Advances in Meteorology The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Estimation of Daily Sunshine Duration from Terra and Aqua MODIS Data Tue, 15 Apr 2014 14:05:38 +0000 Some studies have shown that the estimation of global sunshine duration can be done with the help of geostationary satellites because they can record several images of the same location in a day. In this paper, images obtained from the MODIS (Moderate Resolution Imaging Spectroradiometer) sensors of polar orbiting satellites Aqua and Terra were used to estimate daily global sunshine duration for any region in Turkey. A new quadratic correlation between daily mean cloud cover index and relative sunshine duration was also introduced and compared with the linear correlation. Results have shown that polar orbiting satellites can be used for the estimation of sunshine duration. The quadratic model introduced here works better than the linear model especially for the winter months in which very low sunshine duration values were recorded at the ground stations for many days. H. M. Kandirmaz and K. Kaba Copyright © 2014 H. M. Kandirmaz and K. Kaba. All rights reserved. Aircraft Observations of Ice Particle Properties in Stratiform Precipitating Clouds Mon, 14 Apr 2014 00:00:00 +0000 This study presented airborne measurements of ice particle properties in three stratiform precipitating clouds over northern China. By using horizontal observations at selected altitudes, the distributions of ice water content (IWC), particle habits, and particle size spectrum parameters were investigated. The cloud cases were characterized by high IWC values due to the existence of embedded convective cells. Liquid water contents were rather low with the maxima of less than 0.3 g m−3 and the general values of less than 0.1 g m−3. The occurrence of large dendritic crystals as well as rimed capped columns and branched crystals indicated that ice seeding from the above cloud layer (6 km altitude or above) contributed significantly to both high ice crystal number concentrations and IWCs. Horizontal observations at selected levels suggested the general decreasing trend of IWC with decreasing temperature only in part of the cloud layers but not throughout the cold layer of the multilayered stratiform clouds. Both exponential and gamma functions were used to characterize the particle size spectrum parameters. The slope parameter values of exponential distributions were primarily in the range of 103–104 m−1. In comparison, slope values of the gamma distribution fits spanned more and a relationship was found between the dispersion and slope values. Tuanjie Hou, Hengchi Lei, Zhaoxia Hu, and Jun Zhou Copyright © 2014 Tuanjie Hou et al. All rights reserved. Integrated Monitoring and Assessment Framework of Regional Ecosystem under the Global Climate Change Background Sun, 13 Apr 2014 15:02:25 +0000 Global changes are driving ecosystem alterations, and the effects are becoming more and more obvious. Ecosystem management clarifies the fundamental supporting functions of ecosystems for human survival and sustainable development. Integrated ecosystem monitoring and assessment has become a popular topic of ecology study. However, many scientific questions need to be addressed, including what assessment contents and methods are optimal for temporal and spatial measurements. Therefore, the development of a scientific evaluation framework that includes certain core contents and indicators is very important. This paper proposes a regional integrated ecosystem assessment framework involving comprehensive monitoring. Satellite images are the main data source for different ecosystem and ecological parameters, and these need to be supplemented with the help of surveys or field observation data. A healthy ecosystem is the basis of human survival and sustainable development, and ecological service should be taken as the core of integrated ecosystem assessment. This is decided by the spatial distribution, classification, and patterns of regional ecosystems. That is to say, ecological service, together with ecosystems distribution and pattern, ecological problem indicators, and ecological stress, needs to be integrated analyzed and evaluated. Qiao Wang, Peng Hou, Feng Zhang, and Changzuo Wang Copyright © 2014 Qiao Wang et al. All rights reserved. Monitoring Grassland Tourist Season of Inner Mongolia, China Using Remote Sensing Data Thu, 10 Apr 2014 14:00:29 +0000 Phenology-driven events, such as spring wildflower displays or fall tree colour, are generally appreciated by tourists for centuries around the world. Monitoring when tourist seasons occur using satellite data has been an area of growing research interest in recent decades. In this paper, a valid methodology for detecting the grassland tourist season using remote sensing data was presented. On average, the beginning, the best, and the end of grassland tourist season of Inner