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A Personal Perspective on the Further Reform of the Advances in Atmospheric Sciences

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Advances in Atmospheric Sciences 2002年第4期19卷 757-764页

作者： da-lin zhang Department of Meteorology University of Maryland College Park USA

First of all, I wish to thank the Advances in Atmospheric Sciences (AAS) Editorial Board for recommending the publication of this original letter, summarizing my personal perspective on the reform of AAS, that was distributed during its 19 December 2001 Board meeting. The letter has now been significantly improved by the incorporation of many helpful comments and suggestions from extensive email discussions conducted among over 60 foreign participants, including several board members of AAS, as well as from numerous personal communications (see the acknowledgements section).

关键词： In AAS A Personal Perspective on the Further Reform of the Advances in Atmospheric Sciences

The Impact of the Storm-Induced SST Cooling on Hurricane Intensity

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Advances in Atmospheric Sciences 2006年第1期23卷 14-22页

作者： Tong ZHU da-lin zhang CIRA/CSU at NOAA/NESDIS/ORA Camp Springs MD 20746 USA Department of Meteorology University of Maryland College Park MD 20742 USA

The effects of storm-induced sea surface temperature （SST） cooling on hurricane intensity are investigated using a 5-day cloud-resolving simulation of Hurricane Bonnie （1998）. Two sensitivity simulations are performed in which the storm-induced cooling is either ignored or shifted close to the modeled storm track. Results show marked sensitivity of the model-simulated storm intensity to the magnitude and relative position with respect to the hurricane track. It is shown that incorporation of the storm-induced cooling, with an average value of 1.3℃, causes a 25-hPa weakening of the hurricane, which is about 20 hPa per 1℃ change in SST. Shifting the SST cooling close to the storm track generates the weakest storm, accounting for about 47% reduction in the storm intensity. It is found that the storm intensity changes are well correlated with the air-sea temperature difference. The results have important implications for the use of coupled hurricane-ocean models for numerical prediction of tropical cyclones.

关键词： SST feedback hurricane intensity numerical modeling

Tracking Surface Cyclones with Moist Potential Vorticity

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Advances in Atmospheric Sciences 2004年第5期21卷 830-835页

作者： Zuohao CAO da-lin zhang Meteorological Service of Canada Ontario Canada Department of Meteorology University of Maryland College Park Maryland

Surface cyclone tracks are investigated in the context of moist potential vorticity (MPV). A prognostic equation of surface absolute vorticity is derived which provides a basis for using negative MPV (NMPV) in the troposphere as an alternative approach to track surface cyclones. An observed case study of explosive lee cyclogenesis is performed to test the e?ectiveness of the MPV approach. It is shown that when a surface cyclone signal is absent due to the blocking of the Rocky Mountains, the surface cyclone can be well identi?ed by tracing the peak NMPV.

关键词： cyclone track moist potential vorticity lee cyclogenesis

Sensitivity of Cyclone Tracks to the Initial Moisture Distribution:A Moist Potential Vorticity Perspective

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Advances in Atmospheric Sciences 2005年第6期22卷 807-820页

作者： Zuohao CAO da-lin zhang Meteorological Service of Canada Ontario Canada Department of Meteorology University of Maryland College Park Maryland USA

In this study, the characteristics of moist potential vorticity （MPV） in the vicinity of a surface cyclone center and their physical processes axe investigated. A prognostic equation of surface absolute vorticity is then used to examine the relationship between the cyclone tracks and negative MPV （NMPV） using numerical simulations of the life cycle of an extratropical cyclone. It is shown that the MPV approach developed herein, i.e., by tracing the peak NMPV, can be used to help trace surface cyclones during their development and mature stages. Sensitivity experiments are conducted to investigate the impact of different initial moisture fields on the effectiveness of the MPV approach. It is found that the lifetime of NMPV depends mainly on the initial moisture field, the magnitude of condensational heating, and the advection of NMPV. When NMPV moves into a saturated environment at or near a cyclone center, it can trace better the evolution of the surface cyclone due to the conservative property of MPV. It is also shown that the NMPV generation is closely associated with the coupling of large potential temperature and moisture gradients as a result of frontogenesis processes. Analyses indicate that condensation, confluence and tilting play important but different roles in determining the NMPV generation. NMPV is generated mainly through the changes in the strength of baroclinicity and in the direction of the moisture gradient due to moist and/or dry air mass intrusion into the baroclinic zone.

