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Yang T.,Jiangsu Meteorological Observatory | Lu Z.,Nanjing University of Information Science and Technology | Hu J.,South-Central University for Nationalities
Mathematical Problems in Engineering | Year: 2013

In recent years, air pollution control has caused great concern. This paper focuses on the primary pollutant SO2 in the atmosphere for analysis and control. Two indicators are introduced, which are the concentration of SO2 in the emissions (PSO2) and the concentration of SO2 in the atmosphere (ASO2). If the ASO2 is higher than the certain threshold, then this shows that the air is polluted. According to the uncertainty of the air pollution control systems model, H ∞ control theory for the air pollution control systems is used in this paper, which can change the PSO2 with the method of improving the level of pollution processing or decreasing the emissions, so that air pollution system can maintain robust stability and the indicators ASO2 are always operated within the desired target. © 2013 Tingya Yang et al.

Gao Y.,Nanjing University of Information Science and Technology | Chen Y.,Nanjing University of Information Science and Technology | Jiang Y.,Jiangsu Meteorological Observatory | Peng T.,Institute of Heavy Rain
Shuikexue Jinzhan/Advances in Water Science | Year: 2015

Hydrological simulations are affected by the parameters derived from DEM, which describes the water-shed features. Xitiaoxi River basin was selected to simulate two runoff processes in Jun and Aug to Sep 2011 using the HEC-HMS model with ASTER 30 m DEM, SRTM 90 m DEM and DEM resample data as input for HEC-geoHMS to derive the basin characteristics. The results showed that, the simulated and observed flood were fitting well and the efficiency coefficients of the model were all larger than 0.82, Uni-modal flood showed a better performance in runoff simulation than multi-modal flood. The efficiency coefficients of model based on SRTM 90 m was larger than based on ASTER 30 m DEM and resampled 90 m DEM. The efficiency coefficients of model based on resampled DEM had nonlinear relationship with DEM resolution. The relative error of HEC-HMS simulations based on ASTER 30 m DEM and SRTM 90 m DEM had a difference of 3%-5%. The relative error of simulations based on the SRTM 90 m DEM and the resampled 90 m DEM had a difference of 2%-4%. The maximum difference between the relative error of HEC-HMS simulations based on the resampled 90 m DEM was 11%. ©, 2015, Science Press. All right reserved.

Liu D.Y.,Jiangsu Meteorological Observatory | Yan W.L.,Jiangsu Meteorological Observatory | Yang J.,Nanjing University of Information Science and Technology | Pu M.J.,Jiangsu Meteorological Observatory | And 2 more authors.
Boundary-Layer Meteorology | Year: 2015

A large quantity of advection fog appeared in the Yangtze River delta region between 1 and 2 December 2009. Here, we detail the fog formation and dissipation processes and the background weather conditions. The fog boundary layer and its formation and dissipation mechanisms have also been analyzed using field data recorded in a northern suburb of Nanjing. The results showed the following: (1) This advection fog was generated by interaction between advection of a north-east cold ground layer and a south-east warm upper layer. The double-inversion structure generated by this interaction between the cold and warm advections and steady south-east vapour transport was the main cause of this long-lasting fog. The double-inversion structure provided good thermal conditions for the thick fog, and the south-east vapour transport was not only conducive to maintaining the thickness of the fog but also sustained its long duration. (2) The fog-top altitude was over 600 m for most of the time, and the fog reduced visibility to less than 100 m for approximately 12 h. (3) The low-level jet near the lower inversion layer also played a role in maintaining the thick fog system by promoting heat, momentum and south-east vapour transport. © 2015 Springer Science+Business Media Dordrecht

Wei J.,Nanjing University of Information Science and Technology | Wei J.,Jiangsu Meteorological Observatory | Zhu W.,Nanjing University of Information Science and Technology | Liu D.,Jiangsu Meteorological Observatory | Han X.,Suzhou Meteorological Observatory of Jiangsu Province
Advances in Meteorology | Year: 2016

Based on the surface meteorological data of Jiangsu Province during 1980-2012, the climatic characteristics and the trends of haze were analyzed. The results indicated that during 1980-2012 haze days increased; in particular, severe and moderate haze days significantly increased. In the northern and coastal cities of Jiangsu Province China, haze days showed a significant increase. Haze often appeared in fall and winter and rarely in summer in the study area. It also occurred more often inland, and less along the coast. Haze occurred more often in June due to straw burning in the harvest time. The haze day increased during the 1990s over southern and southwestern Jiangsu Province; in central and northern Jiangsu, haze day increased after 2000. The continuous, regional, and regional continuous haze days all showed increasing trends. As the urban area expanded each year, industrial emissions, coal consumption, and car ownership increased accordingly, resulting in regional temperature increase and relative humidity decrease, which formed the urban heat island and dry island effects. Hence, haze formation and maintenance conditions became more favorable for more haze days, which led to the increase of haze days, and the significant increases of continuous, regional, and regional continuous haze days. © 2016 Jiansu Wei et al.