Mongolia, China, occur in late June (±30 days), early July (±30 days), and late July (±50 days), respectively. In south region, the grassland tourist season appeared relatively late. The length of the grassland tourist season is about 90 days with strong spatial trend. South areas exhibit longer tourist season. Quansheng Ge, Xi Yang, Zhi Qiao, Haolong Liu, and Jun Liu Copyright © 2014 Quansheng Ge et al. All rights reserved. An Analysis of a Severe Turbulence Event Encountered by an Aircraft over the South China Sea and the Application of Numerical Weather Prediction Models in the Early Alerting of the Event Thu, 10 Apr 2014 13:35:27 +0000 In the literature, there is rather limited number of accounts of significant turbulence over the South China Sea, which is an area of busy air traffic. The present paper documents the meteorological observations of an aircraft over the seas west of the Philippines on encountering severe turbulence associated with an area of convection. From the valuable flight data available from this aircraft, it is found that, on encountering the significant turbulence, the aircraft experienced increase in wind speed, strong downdraft, high windshear hazard factor, and, most importantly, high level of eddy dissipation rate, which is a measure of turbulence intensity in civil aviation. The application of numerical weather prediction (NWP) models in the forecasting of this severe turbulence case is also studied. It turns out that the cumulonimbus extent and in-cloud turbulence potential products from World Area Forecast System may have some indication of the occurrence of significant turbulence associated with convection in the area concerned. A mesoscale NWP model even forecasts the possibility of moderate-to-severe turbulence about 24 to 27 hours ahead of the event. P. W. Chan and W. K. Wong Copyright © 2014 P. W. Chan and W. K. Wong. All rights reserved. High-Resolution, Near Real-Time Simulation of Microwave Radiance Using a Simple Land-Cover Based Emissivity Prior Thu, 10 Apr 2014 09:36:17 +0000 Satellite simulators are used to calculate the brightness temperature that would be measured by a space borne sensor under a set of atmospheric conditions accounting for the radiometric characteristics of the sensor and the orbital parameters of the satellite. In this study, a simple approach is proposed for the parameterization of emissivity over land, a key parameter for the calculation of microwave . The rationale is to simulate a large ensemble of emissivity values for each frequency and surface characteristics and then relate the most likely observed value with soil characteristics. The derived emissivity values are used for the simulation of and simulated radiance is then compared with satellite observations. It is shown that this method improves the simulation of radiance and that it is suitable to provide a first guess of the emissivity value (a prior) that can then be refined using iterative procedures. Dimitrios Katsanos, Eduardo García-Ortega, Manuel de Castro, Enrique Arias, and Francisco J. Tapiador Copyright © 2014 Dimitrios Katsanos et al. All rights reserved. Characteristics of Spring Phenological Changes in China over the Past 50 Years Mon, 07 Apr 2014 14:09:18 +0000 In order to understand past plant phenological responses to climate change in China (1963–2009), we conducted trends analysis of spring phenophases based on observation data at 33 sites from the Chinese Phenological Observation Network (CPON). The phenological data on first leaf date (FLD) and first flowering date (FFD) for five broad-leaved woody plants from 1963 to 2009 were analyzed. Since most phenological time series are discontinuous because of observation interruptions at certain period, we first interpolated phenological time series by using the optimal model between the spring warming (SW) model and the UniChill model to form continuous time series. Subsequently, by using regression analysis, we found that the spring phenophases of woody plants in China advanced at a mean rate of 0.18 days/year over the past 50 years. Changes of spring phenophases exhibited strong regional difference. The linear trends in spring phenophases were −0.18, −0.28, −0.21, −0.04, and −0.14 days/year for the Northeast China Plain, the North China Plain, the Middle-Lower Yangtze Plain, the Yunnan-Guizhou Plateau, and South China, respectively. The spatial differences in phenological trends can be attributed to regional climate change patterns in China. Junhu Dai, Huanjiong Wang, and Quansheng Ge Copyright © 2014 Junhu Dai et al. All rights reserved. Climate Predictions: The Chaos and Complexity in Climate Models Thu, 03 Apr 2014 15:54:25 +0000 Some issues which are relevant for the recent state in climate modeling have been considered. A detailed overview of literature related to this subject is given. The concept in modeling of climate, as a complex system, seen through Gödel’s