关键词： cyclone tracks moist potential vorticity mid-latitude cyclones

Rapid urbanization and more extreme rainfall events

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Science Bulletin 2020年第7期65卷 516-518,M0003页

作者： da-lin zhang Department of Atmospheric and Oceanic Science University of MarylandCollege ParkMD 20742USA State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China

With rapid urbanization occurring across developing countries since the late last century,many recent observational studies show statistically significant increases in the intensity and frequency of short-duration(i.e.,less than 6 h)urban extreme rainfall(UER)events over and downwind of major megacities during the warm season,but decreasing trends in light rainfall and rainy day over surrounding areas and also in total regional rainfall[1–4](An UER event is typically defined as a rainfall rate of greater than 95th percentile or higher over an urban region of concern).Moreover,the number of short-duration UER events tends to increase faster than that of long-duration ones,and the increasing UER trend appears to be more pronounced over some of China’s major megacities due to more rapid urbanization during the past three decades[1–3].As an example,a near-century climatology of hourly UER rates at a downwind maximum-accumulated rainfall station from the megacity of Shanghai is given in Fig.1[1],showing an increasing hourly rainfall trend since the rapid urbanization beginning from 1981 that is much greater than a longer-term hourly rainfall trend(Fig.1a).The large increases in the megacity-averaged hourly rainfall trend during Shanghai’s rapid urbanization period are also evident(Fig.1b).

关键词： trend faster urbanization

A fast forward computational method for nuclear measurement using volumetric detection constraints

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Nuclear Science and Techniques 2024年第2期35卷 47-63页

作者： Qiong zhang lin-Lv lin University of Electronic Science and Technology of China Chengdu 610000China

Owing to the complex lithology of unconventional reservoirs,field interpreters usually need to provide a basis for interpretation using logging simulation *** the various detection tools that use nuclear sources,the detector response can reflect various types of information of the *** Monte Carlo method is one of the primary methods used to obtain nuclear detection responses in complex ***,this requires a computational process with extensive random sampling,consumes considerable resources,and does not provide real-time response ***,a novel fast forward computational method(FFCM)for nuclear measurement that uses volumetric detection constraints to rapidly calculate the detector response in various complex environments is ***,the data library required for the FFCM is built by collecting the detection volume,detector counts,and flux sensitivity functions through a Monte Carlo ***,based on perturbation theory and the Rytov approximation,a model for the detector response is derived using the flux sensitivity function method and a one-group diffusion *** environmental perturbation is constrained to optimize the model according to the tool structure and the impact of the formation and borehole within the effective detection ***,the method is applied to a neutron porosity tool for *** various complex simulation environments,the maximum relative error between the calculated porosity results of Monte Carlo and FFCM was 6.80%,with a rootmean-square error of 0.62 *** field well applications,the formation porosity model obtained using FFCM was in good agreement with the model obtained by interpreters,which demonstrates the validity and accuracy of the proposed method.

关键词： Nuclear measurement Fast forward computation Volumetric constraints

Roles of Synoptic to Quasi-Monthly Disturbances in Generating Two Pre-Summer Heavy Rainfall Episodes over South China

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Advances in Atmospheric Sciences 2020年第2期37卷 211-228页

作者： Zhina JIANG da-lin zhang Hongbo LIU State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Department of Atmospheric and Oceanic Science University of MarylandCollege ParkMaryland 20742-2425USA LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

