The dynamical response of the solar corona to surface and sub-surfaceperturbations depends on the chromospheric stratification, and specifically onhow efficiently these layers reflect or transmit incoming Alfv\'en waves. Whileit would be desirable to include the chromospheric layers in the numericalsimulations used to study such phenomena, that is most often not feasible. Wedefined and tested a simple approximation allowing the study of coronalphenomena while taking into account a parametrised chromospheric reflectivity.We addressed the problems of the transmission of the surface rotation to thecorona and that of the generation of polar plumes by Alfv\'en waves (Pinto etal., 2010, 2011). We found that a high (yet partial) effective chromosphericreflectivity is required to properly describe the angular momentum balance inthe corona and the way the surface differential rotation is transmittedupwards. Alfv\'en wave-driven polar plumes maintain their properties for a widerange of values for the reflectivity, but they become bursty (and eventuallydisrupt) when the limit of total reflection is attained.
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