Ozone diurnal variations and mean profiles in the mesosphere, lower thermosphere, and stratosphere, based on measurements from SABER on TIMED

Abstract

Ozone measurements from SABER on the TIMED satellite form a unique data set. They provide global information over the range of local solar times, from the lower stratosphere into the lower thermosphere, from the beginning of 2002, by one instrument. On the basis of zonal means of these data, we present new results from 20 to 100 km in altitude and from 48°S to 48°N in latitude, of ozone diurnal variations over 24 h in local solar time and over an annual cycle. While some of the results are new for the stratosphere, such comprehensive results for the mesosphere and lower thermosphere have not been available before. The diurnal variations generally become increasingly significant from the upper stratosphere into the lower thermosphere and provide information on the photochemistry of ozone and effects of transport over a diurnal cycle. Over most altitudes in the mesosphere and lower thermosphere (MLT), our estimates show the expected decrease in ozone after sunrise, with smaller variations during the day, and the increase near sunset. Outside of a small altitude near 80 km, the nighttime mixing ratios are generally larger than the daytime values. The diurnal variations themselves appear to exhibit variations over an annual cycle, including semiannual and annual variations. We compare the SABER results with data obtained about 10 years earlier by the MLS instrument on UARS, and with results by others based on data from HRDI on UARS, from the Solar Mesosphere Explorer (SME), from selected space shuttle experiments, and from ground‐based measurements. From the middle mesosphere to higher altitudes, departures from local thermodynamic equilibrium (non‐LTE) can be significant, and the uncertainties can be larger than those at lower altitudes.