Shanghai Typhoon Institute of China Meteorological Administration

Shanghai, China

Shanghai Typhoon Institute of China Meteorological Administration

Shanghai, China
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Zhan R.,Shanghai Typhoon Institute of China Meteorological Administration | Zhan R.,University of Hawaii at Manoa | Wang Y.,University of Hawaii at Manoa
Journal of Climate | Year: 2017

The poleward migration of the annual mean location of tropical cyclone (TC) lifetime maximum intensity (LMI) has been identified in the major TC basins of the globe over the past 30 years, which is particularly robust over the western North Pacific (WNP). This study has revealed that this poleward migration consists mainly of weak TCs (with maximum sustained surface wind speed less than 33 m s-1) over the WNP. Results show that the location of LMI of weak TCs has migrated about 1° latitude poleward per decade since 1980, while such a trend is considerably smaller for intense TCs. This is found to be linked to a significant decreasing trend of TC genesis in the southern WNP and a significant increasing trend in the northwestern WNP over the past 30 years. It is shown that the greater sea surface temperature (SST) warming at higher latitudes associated with global warming and its associated changes in the large-scale circulation favor more TCs to form in the northern WNP and fewer but stronger TCs to form in the southern WNP. © 2017 American Meteorological Society.


Zhan R.F.,Shanghai Typhoon Institute of China Meteorological Administration | Ding Y.H.,National Climate Center and Laboratory for Climate Studies | Wu L.G.,Nanjing University of Information Science and Technology | Lei X.T.,Shanghai Typhoon Institute of China Meteorological Administration
Science China Earth Sciences | Year: 2016

Previous studies have revealed a significantly negative correlation between prior winter snow cover over the Tibetan Plateau (TPSC) and tropical cyclone genesis frequency (TCF) over the western North Pacific (WNP) in the following typhoon season. This study revisited this relationship based on long-term observational data. The results showed that the interannual correlation between TCF over the WNP and TPSC experienced a shift in the early 1990s. This correlation is significant during only 1993–2012 and is considerably weak during 1976–1992. The possible reasons causing the shift were examined further, and the results demonstrated that the central Pacific (CP) El Niño-Southern Oscillation (ENSO) has played a vital role in intensifying the interannual relationship between TCF over the WNP and TPSC since the early 1990s. During 1993–2012, TPSC was negatively related to CP ENSO. When TPSC was higher than (lower than) normal, CP ENSO was often in its cold (warm) phase. Such a combination remarkably enhances the relationship of TPSC with the zonal land-sea thermal difference and thus with the summer monsoon over the WNP. Additionally, it enhances the modulation of TPSC on the dynamical environments controlling TCF. As a result, the linkage between TPSC and TCF was significantly strengthened in this period. In sharp contrast, due to the weak relationship between TPSC and ENSO followed by the weak modulation of TPSC on the summer monsoon over the WNP and the dynamical environment during 1976–1992, the linkage between TPSC and TCF was weak during this time period. The results from additional dynamical diagnostic analyses further showed that during 1993–2012 CP ENSO modulated the barotropic energy conversion of zonal winds over the WNP, contributing to the intensified relationship between TPSC and TCF. These results will improve seasonal forecasting of tropical cyclone activity over the WNP. © 2016, Science China Press and Springer-Verlag Berlin Heidelberg.


Zhan R.,Shanghai Typhoon Institute of China Meteorological Administration | Wang Y.,University of Hawaii at Manoa | Tao L.,Nanjing University of Information Science and Technology
Journal of Climate | Year: 2014

Arecent finding is the significant impact of the sea surface temperature anomaly (SSTA) over the east Indian Ocean (EIO) on the genesis frequency of tropical cyclones (TCs) over the western North Pacific (WNP). In this study it is shown that such an impact is significant only after the late 1970s. The results based on both data analysis and numerical model experiments demonstrate that prior to the late 1970s the EIO SSTA is positively correlated with the equatorial central Pacific SSTA and the latter produces an opposite atmospheric circulation response over theWNP to the former.As a result, the impact of the EIOSSTAon the TCgenesis over theWNP is largely suppressed by the latter. After the late 1970s, the area coverage of the EIO SSTA is expanding. This considerably enhances the large-scale circulation response over the WNP to the EIO SSTA and significantly intensifies the impact of the EIOSSTAon TCgenesis frequency over theWNP. The results fromthis study have great implications for seasonal prediction of TC activity over the WNP. © 2014 American Meteorological Society.


