Advances in Meteorology The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Synoptic-Scale Precursors to Tropical Cyclone Rapid Intensification in the Atlantic Basin Wed, 27 May 2015 08:46:40 +0000 Forecasting rapid intensification (hereafter referred to as RI) of tropical cyclones in the Atlantic Basin is still a challenge due to a limited understanding of the meteorological processes that are necessary for predicting RI. To address this challenge, this study considered large-scale processes as RI indicators within tropical cyclone environments. The large-scale processes were identified by formulating composite map types of RI and non-RI storms using NASA MERRA data from 1979 to 2009. The composite fields were formulated by a blended RPCA and cluster analysis approach, yielding multiple map types of RI’s and non-RI’s. Additionally, statistical differences in the large-scale processes were identified by formulating permutation tests, based on the composite output, revealing variables that were statistically significantly distinct between RI and non-RI storms. These variables were used as input in two prediction schemes: logistic regression and support vector machine classification. Ultimately, the approach identified midlevel vorticity, pressure vertical velocity, 200–850 hPa vertical shear, low-level potential temperature, and specific humidity as the most significant in diagnosing RI, yielding modest skill in identifying RI storms. Alexandria Grimes and Andrew E. Mercer Copyright © 2015 Alexandria Grimes and Andrew E. Mercer. All rights reserved. Impact of Climate Change on Temperate and Alpine Grasslands in China during 1982–2006 Mon, 25 May 2015 14:19:51 +0000 Based on GIMMS NDVI and climate data from 1982 to 2006, this study analyzed the impact of climate change on grassland in China. During the growing season, there were significant effects of precipitation on the growth of all the grassland types (), except for meadow vegetation. For the air temperatures, there existed asymmetrical effects of maximum temperature () and minimum temperature () on grassland vegetation, especially for the temperate grasslands and alpine steppe. The growing season NDVI correlated negatively with but positively with for temperate grasslands. Seasonally, these opposite effects were only observed in summer. For alpine steppe, the growing season NDVI correlated positively with but negatively with , and this pattern of asymmetrical responses was only obvious in spring and autumn. Under the background of global asymmetric warming, more attention should be paid to this asymmetric response of grassland vegetation to daytime and night-time warming, especially when we want to predict the productivity of China’s grasslands in the future. Xiangjin Shen, Binhui Liu, Guangdi Li, and Daowei Zhou Copyright © 2015 Xiangjin Shen et al. All rights reserved. Discrepancies in Different Precipitation Data Products in the Bay of Bengal during Summer Monsoon Season Sun, 24 May 2015 13:55:22 +0000 In the east Bay of Bengal (BoB), the precipitation maximum always lies near the eastern coast on the windward side of Mountain Araka Yoma in the summer monsoon season. In this study, different precipitation products are compared in terms of their representation of the offshore rainfall maximum feature in this region. Climatologically, all products examined present similar rainfall distribution except for the CMAP. Significant discrepancies among different products are found in the interannual variation, as illustrated by the contrast features between 2002 and 2005. Based on the TRMM products (except for 3B42RT) and GPCP V1.2, the precipitation maximum occurred near the coast in 2002, while it was about 100–200 km offshore in 2005. However, this difference is not obvious in the GPCP V2.2 and TRMM 3B42RT products. Larger easterly vertical wind shear and warmer SST were present in 2005. Both favor stronger orographically-forced convective systems to propagate offshore, leading to the offshore rainfall maximum in 2005. Therefore, it is suggested that the TRMM 3B40RT, which is mainly based on passive microwave estimates, may be more reliable among different precipitation products in reflecting the precipitation feature in the coastal region of the east BoB. Li Qi and Yuqing Wang Copyright © 2015 Li Qi and Yuqing Wang. All rights reserved. Algorithm Development for the Optimum Rainfall Estimation Using Polarimetric Variables in Korea Sun, 24 May 2015 12:13:32 +0000 In this study, to get an optimum rainfall estimation using polarimetric variables observed from Bislsan radar which is the first polarimetric radar in Korea, rainfall cases for 84 hours caused by different conditions, which are Changma front and typhoon, Changma front only, and typhoon only, occurred in 2011, were analyzed. And rainfall algorithms were developed by using long period drop size distributions with six different raindrop axis ratio relations. The combination of the relations between and , , and , , and and with different rainfall intensity would be an optimum rainfall algorithm if the reference of rainfall would be defined correctly. In the case the reference is not defined adequately, the relation between and , , , and and , , can be used as a representative rainfall relation. Particularly if the qualified is not available, the relation between and , , can be used