Gravity Wave Source Spectra Appropriation for Mesosphere Lower Thermosphere Using Meteor Radar Observations and GROGRAT Model Simulations

Meteor radar observations of gravity wave momentum fluxes (GWMFs) in the 82-94 km altitude region, which is a part of mesosphere lower thermosphere (MLT), are employed to identify the best fit gravity wave source spectrum using Gravity wave Regional or Global Ray Tracer (GROGRAT) model simulations over a low-latitude location, Tirupati (13.63 degrees N, 79.4 degrees E). GROGRAT model is used to propagate a spectrum of gravity waves from the troposphere to the lower thermosphere. A total number of five gravity wave source spectra with various permutations and combinations are considered for the model simulations and by comparing the model simulated and radar observed gravity wave fields in the 82-94 km region, a best fit source spectrum is identified. The significance of the present study lies in appropriating the gravity wave source spectrum using meteor radar observations for the first time, which will have implications in improving gravity parameterization schemes in global models.