Seasonal cycle of hydrogen peroxide on Mars integrated over the Martian disk. Observed regions are centered around 20N during northern spring and summer, and around 20S during northern autumn and winter. Yellow: 3D GCM model considering only the gas phase. Blue: 3D GCM model considering heterogeneous chemistry on water ice grains. Blue circles: 1D model by Krasnopolsky (2009). Green squares: 1D model by Moudden (2007). The figure has been updated from Lefèvre et al. (2008) and Encrenaz et al. (2012).