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Nanjing, China

Zhang N.,Nanjing University | Zhang N.,CAS Institute of Atmospheric Physics | Gao Z.,CAS Institute of Atmospheric Physics | Wang X.,Sun Yat Sen University | Chen Y.,Jiangsu Climate Center
Theoretical and Applied Climatology | Year: 2010

The Yangtze River Delta Economic Belt is one of the most active and developed areas in China and has experienced quick urbanization with fast economic development. The weather research and forecasting model (WRF), with a single-layer urban canopy parameterization scheme, is used to simulate the influence of urbanization on climate at local and regional scales in this area. The months January and July, over a 5-year period (2003-2007), were selected to represent the winter and summer climate. Two simulation scenarios were designed to investigate the impacts of urbanization: (1) no urban areas and (2) urban land cover determined by MODIS satellite observations in 2005. Simulated near-surface temperature, wind speed and specific humidity agree well with the corresponding measurements. By comparing the simulations of the two scenarios, differences in near-surface temperature, wind speed and precipitation were quantified. The conversion of rural land (mostly irrigation cropland) to urban land cover results in significant changes to near-surface temperature, humidity, wind speed and precipitation. The mean near-surface temperature in urbanized areas increases on average by 0.45 ± 0.43°C in winter and 1.9 ± 0.55°C in summer; the diurnal temperature range in urbanized areas decreases on average by 0.13 ± 0.73°C in winter and 0.55 ± 0.84°C in summer. Precipitation increases about 15% over urban or leeward areas in summer and changes slightly in winter. The urbanization impact in summer is stronger and covers a larger area than that in winter due to the regional east-Asian monsoon climate characterized by warm, wet summers and cool, dry winters. © 2010 Springer-Verlag. Source

du Y.,Nanjing University of Information Science and Technology | du Y.,University of Hawaii at Manoa | Li T.,Nanjing University of Information Science and Technology | Li T.,University of Hawaii at Manoa | And 3 more authors.
Climate Dynamics | Year: 2015

The interannual variability of the Asian Subtropical Westerly Jet (ASWJ) in boreal summer is investigated through the diagnosis of 54-year (1960–2013) NCEP/NCAR reanalysis data. The main characteristics of two leading empirical orthogonal function patterns of 200 hPa zonal wind anomalies are the meridional displacement and southwest–northeast tilting of ASWJ. The first leading mode has significant periods of 4.9 years, whereas the second mode has significant periods of 3.6 and 7.7 years, respectively. The two modes exhibit an equivalent barotropic structure, and are associated with a distinctive north–south and east–west dipole rainfall pattern in China, respectively. The positive phase of the first leading mode appears during El Nino developing phase, whereas the positive phase of the second mode occurs during La Nina decaying phase. A mechanism is put forth based on observational analysis and AGCM sensitivity experiments. The positive phase of the first mode is primarily driven by the combined effect of a cold SST anomaly (SSTA) in mid-latitude North Pacific and a warm SSTA in tropical Indian Ocean and Pacific. In response to the SSTA forcing, a zonally oriented north–south tropospheric temperature dipole is induced. While the tropospheric warming in the tropics arises from El Nino like heating, the tropospheric cooling in the mid-latitudes arises possibly from the local SSTA forcing. For the positive phase of the second mode, the upper-tropospheric anticyclonic vorticity anomaly in the east pole arises from local SSTA forcing in North Pacific, whereas the cyclonic anomaly in the west pole results from southeastward Rossby wave energy emanation from North Atlantic to East Asia. © 2015 Springer-Verlag Berlin Heidelberg Source

Zeng Y.,Jiangsu Climate Center | Qiu X.,Nanjing University of Information Science and Technology | Liu C.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Shuikexue Jinzhan/Advances in Water Science | Year: 2014

In the traditional models for areal evapotranspiration estimation, net radiation and its composition elements were generated by simulation of foreign empirical formulas or by interpolation of site observation data, which was one of the key reasons influencing the simulation accuracy of areal evapotranspiration. Using the developed models fitted by the meteorological observation data and the land surface albedo derived by remote sensing data, we achieved distributed modeling results of meteorological elements such as net radiation, air temperature, vapor pressure etc in the Yellow River basin. The heterogeneity of land surface such as topography and land cover diversity was considered in these simulations. With confirmation that the complementary relationship between actual evapotranspiration and potential evapotranspiration is available on a basin-wide scale, distributed simulation of evapotranspiration in the Yellow River basin was generated by coupling the distributed modeling results of the above elements with the advection-aridity model which was founded on the complementary relationship theory. Comparison shows that the spatial distribution of the simulated annual evapotranspiration has a good consistency with the isograms which was derived by water balance and sub-region tests showed that the minimum relative error is 1.14%, the maximum is 26.80% and the whole river basin average is 1.50%. Furthermore, the simulated evapotranspiration indicts the details more fine. The integrated distributed model for areal evapotranspiration simulation was founded on the complementary relationship theory, which takes into account the feedback of regional evapotranspiration upon the near-surface layer atmosphere, and it is easy to use for only taking DEM data and conventional meteorological data as input. Source

Wang K.,Jiangsu Climate Center
2011 International Conference on Multimedia Technology, ICMT 2011 | Year: 2011

This paper presents a new technique that is accomplished by a combination of STBC and OFDM technologies, which can reduce Inter-Symbol Interference (ISI). Random inter-leaver introduced into the STBCOFDM system can improve the performance of system under multi-path fading channel and get a reasonable robustness. © 2011 IEEE. Source

Wang Z.,Chinese Academy of Meteorological Sciences | Zhang H.,National Climate Center | Li J.,Canadian Center for Climate Modeling and Analysis | Jing X.,National Climate Center | Lu P.,Jiangsu Climate Center
Journal of Geophysical Research: Atmospheres | Year: 2013

Optical properties of clouds containing black carbon (BC) particles in their water droplets are calculated by using the Maxwell Garnett mixing rule and Mie theory. The obtained cloud optical properties were then applied to an interactive system by coupling an aerosol model with a General Circulation Model. This system is used to investigate the radiative forcing and the equilibrium climate response due to BC in cloud droplets. The simulated global annual mean radiative forcing at the top of the atmosphere due to the BC in cloud droplets is found to be 0.086Wm2. Positive radiative forcing can be seen in Africa, South America, East and South Asia, and West Europe, with a maximum value of 1.5Wm2 being observed in these regions. The enhanced cloud absorption is shown to increase the global annual mean values of solar heating rate, water vapor, and temperature, but to decrease the global annual mean cloud fraction. Finally, the global annual mean surface temperature is shown to increase by +0.08 K. The local maximum changes are found to be as low as 1.5K and as high as +0.6 K. We show there has been a significant difference in surface temperature change in the Southern and Northern Hemisphere (+0.19K and 0.04 K, respectively). Our results show that this interhemispheric asymmetry in surface temperature change could cause a corresponding change in atmospheric dynamics and precipitation. It is also found that the northern trade winds are enhanced in the Intertropical Convergence Zone (ITCZ). This results in northerly surface wind anomalies which cross the equator to converge with the enhanced southern trade winds in the tropics of Southern Hemisphere. This is shown to lead to an increase (a decrease) of vertical ascending motion and precipitation on the south (north) side of the equator, which could induce a southward shift in the tropical rainfall maximum related to the ITCZ. © 2013. American Geophysical Union. All Rights Reserved. Source

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