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Analysis of Pressure Forcings for the Vertical Turbulent Fluxes in the Convective Boundary Layer at Gray Zone Resolutions

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Journal of Meteorological Research 2023年第6期37卷 841-854页

作者： Yahua WANG xiaoping cheng Jianfang FEI Bowen ZHOU College of Meteorology and Oceanography National University of Defense TechnologyChangsha410005China Key Laboratory of Electro-Optical Countermeasures Test and Evaluation Technology Luoyang471000China Key Laboratory for Mesoscale Severe Weather Ministry of EducationSchool of Atmospheric SciencesNanjing UniversityNanjing210000China

At kilometer and sub-kilometer resolutions,known as the numerical gray zone for boundary layer turbulence,the atmospheric boundary layer turbulence becomes partially resolved and partially subgrid-scale(SGS) in a numerical model,thus requiring scale-adaptive turbulence *** schemes are often built by modifying the existing parameterizations,either the planetary boundary layer(PBL) schemes or the large-eddy simulation(LES) closures,to produce the right SGS turbulent fluxes at gray zone ***,the underlying forcings responsible for the changes in the vertical turbulent fluxes are largely ignored in these *** study follows the original approach of Wyngaard(2004) and analyzes the turbulent buoyancy and momentum flux budgets,to gain a better understanding of the variations of flux forcings at gray zone *** investigation focuses on the pressure covariance term,which is one of the most dominant terms in the budget *** using the coarse-grained LES of a dry convective boundary layer(CBL) case as reference,two widely-used pressure covariance models are evaluated and optimized across the gray zone resolution *** optimized linear model is further evaluated a priori against another dry CBL case with a different bulk stability,and a shallow-cumulus-topped boundary layer *** model applies well to both cases,and notably shows good performance for the cloud *** on the analysis of the flux forcings and the optimized pressure model,a scale-adaptive turbulence model for the gray zone is derived from the steady-state flux budgets.

关键词： convective boundary layer gray zone flux budget pressure covariance turbulence parameterization

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Mature typhoon “cloud gyro” model and numerical simulation study

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Science China Earth Sciences 2020年第5期63卷 749-756页

作者： Xiaogang HUANG Xiangcheng LI xiaoping cheng Chenxi ZHANG Juli DING College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China PLA Troop 92664 Haiyang 265100China

Due to the coarse temporal resolution of the best track databases for typhoons,some small-scale characteristics of typhoon motion have been *** order to reveal the fine features of typhoon motion,the dense cloud within the radius of maximum wind(RMW)of mature typhoons,defined as a“cloud gyro”that simultaneously spins around its own rotational axis and precesses around the vertical axis,is approximated to a rigid *** on the principles of gyrodynamics,the derived mathematical model of a typhoon track indicates that typhoon movement is composed of translational motion governed by the steering flow and superimposed precessional motion that manifests as the inherent characteristics of typhoon tracks,especially with the external *** temporal resolution numerical simulation of a real case verifies the conclusion of this study,which is that the smaller the RMW,the larger the tangential wind speed or the larger the external torque,and the more obviously precessional motion manifests.

关键词： Mature typhoon Cloud gyro Precession angular velocity

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Effect of wind-current interaction on ocean response during Typhoon KAEMI(2006)

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Science China Earth Sciences 2013年第3期56卷 418-433页

作者： LIU Lei FEI JianFang cheng xiaoping HUANG XiaoGang PLA University of Science and Technology