as an optimum rainfall relation in Korea. Cheol-Hwan You and Dong-In Lee Copyright © 2015 Cheol-Hwan You and Dong-In Lee. All rights reserved. Chemical Compositions of Dew and Scavenging of Particles in Changchun, China Thu, 21 May 2015 14:08:02 +0000 Dew and rain water were collected during 2013 and 2014 in Changchun, China. The dew was analyzed and the following parameters were measured: pH, EC, TDS, major anions (F−, Cl−, , and ), and major cations (, Na+, K+, Ca2+, and Mg2+). The mean pH, EC, and TDS values of dew were comparable with the values for rainwater. The pH values of dew and rain were 6.72 and 6.16, respectively. Both EC (308 μS/cm) and TDS (154 mg/L) of dew were higher than those in rain samples. The concentration of main ions in dew was 1.5–5.7 times higher than levels in rainwater. The near-neutral pH values in dew were caused by the neutralization of acidity and buffering by the alkaline elements of soil origin (Ca2+). This neutralization was confirmed by a strong correlation between the acidic ions ( and ) and the major cations (Ca2+ and Mg2+). Natural dust made an important contribution to the ions present in dews, but the presence of sulfate concentrations that are notably higher than rain water (up to 1584.5 μeq/L) indicated a significant contribution of anthropogenic sources. Dew has the ability to capture particulates, and the purifying effect on the underlying surface was obvious. Yingying Xu, Hui Zhu, Jie Tang, and Yingzi Lin Copyright © 2015 Yingying Xu et al. All rights reserved. A Numerical Study of the Beijing Extreme Rainfall of 21 July 2012 and the Impact of Topography Thu, 21 May 2015 10:59:01 +0000 The extreme rainfall on 21 July 2012 is the heaviest rainfall that has occurred in Beijing since 1961. Observations and WRF (Weather Research and Forecasting) model are used to study the effect of MCS (mesoscale convective system) and topography on the rainfall. In this high-impact event, a quasi-stationary MCS developed in a favorable moist environment. The numerical simulation successfully reproduced the amount, location, and time evolution of the rainfall despite 4–6 h delay. In particular, the model reproduced the repeat passage of convective cells at the leading convergence line region along Taihang Mountains and the trailing stratiform region, producing the rainfall at nearly the right position. Results indicate the important roles of mesolow and low-level jet in maintaining the conditional instability that lifted the moist air to trigger deep convection and the repeated initiation and movement of the line shaped convective cells that produced the rainfall. The sensitive experiment was then further carried out to examine the effect of topography on this heavy rainfall. The reduction in model elevation field significantly influenced the above mesoscale systems, which lead to convective cells becoming less organized, and the peak rainfall amount in Beijing decreased by roughly 50%. Hongxiong Xu and Wenqing Yao Copyright © 2015 Hongxiong Xu and Wenqing Yao. All rights reserved. Advances in Urban Biometeorology 2014 Wed, 20 May 2015 13:34:42 +0000 Panagiotis Nastos, Andreas Matzarakis, Marialena Nikolopoulou, and Tzu-Ping Lin Copyright © 2015 Panagiotis Nastos et al. All rights reserved. Extreme Precipitation Changes in the Semiarid Region of Xinjiang, Northwest China Wed, 20 May 2015 11:44:07 +0000 This study focuses on extreme precipitation changes in Xinjiang Province of Northwest China, which has experienced an increase in climate disasters in recent years. This paper investigates extreme precipitation events in Xinjiang, using 54 stations with daily precipitation records from the period 1961–2008. Different statistical tests and approaches were used to check the significance of trends of single and Xinjiang regionally aggregated precipitation series for intensity and in frequency. There were predominantly positive trends in annual maximum precipitation and a remarkable increment in the frequency of extreme precipitation over certain thresholds (from 10 to 40 mm). Although the series of frequencies exceeding thresholds had positive trends, only a minority were statistically significant. This lack of significance is because of the high variability of extreme precipitation in space and time. Thus, significant trends were evident when we assessed the extreme precipitation indicators of intensity and frequency at the regional level, both in intensity and frequency over thresholds, with a clearer signal in Xinjiang. Yanwei Zhang, Quansheng Ge, and Minzhe Liu Copyright © 2015 Yanwei Zhang et al. All rights reserved. Spatial and Seasonal Variation in Rain Use Efficiency in Semiarid Grasslands of Inner Mongolia Wed, 20 May 2015 06:56:37 +0000 Rain use efficiency (RUE) is an important indicator for identifying the response of plant production to variation in precipitation patterns, especially in semiarid ecosystem grasslands of Inner Mongolia. We have investigated the response and spatial patterns of RUE to precipitation patterns based on five years (2006, 2007, 2008, 2012, and 2013) of records from semiarid ecosystem sites across Inner Mongolia. Our results showed that was lowest in the wettest year (2012) and highest in the year following the driest year (2008). There was no significant correlation between and in typical and desert steppe. was strongly correlated