In this study,power spectral analysis and bandpass filtering of daily meteorological fields are performed to explore the roles of synoptic to quasi-monthly disturbances in influencing the generation of pre-summer heavy rainfall over South *** heavy rainfall episodes are selected during the months of April-June 2008-15,which represent the collaboration between the synoptic and quasi-biweekly disturbances and the synoptic and quasi-monthly disturbances,*** show that the first heavy rainfall episode takes place in a southwesterly anomalous flow associated with an anticyclonic anomaly over the South China Sea(SCS)at the quasi-biweekly scale with 15.1%variance contributions,and at the synoptic scale in a convergence zone between southwesterly and northeasterly anomalous flows associated with a southeastward-moving anticyclonic anomaly on the leeside of the Yungui Plateau and an eastwardpropagating anticyclonic anomaly from higher latitudes with 35.2%variance *** contrast,the second heavy rainfall episode takes place in southwest-to-westerly anomalies converging with northwest-to-westerly anomalies at the quasi-monthly scale with 23.2%variance contributions to the total rainfall variance,which are associated with an anticyclonic anomaly over the SCS and an eastward-propagating cyclonic anomaly over North China,*** the synoptic scale,it occurs in south-to-southwesterly anomalies converging with a cyclonic anomaly on the downstream of the Yungui Plateau with 49.3%variance *** both cases,the lower-tropospheric mean south-to-southwesterly flows provide ample moisture supply and potentially unstable conditions;it is the above synoptic,quasi-biweekly or quasimonthly disturbances that determine the general period and distribution of persistent heavy rainfall over South China.

关键词： synoptic scale pre-summer rainfall quasi-biweekly scale quasi-monthly disturbances

Is the Isentropic Surface Always Impermeable to the Potential Vorticity Substance?

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Advances in Atmospheric Sciences 2012年第1期29卷 29-35页

作者： Chanh Q. KIEU da-lin zhang Laboratory of Climate and Weather Research Hanoi College of Science Vietnam National University Vietnam 10000 Department of Atmospheric and Oceanic Science University of Maryland College Park Maryland 20740

The impermeability of isentropic surfaces by the potential vorticity substance （PVS） has often been used to help understand the generation of potential vorticity in the presence of diabatic heating and friction. In this study, we examined singularities of isentropic surfaces that may develop in the presence of diabatic heating and the fictitious movements of the isentropic surfaces that are involved in deriving the PVS impermeability theorem. Our results show that such singularities could occur in the upper troposphere as a result of intense convective-scale motion, at the cloud top due to radiative cooling, or within the well-mixed boundary layer. These locally ill-defined conditions allow PVS to penetrate across an isentropic surface. We conclude that the PVS impermeability theorem is generally valid for the stably stratified atmosphere in the absence of diabatic heating.

关键词： PV substance impermeability singularities of isentropic surfaces diabatic heating

Mesoscale Barotropic Instability of Vortex Rossby Waves in Tropical Cyclones

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Advances in Atmospheric Sciences 2010年第2期27卷 243-252页

作者：钟玮陆汉城 da-lin zhang Institute of Meteorology PLA University of Science and Technology Nanjing 211101 Department of Atmospheric and Oceanic Science University of Maryland College Park Maryland 20742 USA

In this study, the barotropic stability of vortex Rossby waves （VRWs） in 2D inviscid tropical cyclone （TC）-like vortices is explored in the context of rotational dynamics on an f-plane. Two necessary instable conditions are discovered：（a） there must be at least one zero point of basic vorticity gradient in the radial scope; and （b） the relative propagation velocity of perturbations must be negative to the basic vorticity gradient, which reflects the restriction relationship of instable energy. The maximum growth rate of instable waves depends on the peak radial gradient of the mean vorticity and the tangential wavenumber （WN）. The vortex-semicircle theorem is also derived to provide bounds on the growth rates and phase speeds of VRWs. The typical basic states and different WN perturbations in a tropical cyclone （TC） are obtained from a high resolution simulation. It is shown that the first necessary condition for vortex barotropic instability can be easily met at the radius of maximum vorticity （RMV）. The wave energy tends to decay （grow） inside （outside） the RMV due mainly to the negative （positive） sign of the radial gradient of the mean absolute vorticity. This finding appears to help explain the developemnt of strong vortices in the eyewall of TCs.

关键词： vortex Rossby waves vortex barotropic instability vortex semicircular theorem tropical cyclone