Trapped Lee Waves Observed during PYREX by Constant Volume Balloons: Comparison with Meso-NH Simulations

The main objective of the present paper is the use of a constant volume balloon (CVB) as a tool to (i) study trapped lee waves and (ii) assess the forecasting capability of a nonhydrostatic numerical model. Then, CVB data obtained during the Pyrenees Experiment (PYREX) are compared with nonhydrostatic two-dimensional trapped lee waves simulated by the Meso-NH model. This model is a community research model based on the Lipps–Hemler form of the anelastic system, which has been recently developed by the CNRM of Meteo-France and the Laboratoire d’Aerologie of Universite Paul Sabatier in France. To analyze how the CVB responds to lee waves, a simple CVB model is first applied to academic atmospheric stationary wave flows, analogous to those encountered during PYREX. This model takes into account the vertical velocity of the surrounding air, geometrical parameters of the balloon, and the atmospheric heating processes. Results show that the CVB reacts well to the atmospheric wave period, with a phase d...