with both annual precipitation (AP) and growing season precipitation (GSP) compared to . , therefore, cannot be used in place of . increased with species richness. The relationship between and species richness was significantly correlated in meadow steppe, typical steppe, and desert steppe. Our findings can shed light on the spatial utilization pattern of seasonal rainfall in semiarid grassland ecosystems. Jyoti Bhandari, Xuebiao Pan, and G. C. Dhruba Bijaya Copyright © 2015 Jyoti Bhandari et al. All rights reserved. A Comparative Study on the Positive Lightning Return Stroke Electric Fields in Different Meteorological Conditions Tue, 19 May 2015 12:09:21 +0000 Positive cloud-ground lightning is considerably more complex and less studied compared to the negative lightning. This paper aims to measure and characterize the significant parameters of positive return strokes electric field, namely, the zero-to-peak rise time, 10–90% rise time, slow front duration, fast transition rise time (10–90%), zero-crossing time, and opposite polarity overshoot relative to peak. To the best of the authors’ knowledge, this is the first time such detailed characteristics of positive lightning in Malaysia are thoroughly analyzed. A total of 41 positive lightning flashes containing 48 return strokes were analyzed. The average multiplicity is 1.2 strokes per flash. The majority of positive lightning was initiated from the primary positive charge rather than as a byproduct of in-cloud discharges. The cumulative probability distribution of rise time parameters, opposite polarity overshoot relative to peak, and slow front amplitude relative to peak are presented. A comparison between studies in four countries representing tropic, subtropic, and temperate regions was also carried out. Measured parameters in Florida, Sweden, and Japan are generally lower than those in Malaysia. Positive lightning occurrences in tropical regions should be further studied and analyzed to improve our current understanding on positive return strokes. Chin-Leong Wooi, Zulkurnain Abdul-Malek, Behnam Salimi, Noor Azlinda Ahmad, Kamyar Mehranzamir, and Saeed Vahabi-Mashak Copyright © 2015 Chin-Leong Wooi et al. All rights reserved. Future Changes in Human-Biometeorological Index Classes in Three Regions of Luxembourg, Western-Central Europe Mon, 18 May 2015 14:11:15 +0000 Projected climate change will cause increasing air temperatures affecting human thermal comfort. In the highly populated areas of Western-Central Europe a large population will be exposed to these changes. In particular Luxembourg—with its dense population and the large cross-border commuter flows—is vulnerable to changing thermal stress. Based on climate change projections we assessed the impact of climate change on human thermal comfort over the next century using two common human-biometeorological indices, the Physiological Equivalent Temperature and the Universal Thermal Climate Index. To account for uncertainties, we used a multimodel ensemble of 12 transient simulations (1971–2098) with a spatial resolution of 25 km. In addition, the regional differences were analysed by a single regional climate model run with a spatial resolution of 1.3 km. For the future, trends in air temperature, vapour pressure, and both human-biometeorological indices could be determined. Cold stress levels will decrease significantly in the near future up to 2050, while the increase in heat stress turns statistically significant in the far future up to 2100. This results in a temporarily reduced overall thermal stress level but further increasing air temperatures will shift the thermal comfort towards heat stress. Hanna Leona Lokys, Jürgen Junk, and Andreas Krein Copyright © 2015 Hanna Leona Lokys et al. All rights reserved. Changing Trends in Meteorological Elements and Reference Evapotranspiration in a Mega City: A Case Study in Shenzhen City, China Mon, 18 May 2015 08:40:57 +0000 Shenzhen city was a farmland region before 1978, and it then developed to a mega city in China. This type of change in city can greatly affect the climatic conditions. In this study, the daily, monthly, and annual climatic variables and the reference crop evapotranspiration (ET0) for Shenzhen from 1954 to 2012 were computed using the FAO Penman-Monteith equation (PM), and these parameters were analyzed to study the temporal trends of ET0 and meteorological factors. The trends and the time points of abrupt changes of ET0 and meteorological factors were tested using Mann-Kendall methods. Results show that, in the past 59 years, the annual ET0 first decreased from 1954 to 1978, then increased from 1979 to 1990, and now varied slightly after 1990. The mean air temperature rose gradually, and the relative humidity decreased as a whole. These trends finally resulted in an increasing trend in vapor pressure deficit (VPD). The wind speed showed a slightly decreasing trend. Both the annual total sunshine duration and net radiation showed trends of rapid decline. ET0 change is sensitive to the hours of sunshine and VPD. The significant increase in ET0 after 1979 was mainly due to the increased air temperature and decreased relative humidity. Haijun Liu, Xian Zhang, Liwei Zhang, and Xuming Wang Copyright © 2015 Haijun Liu et al. All rights reserved. Influence of Urban Microclimate on Air-Conditioning Energy Needs and Indoor