theorem and Rosen’s definition of complexity and predictability is discussed. Occurrence of chaos in computing the environmental interface temperature from the energy balance equation given in a difference form is pointed out. A coupled system of equations, often used in climate models, was analyzed. It is shown that the Lyapunov exponent mostly has positive values allowing presence of chaos in this system. The horizontal energy exchange between environmental interfaces, which is described by the dynamics of driven coupled oscillators, was analyzed. Their behavior and synchronization, when a perturbation is introduced in the system, as a function of the coupling parameter, the logistic parameter, and the parameter of exchange, were studied calculating the Lyapunov exponent under simulations with the closed contour of environmental interfaces. Finally, we have explored possible differences in complexities of two global and two regional climate models using their air temperature and precipitation output time series. The complexities were obtained with the algorithm for calculating the Kolmogorov complexity. D. T. Mihailović, G. Mimić, and I. Arsenić Copyright © 2014 D. T. Mihailović et al. All rights reserved. Influences of Urban Expansion on Urban Heat Island in Beijing during 1989–2010 Mon, 31 Mar 2014 13:43:10 +0000 Beijing has experienced rapid urbanization and associated urban heat island (UHI) effects. This study aimed at analyzing the impact of urban form on UHI in Beijing using TM/ETM images between 1989 and 2010. Spatial analysis was proposed to explore the relationships between area, compactness ratio, the gravity centers of urban land, and UHI. The UHI in Beijing spatially represented a “NE-SW” spindle. The land surface temperature (LST) was higher in south than in north. Urban Heat Island Ratio Index (URI) was well interrelated with urban land area in different zones. Under the similar urban land area condition, UHI and compactness ratio of urban land were in positive correlation. The moving direction of the UHI gravity center was basically in agreement with urban land sprawl. The encroachment of urban land on suburban land is the leading source of UHI effect. The results suggest that urban design based on urban form would be effective for regulating the thermal environment. Zhi Qiao, Guangjin Tian, Lixiao Zhang, and Xinliang Xu Copyright © 2014 Zhi Qiao et al. All rights reserved. Probabilistic Ensemble Forecast of Summertime Temperatures in Pakistan Sun, 30 Mar 2014 07:39:24 +0000 Snowmelt flooding triggered by intense heat is a major temperature related weather hazard in northern Pakistan, and the frequency of such extreme flood events has increased during the recent years. In this study, the probabilistic temperature forecasts at seasonal and subseasonal time scales based on hindcasts simulations from three state-of-the-art models within the DEMETER project are assessed by the relative operating characteristic (ROC) verification method. Results based on direct model outputs reveal significant skill for hot summers in February 3–5 (ROC with lower 95% confidence limit of 0.538) and February 4-5 (ROC with lower 95% confidence limit of 0.623) forecasts when validated against observations. Results for ERA-40 reanalysis also show skill for hot summers. Skilful probabilistic ensemble forecasts of summertime temperatures may be valuable in providing the foreknowledge of snowmelt flooding and water management in Pakistan. Muhammad Hanif Copyright © 2014 Muhammad Hanif. All rights reserved. Numerical Study of Traffic Pollutant Dispersion within Different Street Canyon Configurations Tue, 25 Mar 2014 15:20:01 +0000 The objective of this study is to numerically study flow and traffic exhaust dispersion in urban street canyons with different configurations to find out the urban-planning strategies to ease the air pollution. The Computational Fluid Dynamics (CFD) model used in this study—Open Source Field Operation and Manipulation (OpenFOAM) software package—was firstly validated against the wind-tunnel experiment data by using three different k-ε turbulence models. And then the patterns of flow and dispersion within three different kinds of street canyon configuration under the perpendicular approaching flow were numerically studied. The result showed that the width and height of building can dramatically affect the pollution level inside the street canyon. As the width or height of building increases, the pollution at the pedestrian level increases. And the asymmetric configuration (step-up or step-down street canyon) could provide better ventilation. It is recommended to design a street canyon with nonuniform configurations. And the OpenFOAM software package can be used as a reliable tool to study flows and dispersions around buildings. Yucong Miao, Shuhua Liu, Yijia Zheng, Shu Wang, and Yuan Li Copyright © 2014 Yucong Miao et al. All rights reserved. Large-Scale