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Wang C.,Key Laboratory of Meteorological Disaster of Ministry of Education | Wang C.,Nanjing University of Information Science and Technology | Wang X.,Ocean University of China | Su R.,Ocean University of China | And 3 more authors.
Ecotoxicology and Environmental Safety | Year: 2011

A newly proposed three-dimensional model for the effects of heavy metals on the growth of batch cultures of algae that allows the estimation of the no detected toxic effect concentration (NDEC) is presented. Two batch assays with exposure to copper were investigated in situ. As an endpoint in the in situ studies of ecotoxicology, the carrying capacity, a parameter of the logistic growth model, possesses higher sensitivity and reliability than the routine ecotoxicological endpoints in terms of the analysis based on the theoretical arguments and experimental results. Using the carrying capacity (Bf) as the ecotoxicological endpoint, the NDEC from the proposed model is compared to the NOEC and EC05 on the basis of field derived data. The results indicate that the NDEC is a promising possible alternative parameter to the NOEC. © 2010 Elsevier Inc.


Zhao Q.-H.,Key Laboratory of Meteorological Disaster of Ministry of Education | Zhao Q.-H.,Nanjing University of Information Science and Technology | Sun J.-H.,Yunnan Institute of Meteorological Science
Wuli Xuebao/Acta Physica Sinica | Year: 2013

The variation of the surface mixed layer depth may affect not only the evolution of aquatic ecosystem, but also the temporal-spatial distribution of precipitation and climate in the basin. Based on the meteorological data and water temperature profiles observed in Erhai Lake (located in the Tibetan Plateau) and Taihu Lake (located in the Taihu Plain), the variation features and the mechanisms of the surface mixed layer depths are investigated. The stratification in Erhai Lake can be established and sustained in summer; the diurnal stratification in Erhai Lake can also be established, However, in both summer and autumn, stratification may exist in Taihu Lake. The time length of stratification is longer in Erhai Lake than that in Lake Taihu in the autumn. And the surface mixed layer depths in Erhai Lake are shallower than those in Taihu Lake in summer and autumn. The transformation frequency between establishment and destruction of stratification in Taihu Lake is faster than that in Erhai Lake, which illustrated that the response of water body in Taihu Lake to atmospheric variation is quicker than that in Erhai Lake. The water depth is a key factor which prevents such shallow lakes as Taihu Lake from establishing and maintainaning stratifications and in a suitable radiation condition the stratification will exist. The net radiation is a key factor that determines the stratification and the length of the time when the stratification can be sustained in lakes whose depths are the same as that of Erhai Lake. The research result in this paper is helpful for exploring the coupling mechanism of the turbulence of water and air and the evolution law of aquatic ecosystem. © 2013 Chinese Physical Society.


Yang Z.-J.,Key Laboratory of Meteorological Disaster of Ministry of Education | Yang Z.-J.,Nanjing University of Information Science and Technology | Chen L.,Key Laboratory of Meteorological Disaster of Ministry of Education | Chen L.,Nanjing University of Information Science and Technology | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2010

The degradation degree of MOV can not be estimated timely and efficiently by U1mA and Ileakage which are the detection parameters of MOV-model SPD in the current, therefore, it is critical important for a new method to estimate the degradation degree of MOV. The process of the degradation of ZnO varistors is necessarily companied by capacitance change, according to the major factors of affecting MOV capacitance and the reasons of the degradation of ZnO varistors, such as Schottky barrier change of the grain boundary and the theory of ion migration, etc. It is found that the capacitance of MOV increases with increasing degradation degree by the experiment of degradate MOV-model SPD in different impact tests. In particular, the capacitance of MOV approximately linearly increases with the increasing impact numbers by the experiment under the impact of the In value. The significance of the capacitance growth could estimate the degradation degree of MOV was first proposed by the experiments, and the reasons of the degradation of MOV, based on the combination of the three parameters, U1mA, Ileakage and capacitance was analyzed.


Sun S.,Nanjing University of Information Science and Technology | Sun S.,Key Laboratory of Meteorological Disaster of Ministry of Education | Sun S.,North Carolina State University | Chen H.,Key Laboratory of Meteorological Disaster of Ministry of Education | And 5 more authors.
Journal of Hydrology | Year: 2014