Thermal Comfort in Houses Mon, 18 May 2015 06:36:49 +0000 A long-term climate measurement was implemented in the third largest city of Taiwan, for the check of accuracy of morphing approach on generating the hourly data of urban local climate. Based on observed and morphed meteorological data, building energy simulation software EnergyPlus was used to simulate the cooling energy consumption of an air-conditioned typical flat and the thermal comfort level of a naturally ventilated typical flat. The simulated results were used to quantitatively discuss the effect of urban microclimate on the energy consumption as well as thermal comfort of residential buildings. The findings of this study can serve as a reference for city planning and energy management divisions to study urban sustainability strategies in the future. Feng-Chi Liao, Ming-Jen Cheng, and Ruey-Lung Hwang Copyright © 2015 Feng-Chi Liao et al. All rights reserved. Evaluating the Effects of Façade Greening on Human Bioclimate in a Complex Urban Environment Mon, 18 May 2015 06:17:59 +0000 The evaluation of the effectiveness of countermeasures for a reduction of urban heat stress, such as façade greening, is challenging due to lacking transferability of results from one location to another. Furthermore, complex variables such as the mean radiant temperature are necessary to assess outdoor human bioclimate. We observed in front of a building façade in Berlin, Germany, which is half-greened while the other part is bare. was reduced (mean 2 K) in front of the greened compared to the bare façade. To overcome observational shortcomings, we applied the microscale models ENVI-met, RayMan, and SOLWEIG. We evaluated these models based on observations. Our results show that (MD = −1.93 K) and downward short-wave radiation (MD = 14.39 W/m2) were sufficiently simulated in contrast to upward short-wave and long-wave radiation. Finally, we compare the simulated reduction of with the observed one in front of the façade greening, showing that the models were not able to simulate the effects of façade greening with the applied settings. Our results reveal that façade greening contributes only slightly to a reduction of heat stress in front of building façades. Britta Jänicke, Fred Meier, Marie-Therese Hoelscher, and Dieter Scherer Copyright © 2015 Britta Jänicke et al. All rights reserved. Temporal Differences of Urban-Rural Human Biometeorological Factors for Planning and Tourism in Szeged, Hungary Sun, 17 May 2015 14:01:55 +0000 Heat load and cold stress can provoke annoyance and even health issues. These climatic situations should be avoided by tourists and locals to prevent negative experiences. Thermal comfort indices are required, as they combine meteorological and thermophysiological parameters. The Physiologically Equivalent Temperature (PET) is easy to understand and interpret also for nonexperts like tourists or decision-makers. The Hungarian Meteorological Service and the University of Szeged run an urban and a rural weather station close to Szeged, which build the basis for the human biometeorological analysis for a twelve-year period between 2000 and 2011. The maximum, mean, and minimum air temperature of both stations were compared to detect the differences of thermal dynamics. Heat and cold stress are quantified by analyzing the PET frequencies at 14 CET. The air temperature of urban areas is on average 1.0°C warmer than rural areas (11.4°C). Heat stress is more frequent in urbanized areas (6.3%) during summer months at 14 CET, while thermal acceptance is more frequent for surrounding rural areas (5.9%) in the same period. The Climate-Tourism/Transfer-Information-Scheme is a possibility to present the meteorological and human biometeorological data which is interesting for decision-making and tourism in a well-arranged way. Ronja Vitt, Ágnes Gulyás, and Andreas Matzarakis Copyright © 2015 Ronja Vitt et al. All rights reserved. Investigating Thermal Comfort and User Behaviors in Outdoor Spaces: A Seasonal and Spatial Perspective Sun, 17 May 2015 13:04:09 +0000 Numerous studies have examined the correlation between the number of attendants in a given outdoor environment and thermal indices to understand how the environmental planning has an impact on the users. However, extensive observations should be conducted to examine the detailed static and dynamic behavior patterns of users. We conducted dynamic observations at a stepped plaza to perform on-site measurements of the physical environment and observations of users behaviors, including their resting positions, movements, and stay durations. The results indicated that more people rested on the steps during the cool season than hot season. Compared to neutral temperatures, people demonstrated higher heat tolerance to the hot season. The results indicated that more than 75% of users preferred to remain in shaded areas and stayed longer than in the sunlight. The people tended to engage in static activities in environments that exhibit sufficient shading. The shaded areas were conducive to static activities as the summer grew hotter. The results verified that the people of Taiwan would avoid sunlight and desire shaded spaces based on their previous climate experiences and expectations, which can serve as a reference for outdoor space design to improve the usability and quality of open