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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

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

Future Changes in the Impact of North Pacific Midlatitude Oceanic Frontal Intensity on the Wintertime Storm Track in CMIP5 Models

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Journal of Meteorological Research 2020年第6期34卷 1199-1213页

作者： Yao YAO Zhong ZHONG Xiu-Qun YANG xiaogang huang College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073 Jiangsu Collaborative Innovation Center for Climate Change School of Atmospheric SciencesNanjing UniversityNanjing 210023 Army Academy of Artillery and Air Defense(Nanjing Campus) Nanjing 211132

The storm track and oceanic front play an important role in the midlatitude air–sea *** this study,future changes in the impact of the North Pacific midlatitude oceanic frontal intensity on the wintertime storm track are projected based on climate model outputs from the Coupled Model Intercomparison Project Phase 5(CMIP5).The performance of 13 CMIP5 models is evaluated,and it is found that a majority of these models are capable of reproducing the northward intensification of the storm track in response to the strengthened oceanic *** ensemble means of outputs from six best models under three Representative Concentration Pathway(RCP)scenarios(RCP2.6,RCP4.5,and RCP8.5)are compared with the results of the historical simulation,and future changes are *** is found that the impact of the oceanic frontal intensity on the storm track tends to get stronger and extends further westward in a warming climate,and the largest increase appears in the RCP8.5 *** analysis reveals that the stronger impact of the oceanic front on the storm track in the future may be partially attributed to the greater oceanic frontal impact on the near-surface baroclinicity,which is mainly related to the intensified oceanic frontal impact on the meridional potential temperature gradient under the climate change ***,this process can hardly explain the increasing impact of the oceanic front on the upstream of the storm track.

关键词： storm track midlatitude oceanic front climate change Coupled Model Intercomparison Project Phase 5(CMIP5)

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

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

Advancements and New Frontiers in Offshore Seismic Exploration Technology

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Journal of Earth Science 2024年第5期35卷 1749-1757页

作者： Yuhong Xie Yunfei Ye xiaogang huang Wenbo Sun Yanwen Wei China National Offshore Oil Corporation Beijing 100010China CNOOC Nanhai Oil and Gas Energy Academician Workstation Haikou 570312China CNOOC Research Institute Ltd. Beijing 100028China National Engineering Research Center of Offshore Oil and Gas Exploration Beijing 100028China

0 INTRODUCTION China's external dependence on oil and gas remains high,making the independent exploration and development of oil and gas resources crucial for ensuring national energy security and the sustainable development of the economy and *** 2023,China continued to step up its efforts in offshore oil and gas exploration and development,with offshore crude oil production surpassing 62 million tons,accounting for about 70%of the national increase in crude oil *** offshore oil and gas exploration and development is of great significance for guaranteeing national energy security.

关键词： offshore guarantee continued

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)

Evaluation of lightning-induced overvoltage on a 10 kV distribution line based on electromagnetic return-stroke model using finite-difference time-domain

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High Voltage 2024年第2期9卷 356-366页

作者： Pan Duan Lianfang Zhang xiaogang huang Jian Sun Yue Qi Qing Yang School of Automation Chongqing University of Posts and TelecommunicationsChongqingChina Chongqing Power Co Tongnan BurChongqingChina China Southern Power Grid Science Research Institute GuangzhouChina State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina

Accurate simulation of lightning-induced overvoltage for overhead distribution lines is helpful to prevent lightning trip *** electromagnetic return-stroke model was used to represent lightning and then a 3D finite-difference time-domain(FDTD)method was adopted to simulate the lightning-induced overvoltage on a distribution line without a field-line coupling *** lightning-induced overvoltage behave for different ground conductivity and varying distance between the distribution line and the lightning channel was *** results showed that the overvoltage waveforms at the centre point of the line corresponding to lightning strikes on the lossy ground and an ideal ground(σ=∞)were similar;however,the peak amplitudes of the waveform were affected by soil conductivity at a close *** relationship between magnitude of the overvoltage and distance can be described by a second-order exponential decay ***,the overvoltage calculated using the proposed model was compared with those obtained based on Agrawal's model and measurements made using the newly developed intelligent insulator on *** these comparisons,it could be concluded that the FDTD method with the electromagnetic return-stroke model produces reasonably accurate results of the attenuated oscillation waveform,which can better reproduce the overvoltage on operational distribution lines.

关键词： lightning distribution return

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