On the inclusion of Limb Infrared Monitor of the Stratosphere version 6 ozone in a data assimilation system

Abstract

AbstractVersion 6 ozone profiles for 1978–1979 from the Limb Infrared Monitor of the Stratosphere experiment on the NIMBUS 7 satellite (or LIMS v6) are assimilated into an updated version of the GEOS‐5 model of NASA. First, an assimilation study is carried out using GEOS‐5 version 7.2 (v7.2) and solar backscatter ultraviolet (SBUV) version 8.6 ozone profiles. Then, a second study is conducted that ingests both the LIMS and SBUV ozone, as weighted by their estimated absolute error vectors. Ozone from this second study compares well with independent observations from the Stratospheric Aerosol and Gas Experiment (SAGE I) and from the time series of ozonesonde data at Hohenpeissenberg and at Wallops Island. Assimilation of the LIMS data gives improved ozone distributions in the upper stratosphere (pressure < 5 hPa) and in the polar night region—the latter where solar backscatter ultraviolet (SBUV) is not observed. The LIMS ozone leads to improved total column ozone analyses in winter/spring outside of the tropics, based on independent comparisons with total ozone from the Total Ozone Mapping Spectrometer. The LIMS ozone also adds information in the tropics on coherent structural features at 20–30 hPa, related to the phase transition of the quasi‐biennial oscillation wind field. It is affirmed that the process of data assimilation represents a cost‐effective way of characterizing new and/or reprocessed satellite ozone data sets. It is concluded that the GEOS‐5 v7.2 model with the addition of the LIMS data can improve analyses of ozone in 1978–1979.