The Weather Research and Forecasting （WRF） model, the Princeton Ocean Model （POM）, and the wave model （WAVEWATCH III） are used to develop a coupled atmosphere-wave-ocean model, which involves different physical pro- cesses including air-forcing, ocean feedback, wave-induced mixing and wave-current interaction. In this paper, typhoon KAEMI （2006） has been examined to investigate the effect of wind-current interaction on ocean response based on the coupled atmosphere-ocean-wave model, i.e., considering the sea surface currents in the calculation of wind stress. The results show that the wind-current interaction has a noticeable impact on the simulation of 10 m-winds. The model involving the effect of the wind-current interaction can dramatically improve the typhoon prediction. The wind-current interaction prevents excessive momentum fluxes from being transferred into the upper ocean, which contributes to a much smaller turbulence kinetic energy （TKE）, vertical diffusivity, and horizontal advection and diffusion. The Sea Surface Temperature （SST） cooling induced by the wind-current interaction during the initial stage of typhoon development is so minor that the typhoon intensity is not very sen- sitive to it. When the typhoon reaches its peak, its winds can disturb thermocline, and the cold water under the thermocline is pumped up. However, this cooling process is weakened by the wind-current interaction, as ocean feedback delays the decay of the typhoon. Meanwhile, the temperature below the depth of 30 m shows an inertial oscillation with a period about 40 hours （-17°N） when sudden strong winds beat on the ocean. Due to faster currents, the significant wave height decreases as ignoring the wind-current interaction, while this process has a very small effect on the dominant wave length.

关键词： coupled atmosphere-wave-ocean model typhoon wave induced mixing SST cooling wave state

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Impacts of the Lowest Model Level Height on Tropical Cyclone Intensity and Structure

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Advances in Atmospheric Sciences 2014年第2期31卷 421-434页

作者： MA Zhanhong FEI Jianfang HUANG Xiaogang cheng xiaoping College of Meteorology and Oceanography PLA University of Science and Technology

Variable thicknesses in the lowest half-ηmodel level （LML） are often used in atmospheric models to compute surface diagnostic fields such as surface latent and sensible heat *** effects of the LML on simulated tropical cyclone （TC）evolution were investigated in this study using the Weather Research and Forecasting （WRF） *** results demonstrated notable influences of the LML on TC evolution when the LML was placed below 12 *** TC intensification rate decreased progressively with a lowering of the LML,but its ultimate intensity change was relatively *** maximum 10-m winds showed different behavior to minimum sea level pressure and azimuthally-averaged tangential winds,and thus the windpressure relationship was changed accordingly by varying the *** TC circulation was more contracted in association with a higher *** latent heat fluxes were enhanced greatly by elevating the LML,wherein the wind speed at the LML played a dominant *** changes in the wind speed at the LML were dependent not only on their profile differences,but also the different heights they were taken *** to the enhanced surface heat fluxes,more intense latent heat release occurred in the eyewall,which boosted the storm＇s intensification.A higher LML tended to produce a stronger storm,and therefore the surface friction was reinforced,which in turn induced stronger boundary layer inflow together with increased diabatic heating.

关键词： tropical cyclone lowest model level simulation

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Efficient Polymer Solar Cells Based on Solution-processed Vanadium Oxide as Hole-extracting Layer

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Chinese Journal of Chemistry 2013年第11期31卷 1423-1427页

作者： Biao Xiao xiaoping cheng Baofeng Zhao Hongbin Wu Institute of Polymer Optoelectronic Materials and Devices State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou Guangdong 510640 China

Here we reported the fabrication of efficient polymer solar cells from regioregular poly（3-hexylthiophene）（P3HT）：fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester （PC6jBM） mixtures, in which solution- processed vanadium oxide （VOx） was used as a hole-extracting layer （HEL）. The obtained devices exhibited a high power conversion efficiency of 3.96%, and can be enhanced to 4.06% and 4.16%, respectively, when two types of PEDOT：PSS with different conductivities were used in conjunction with the VOx layer. All the VOx-based devices showed a high fill factor （FF） over 70%, which was ascribed to efficient hole extracting efficiency associated with the solution-processed VOx hole-extracting layer. The origins of the improvement were also studied by transmission spectra, atomic force microscope （AFM）, and capacitance-voltage characteristics.