With the changing climate, global and regional hydrological cycles have evolved significantly. Yet and despite numerous previous studies, the respective impacts of climate and vegetation changes on water cycle remain poorly understood. In order to better understand the changes of the hydrological cycle at basin scale, four typical basins within the Poyang Lake Basin for showing different responses to climate and vegetation changes were studied. Observed annual streamflows increased by a rate between 0.54 and 2.59m3s-1year-1 in the Meigang, Saitang and Gaosha Basins, but decreased by 0.54m3s-1year-1 in the Xiashan Basin. The SWAT (Soil and Water Assessment Tool) model modified by involving the better descriptions of plant physiology effects, was used to separate among the respective impacts of climate and vegetation changes on the basins' hydrological processes. The results from sensitivity experiments suggested that, (1) the decrease in ET was mainly because of the decreased wind speed, which reduced ET by 2.72, 0.50, and 1.36mmyear-2 in the Meigang, Saitang and Gaosha Basins, respectively; the increased streamflow with the rates of 1.25, 1.55, and 0.75m3s-1year-1, respectively, was more likely to explain the increase of water quantities, while the increased streamflow in the Xiashan Basin was attributed to the increase in precipitation; (2) vegetation changes tended to slightly increase ET (less than 0.20mmyear-2) and decrease the streamflow (less than -0.10m3s-1year-1) in all the basins, implying that vegetation played a less important role in the changing hydrological cycle. Strikingly, it was found that the increase in extreme precipitation was associated with a decrease in ET, possibly because extreme precipitation could rapidly turn into streamflow, limiting water infiltration into soils and subsequent evaporation. © 2014 Elsevier B.V.


Sun S.,Nanjing University of Information Science and Technology | Sun S.,Key Laboratory of Meteorological Disaster of Ministry of Education | Chen H.,Key Laboratory of Meteorological Disaster of Ministry of Education | Ju W.,Nanjing University | And 4 more authors.
International Journal of Climatology | Year: 2014

To account for CO2 impacts on the vegetation leaf area index (LAI) and the different responses of stomatal conductance in various vegetation species, the modified Soil and Water Assessment Tool (SWAT) model is calibrated in the Xinjiang Basin with the measured daily streamflow from 1961 to 1970, showing that SWAT accurately reproduces monthly and annual streamflow from 1971 to 2005 and actual evapotranspiration (AET) from 1983 to 2005. AET and streamflow in the basin for the 21st century are assessed using a multi-model ensemble approach in which downscaled and bias corrected outputs are compared to the baseline (1971-1999) and used to drive the SWAT model. The ensemble average annual precipitation decreases in the three scenarios, with maximum decreases of 7.61% during 2011-2050 and 4.80% during 2051-2090 in scenario A2. In contrast, the ensemble average annual and monthly temperature (minimum and maximum) increase by different amounts during the two periods in each scenario. For each emissions scenario, the ensemble average annual AET will increase, while the average annual streamflow will decrease. Under the A2 scenario, the maximum changes of average annual AET (streamflow) are +18.31% (-20.93%) and +20.93% (-23.43%) during 2011-2050 and 2051-2090, respectively. Compared to the baseline, the ensemble average annual minimum streamflow during 2011-2050 will decrease by approximately 20% under the A1B and A2 scenarios and by 7% in the B1 scenario. Thus, the ensemble average annual maximum streamflow will decrease under each scenario during the two periods, except for a 6.42% increase in the A1B scenario during 2051-2090. A Generalized Extreme Value (GEV) analysis, simultaneously, suggests that the maximum annual streamflow will decrease during the two periods under each scenario, with exception during 2051-2090 in the scenario A1B, and the magnitudes will decrease for 2-, 5-, 10-, 20- and 50-year return periods. © 2013 Royal Meteorological Society.


Chen Y.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters | Chen Y.,Key Laboratory of Meteorological Disaster of Ministry of Education | Xia X.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters | Xia X.,Key Laboratory of Meteorological Disaster of Ministry of Education | And 4 more authors.
Meteorology and Atmospheric Physics | Year: 2016

Atmospheric moisture content or humidity is an important analysis variable of any meteorological data assimilation system. The humidity analysis can be univariate, using humidity background (normally short-range numerical forecasts) and humidity observations. However, more and more data assimilation systems are multivariate, analyzing humidity together with wind, temperature and pressure. Background error covariances, with unbalanced velocity potential and humidity in the multivariate formulation, are generated from weather research and forecasting model forecasts, collected over a summer rainy season and a winter dry season. The unbalanced velocity potential and humidity related correlations are shown to be significantly larger, indicating more important roles unbalanced velocity potential and humidity play, in the rainy season than that in the dry season. Three cycling data assimilation experiments of two rainfall events in the middle and lower reaches of the Yangtze River are carried out. The experiments differ in the formulation of the background error covariances. Results indicate that only including unbalanced velocity potential in the multivariate background error covariance improves wind analyses, but has little impact on temperature and humidity analyses. In contrast, further including humidity in the multivariate background error covariance although has a slight negative effect on wind analyses and a neutral effect on temperature analyses, but significantly improves humidity analyses, leading to precipitation forecasts more consistent with China Hourly Merged Precipitation Analysis. © 2016 Springer-Verlag Wien


Ni D.-H.,Key Laboratory of Meteorological Disaster of Ministry of Education | Sun Z.-B.,Key Laboratory of Meteorological Disaster of Ministry of Education | Li Z.-X.,Key Laboratory of Meteorological Disaster of Ministry of Education | Li Z.-X.,CAS Institute of Atmospheric Physics | And 2 more authors.
Jiefangjun Ligong Daxue Xuebao/Journal of PLA University of Science and Technology (Natural Science Edition) | Year: 2010

