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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. Source


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. Source


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. Source


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. Source


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. Source

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