Li J.,Environment Canada | Chylek P.,Los Alamos National Laboratory | Zhang F.,Chinese Academy of Meteorological Sciences | Zhang F.,Shanghai Typhoon Institute of China Meteorological Administration
Journal of the Atmospheric Sciences | Year: 2014

The physical characteristics of extratropical cyclones are investigated based on nonequilibrium thermodynamics. Nonequilibrium thermodynamics, using entropy as its main tool, has been widely used in many scientific fields. The entropy balance equation contains two parts: the internal entropy production corresponds to dissipation and the external entropy production corresponds to boundary entropy supply. It is shown that dissipation is always present in a cyclone and the dissipation center is not always coincident with the low-pressure center, especially for incipient cyclones. The different components of internal entropy production correspond to different dissipation processes. Usually the thermal dissipation due to turbulent vertical diffusion and convection lags geographically the dynamic dissipation due to wind stress. At the incipient stage, the dissipation is mainly thermal in nature. A concept of temperature shear is introduced as the result of thermal dissipation. The temperature shear provides a useful diagnostic for extratropical cyclone identification. The boundary entropy supply and the entropy advection are also strongly associated with cyclones. The entropy advection is generally positive (negative) in the leading (trailing) part of a cyclone. A regional study in the western Pacific clearly demonstrates that the surface entropy flux and temperature shear are the most reliable early signals of cyclones in the cyclogenesis stage. © 2014 American Meteorological Society.


Zhan R.,Shanghai Typhoon Institute of China Meteorological Administration | Wang Y.,University of Hawaii at Manoa | Wen M.,Chinese Academy of Meteorological Sciences
Journal of Climate | Year: 2013

The sea surface temperature gradient (SSTG) between the southwestern Pacific Ocean (40°-20°S, 160°E-170°W) and the western Pacific warm pool (0°-16°N, 125°-165°E) in boreal spring has been identified as a new factor that controls the interannual variability of tropical cyclone (TC) frequency over the western North Pacific Ocean (WNP). This SSTG can explain 53% of the total variance of the WNP TC genesis frequency during the typhoon season for the period 1980-2011. The positive SSTG anomaly produces an anomalous cross-equatorial pressure gradient and thus anomalies in low-level southward cross-equatorial flow and tropical easterlies over the central-western Pacific. The anomalous easterlies further produce local equatorial upwelling and seasonal cooling in the central Pacific, which in turn maintains the easterly anomalies throughout the typhoon season. These dynamical/thermodynamical effects induced by the positive SSTG anomaly lead to a reduced low-level cyclonic shear, increased vertical wind shear, and weakened monsoon trough over the WNP, greatly suppressing WNP TC genesis during the typhoon season. This implies that the spring SSTG could be a good predictor for WNP TC genesis frequency. © 2013 American Meteorological Society.


Ying M.,Shanghai Typhoon Institute of China Meteorological Administration | Wu G.,CAS Institute of Atmospheric Physics | Liu Y.,CAS Institute of Atmospheric Physics | Sun S.,CAS Institute of Atmospheric Physics
Science China Earth Sciences | Year: 2012

