Multi-scale Simulation Of Typhoon Wind Fields Considering Historical And Future Climate Change

The southeast coastal areas in China suffer the most severe typhoon disaster.There are about 6 typhoon-level tropical cyclones entering the coastal 24-hour warning line every year and posing a threat to the super high-rise buildings,transmission towers and wind turbines in coastal areas.And global climate change will continuously affect the intensity of typhoons in the future Therefore,it's of practical significance to accelerate the analysis of typhoon evolution and characteristics of typhoon wind fields,establish and improve the short-term typhoon disaster warning and post-disaster assessment systems for coastal engineering structures under construction and during operation,and take into account the impact of future climate changes on the assessment of extreme typhoon disasters in coastal areas.Combining the mesoscale numerical weather prediction model considering historical and future climate data,with field measurements and theoretical analysis,the following studies involving the offshore typhoon evolution,typhoon wind fields of engineering site,statistical feature of typhoon wind profile and the future climate impact on landing typhoons were carried out in the following:1.Intensified offshore typhoon simulation based on WRF model:Aiming at three typically rapid-intensified typhoons in the Northwest Pacific in recent years,the high-resolution simulation based on WRF model were carried out to study the typhoon evolution.And the sensitivity experiments to different grid resolution,microphysics schemes and sea surface flux schemes were also conduted,focusing the analysis of the intensification and weakening stage of three typhoons.At the same time,the observed typhoon tracks,intensity and rainfall and other measured data by the China Meteorological Administration were used to verify and analyze the simulation results.2.Simulation of urban near-surface wind fields based on cross-scale typhoon simulation framework:Combining the typhoon module in WRF,different turbulence modeling schemes and the digital terrain and landform processing technology based on geographic information system(GIS),a cross-scale typhoon wind field simulation framework suitable for any complex urban engineering site is proposed.First,a mesoscale typhoon simulation is carried out based on the typhoon module and the two-way nested moving grid scheme.And then the typhoon simulation results are used as the initial and boundary conditions of WRF-LES,and the multi-scale local typhoon wind field is carried out considering the high-precision topography and landform.Based on the measured data of near-surface wind fields at the location of Jiubao Bridge during the passage of Typhoon Can-hom(2015)in Hangzhou,the multi-scale numerical experiments were designed in detail and the validity and practicality of the multi-scale typhoon wind field simulation framework proposed in this chapter was verified and disccussed.3.High-resolution simulation and analysis of typhoon wind fields over the coastal complex trerrains:The characteristics of the time-varing wind speed and wind direction over the coastal areas and complex terrain of Zhoushan Island were analyzed during the influence of the typhoon Taili's peripheral wind fields,based on the measured data of the wind field along the coastal station site from the China Meteorological Administration and the Zhoushan transmission lines.And then the high-resolution topographic and landform data and multi-nested grids in WRF model were used to simulate the 50-meter-grid typhoon wind fields over Zhoushan complex terrains.Based on the measured data,the typhoon tracks and micro-scale wind field simulation at Zhoushan location were verified.And the three-dimensional time-varing wind fields at different typical locations over complex terrain were analyzed and discussed.4.Statistical analysis of typhoon wind profiles over Southeast China Sea based on reanalysis dataset:According to the latest high-resolution meteorological reanalysis data ERA5 published by European Centre for Medium-Range Weather Forecasts,combined with the AHW typhoon simulation results,the characteristics of typhoon boundary layer structure were compared and analyzed.With a large number of wind profile samples,the low-level jet features near the typhoon center are systematically investigated.This study aims to reveal the azimuthal distribution of the low-level jet(LLJ)wind profile near typhoon center in the southeastern coastal areas of China.And finally a quadrant-dependent TC wind profile models considering LLJ features were proposed for determining design wind loads on supertall buildings in typhoon-prone coastal areas of China.5.Assessment of future landing typhoons considering global climate change:Based on the climate data from CMIP5 global models,the quantitative analysis of the sea surface temperature in the Pacific Northwest and coastal areas of China during the typhoon season was performed under different climate states.Then useing the climate data of thermodynamic variables such as temperature and atmospheric humidity,this study implement the WRF-PGW IX(Pseudo-global Warming)technology to conduct a mesoscale simulation evaluation of the ten super typhoons that landed in China's coastal areas under the background of global climate change.The intensity changes during landing time were analyzed to provide a reference for future typhoon disaster assessment.