Evolution Mechanisms Of Warm-core Structure Of Hurricane Edouard (2014)

This paper takes Hurricane Edouard(2014)as the research example.First of all,its warm-core structure in reanalysis/analysis and satellite data sets are evaluated using HS3 dropsonde observations in the eye of Hurricane Edouard.FNL analysis data is found to be suitable for hurricane warm-core studies.Therefore,FNL data is selected as the forced field to run WRF numerical simulation experiment and explore the mechanisms of warm-core evolution by using potential temperature budget analysis.The following conclusions are drawn: 1.All of the data sets generally underestimate the warm-core strength of Edouard.AMSU-A shows the smallest error in the upper troposphere but the largest error in the lower troposphere.Its successor,ATMS,significantly improves the representation of low-level warming while maintaining its performance in the middle and upper troposphere.2.Two versions of FNL data at different resolutions show better performance than the other reanalyses.MERRA-2,JRA-55,and ERA-I could represent the vertical warm-core structure,but they markedly underestimate the warm-core strength.MERRA and NARR Reanalysis have the worst skills when reproducing warm cores.MERRA-2 considerably outperforms its predecessor,MERRA.3.The warm-core evolution of Edouard in six reanalysis/analysis data sets is diagnosed and compared.Different physical processes such as diabatic heating and vertical and horizontal advection may be responsible for warm-core generation at different stages during its lifetime.The inaccurate representation of these physical processes in the reanalyses/analyses results in errors in the warm-core strength and height.It is suggested that vortex relocation/bogusing,assimilation of tropical cyclone(TC)observation data,and model parameterizations are important to adequately represent warm cores in terms of strength and three-dimensional structure.4.The WRF numerical model reasonably well reproduces the path and intensity of Hurricane Edouard.The simulated warm-core structures are basically consistent with the HS3 dropsonde observations.Therefore,the evolution mechanisms of its warm core can be explored using WRF data.The results shows that the warm-core height varied throughout the lifetime of Hurricane Edouard.The physical mechanisms of the evolution of warm-core height in three stages,that is,rising,unchanged and decreasing of warm-core height,are diagnosed by using potential temperature budget equation.The results show that the total advection plays an important role in the evolution of warm-core height.The strong cooling from the total advection and the strong warming from the diabatic heating cancel each other in the eye wall region.The radiation and boundary layer scheme have little influence on the warm-core evolution.During the rising stage of warm core,the mean vertical advection and the eddy horizontal advection have a tremendous impact on the total advection.The mean vertical advection is the most important factor when the warm-core height remains unchanged and decreases.