Characteristics Of Atmospheric Boundary Layer Height In China And A Large Eddy Simulation Of Hurricane

As we all know,the atmospheric boundary layer is the main channel of material and energy exchanged between the earth and atmosphere.It is also the major place for human life and production,being closely related to the development of human beings.Complex terrain and changeable climatic conditions of China affect the structure of the boundary layer at all times.Based on the ERA-Interim data during the period from 1979 to 2015 and observation data during the period from 2010 to 2015 of atmospheric boundary layer in China,the structural characteristics and boundary height over China are analyzed.The main conclusions are as follows:(1)The amplitude of boundary layer height in spring and summer is greater than that in autumn and winter in seasonal variation.In addition to individual regions,reanalysis data are similar to trends in L band radiosonde data.(2)The internal structure change and development of atmospheric boundary layer is affected by weather factors,including surface conditions,climate type elements and so on.Through correlation analysis,we believe that the boundary layer height in 20BJT showed a good positive correlation with 10m wind and surface temperature.(3)Different underlying surface conditions and climate types affect the height and state of the boundary layer.As far as daily change is concerned,the peak of the boundary layer height appears in the afternoon,and the daily amplitude of the boundary layer in the northwest and the plateau is much larger than that in other areas.In addition,the abiliity of simulating the atomsphere of high resolution numerical weather predicition model is an important way to improve the ability to simulate the atmospheric numerical weather model.Based on the analysis of high resolution numerical model's ability in atmospheric multi-scale movement simulation,such as large eddy simulations(LESs),helps us to better understand the internal structure of the planetary boundary layer,including the generation of roll in PBL.Our LES study investigates the impact of storm-induced sea surface temperature(SST)cooling on the roll vortices generated by the convective and dynamic instability in the ABL of Hurricane Isaac(2012)and the roll induced transport using hindcasting large eddy simulations(LESs)configured from the multiply nested Weather Research&Forecasting model.Two experiments are performed:one forced by the Unified Wave INterface-Coupled Model and the other with the SST replaced by the NCEP FNL analysis that does not include the storm-induced SST cooling.The simulations show that the roll vortices are the prevalent eddy circulations in the ABL of Isaac.The storm-induced SST cooling causes the ABL stability falls in a range that satisfies the empirical criterion of roll generation by dynamic instability,whereas the ABL stability without considering the storm-induced SST cooling meets the criterion of roll generation by convective instability.The ABL roll is skewed and the increase of convective instability enhances the skewness.Large convective instability leads to large vertical transport of heat and moisture;whereas the dominant dynamic instability results in large turbulent kinetic energy but relatively weak heat and moisture transport.