Update and rename percussion.md to percusion.md

Description of PERCUSION

orcestra_book/_toc.yml

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     - file: bowtie
     - file: piccolo
     - file: score

orcestra_book/percusion.md

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+#  PERCUSION
+
+**Persistent EarthCare underflight studies of the ITCZ and organized convection**
+
+*Lead PIs: Julia Windmiller, Bjorn Stevens, Lutz Hirsch (MPI-M), Felix Ament, Ann-Kristin Naumann (UHH), Susanne Crewell, Claudia Acquistapace, Sabrina Schnitt (U Cologne), Bernhard Mayer (LMU), Manfred Wendisch, André Ehrlich (U Leipzig), Silke Gross (DLR),*
+
+PERCUSION is a German initiative that uses the German research aircraft [HALO](https://halo-research.de) and ESA's [EarthCARE](https://earth.esa.int/eogateway/missions/earthcare) satellite aiming to test factors hypothesized to influence the organization of deep maritime convection in the tropics, and the influence of convective organization on its larger-scale environment.
+PERCUSION will extend the NARVAL missions and EUREC4A cases to missing convective (and aerosol) regimes and contribute to a broader view of cloud-circulation coupling over the tropical oceans. PERCUSION will add a new dimension to the previous measurements through it’s
+
+Focus on deep convection close to and at the Intertropical Convergence Zone. This will complement the EUREC4A measurements, which have focused on the winter downstream trade-wind regimes and provide a more comprehensive picture of the tropical circulation.
+Studying the impact of different aerosol regimes. HALO will operate three weeks in the western (42W-60W) tropical Atlantic flying out of Barbados, and three weeks in the eastern (25W-43W) flying out of Cape Verde, respectively. This will contrast clouds and circulation in relatively particulate-free air, or in aged dust layers, in the west, with air masses with large (Saharan) dust burdens in the east.
+Towards a global coverage by locally validating EarthCARE. The upcoming EarthCARE satellite will become a spaceborne cloud observatory and will enable us to extend local studies to globa al scale. To establish confidence in EarthCARE products and inform their most intelligent use, we will intensively use HALO underflights for validation purposes.