Dynamics, Anomalous Flows, and Teleconnections Sun, 23 Mar 2014 13:59:37 +0000 Anthony R. Lupo, Stephen J. Colucci, Yafei Wang, and Igor I. Mokhov Copyright © 2014 Anthony R. Lupo et al. All rights reserved. Trends in Moisture Index, Farmland Area, and Their Combined Effects on Grain Production in Northern China Thu, 20 Mar 2014 08:22:49 +0000 China policies and Grain-for-Green Project have led to changes in farmland area and grain production. Climate change was also occurring during this period. To analyze the effects of land use and climate change on grain production, the area of farmland in northern China during 1988–2008 was determined from remote sensing images, a moisture index (MI) was calculated from daily meteorological data obtained from weather stations, and unit grain production was obtained from statistical yearbooks. Using statistical and spatial analyses, we determined that MI decreased across most of the study area during this period. This decrease in humidity caused humid zones to decrease and semiarid areas to increase. Combined effects of decreased humid area and conversion of farmland resulted in a decrease in agricultural land in humid areas and an increase in semiarid and arid areas. Increases in unit grain production, machine power, and irrigated farmland area led grain production to increase from 122,799,081 to 188,532,597 ton in humid areas, from 28,875,900 to 115,976,814 in semiarid areas, and from 7,622,100 to 15,490,026 in arid areas, respectively. Increased unit grain production and farmland resulted in increased importance of semiarid areas for grain production. Qingshui Lu, Zhiqiang Gao, Xinliang Xu, Jicai Ning, and Xiaoli Bi Copyright © 2014 Qingshui Lu et al. All rights reserved. Relationship between Size of Cloud Ice and Lightning in the Tropics Thu, 20 Mar 2014 00:00:00 +0000 The association of lightning flashes with mean cloud ice size over continental and oceanic region in the tropical areas has been analyzed using the observations from various satellite platforms (MODIS, TRMM, and LIS) for the period 2000–2011. We found that frequency of lightning in general is higher over the continental region compared to oceanic region, whereas larger size of cloud ice is observed over the oceanic regions compared to the continental regions. Relationship between lighting and cloud ice size shows similar features over both continental and oceanic regions. For the first time, we show that total lighting increases with increase in the cloud ice size; attends maximum at certain cloud ice size and then decreases with increase in cloud ice size. Maximum lightning occurred for the mean cloud ice size of around 23–25 µm over the continental region and mean cloud ice size of around 24–28 µm over the oceanic region. Based on our observation we argue that the relation between lightning and mean cloud ice size follow the curve linear pattern, and not linear. Deen Mani Lal, Sachin D. Ghude, Jagvir Singh, and Suresh Tiwari Copyright © 2014 Deen Mani Lal et al. All rights reserved. Improving the Operational Methodology of Tropical Cyclone Seasonal Prediction in the Australian and the South Pacific Ocean Regions Mon, 17 Mar 2014 14:00:31 +0000 Tropical cyclones (TCs) can have a major impact on the coastal communities of Australia and Pacific Island countries. Preparedness is one of the key factors to limit TC impacts and the Australian Bureau of Meteorology issues an outlook of TC seasonal activity ahead of TC season for the Australian Region (AR; 5°S to 40°S, 90°E to 160°E) and the South Pacific Ocean (SPO; 5°S to 40°S, 142.5°E to 120°W). This paper investigates the use of support vector regression models and new explanatory variables to improve the accuracy of seasonal TC predictions. Correlation analysis and subsequent cross-validation of the generated models showed that the Dipole Mode Index (DMI) performs well as an explanatory variable for TC prediction in both AR and SPO, Niño4 SST anomalies—in AR and Niño1+2 SST anomalies—in SPO. For both AR and SPO, the developed model which utilised the combination of Niño1+2 SST anomalies, Niño4 SST anomalies, and DMI had the best forecasting performance. The support vector regression models outperform the current models based on linear discriminant analysis approach for both regions, improving the standard deviation of errors in cross-validation from 2.87 to 2.27 for AR and from 4.91 to 3.92 for SPO. J. S. Wijnands, K. Shelton, and Y. Kuleshov Copyright © 2014 J. S. Wijnands et al. All rights reserved. Statistical Prediction of Summer Rainfall and Vegetation in the Ethiopian Highlands Mon, 17 Mar 2014 11:39:28 +0000 Year-to-year fluctuations of Ethiopia climate are investigated to develop statistical predictions at one-season lead time. Satellite vegetation data from NASA and rainfall from ARC2 are the basis for analysis. The “target” seasons are May–July and August–October, while “predictors” are