Through the monthly NCEP/NCAR reanalyses during 1968-2009, and the monthly precipitation and temperature data of 160 stations over China during 1968-2008, the spatiotemporal characteristics of the Middle East jet stream (MEJS) and its relationship with China precipitation and temperature in winter were studied by means of EOF analysis. The results show that MEJS has three main spatial modes with variance contributions of 26.9%, 20.9% and 17.0%, respectively, that the first mode reflects the westerly anomaly characteristic in the part of lower stream, the second one the north-south anti-phase anomaly characteristic in the MEJS area, and the third one the westerly anomaly characteristic in the part of upper stream, that the index of MEJS has obvious interannual variation with 2-4-yr and quasi-8-yr periodic oscillations, and that there is a significant negative (positive) correlation between the MEJS index and temperature (precipitation) in Southwest China (South China), and the significant difference of temperature (precipitation) between the strong and the weak MEJS years mainly lies in Southwest China (South China) with the maximum temperature precipitation difference of 3 °C (180 mm) in winter.


Yang S.,Chinese Academy of Meteorological Sciences | Wu B.,Chinese Academy of Meteorological Sciences | Zhang R.,Chinese Academy of Meteorological Sciences | Zhou S.,Key Laboratory of Meteorological Disaster of Ministry of Education
Acta Meteorologica Sinica | Year: 2013

NCEP/NCAR daily reanalysis data and Chinese daily gridded precipitation data are used to study the relationship between an aprupt drought-flood transition over the mid-low reaches of the Yangtze River in 2011 and the intraseasonal oscillation (ISO; 30-60 days) in the mid-high latitude meridional circulation of the upper troposphere over East Asia. The abrupt transition from drought to flood occurs in early June. The first two recovered fields of the complex empirical orthogonal function show that northward-propagating westerlies from low latitudes converge with southward-propagating westerlies from high latitudes over the mid-low reaches of the Yangtze River (MLRYR) in mid-late May. The timing of this convergence corresponds to the flood period in early-mid June. The ISO index is significantly and positively correlated with rainfall over the MLRYR. During the dry phase (before the transition), the upper troposphere over the MLRYR is characterized by cyclonic flow, easterly winds, and convergence. The regional circulation is dominated by a wave train with a cyclone over east of Lake Baikal, an anticyclone over northern China, and a cyclone over the MLRYR. During the wet phase, the situation is reversed. The configuration of the wave train during the dry phase favors the southward propagation of westerly wind disturbances, while the configuration of the wave train during the wet phase favors the development and maintenance of a pumping effect and sustained ascending motions over the MLRYR. © 2013 The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg.


Wang W.,Key Laboratory of Meteorological Disaster of Ministry of Education | Cai X.,Key Laboratory of Meteorological Disaster of Ministry of Education | Long X.,Lanzhou University
Hydraulic Engineering III - Proceedings of the 3rd Technical Conference on Hydraulic Engineering, CHE 2014 | Year: 2015

The long-lasting rainy season over East Asia in early summer is called Meiyu in China and Baiu in Japan. In June 1999, the precipitation in middle and low basin of Yangzi River is twice the average in normal years. A model simulation of “99.6” Meiyu Front rainstorm by nonhydrostatic mesoscale model MM5V3 is analyzed in an effort to study the mechanism of the Meiyu front. The diagnosis of Convective Momentum Transport (CMT) shows that, the budget residual X of the horizontal momentum has different effects in different periods of the low vortex with the shear line: On low levels, X strengthened the southwest flow to north on the occurring stage, on middle levels, X accelerated northwest flow behind East Asia Trough to north and also accelerated northwest flow ahead of East Asia Trough to the south. All these were in favor of deepening the East Asia Trough and mingling cold and warm air, and gave favorable conditions to produce rainstorm. © 2015 Taylor & Francis Group, London, UK.


PubMed | Key Laboratory of Meteorological Disaster of Ministry of Education
Type: Journal Article | Journal: Ecotoxicology and environmental safety | Year: 2011

A newly proposed three-dimensional model for the effects of heavy metals on the growth of batch cultures of algae that allows the estimation of the no detected toxic effect concentration (NDEC) is presented. Two batch assays with exposure to copper were investigated in situ. As an endpoint in the in situ studies of ecotoxicology, the carrying capacity, a parameter of the logistic growth model, possesses higher sensitivity and reliability than the routine ecotoxicological endpoints in terms of the analysis based on the theoretical arguments and experimental results. Using the carrying capacity (B(f)) as the ecotoxicological endpoint, the NDEC from the proposed model is compared to the NOEC and EC(05) on the basis of field derived data. The results indicate that the NDEC is a promising possible alternative parameter to the NOEC.

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