In general, the tropical cyclone (TC) activity is considered to be influenced by the heat content of underlying ocean, vertical shear of horizontal wind, vorticity in the low troposphere, moisture in the troposphere, and favorable condition for deep convection development. However, these factors by nature merely present the internal factors of either atmosphere or ocean which influence the TC activity. In fact, the energy budget of the Earth system and its variation, modulated by the land-sea thermal contrast, are the intrinsic reasons responsible for the variation of TC activity. Here we investigate the modulation of diabatic heating distribution associated with the land-sea thermal contrast on the distribution of TC activity energy source and sink as well as the seasonality. An accumulated energy increment index (AEI) is defined using the TC best track data, and the energy sources and sinks of TC activity are then diagnosed effectively and practically according to the distribution of AEI. Results show that the thermal contrast of land and ocean is the primary reason for asymmetric distribution of TC activity about the Equator as well as the zonally asymmetric distribution of TC activity. The energy sources of TC activity are dominated by condensation heating of deep convection or double-dominant heating, which includes the condensation heating and cooling of longwave radiation (LO), while the sink areas are dominated by LO. The large scale diabatic heating associated with land-sea thermal contrast results in more favorable conditions for TC activity over the west part of oceans than those over the east parts. Moreover, the intensity of interaction of different diabatic heating over the west and east parts of ocean is also affected by the zonal scale of the oceans, which induces the difference of TC activity over the western North Pacific (WNP) and North Atlantic (ATL). The favorable westerlies and anticyclonic vertical shear associated with the tropical zonally asymmetric diabatic heating also contribute to the most intense TC activity over the WNP. The variation of large scale diabatic heating modulates the annual cycle of TC energy sources and sinks. In particular, the annual cycle over the WNP is the most typical one among the three basins (the WNP, the south Indian Ocean, and western South Pacific) that are characterized by the meridional shift of the energy sources and sinks. However, sources over the eastern North Pacific tend to extend westward and withdraw eastward associated with the variation of LO, while over the ATL, sources always merge from small pieces into a big one as the different diabatic heating over its west and east parts interacts with each other. Over the boreal Indian Ocean, the subcontinental scale land-sea heating contrast modifies the large scale circulation, and consequently contributes to the bimodal annual cycle of TC activity. In summary, TC activities are closely related to the interaction among various components of the climate system more than the atmosphere and ocean. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.


Yang X.,Institute of Meteorological science | Tian Z.,Shanghai Climate Center | Chen B.,Shanghai Typhoon Institute of China Meteorological Administration
International Journal of Climatology | Year: 2013

Dense meteorological station network-derived data on daily surface air temperatures over the period 1961-2007 were used to investigate the changes in the thermal growing season (GS) indicators for east China. The 394 stations are classified into six categories: metropolises, large cities, medium-sized cities, small cities, suburbs, and rural area using satellite-measured night-time light imagery and census data. Only the temperature data on 258 small cities and rural stations were used to calculate the GS indicators to reflect more 'natural' changes in thermal GS parameters. During the studied period, the regional mean length of the GS significantly extended by 3.05 and 2.61 d decade-1 for base temperatures of 5 and 10 °C, respectively. This extension is attributed primarily to the GS initiating at an earlier time (2.49 and 2.10 d decade-1 for base temperatures of 5 and 10 °C, respectively), rather than to the delayed end of the GS (0.55 and 0.51 d decade-1 for base temperatures of 5 and 10 °C, respectively). The mean growing degree days (GDD) has increased by 51.84 and 35.89 degree days decade-1 on average at temperatures higher than 5 and 10 °C. When the temperature data from all the 394 stations(including metropolis, large city, medium city, and suburban) were used to calculate the GS indicators, urban heat island (UHI) effects were evident, especially in highly urbanized Yangtze River Delta. The GS extension and GDD increase in metropolises increased by more than onefold over those observed for rural areas. This result indicates significant UHI effects on climatic GS changes. On the basis of the GDD changes, we find that UHI effects contributed to more than 10% in the GDD increase at temperatures higher than 10 °C. Therefore, excluding the urbanization effects from station observational data in evaluating changes in GS indices is necessary, especially for regions characterized by rapid urbanization. © 2012 Royal Meteorological Society.