December–February and March–May, respectively. Global fields of surface temperature, sea level air pressure, and upper and lower level zonal winds are employed in point-to-field correlations. After step-wise multivariate regression, the leading predictors are: surface temperature across Europe (cold-favourable), 850 mb zonal winds over the tropical Atlantic (easterly-favourable), and surface temperature in the tropical Indian Ocean (cold-favourable). Predictive algorithms for early and late rainfall exhibit a consistent fit of ~0.50, while those for vegetation reach ~0.65 in late summer, indicating that fluctuations in food resources could be forewarned. Mark R. Jury Copyright © 2014 Mark R. Jury. All rights reserved. Dry Deposition from Sahara Sources Regions of Western Africa Mon, 17 Mar 2014 11:36:16 +0000 Sahara dust storms during March 2004 have attracted much attention from the dust-research community due to their intensity, wide coverage, and endurance. In the present work, the dry deposition mechanisms of mineral dust are analysed during an event on the 3 March 2004 over the Northwest African coast. This particular case was chosen based on the strong dry removal that occurred, rendering it ideal for examining the deposition processes. The simulation of synoptic conditions and dry deposition of four dust particles including clay, small silt, large silt, and sand was performed with Eta model, coupled with a desert dust cycle module. The results have been compared with surface data from weather stations in North Africa, data of dry metals from stations located in Gran Canaria, and various satellite images such as European Organization for the Exploitation of Meteorological Satellites and Moderate Resolution Imaging Spectroradiometer for the period in question. B. Douaiba, A. Azzi, A. Khorsi, and A. Benlefki Copyright © 2014 B. Douaiba et al. All rights reserved. Wind Velocity Decreasing Effects of Windbreak Fence for Snowfall Measurement Sun, 16 Mar 2014 11:52:38 +0000 Meteorological observatories use measuring boards on even ground in open areas to measure the amount of snowfall. In order to measure the amount of snowfall, areas unaffected by wind should be found. This study tried to determine the internal wind flow inside a windbreak fence, identifying an area unaffected by wind in order to measure the snowfall. We performed a computational fluid dynamics analysis and wind tunnel test, conducted field measurements of the type and height of the windbreak fence, and analyzed the wind flow inside the fence. The results showed that a double windbreak fence was better than a single windbreak fence for decreasing wind velocity. The double fence (width 4 m, height 60 cm, and fixed on the bottom) has the greatest wind velocity decrease rate at the central part of octagonal windbreak. Ki-Pyo You and Young-Moon Kim Copyright © 2014 Ki-Pyo You and Young-Moon Kim. All rights reserved. Estimation of Total Yearly CO2 Emissions by Wildfires in Mexico during the Period 1999–2010 Sun, 16 Mar 2014 09:22:29 +0000 The phenomenon of wildfires became a global environmental problem which demands estimations of their CO2 emissions. Wildfires have deteriorated the air quality increasingly. Using available information on documented wildfires and a data set of satellite detected hot spots, total yearly emissions of CO2 in Mexico were estimated for the period 1999–2010. A map of the main vegetation groups was used to calculate total areas for every vegetation type. The yearly number of hot spots per vegetation type was calculated. Estimates of emitted CO2 in a wildfire were then accomplished by considering parameters such as: forest fuel load, vegetation type, burning efficiency, and mean burned area. The number of wildfires and total affected areas showed an annual variability. The yearly mean of affected area by a single wildfire varied between 0.2 and 0.3 km2. The total affected area during the period 1999 to 2010 was 86800 km2 which corresponds to 4.3% of the Mexican territory. Total CO2 emissions were approximately 112 Tg. The most affected vegetation types were forest and rainforest. Flor Bautista Vicente, Noel Carbajal, and Luis Felipe Pineda Martínez Copyright © 2014 Flor Bautista Vicente et al. All rights reserved. Maritime-Continental Contrasts in the Properties of Low-Level Clouds: A Case Study of the Summer of the 2003 Yamase, Japan, Cloud Event Thu, 13 Mar 2014 16:44:47 +0000 Satellite data were used to investigate maritime-continental differences in the characteristics of the low-level cloud (the Yamase cloud) that covered northeast Japan during the summer of 2003. The features of the Yamase cloud were found to be almost the same as those of general stratus clouds but with a smaller effective radius () and a greater optical thickness () over land, as compared with general stratus clouds. The values of over land (average, 11.8 μm) were smaller than those over the