<p>Water repartition in the stratosphere is a key compound in the atmospheric chemical and<br>radiative equilibrium. Since the 80&#8217;s, an increase of the water concentration in the<br>stratosphere has been observed.This presence in the stratosphere can be explained by the<br>slow ascent of air mass above convective clouds in tropical regions. The amount of water<br>vapor entering in the stratosphere depends on the coldest temperature and countered<br>during this slow ascent because it can lead to ice cristal formation that sediment and<br>dehydrate the air masses. But some other processes may contribute to the stratospheric<br>water budget, especially to explain the increase of water vapor. Stratospheric overshoots<br>phenomenon can take part in the stratospheric hydratation, by injecting directly water ice in<br>the stratosphere. Injected ice water, by sublimation, will hydrate stratosphere locally. The<br>local role of overshoots is better known but their contributions at the global scale steal need<br>to be quantified. In order to estimate this contribution, previous studies have used the 3D<br>simulation mesoscale model BRAMS to show overshoot impact in the upper Tropical<br>Tropopause Layer (TTL). These studies are the starting point of our study.</p><p>The aim of this paper is to present the new development inside BRAMS to nudge<br>stratospheric ice injection by overshoots. It uses an overshoot occurrence climatology from<br>MHS (Microwave Humidity Sounder) satellite measurement. Ice injection in the model is<br>made according to ice model categories previously shown to be present in the overshoot<br>plumes with ratios already diagnosed in previous studies. Ice injection is made between two<br>layers of TTL&#8217;s stratospheric part: between 380 and 385K and between 385 et 400K. Nudging<br>is triggered only if, in the grid mesh (20 x 20 km) where MHS has detected an overshoot,<br>BRAMS computes a cumulonimbus with a top above 13.5km. For the layer above 385 K<br>isentrope, a subgrid box of 2 km x 2 km is considered for the computation of ice injection.<br>Sensibility test of this nudging scheme will be presented in this presentation.&#160;</p>
Impact flash evolution of CO
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ice, water ice, and frozen Martian and lunar regolith simulant targets