Shen C.,Nanjing Meteorological Bureau | Sun Y.,Jiangsu Meteorological Observatory | Yin D.,Jiangsu Meteorological Service Center | Bao J.,Jiangsu Meteorological Service Center
Journal of Natural Disasters | Year: 2015

By introducing the calculation model of disaster magnitude, the rainstorm flood disaster data of Jiangsu Province from 2004 to 2013 was assessed and a gradation criterion of rainstorm flood disaster was given. On this basis, this paper analyzes the relationship between occurring frequency of rainstorm flood disaster and rainfall, determines the critical rainfall threshold and constructs a disaster magnitude prediction model. The results show that light and medium disasters of rainstorm flood occurr most frequently in Jiangsu Province. The regions where the disaster occurs frequently and seriously are located in the northwest, the east and the area along the Yangtze River, while the regions where the disaster occurs infrequently and lightly are located in the area along the Huaihe River and the south of Jiangsu Province. The rainstorm flood disaster induced by plum rains front occurr most frequently, the disaster magnitude of rainstorm flood disaster induced by tropical system is the maximum, while the disaster induced by meso - and micro - scale system occurs most infrequently and the disaster magnitude is the minimum. The critical rainfall intensity inducing vainstorm flood disaster in Jiangsu Province is 18 ∼ 20 mm/h, the critical 24 h maximum rainfall is 35 ∼40mm. The stepwise regression equation established by the selected precipitation factor has a bit high prediction rate of light and medium disaster, while the prediction results of large and major disasters are acceptable.

Wu Z.,Nanjing University of Information Science and Technology | Chen S.,Jiangsu Meteorological Observatory | He J.,Nanjing University of Information Science and Technology | Chen H.,Nanjing University of Information Science and Technology
Atmosphere - Ocean | Year: 2014

The sea surface temperature (SST) or sea level pressure (SLP) has usually been used to measure the strength of El Niño-Southern Oscillation (ENSO) events. In this study, two new indices, based on the upper-ocean heat content (HC), are proposed to quantify the two "flavours" of El Niño (i.e., the Cold Tongue El Niño (CTE) and Warm Pool El Niño (WPE)). Compared with traditional SST or SLP indices, the new HC-based indices can distinguish CTE and WPE events much better and also represent the two leading modes of the interannual variability of the atmosphere-ocean coupled system in the tropical Indo-Pacific region. The two leading modes are obtained by performing multivariate Empirical Orthogonal Function analysis on two oceanic variables (SST and HC) over the tropical Pacific (30°S-30°N, 120°E-80°W) and six atmospheric variables (outgoing longwave radiation, SLP, streamfunction, and velocity potential at 850 hPa and 200 hPa) over the tropical Indo-Pacific region (30°S-30°N, 60°E-80°W) for the period 1980-2010. Because the two new HC-based indices are capable of better depicting coherent variations between the ocean and atmosphere, they can provide a supplementary tool for ENSO monitoring of and climate research into the two flavours of El Niño. © 2014 Taylor & Francis.

Hou J.,Nanjing University of Information Science and Technology | Hou J.,Jiangsu Meteorological Observatory | Guan Z.,Nanjing University of Information Science and Technology
Acta Meteorologica Sinica | Year: 2013

