A method to derive the Site Atmospheric State Best Estimate (SASBE) of ozone profiles from radiosonde and passive microwave data

Abstract

Abstract. We present a method to derive the site atmospheric state best estimate (SASBE) of the ozone profile combining brightness temperature spectra around the 142 GHz absorption line of ozone measured by the microwave radiometer SOMORA and ozone profiles measured by the radiosonde (RS). The SASBE ozone profile is obtained using the radiosonde ozone profile as a priori information in an optimal estimation retrieval of the SOMORA radiometer. The resulting ozone profile ranges from ground up to 65 km altitude and makes optimal use of the available information at each altitude. The high vertical resolution of the radiosonde profile can be conserved and the uncertainty of the SASBE is well defined at each altitude. A SASBE ozone profile dataset has been generated for Payerne, Switzerland, with a temporal resolution of 3 profiles a week for the time period ranging from 2011 to 2013. The relative difference of the SASBE ozone profiles to the AURA/MLS ozone profiles lies between −3 to 6% over the vertical range of 20–65 km. Above 20 km, the agreement between the SASBE and AURA/MLS ozone profiles is better than the agreement between the operational SOMORA ozone data set and AURA/MLS. Below 20 km the SASBE ozone data are identical to the radiosonde measurements. The same method has been applied to ECWMF-ERA interim ozone profiles and SOMORA data to generate a SASBE dataset with a time resolution of 4 profiles per day. These SASBE ozone profiles agree between −4 and +8% with AURA/MLS. The improved agreement of the SASBE datasets with AURA/MLS above 20 km demonstrates the benefit of better a priori information in the retrieval of ozone from brightness temperature data.

Final response

“…4a turns southward before reaching the vortex erosion region above the Caspian Sea. Figures 4a and 5a are appropriate for visualizing the surf zone of the midlatitude stratosphere in winter (McIntyre and Palmer, 1984). Figures 4a and 5a also show the anti-correlation of the spatial distributions of ozone and water vapour in the mid-stratosphere since stratospheric polar air is rich in water vapour and poor in ozone.…”

“…Therefore, the retrieved ozone values at these altitudes are primarily based on the measured line spectrum. For technical details, measurement principle and retrieval procedure of the instruments; see, for example, Moreira et al (2015), Peter (1997), Hocke et al (2007), Maillard Barras et al (2009Barras et al ( , 2015 and references included therein. An intercomparison study of Hocke et al (2007) indicated that the relative differences between SOMORA and Aura/MLS are less than 10 %.…”

“…Rossby wave breaking occurs in the middle and upper stratosphere during the winter season. In particular, the midlatitudes are regarded as the surf zone of the stratosphere where the material erosion of the polar vortex takes place (McIntyre and Palmer, 1984). The material erosion of the vortex leads to water vapour filaments at midlatitudes since the vortex air is rich in water vapour which has a long lifetime in the stratosphere.…”

Combining Data from the Distributed GRUAN Site Lauder-Invercargill, New Zealand, to Provide a Site Atmospheric State Best Estimate of Temperature

“…Most overpasses of a satellite during the years 1997-2012 will lead to a close collocation in time, given the hourly resolution of the SASBE. Using individual radiosonde measurements rather than a SASBE can minimise the number of collocations significantly, as was the case in Calbet et al (2017), who analysed differences between the Infrared Atmospheric Sounding Interferometer (IASI, Siméoni et al, 1997) and GRUAN radiosonde profiles, but was limited to using data from one GRUAN site only. If the satellite data product, i.e.…”

An Atlantic streamer in stratospheric ozone observations and SD-WACCM simulation data

“…Therefore, the retrieved ozone values at these altitudes are primarily based on the measured line spectrum. For technical details, measurement principle and retrieval procedure of the instruments; see, for example, Moreira et al (2015), Peter (1997), Hocke et al (2007), Maillard Barras et al (2009Barras et al ( , 2015 and references included therein. An intercomparison study of Hocke et al (2007) (Moreira et al, 2015;Studer et al, 2014Studer et al, , 2012Keckhut et al, 2010;Flury et al, 2009;Steinbrecht et al, 2009;Hocke et al, 2007;Dumitru et al, 2006).…”