ocean (13.5 μm), and the values of and the cloud water path over land (20 and 145 gm−2, resp.) showed larger spatial variances than those over the ocean (10 and 86 gm−2, resp.), although the cloud top altitude was nearly the same over both ocean and land (1–3 km). We suggest that this maritime-continental contrast is a result of the combined effects of topography and aerosols characteristics. The Yamase wind blowing from the ocean is forced upwards in coastal regions by the steep mountainous terrain. The updraft drives the inhomogeneity in cloud parameters, and a convective-like cloud develops without precipitation. The relationship between and suggests high aerosol concentrations and unstable conditions over land. Nawo Eguchi, Tadahiro Hayasaka, and Masahiro Sawada Copyright © 2014 Nawo Eguchi et al. All rights reserved. Evaluating the Marginal Land Resources Suitable for Developing Bioenergy in Asia Thu, 13 Mar 2014 13:52:32 +0000 Bioenergy from energy plants is an alternative fuel that is expected to play an increasing role in fulfilling future world energy demands. Because cultivated land resources are fairly limited, bioenergy development may rely on the exploitation of marginal land. This study focused on the assessment of marginal land resources and biofuel potential in Asia. A multiple factor analysis method was used to identify marginal land for bioenergy development in Asia using multiple datasets including remote sensing-derived land cover, meteorological data, soil data, and characteristics of energy plants and Geographic Information System (GIS) techniques. A combined planting zonation strategy was proposed, which targeted three species of energy plants, including Pistacia chinensis (P. chinensis), Jatropha curcas L. (JCL), and Cassava. The marginal land with potential for planting these types of energy plants was identified for each 1 km2 pixel across Asia. The results indicated that the areas with marginal land suitable for Cassava, P. chinensis, and JCL were established to be 1.12 million, 2.41 million, and 0.237 million km2, respectively. Shrub land, sparse forest, and grassland are the major classifications of exploitable land. The spatial distribution of the analysis and suggestions for regional planning of bioenergy are also discussed. Jingying Fu, Dong Jiang, Yaohuan Huang, Dafang Zhuang, and Wei Ji Copyright © 2014 Jingying Fu et al. All rights reserved. Impact of Preceding El Niño and the Indian Ocean Dipole on the Southern China Precipitation in Early Summer Tue, 11 Mar 2014 09:27:03 +0000 Delayed impacts of El Niño and the Indian Ocean Dipole in positive phase (P-IOD) on the South China early monsoon were investigated by observations and simulations. The most significant correlation between IOD index (IODI) and NINO3 appeared in boreal autumn. A new index (IODN3) related to the intensity of El Niño and IOD was created. Three indexes in boreal autumn were positively well correlated with the rainfall over the Yangtze River and its southern area (rain-YRBS) in next June. The most significant correlation appeared between IODN3 and rain-YRBS. Positive rain-YRBS anomalies in June tend to occur after P-IOD or El Niño solely matured in previous boreal autumn. However, when both events matured in boreal autumn, rain-YRBS anomalies tended to be more enhanced, which suggests that a delayed combined influence of both events on rain-YRBS in June was larger than that of either event alone. There was a low level anticyclonic circulation around the Philippines (PSAC) that developed in boreal autumn and was maintained until the following June when the single event occurred. However, a much stronger PSAC tended to occur when both events matured. The stronger PSAC could transport more water vapor to YRBS and cause more rainfall there in June. Yan Li, Yafei Wang, Lin Mu, Qingyuan Wang, Jun Song, and Guosong Wang Copyright © 2014 Yan Li et al. All rights reserved. Characterization of West African Jet Streams and Their Association to ENSO Events and Rainfall in ERA-Interim 1979–2011 Wed, 05 Mar 2014 13:36:56 +0000 The interannual variability of West African jet streams and their association with rainfall are reexamined using European Reanalysis ERA-Interim 1979–2011. The objective of the study is to characterize their climatology and role in rainfall variability in western Sahel. Wavelet analysis was used on wind speed data and implications to ENSO were discussed subsequently. Our results show that while the low-level African Westerly Jet (AWJ) correlates well with rainfall south of the equator in boreal winter months, the Tropical Easterly Jet (TEJ) and African Easterly Jet (AEJ) correlate better with rainfall north of the equator in the boreal summer months. Results of interannual-to-decadal variability in 200 mb, 600 mb, and 850 mb of zonal wind reveal that there is enhanced variability in the 2–8 year band. Also, the TEJ, AEJ, and AWJ fluctuations are