Diagnosis of the Slantwise Development of Isentropic and Moist Isentropic Surfaces
等熵面和湿等熵面倾斜发展的诊断分析

The inclination equations for isentropic and moist isentropic surfaces,which can be used to diagnose the slantwise evolution of isentropic and moist isentropic surfaces,are derived from the thermodynamic and water vapor equations in isobaric coordinates.It is shown that the local change of inclination of isentropic surface is dominated by the terms associated with advection,velocity shear and diabatic heating.Besides the three terms mentioned above,the forcing terms in the inclination equation of moist isentropic surface includes the term of vertical and meridional shears of vertical heating flux.The analysis of NCEP/NCAR data reveals that the positive high-valued areas of atmospheric baroclinicity,relative vertical vorticity are mainly located in the positive high-valued areas of inclinations of isentropic and moist isentropic surfaces.This indicates that the atmospheric baroclinicity,relative vertical vorticity are closely related to the inclinations of isentropic and moist isentropic surfaces.The term of vertical velocity shear,especially the term associated with meridional shear of vertical velocity is the chief factor affecting the slantwise development of isentropic surface.The contribution coming from the terms associated with vertical shear of zonal and meridional velocities to the slantwise evolution of moist isentropic surface is much more important than that of the other forcing terms in the inclination equation of moist isentropic surface.