关键词： polymer solar cells vanadium oxide hole-extracting layer solution-processed

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Enhancing Tropical Cyclone Intensity Estimation from Satellite Imagery through Deep Learning Techniques

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Journal of Meteorological Research 2024年第4期38卷 652-663页

作者： Wen YANG Jianfang FEI Xiaogang HUANG Juli DING xiaoping cheng College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410008 Beijing Institute of Applied Meteorology Beijing 100029

This study first utilizes four well-performing pre-trained convolutional neural networks(CNNs) to gauge the intensity of tropical cyclones(TCs) using geostationary satellite infrared(IR) *** models are trained and tested on TC cases spanning from 2004 to 2022 over the western North Pacific *** enhance the models performance,various techniques are employed,including fine-tuning the original CNN models,introducing rotation augmentation to the initial dataset,temporal enhancement via sequential imagery,integrating auxiliary physical information,and adjusting *** optimized CNN model,i.e.,visual geometry group network(VGGNet),for TC intensity estimation is ultimately *** applied to the test data,the model achieves a relatively low mean absolute error(MAE) of 4.05 m s~(-1).To improve the interpretability of the model,the SmoothGrad combined with the Integrated Gradients approach is *** analyses reveal that the VGGNet model places significant emphasis on the distinct inner core region of a TC when estimating its ***,it partly takes into account the configuration of cloud systems as input features for the model,aligning well with meteorological *** several improvements made to this model's performance offer valuable insights for enhancing TC intensity forecasts through deep learning.

关键词： tropical cyclone intensity deep learning satellite imagery

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Maintenance and Sudden Change of a Strong Elevated Ducting Event Associated with High Pressure and Marine Low-Level Jet

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Journal of Meteorological Research 2020年第6期34卷 1287-1298页

作者： Zhichao LIANG Juli DING Jianfang FEI xiaoping cheng Xiaogang HUANG College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101 296746 Troops of PLA Korla 841000

Capture of a strong elevated ducting event,especially its maintenance and sudden change,is of great value to airborne radar to achieve its beyond-the-line-of-sight ***,the knowledge is not easily accessible over the open ocean and hence very *** the Air–Sea Interaction Survey(ASIS)over the western North Pacific(WNP)in May 2016,a strong elevated ducting event with a long-life period and sudden change in its evolution was *** from the ASIS,images from the Himawari-8 satellite,reanalysis data from the ECMWF,and Weather Research and Forecasting(WRF)model,were used to analyze the maintenance and sudden change of this strong ducting event,together with the model performance on simulating *** results showed that the maintenance of strong elevated ducts,with their tops ranging from 750 to 1050 m and average strength of approximately 38 M units,was caused by a strong dry air mass capping over the wet marine atmospheric boundary layer(MABL),together with the subsidence inversion associated with high *** WRF model performs well in simulating ***,a sudden increase in duct height with a slight decrease of strength was recorded by the subsequent GPS radiosonde,which was finally contributed to the mechanical turbulent inversion and hydrolapse associated with the marine low-level jet(MLLJ).The height of the maximum horizontal wind speed(Umh)of the MLLJ corresponds well with the bottom of the trapping ***,these jet-relevant ducts are generally weak and it is difficult to accurately simulate them by using the mesoscale numerical model,since the wind-shear produced eddies are too small to be properly parameterized.

关键词： atmospheric ducts elevated ducts marine atmospheric boundary layer(MABL) low-level jet numerical simulation

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Estimating the Correlated Observation-Error Characteristics of the Chinese FengYun Microwave Temperature Sounder and Microwave Humidity Sounder

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Advances in Atmospheric Sciences 2018年第11期35卷 1428-1441页

作者： Ting WANG Jianfang FEI xiaoping cheng Xiaogang HUANG Jian ZHONG College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China China Satellite Maritime Tracking and Control Department Jiangyin 214431China

In operational data assimilation systems, observation-error covariance matrices are commonly assumed to be ***, inter-channel and spatial observation-error correlations are inevitable for satellite radiances. The observation errors of the Microwave Temperature Sounder(MWTS) and Microwave Humidity Sounder(MWHS) onboard the FengYun-3A(FY-3A) and FY-3B satellites are empirically assigned and considered to be uncorrelated when they are assimilated into the WRF model's Community Variational Data Assimilation System(WRFDA). To assimilate MWTS and MWHS measurements optimally, a good characterization of their observation errors is necessary. In this study, background and analysis residuals were used to diagnose the correlated observation-error characteristics of the MWTS and MWHS. It was found that the error standard deviations of the MWTS and MWHS were less than the values used in the WRFDA. MWTS had small inter-channel errors, while MWHS had significant inter-channel errors. The horizontal correlation length scales of MWTS and MWHS were about 120 and 60 km, respectively. A comparison between the diagnosis for instruments onboard the two satellites showed that the observation-error characteristics of the MWTS or MWHS were different when they were onboard different satellites. In addition, it was found that the error statistics were dependent on latitude and scan *** forecast experiments showed that using a modified thinning scheme based on diagnosed statistics can improve forecast accuracy.

