Anewanalyticalmodelwasdevelopedtopredictthegravitywavedrag(GWD)inducedbyanisolated3-dimensionalmountain,overwhichastratified,non-rotatingnon-Boussinesqshearedflowisimpinged.Themodelisconfinedtosmallamplitudemotionandassumestheambientvelocityvaryingslowlywithheight.ThemodifiedTaylor-GoldsteinequationwithvariablecoefficientsissolvedwithaWentzel-Kramers-Brillouin(WKB)approximation,formallyvalidathighRichardsonnumbers.WiththisWKBsolution,genericformulaeofsecondorderaccuracy,fortheGWDandsurfacepressureperturbation(bothforhydrostaticandnon-hydrostaticflow)arepresented,enablingarigoroustreatmentontheeffectsbyverticalvariationsinwindprofiles.Inanidealtesttothecircularbell-shapedmountain,itwasfoundthatwhenthewindislinearlysheared,thattheGWDdecreasesastheRichardsonnumberdecreases.However,theGWDforaforwardshearedwind(windincreaseswithheight)decreasesalwaysfasterthanthatforthebackwardshearedwind(winddeceaseswithheight).Thisdifferenceisevidentwheneverthemodelishydrostaticornot.