urban spaces. Kuo-Tsang Huang, Tzu-Ping Lin, and Hsiao-Chi Lien Copyright © 2015 Kuo-Tsang Huang et al. All rights reserved. Contribution of Greening and High-Albedo Coatings to Improvements in the Thermal Environment in Complex Urban Areas Sun, 17 May 2015 12:44:42 +0000 The aim was to identify microclimate characteristics in relation to ground cover in green areas and the reflectivity of building coating materials. Furthermore, microclimate modeling of temperatures was conducted using ENVI-met, to analyze the effects of improved thermal environments based on increased green areas and increased reflectivity of exterior coatings. The accuracy of ENVI-met was validated through comparisons with field temperature measurements. The RMSE deviation of the predicted and actual field temperature values was 3–6°C; however, the explanatory power was as high as 60%. ENVI-met was performed for commercial and single residential areas that have high densities of artificial cover materials, before and after changes related to development of green areas and to increase in the reflectivity of coating materials. The results indicated that both areas exhibited distinct temperature reductions due to the creation of green spaces. When the reflectivity of the coating material was increased, a temperature increase was observed in all land-use types. Therefore, in order to improve the thermal environment of complex urban areas, it is necessary to improve green-area development and to use high-reflectivity ground and building cover materials, while taking into account the spatial characteristics of land-use types and their surrounding areas. Bonggeun Song and Kyunghun Park Copyright © 2015 Bonggeun Song and Kyunghun Park. All rights reserved. Drought Trends and Temperature Influence in Zhanghe River Basin, China Sun, 17 May 2015 11:50:57 +0000 Our study area is one of the semiarid region of the China with under water stress condition that causes economic damage. The main objective of this study is to apply standardized precipitation evapotranspiration index (SPEI) and to use linear regression to calculate drought conditions in the study area. For this purpose, data from 1980 to 2010 was analyzed at different (1, 6, 12, and 24 months) time scales. Results depicted both dry and wet periods in the study area; occurrence of dry span with different frequency and magnitude was increased over last decades (2000–2010) at most of the stations. Statistical results demonstrated that temperature was decreased in the 1st decade in most of stations but in two decades from 1990 to 2000 and 2001 to 2010, temperature was increased except in Changzhi station. These results could be a future reference for developing information programs about monitoring and early drought information, planning of existing reservoirs, and management of water resources under climate conditions. Bakhtawar Wagan, Zhanyu Zhang, Feng Baoping, Si Han, and Amos T. Kabo-bah Copyright © 2015 Bakhtawar Wagan et al. All rights reserved. Influence of the Three Gorges Project on the Water Resource Components of Poyang Lake Watershed: Observations from TRMM and GRACE Sun, 03 May 2015 12:36:14 +0000 The Three Gorges Project (TGP) has received many criticisms about its potential effects on the changes in the downstream ecosystems. Poyang Lake is the largest body of water downstream of the TGP, and it is not immune to these changes. TRMM and GRACE data were introduced in this study to estimate river-lake water exchange, from which the hydrological responses of Poyang Lake could be identified. A significant decreasing trend of the runoff coefficient has been observed since 2003, resulting in 6.02 km3 more water discharge from the lake into the Yangtze River than under normal conditions. No significant interannual changes occurred in the water level or local precipitation, and GRACE observations revealed that groundwater discharge appeared to be the most likely compensation for the water loss. A novel approach, namely, the groundwater abnormality index (GAI), was developed to depict the water exchange using GRACE and surface water observations. Lower than normal GAIs were found between 2003 and 2005, reaching a minimum of −29.26 in October 2003, corresponding to ten times of the mean GAI during 2006–2012, clearly indicating a significant water exchange in Poyang Lake Basin from groundwater to surface water after the TGP impoundment. Xiaobin Cai, Lian Feng, Yuxi Wang, and Xiaoling Chen Copyright © 2015 Xiaobin Cai et al. All rights reserved. Identifying and Evaluating Chaotic Behavior in Hydro-Meteorological Processes Thu, 30 Apr 2015 11:36:11 +0000 The aim of this study is to identify and evaluate chaotic behavior in hydro-meteorological processes. This study poses the two hypotheses to identify chaotic behavior of the processes. First, assume that the input data is the significant factor to provide chaotic characteristics to output data. Second, assume that the system itself is the significant factor to provide chaotic characteristics to output data. For solving this issue, hydro-meteorological time series such as precipitation, air temperature, discharge, and storage volume were collected in the Great Salt Lake and Bear River Basin, USA. The time series in the period of approximately one year were extracted from the original series using the wavelet transform. The