Zhan R.,Shanghai Typhoon Institute of China Meteorological Administration | Zhan R.,University of Hawaii at Manoa | Wang Y.,University of Hawaii at Manoa | Lei X.,Shanghai Typhoon Institute of China Meteorological Administration
Journal of Climate | Year: 2011

This study attempts to understand contributions of ENSO and the boreal summer sea surface temperature anomaly (SSTA) in the East Indian Ocean (EIO) to the interannual variability of tropical cyclone (TC) frequency over the western North Pacific (WNP) and the involved physical mechanisms. The results show that both ENSO and EIO SSTA have a large control on the WNP TC genesis frequency, but their effects are significantly different. ENSO remarkably affects the east-west shift of the mean genesis location and accordingly contributes to the intense TC activity. The EIO SSTA affects the TC genesis in the entire genesis region over the WNP and largely determines the numbers of both the total and weak TCs. ENSO modulates the large-scale atmospheric circulation and barotropic energy conversion over the WNP, contributing to changes in both the TC genesis location and the frequency of intense TCs. The EIO SSTA significantly affects both the western Pacific summer monsoon and the equatorial Kelvin wave activity over the western Pacific, two major large-scale dynamical controls of TC genesis over the WNP. In general the warm (cold) EIO SSTA suppresses (promotes) the TC genesis over the WNP. Therefore, a better understanding of the combined contributions of ENSO and EIO SSTA could help improve the seasonal prediction of the WNP TC activity. © 2011 American Meteorological Society.


Yang X.,Shanghai Typhoon Institute of China Meteorological Administration | Yang X.,Institute of Meteorological science | Hou Y.,Shanghai Climate Center | Chen B.,Shanghai Typhoon Institute of China Meteorological Administration
Journal of Geophysical Research: Atmospheres | Year: 2011

Monthly mean surface air temperature data from 463 meteorological stations, including those from the 1981-2007 ordinary and national basic reference surface stations in east China and from the National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, are used to investigate the effect of rapid urbanization on temperature change. These stations are dynamically classified into six categories, namely, metropolis, large city, medium-sized city, small city, suburban, and rural, using satellite-measured nighttime light imagery and population census data. Both observation minus reanalysis (OMR) and urban minus rural (UMR) methods are utilized to detect surface air temperature change induced by urbanization. With objective and dynamic station classification, the observed and reanalyzed temperature changes over rural areas show good agreement, indicating that the reanalysis can effectively capture regional rural temperature trends. The trends of urban heat island (UHI) effects, determined using OMR and UMR approaches, are generally consistent and indicate that rapid urbanization has a significant influence on surface warming over east China. Overall, UHI effects contribute 24.2% to regional average warming trends. The strongest effect of urbanization on annual mean surface air temperature trends occurs over the metropolis and large city stations, with corresponding contributions of about 44% and 35% to total warming, respectively. The UHI trends are 0.398°C and 0.26°C decade-1. The most substantial UHI effect occurred after the early 2000s, implying a significant effect of rapid urbanization on surface air temperature change during this period. Copyright 2011 by the American Geophysical Union.


Fang P.,Shanghai Typhoon Institute of China Meteorological Administration | Shi J.,Shanghai Meteorological Bureau | Wang Q.,Shanghai Meteorological Bureau | Han Z.,Shanghai Meteorological Bureau | And 2 more authors.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2013

By using the wind tunnel and numerical simulation methods, the wind environment among tall buildings in the highly simplified Lujiazui zone was studied. The reliability of the numerical simulation method was the main focus in the research. The effect of the exposure category of the wind field on the wind environment among tall buildings was also analyzed. It can be concluded that the reliability of the numerical method is further enhanced for the better simulation of the inlet flow boundary conditions by using the modified wall function. The numerical simulation results show that the wind speed ratio from wind field with exposure category D is larger than that of exposure category B near the land surface. Along the wind direction, there exists the domain with higher wind speed ratio near the edges of the upwind sides of the buildings and between the buildings, and the domain with lower wind speed ratio before and after the buildings. These are mainly caused by the separating flow, channeling effect, stagnation effect and shielding effect, respectively.

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