coupled with variations in southern oscillation. Further analysis suggests a statistically significant association between TEJ and the El Niño events of the 1980s that led to intense drought in the Sahel region of West Africa. The 2007 moderate La Niña shows a statistically significant coherence with the 500 mb, 600 mb, and 850 mb jets. These associations are also phase locked, suggesting that the association may be more than by chance. Churchill Okonkwo, Belay Demoz, and Sium Tesfai Copyright © 2014 Churchill Okonkwo et al. All rights reserved. Observations and Modeling of the Climatic Impact of Land-Use Changes Wed, 05 Mar 2014 11:50:31 +0000 Xiangzheng Deng, Burak Güneralp, and Hongbo Su Copyright © 2014 Xiangzheng Deng et al. All rights reserved. Observation Study on the Size Distribution of Sand Dust Aerosol Particles over Yinchuan, China Wed, 05 Mar 2014 09:30:34 +0000 The Yinchuan area, which lies in the eastern part of Northwest China, is one of the main transportation paths and origins of sand dust in China. In order to investigate the aerosol number size distribution and its temporal-spatial evolution over this area, direct solar radiation data taken from September 2012 to October 2013 by a sun photometer CE-318 located at Beifang University of Nationalities (106°29′E, 38°13′N) were analyzed. The particle number size distributions were retrieved from the aerosol optical depth (AOD) by use of the extinction inversion method. The experiment results show that although the averaged size distribution satisfies basically the Junge function, there are two obvious peaks at the particle radius of 0.6 m and 1.4 m, respectively. Because sand-dust weather occurs frequently, the particle size distribution in Spring is obviously larger than that in other seasons, which coincides with AOD variation tendency. Moreover, in sand-dust weather the particles number concentration is larger than that of background weather with one order of magnitude, especially for the number of concentration of large particles and giant particles. The research results have very important reference value for quantitative study of the influence of aerosol on atmosphere physics and chemistry process and monitoring of sand-dust weather and air pollution of this area. Jiandong Mao, Hongjiang Sheng, Hu Zhao, and Chunyan Zhou Copyright © 2014 Jiandong Mao et al. All rights reserved. Representation of Ethiopian Wet Spells in Global and Nested Models Wed, 05 Mar 2014 06:32:26 +0000 Weather forecast and reanalysis models exhibit different performance in daily rainfall estimation over the Ethiopian highlands, 2000–2012, with ECMWF closer to observations than other models. Background is given to illustrate the Hadley circulation and easterly jets over Ethiopia, using sections on 37°E in July–August 2011. ECMWF reanalysis has a narrow band of rainfall >15 mm/day on 10°N, consistent with TRMM satellite estimates, associated with a steep gradient in meridional wind. MERRA and GFS models have a wider band of rainfall and weaker gradients in meridional winds. The contrasting background states influence a nested WRF model simulation of heavy rain in the upper Nile Valley on 29 July, 2011. The GFS (ECMWF) initialization yields stronger northerly (southerly) winds north (south) of Ethiopia, while aircraft observations are southerly at 850 mb and northerly at 700 mb. ECMWF produces heavy and widespread rainfall consistent with observations, with a potentially more realistic simulation of the Hadley circulation. Mark R. Jury and Sen Chiao Copyright © 2014 Mark R. Jury and Sen Chiao. All rights reserved. Changes in Production Potential in China in Response to Climate Change from 1960 to 2010 Wed, 05 Mar 2014 00:00:00 +0000 From the Global Agro-Ecological Zone (GAEZ) model, changes in the three climate factors (temperature, precipitation, and solar radiation) over the past five decades showed different trends and that production potential was impacted significantly by the geographic heterogeneity of climate change. An increase of approximately 1.58 million tons/decade in production potential correlated with climate change. Regions with increased production potential were located mainly in the Northeast China Plain, the northern arid and semiarid region, and the Huang-Huai-Hai Plain. Regions with decreased production potential were located mainly in the Middle-lower Yangtze Plain and southern China. The climate factors that impacted production potential varied by region. In the Northeast China Plain, increased temperature was the major cause of the increased production potential. In the northern arid and semiarid region, temperature and precipitation were the major factors affecting production potential, but their effects were in opposition to each other. In southern China, increased temperature and decreased solar radiation caused a decreased production potential. In the Middle-lower Yangtze Plain, a decrease