A dynamical model for diagnosing orographic rainfall across Assam–Burma hills in India

Abstract

An attempt has been made to diagnose the orographic rainfall associated with internal gravity waves excited by the Assam–Burma hills (ABH) in India, during south west monsoon season (SWMS). To develop this model ABH has been synthesised by two 3-D elliptical barriers, separated by a valley of some finite distance. In this paper, a three dimensional frictionless, laminar, adiabatic, boussinesq, non-rotating and inviscid moist airflow with realistic vertical variation of wind and temperature, has been considered. Here also the basic flow consists of two components such as zonal wind component U(z) and meridional wind component V(z). The perturbation technique is used to linearise the governing equations of the airflow and to obtain perturbation vertical velocity ( $$w^{\prime}$$ ) the quasi-numerical approach have been used. The perturbation vertical velocity ( $$w^{\prime}$$ ) is used to compute the rainfall intensity (RFI) over ABH during SWMS. Also, we examine the sensitivity of the computed RFI on the length (d) of the valley. Finally, the computed results have compared with Gridded Rainfall Data set, generated by India meteorological Department (IMD), India.