NDSC millimeter wave ozone observations at Lauder, New Zealand, 1992–1998: Improved methodology, validation, and variation study

Abstract

Abstract. A ground-based millimeter wave radiometer for the Network for the Detection of Stratospheric Change (NDSC) was installed at Lauder, New Zealand (45øS, 169.7øE) in November 1992. It has been monitoring the middle atmospheric ozone with nearly continuous operation since then. Owing to special complications in the observing conditions at this southern midlatitude site, three refinements to the data analysis and calibration techniques were proposed: (1) the use of a radiative model of local tropospheric climate adopted to the low surface elevation of the observing site, (2) the correction of observing angle measurements due to the settling of the foundation of the site, and (3) the improved method of radiometric temperature determination of calibration sources. All data from 1992 to 1998 were reprocessed with these modifications implemented. The retrieved ozone profiles are compared to sonde, two lidars, and satellite (Halogen Occultation Experiment (HALOE), Stratospheric Aerosol and Gas Experiment (SAGE II)) overpass measurements. The agreement is very good, with mean differences from 56 to 1 mbar of generally 2-3% for the comparisons with sonde, HALOE, and SAGE II, and generally <5% for the comparisons with lidars when large samples are considered. The root-mean-square scatter about the mean differences is mostly consistent with the expected (combined) precision. In comparisons with these correlative measurements, the millimeter wave ozone observations are found to have no seasonal bias, no comparison bias due to the a priori profiles used in millimeter wave data retrievals, and no observable instrument drift from 1992 to 1998. Better agreement is found in the comparison with sonde data if suspected vertical shifts in the sonde profiles are considered. The variations seen in the 6 year millimeter wave ozone data are shown to be mostly in line with photochemistry and dynamic transport processes in the mid austral latitudes. These processes, however, are apparently modulated somewhat by the Antarctic polar vortex circulation in winter seasons in the upper stratosphere.

Geophysical validation of MIPAS-ENVISAT operational ozone data

“…The individual errors bars usually are given in each ozone data file. Typical accuracy ranges from 5% at 20 km to 20% at 70 km where the information content is smaller leaving a larger weight to a priori constraints Tsou, , 2000. Its low vertical resolution poses additional problems for comparisons, for which dedicated methods have been developed (Calisesi et al, 2005).…”

Technical Note: Validation of Odin/SMR limb observations of ozone, comparisons with OSIRIS, POAM III, ground-based and balloon-borne instruments

“…Altitude resolution and accuracy of the retrieved stratospheric ozone profiles are 7 to 10 km and 7 to 10%, respectively. Many studies have validated ozone profiles from microwave radiometers (e.g., McDermid et al, 1998;McPeters et al, 1999;Tsou et al, 2000). More detailed descriptions of the Lidar and Microwave NDACC instruments are given by Steinbrecht et al (2006).…”

Intercomparison of stratospheric ozone and temperature profiles during the October 2005 Hohenpeißenberg Ozone Profiling Experiment (HOPE)

“…While the first intercomparisons resulted in major hardware and software improvements (McGee et al, 1991(McGee et al, , 1993(McGee et al, , 1995a, the configuration of the NASA lidar has been very stable and mature since about 1995. Comparisons of the NASA lidar at Haute Provence , Mauna Loa (McPeters et al, 1999), and Lauder (McDermid et al, 1998a, b) have shown that it measures ozone profiles with less than 5% bias between 15 and 45 km altitude, and with less than 3% bias between 20 and 40 km (see also Tsou et al, 2000;Keckhut et al, 2004). Precision (repeatability) is typically better than 3% between 20 and 40 km, dropping to 10% at 15 or 45 km, and to 50% near 50 km.…”