generated time series from summation of sine functions were fitted to each series and used for investigating the hypotheses. Then artificial neural networks had been built for modeling the reservoir system and the correlation dimension was analyzed for the evaluation of chaotic behavior between inputs and outputs. From the results, we found that the chaotic characteristic of the storage volume which is output is likely a byproduct of the chaotic behavior of the reservoir system itself rather than that of the input data. Soojun Kim, Yonsoo Kim, Jongso Lee, and Hung Soo Kim Copyright © 2015 Soojun Kim et al. All rights reserved. Evaluation of Three Satellite Precipitation Products TRMM 3B42, CMORPH, and PERSIANN over a Subtropical Watershed in China Thu, 30 Apr 2015 09:31:39 +0000 This study conducted a comprehensive evaluation of three satellite precipitation products (TRMM (Tropical Rainfall Measuring Mission) 3B42, CMORPH (the Climate Prediction Center (CPC) Morphing algorithm), and PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks)) using data from 52 rain gauge stations over the Meichuan watershed, which is a representative watershed of the Poyang Lake Basin in China. All the three products were compared and evaluated during a 9-year period at different spatial (grid and watershed) and temporal (daily, monthly, and annual) scales. The results showed that at daily scale, CMORPH had the best performance with coefficients of determination () of 0.61 at grid scale and 0.74 at watershed scale. For precipitation intensities larger than or equal to 25 mm, RMSE% of CMORPH and TRMM 3B42 were less than 50%, indicating CMORPH and TRMM 3B42 might be useful for hydrological applications at daily scale. At monthly and annual temporal scales, TRMM 3B42 had the best performances, with high ranging from 0.93 to 0.99, and thus was deemed to be reliable and had good potential for hydrological applications at monthly and annual scales. PERSIANN had the worst performance among the three products at all cases. Junzhi Liu, Zheng Duan, Jingchao Jiang, and A-Xing Zhu Copyright © 2015 Junzhi Liu et al. All rights reserved. Statistical and Physical Descriptions of Raindrop Size Distributions in Equatorial Malaysia from Disdrometer Observations Mon, 27 Apr 2015 12:55:51 +0000 This work investigates the physical characteristics of raindrop size distribution (DSD) in an equatorial heavy rain region based on three years of disdrometer observations carried out at Universiti Teknologi Malaysia’s (UTM’s) campus in Kuala Lumpur, Malaysia. The natural characteristics of DSD are deduced, and the statistical results are found to be in accordance with the findings obtained from others disdrometer measurements. Moreover, the parameters of the Gamma distribution and the normalized Gamma model are also derived by means of method of moment (MoM) and maximum likelihood estimation (MLE). Their performances are subsequently validated using the rain rate estimation accuracy: the normalized Gamma model with the MLE-generated shape parameter µ was found to provide better accuracy in terms of long-term rainfall rate statistics, which reflects the peculiarities of the local climatology in this heavy rain region. These results not only offer a better understanding of the microphysical nature of precipitation in this heavy rain region but also provide essential information that may be useful for the scientific community regarding remote sensing and radio propagation. Hong Yin Lam, Jafri Din, and Siat Ling Jong Copyright © 2015 Hong Yin Lam et al. All rights reserved. An Assessment of Human versus Climatic Impacts on Jing River Basin, Loess Plateau, China Thu, 23 Apr 2015 08:40:26 +0000 The impacts of climate change and human activities on runoff and sediment load are too integrated to distinguish their own contributions. We develop a new method to assess the impact of human activities based on paired years with similar precipitation and evapotranspiration (ET0) conditions (SPEC) using a 55-year monthly data of climate, runoff, and sediment load in 1958–2012 at Zhangjiashan Hydrologic Station of Jing River, Loess Plateau, China. The SPEC of paired periods is defined by similar annual amounts (difference less than 2.0%) and similar process (linear correlations of monthly data less than 0.05) which could set a precondition fixing the possible influence of climate factors. The runoff declined in all nine paired years, but the sediment load and concentration decreased in seven (78%) and six (67%) paired years, respectively. The further analysis with available data of land use and land cover (LUC), Normalized Difference Vegetation Index (NDVI), and soil and water measures in this basin and the results could explain impacts of human activities well. The method could be used combining with the traditional methods in hydrological research. Yi He, Fei Wang, Xingmin Mu, Huiting Yan, and Guangju Zhao Copyright © 2015 Yi He et al. All rights reserved. Validation of the New Algorithm for Rain Rate Retrieval from AMSR2 Data Using TMI Rain Rate Product Tue, 21 Apr 2015 13:14:31 +0000 A new algorithm is derived for rain rate (RR) estimation from Advanced Microwave Sounding Radiometer 2 (AMSR2) measurements taken at 6.9, 7.3, and 10.65 GHz. The algorithm is based on the numerical simulation of brightness temperatures () for AMSR2 lower frequency