in solar radiation was the major factor resulting in decreased production potential. In the Huang-Huai-Hai Plain, changes in temperature and solar radiation had large but opposite effects on production potential. Luo Liu, Xi Chen, Xinliang Xu, Yong Wang, Shuang Li, and Ying Fu Copyright © 2014 Luo Liu et al. All rights reserved. NDVI-Based Vegetation Change in Inner Mongolia from 1982 to 2006 and Its Relationship to Climate at the Biome Scale Mon, 03 Mar 2014 16:44:26 +0000 Based on the normalized difference vegetation index (NDVI), we analyzed vegetation change of the six major biomes across Inner Mongolia at the growing season and the monthly timescales and estimated their responses to climate change between 1982 and 2006. To reduce disturbance associated with land use change, those pixels affected by land use change from the 1980s to 2000s were excluded. At the growing season scale, the NDVI increased weakly in the natural ecosystems, but strongly in cropland. Interannual variations in the growing season NDVI for forest was positively linked with potential evapotranspiration and temperature, but negatively correlated with precipitation. In contrast, it was positively correlated with precipitation, but negatively related to potential evapotranspiration for other natural biomes, particularly for desert steppe. Although monthly NDVI trends were characterized as heterogeneous, corresponding to monthly variations in climate change among biome types, warming-related NDVI at the beginning of the growing season was the main contributor to the NDVI increase during the growing season for forest, meadow steppe, and typical steppe, but it constrained the NDVI increase for desert steppe, desert, and crop. Significant one-month lagged correlations between monthly NDVI and climate variables were found, but the correlation characteristics varied greatly depending on vegetation type. Linghui Guo, Shaohong Wu, Dongsheng Zhao, Yunhe Yin, Guoyong Leng, and Qingyu Zhang Copyright © 2014 Linghui Guo et al. All rights reserved. Wind Field of a Nonmesocyclone Anticyclonic Tornado Crossing the Hong Kong International Airport Sun, 02 Mar 2014 12:29:01 +0000 A nonmesocyclone tornado traversed the Hong Kong International Airport on September 6, 2004 directly impacting a surface weather station. This allowed for 1-second 10-meter above ground level (AGL) wind observations through the core of the tornado. Integration of these 10-meter AGL wind data with Ground-Based Velocity Track (GBVTD) wind retrievals derived from LIDAR data provided a time history of the three-dimensional wind field of the tornado. These data indicate a progressive decrease in radial inflow with time and little to no radial inflow near the time the tornado crosses the surface weather station. Anemometer observations suggest that the tangential winds approximate a modified-Rankine vortex outside the radius of maximum winds, suggesting that frictionally induced radial inflow was confined below 10 m AGL. The radial-height distribution of angular momentum depicts an increase in low-level angular momentum just prior to the tornado reaching its maximum intensity. Karen A. Kosiba, Paul Robinson, P. W. Chan, and Joshua Wurman Copyright © 2014 Karen A. Kosiba et al. All rights reserved. Trends of Convective and Stratiform Precipitation in the Czech Republic, 1982–2010 Sun, 02 Mar 2014 12:13:00 +0000 The study examines trends in characteristics of convective and stratiform precipitation in the Czech Republic over 1982–2010. The spatially averaged trends in convective precipitation are rising for indices of mean precipitation, and the increases are significant in all seasons except for winter. For extremes, the trends are spatially much more variable and insignificant, but increases tend to prevail as well. The trends in convective precipitation are larger in the western part of the country where Atlantic influences are stronger. For characteristics of stratiform precipitation, the trends are usually smaller compared to those of convective precipitation, but increases prevail too. They are significant in autumn, especially for extremes, and larger in the eastern part of the country where Mediterranean cyclones play more important role. The trends in convective precipitation tend to be more pronounced at lowland than higher-elevated stations while an opposite pattern prevails for stratiform precipitation. The results suggest that in spring and summer, when convective precipitation represents an important fraction of the total amounts in central Europe (around 30% and 50%, respectively), the observed increases in total precipitation are mainly due to increases in convective precipitation. In autumn, increases in both convective and stratiform precipitation are important, and the trends are weakest and least pronounced in winter. Zuzana Rulfová and Jan Kyselý Copyright © 2014 Zuzana Rulfová and Jan Kyselý. All rights reserved.