关键词： data assimilation correlated observation errors MWTS(Microwave Temperature Sounder) MWHS(Microwave Humidity Sounder)

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Remote Impact of Blocking Highs on the Sudden Track Reversal of Tropical Cyclones

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Advances in Atmospheric Sciences 2015年第11期32卷 1517-1532页

作者： LUO Xia FEI Jianfang HUANG Xiaogang cheng xiaoping YU Kun College of Meteorology and Oceanography PLA University of Science and Technology

Previous work showed that some tropical cyclones （TCs） in the western Pacific Ocean undergo sudden track reversal, and the onset, maintenance and decay of blocking highs （BHs） coexisted with 19 of the studied TCs with sudden track reversal. In these cases, the phase relations between the BH, the continental high （CH）, the subtropical high （SH） and the suddenly reversed TCs could be classified into types A, B, C and D. Types C and D were the focal point of this follow-up study, in which Typhoon Pabuk （2007） and Lupit （2009） were employed to conduct numerical simulations. The results showed that the reversed tracks of Pabuk （2007） and Lupit （2009） could have been affected by the BH, particularly in terms of the turning location and the trend of movement after turning. Specifically, the two main features for Pabuk （2007） in the BH perturbations were the deflection of its turning point and a distinct anticlockwise rotation. Lupit （2009） deviated to the southwest and finally made landfall in the Philippines, or experienced further eastward movement, in the perturbed BH. The impact mechanisms can be attributed to the change in the vorticity field transported from the BH, leading to an intensity variation of midlatitude systems. BHs may have a positive feedback effect on the strength of the westerly trough （TR）, as indicated by a weakened and strengthened TR corresponding to negative and positive BH perturbations, respectively.

关键词： blocking high tropical cyclone suddenly reversed track numerical simulation

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Analysis of the Winter Cloud-to-Ground Lightning Activity and Its Synoptic Background in China during 2010-20

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Advances in Atmospheric Sciences 2022年第6期39卷 985-998页

作者： Manman MA Xiaogang HUANG Jianfang FEI Chi ZHANG Chao LI xiaoping cheng College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China Unit 94116 of PLA Hetian 848000China Jiangsu Meteorological Observatory Nanjing 210008China

Cloud-to-ground(CG)lightning data and the ECMWF ERA-Interim reanalysis dataset are analyzed to gain insight into the spatiotemporal distribution and synoptic background of winter-season CG flashes between December 2010 and February 2020 in *** identify three Winter Lightning Frequent Areas(WLAs):the southwest side of the Yunnan-Guizhou Plateau(WLA1),the east side of the Yunnan-Guizhou Plateau(WLA2),and the Poyang Lake Plain(WLA3).The CG lightning flashes most frequently occur at local midnight and have a monthly peak in *** CG lightning in WLA1 is mostly generated in non-frontal weather;however,the lightning in WLA2 and WLA3 mostly occurs in frontal *** frontal circulation situation is divided into four typical types:transversal trough after high pressure,low vortex,confrontational convergence,and asymptotic *** all typical weather patterns,the lightning occurs downstream of a 500 hPa trough and is accompanied by a southwesterly low-level *** convective parameters of winter thunderstorms differ greatly from those of summer *** maximum convective available potential energy(MCAPE)and K-index(KI)are more useful metrics than convective available potential energy(CAPE)and Showalter index(SI)during *** study further deepens the understanding of the distribution characteristics of winter CG lightning in China,which motivates further research to improve the ability of winter thunderstorm prediction.

关键词： winter thunderstorms CG lightning spatiotemporal characteristics ADTD

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