channels, using a simplified radiation transfer model. Simultaneous meteorological and hydrological observations, supplemented with modeled values of cloud liquid water content and rain rate values, are used for the calculation of an ensemble of AMSR2 s and RRs. Ice clouds are not taken into account. AMSR2 brightness temperature differences at C- and X-band channels are then used as inputs to train a neural network (NN) function for RR retrieval. Validation is performed against Tropical Rain Measurement Mission (TRMM) Microwave Instrument (TMI) RR products. For colocated AMSR2-TMI measurements, obtained within 10 min intervals, errors are about 1 mm/h. The new algorithm is applicable for RR estimation up to 20 mm/h. For  mm/h the retrieval error is 0.3 mm/h. For  mm/h the algorithm significantly underestimates TMI RR. Elizaveta Zabolotskikh and Bertrand Chapron Copyright © 2015 Elizaveta Zabolotskikh and Bertrand Chapron. All rights reserved. Forming High Ozone Concentration in the Ambient Air of Southern Taiwan under the Effects of Western Pacific Subtropical High Tue, 21 Apr 2015 07:51:11 +0000 Due to the distinct geographical and meteorological conditions of Taiwan, air pollutants concentrations in the ambient air of it may vary with seasons. Accordingly, this study aimed to investigate the formation of high O3 concentration in the ambient air of Southern Taiwan during summers. A high O3 concentration case occurring between June 28 and July 2, 2013, was modeled and analyzed with WRF-Chem meteorological and air quality model. During the investigated period, a typical western Pacific subtropical high (WPSH) covered most East Asia, including Taiwan and its surrounding areas. The observations showed strong correlations between WPSH invasion and forming high O3 concentrations. The dispersion of air pollutants in the ambient air is not sufficient to dilute their concentrations. In the afternoon of June 30, more than 60% of the air quality monitoring stations found O3 concentrations exceeding 100 ppb, which were 2~3 times higher than their normal concentrations. Model simulation results verified that the presence of the WPSH hindered the dilution and transportation of air pollutants in ambient air. In addition, the air quality would be getting worse due to the leeward sides caused by the counter clockwise vertex formed in Southwestern Taiwan. Kuo-Cheng Lo and Chung-Hsuang Hung Copyright © 2015 Kuo-Cheng Lo and Chung-Hsuang Hung. All rights reserved. Systematic Evaluation of Satellite-Based Rainfall Products over the Brahmaputra Basin for Hydrological Applications Mon, 20 Apr 2015 14:08:18 +0000 Estimation of the flow generated in the Brahmaputra river basin is important for establishing an effective flood prediction and warning services as well as for water resources assessment and management. But this is a data scarce region with few and unevenly distributed hydrometeorological stations. Five high-resolution satellite rainfall products (CPC RFE2.0, RFE2.0-Modified, CMORPH, GSMaP, and TRMM 3B42) were evaluated at different spatial and temporal resolutions (daily, dekadal, monthly, and seasonal) with observed rain gauge data from 2004 to 2006 to determine their ability to fill the data gap and suitability for use in hydrological and water resources management applications. Grid-to-grid (G-G) and catchment-to-catchment (C-C) comparisons were performed using the verification methods developed by the International Precipitation Working Group (IPWG). Comparing different products, RFE2.0-Modified, TRMM 3B42, and CMORPH performed best; they all detected heavy, moderate, and low rainfall but still significantly underestimated magnitude of rainfall, particularly in orographically influenced areas. Overall, RFE2.0-Modified performed best showing a high correlation coefficient with observed data and low mean absolute error, root mean square error, and multiple bias and is reasonably good at detecting the occurrence of rainfall. TRMM 3B42 showed the second best performance. The study demonstrates that there is a potential use of satellite rainfall in a data scarce region. Sagar Ratna Bajracharya, Wahid Palash, Mandira Singh Shrestha, Vijay Ratan Khadgi, Chu Duo, Partha Jyoti Das, and Chhimi Dorji Copyright © 2015 Sagar Ratna Bajracharya et al. All rights reserved. Effects of ENSO on Autumn Rainfall in Central Vietnam Mon, 20 Apr 2015 13:21:38 +0000 28 years (1980–2007) of station and gridded reanalysis data were used to investigate the effects of El Niño/Southern Oscillation (ENSO) on autumn rainfall in the Extended Central Vietnam (ECV) region. Results show that, under El Niño conditions, autumn rainfall in Central Vietnam is reduced by about 10 to 30%. This reduction seems to be caused by a weakening of the North East monsoon circulation, which appears to be linked to an anomalous anticyclonic vortex and a positive sea level pressure anomaly over the East Sea. In addition, the disappearance of a secondary moisture source over the southern region of the East Sea also favors the reduction in rainfall over this region. Conversely, during La Niña, the total autumn rainfall in the ECV region increases by about 9 to 19%. The strengthening of the North East monsoon, with a cyclonic wind anomaly over the East Sea, helps to increase the moisture supply to the area by about 10 to 20%, resulting in enhanced rainfall in