MOIST SYMMETRICAL INSTABILITY - A NUMERIC AL-SIMULATION USING REAL CASE DATA

This Note presents the results of a numerical simulation of Moist Symm etric Instability (MSI) of a basic state corresponding to a real situa tion observed during MFDP/FRONTS 87 field experiment. Several experime ntal studies have proposed MSI as being responsible for rainbands in t he vicinity of fronts, but no unambiguous proof (like their numerical simulation) has yet been given. In our case, we clearly obtain the ons et of symmetric instability and we show that it bears strong similarit ies with idealized cases. The experimental data give some clues indica ting that the instability could have occurred in reality, but no final proof is available.