The 2‐Day Photochemical Oscillations in the Mesopause Region: The First Experimental Evidence?

In this study, we analyze the main features of the 2‐day photochemical oscillations (2DPO) in the mesopause region (80–90 km) caused by the nonlinear response of mesospheric chemistry to 1‐day variations of solar radiation. The main indicators of 2DPO useful for subsequent detection of this phenomenon in satellite data are extracted from the theoretical data sets obtained using different chemical‐transport modeling approaches. The indicators are applied to find examples of these oscillations in the nighttime profiles of H and O concentration for the year 2003, taken from the SABER database. The 2DPO appearance/suppression is controlled by a local value of vertical eddy diffusion coefficient Dzz which is a critical parameter for three‐dimensional constituent distributions in the upper mesosphere and lower thermosphere. Thus, the experimental registration of 2DPO can be used to validate and subsequently improve the retrieval procedures in future determinations of a detailed distribution of Dzz. Plain Language Summary For the first time, modern methods of Earth's satellite remote sensing revealed nontrivial chemical oscillations in the mesopause region which is the most interesting but poorly understood region of the atmosphere. Key Points We analyze the main features of the 2‐day photochemical oscillations in the mesopause region caused by diurnal variations of solar radiation We derive the indicators of these oscillations and apply them to the SABER data We present quite a number of H profiles that may indicate the existence of the 2‐day oscillations in the real mesopause