the ECV. It is also found that the La Niña conditions do not only cause an increase in rainfall, but also change the temporal distribution of the monthly rainfall over the region, with more rainfall in the latter months of the year. Thang Van Vu, Hieu Trong Nguyen, Thang Van Nguyen, Hiep Van Nguyen, Huong Thi Thanh Pham, and Lan Thi Nguyen Copyright © 2015 Thang Van Vu et al. All rights reserved. On the Robustness of the Weakening Effect of Anthropogenic Aerosols on the East Asian Summer Monsoon with Multimodel Results Mon, 20 Apr 2015 11:16:46 +0000 Using outputs from 10 CMIP5 models with fixed sea surface temperature, we investigate the fast response of the East Asian summer monsoon (EASM) and summer precipitation in East China to anthropogenic aerosols. To address this topic, we employ two commonly used EASM indices that can represent zonal and meridional land-sea thermal contrast, respectively. The results reveal that the notion of a weakened EASM in response to increased anthropogenic aerosols is a robust one, as well as decreased precipitation in East China. The ensemble mean of decreased precipitation in the aerosol run was about 6.6% in comparison to the CTL run and could be enlarged to 8.3% by excluding the experiments with the aerosol direct effect only. Convective precipitation was found to be the primary contributor (>80%) to the reduction of total precipitation. The combination of direct and indirect effects of aerosols can decrease solar radiation reaching the Earth’s surface and eventually modulate large-scale EASM circulation and suppress summer precipitation in East China. The uncertainties and discrepancies among the models highlight the complexity of interaction in aerosol-precipitation processes when investigating present and future changes of the EASM. Hongli Wang, Xiaoning Xie, and Xiaodong Liu Copyright © 2015 Hongli Wang et al. All rights reserved. Using Artificial Intelligence to Retrieve the Optimal Parameters and Structures of Adaptive Network-Based Fuzzy Inference System for Typhoon Precipitation Forecast Modeling Mon, 20 Apr 2015 10:08:00 +0000 This study aims to construct a typhoon precipitation forecast model providing forecasts one to six hours in advance using optimal model parameters and structures retrieved from a combination of the adaptive network-based fuzzy inference system (ANFIS) and artificial intelligence. To enhance the accuracy of the precipitation forecast, two structures were then used to establish the precipitation forecast model for a specific lead-time: a single-model structure and a dual-model hybrid structure where the forecast models of higher and lower precipitation were integrated. In order to rapidly, automatically, and accurately retrieve the optimal parameters and structures of the ANFIS-based precipitation forecast model, a tabu search was applied to identify the adjacent radius in subtractive clustering when constructing the ANFIS structure. The coupled structure was also employed to establish a precipitation forecast model across short and long lead-times in order to improve the accuracy of long-term precipitation forecasts. The study area is the Shimen Reservoir, and the analyzed period is from 2001 to 2009. Results showed that the optimal initial ANFIS parameters selected by the tabu search, combined with the dual-model hybrid method and the coupled structure, provided the favors in computation efficiency and high-reliability predictions in typhoon precipitation forecasts regarding short to long lead-time forecasting horizons. Chien-Lin Huang, Nien-Sheng Hsu, Chih-Chiang Wei, and Chun-Wen Lo Copyright © 2015 Chien-Lin Huang et al. All rights reserved. Effect of Data Assimilation Using WRF-3DVAR for Heavy Rain Prediction on the Northeastern Edge of the Tibetan Plateau Mon, 20 Apr 2015 09:29:28 +0000 The numerical weather prediction (NWP) is gaining more attention in providing high-resolution rainfall forecasts in the arid and semiarid region. However, the modeling accuracy is negatively affected by errors in the initial conditions. Here we investigate the potential of data assimilation in improving the NWP rainfall forecasts in the northeastern Tibetan Plateau. Three of three-dimensional variational (3DVar) data assimilation experiments were designed on running the advanced research weather research forecast (WRF) model. Two heavy rain events selected with different rainfall distribution in space and time are utilized to examine the improvement for rainfall forecast after data assimilation. For the spatial distribution, the improvement of rainfall accumulation and area is obvious for the both two events. But for the temporal variation, the improvement is more obvious for the event with even rainfall distribution in time, while the effect of data assimilation is not ideal for the rainfall event with uneven distribution in space and time. It is noteworthy that, for both the spatial and temporal distribution of rainfall, satellite radiances have greater effect on rainfall forecasts than surface and upper-air meteorological observations in this high-altitude region. Moreover, the data assimilation experiments provide more detail information to the initial fields. Junhua Yang, Keqin Duan, Jinkui Wu, Xiang Qin, Peihong Shi, Huancai Liu, Xiaolong Xie, Xiao Zhang, and Jianyong Sun Copyright © 2015 Junhua Yang et al. All rights reserved.