity index (precipitation/potential evapotranspiration), and analyzed its association with meteorological factors. The results suggest that North Xinjiang is becoming more humid with an increasing trend in aridity index. Precipitation, temperature, and relative humidity have positive correlation with aridity, and evapotranspiration, sunshine hours, and wind speed have negative correlation with aridity. Wind speed and sunshine hours have a higher sensitivity and more contribution to aridity. This study provides an understanding of the effect of recent climate change on drought in northwest China. Yanfeng Wu, Guangxin Zhang, Hong Shen, Y. Jun Xu, and Batur Bake Copyright © 2016 Yanfeng Wu et al. All rights reserved. Impact of Climate Change on Hydrologic Extremes in the Upper Basin of the Yellow River Basin of China Sun, 29 May 2016 07:37:01 +0000 To reveal the revolution law of hydrologic extremes in the next 50 years and analyze the impact of climate change on hydrologic extremes, the following main works were carried on: firstly, the long duration (15 d, 30 d, and 60 d) rainfall extremes according to observed time-series and forecast time-series by dynamical climate model product (BCC-CSM-1.1) were deduced, respectively, on the basis that the quantitative estimation of the impact of climate change on rainfall extremes was conducted; secondly, the SWAT model was used to deduce design flood with the input of design rainfall for the next 50 years. On this basis, quantitative estimation of the impact of climate change on long duration flood volume extremes was conducted. It indicates that (1) the value of long duration rainfall extremes for given probabilities (1%, 2%, 5%, and 10%) of the Tangnaihai basin will rise with slight increasing rate from 1% to 6% in the next 50 years and (2) long duration flood volume extremes of given probabilities of the Tangnaihai basin will rise with slight increasing rate from 1% to 6% in the next 50 years. The conclusions may provide technical supports for basin level planning of flood control and hydropower production. Jun Wang, Zhongmin Liang, Dong Wang, Tian Liu, and Jing Yang Copyright © 2016 Jun Wang et al. All rights reserved. Statistical Analysis of Relationship between Daytime Lidar-Derived Planetary Boundary Layer Height and Relevant Atmospheric Variables in the Semiarid Region in Northwest China Thu, 19 May 2016 08:57:55 +0000 Accurate identification of key parameters for data assimilation is important in simulating the planetary boundary layer height (PBLH) and structure evolution in numerical weather prediction models. In this study, surface observational data and lidar-derived PBLH on 42 cloudless days from June 2007 to May 2008 are used to quantify the statistical relationships between surface parameters and the PBLH at a semiarid climate observational site in Northwest China. The results indicate that surface upward long wave radiation, surface temperature, and surface sensible heat fluxes show strong correlations with the PBLH with correlation coefficients at a range of 0.63–0.72. But these parameters show varying correlation response time to the different stages of PBL development. Furthermore, the air temperature shows the highest correlation with the PBLH near the surface and the correlation decreases with increasing height. Ruijun Dang, Hong Li, Zhiguo Liu, and Yi Yang Copyright © 2016 Ruijun Dang et al. All rights reserved. A Simulation and Validation of CLM during Freeze-Thaw on the Tibetan Plateau Tue, 17 May 2016 07:24:44 +0000 The applicability of a new soil hydraulic property of frozen soil scheme applied in Community Land Model 4.5 (CLM4.5), in conjunction with an impedance factor for the presence of soil ice, was validated through two offline numerical simulations conducted at Madoi (GS) and Zoige (ZS) on the Tibetan Plateau (TP). Sensitivity analysis was conducted via replacing the new soil hydraulic property scheme in CLM4.5 by the old one, using default CLM4.5 runs as reference. Results indicated that the new parameterization scheme ameliorated the surface dry biases at ZS but enlarged the wet biases which existed at GS site due to ignoring the gravel effect. The wetter surface condition in CLM4.5 also leads to a warmer surface soil temperature because of the greater heat capacity of liquid water. In addition, the combined impact of new soil hydraulic property schemes and the ice impedance function on the simulated soil moisture lead to the more reasonable simulation of the starting dates of freeze-thaw cycle, especially at the thawing stage. The improvements also lead to the more reasonable turbulent fluxes simulations. Meanwhile, the decreased snow cover fraction in CLM4.5 resulted in a lower albedo, which tended to increase net surface radiation compared to previous versions. Further optimizing is needed to take the gravel into account in the numerical description of thermal-hydrological interactions. Xuewei Fang, Siqiong Luo, Shihua Lyu, Boli Chen, Yu Zhang, Di Ma, and Yan Chang Copyright © 2016 Xuewei Fang et al. All rights reserved.