Based on daily precipitation data from 212 stations in East China and NCEP/NCAR daily global final analysis data in June and July from 2000 to 2010, the climatological characteristics of frontogenesis and related circulations have been analyzed. The results demonstrate that frontogenesis function distributes non-uniformly in East China. The different terms of the kinematic frontogenesis show different intensities and distributions of frontogenesis. The strongest frontogenesis integrated from different kinematic frontogenesis terms is observed in the Jianghuai area. Frontogenesis events are separated into four types as per the different shear and convergence types of horizontal wind along the strong frontogenesis band at 850 hPa. The four types include the warm shear type, cold shear type (with two subtypes), west wind convergence type, and east wind convergence type. The events in different frontogenesis types occur with different frequencies over the past decade. The warm shear type occurs most frequently. Different types of frontogenesis have distinctive horizontal and vertical structures. Strong frontogenesis is featured with 340-K contour of θ se parallel to the frontal zone in the vertical. Varied large-scale circulation patterns manifested in shifted location and strength of cyclone or anticyclone, wind convergence, as well as vertical circulation structure are associated with different types of frontogenesis. Moreover, a strong positive correlation between frontogenesis and precipitation is found, i.e., the stronger the frontogenesis, the more precipitation there is. Daily precipitation related to the warm shear type frontogenesis is the largest, and often occurs inside the frontal zone with the same orientation with the strong frontogenesis belt. The second largest daily precipitation occurs with the cold shear type frontogenesis, and related rainfall is usually observed to the south of the frontal zone, with the rain belt extending northeastward. Precipitation related to the west wind convergence type frontogenesis is the third largest, occurring mostly in the south of the frontal zone. © 2013 The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg.

Yan S.,Jiangsu Meteorological Observatory | Peishu Z.,Jiangsu Meteorological Observatory
2012 IEEE 5th International Conference on Advanced Computational Intelligence, ICACI 2012 | Year: 2012

An attempt is made to find the regional precipitation characteristics during the Meiyu period in Jiangsu province. Derived from layered cluster analysis, the Jiangsu province is divided into three regions: Region 1, the northern Huaihe Area; Region 2, regions along Huaihe River and between Huaihe River and Yangtze River; Region 3, regions along Yangtze River and the southern region of Jiangsu province. The dataset used consists of records of daily precipitation from 66 meteorological stations over Jiangsu province during 49 yr (1961-2009). Using Morlet wavelet, binomial moving average method and composite analysis, we found that: 1. the precipitation anomaly shows different inter-annual and inter-decadal characteristics in the three regions during the Meiyu period. The 2 yr and 4 yr oscillation cycle exhibits after the 1980s, and the 6 yr oscillation cycle exhibits in the late 1980s and the middle 1990s over the most area to the south of Huaihe River. While in the northern Huaihe Area, the oscillation cycles were 7 yr, 4 yr, and 3yr. Although precipitation anomaly is different from the regions, there is a strong positive correlation between precipitation index I in Jiangsu province and that in the 3 regions, respectively. Besides, the Region 2 and Region 3 showed the lowest correlation among those of different regions. © 2012 IEEE.

Su T.,CAS Institute of Atmospheric Physics | Su T.,Fujian Meteorological Observatory | Xue F.,CAS Institute of Atmospheric Physics | Sun H.,Jiangsu Meteorological Observatory | Zhou G.,CAS Institute of Atmospheric Physics
Acta Oceanologica Sinica | Year: 2015

On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences (CAS-ESM-C) in simulating the El Niño-Southern Oscillation (ENSO) cycle is evaluated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature (SST) in the tropical Pacific, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the El Niño onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster development of an El Niño. During the decay stage, owing to a stronger El Niño in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an El Niño decays into a La Niña through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attributed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean. © 2015, The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg.

Sun Y.,Jiangsu Meteorological Observatory | Yin D.,Jiangsu Meteorological Observatory | Zong P.,Jiangsu Meteorological Observatory
Journal of Natural Disasters | Year: 2013

Based on the 1961-2010 daily meteorological observation data in Jiangsu Province and monthly circulation index data compiled by National Climate Center, This paper statistically analyzed the rime and glaze days using the fuzzy clustering, wavelet analysis, trend analysis, and relative analysis methods, etc., to investigate the freezing disaster characteristics in Jiangsu Province. Results are as follows: (1) Different areas have different characteristics of freezing disasters in. In Jiangsu province, freezing weather occurs more frequently in the northwest area than that in the southeast area. (2) Rime and glaze mainly occur in the northern Huaihe area and the north area of the Yangtze-Huai River Basin. Except for the areas mentioned above, the Yangtze river and its north area are also involved in rime regions, which are larger than glaze regions. Besides, rime days are more than glaze days. (3) Rime days and glaze days decrease obviously in most areas of Jiangsu Province. (4) Based on the climate characteristics of freezing days, 66 stations in Jiangsu Province were divided into three parts using a layered Clustering method. In different areas, rime days and glaze days show that the cycle and intensity of inter-annual and inter-decadal oscillations are different in different periods. (5) There is a strong positive correlation between freezing, rime, glaze days and area, intensity index of polar vortex over Asia, Tibet Plateau index, and East Asia trough intensity index. The variation of those indexes may result in variations of freezing days in Jiangsu Province.

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