Ding-Yi Wang

Mixing Processes during the Antarctic Vortex Split in September–October 2002 as Inferred from Source Gas and Ozone Distributions from ENVISAT–MIPAS

Abstract In late September 2002, an Antarctic major stratospheric warming occurred, which led to a strong distortion of the southern polar vortex and to a split of its mid- and upper-stratospheric parts. Such an event had never before been observed since the beginning of regular Antarctic stratospheric temperature observations in the 1950s. The split is studied by means of nonoperational level-2 CH4, N2O, CFC-11, and O3 data, retrieved at the Institute for Meteorology and Climate Research Karlsruhe (IMK) from high-resolution atmospheric limb emission spectra from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the European research satellite, Environmental Satellite (ENVISAT). Retrieved horizontal and vertical distributions of CH4 and N2O show good consistency with potential vorticity fields of the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis for the entire period under investigation, even for fine structures such as vortex filaments. Tracer correlatio...

Evaluation of Stratospheric Radio Occultation Retrieval Using Data from CHAMP, MIPAS, GOMOS, and ECMWF Analysis Fields

Two radio occultation (RO) retrieval schemes designed at IGAM to enhance the performance at high altitudes are presented, applied to CHAMP RO data, and validated against ECMWF analyses, GFZ operational retrieval, ENVSAT/MIPAS-, and ENVIAT/GOMOS-derived temperature profiles. IGAM proposes to include background information into the RO retrieval only at one point at bending angle level in order to be able to track error characteristics of the retrieved product. The results show very good agreement with GFZ retrieval and ECMWF analysis below 15 km and, depending on the background information used, either a significant warm bias or essentially no bias up to 30 km. Compared to MIPAS, the only independent data source, the IGAM/ECMWF retrieval is unbiased up to 40 km.

Comparisons of MIPAS-observed temperature profiles with other satellite measurements

MIPAS on ENVISAT measures vertical profiles of atmospheric temperature, ozone, and other species with nearly global coverage and high accuracy/precision. The standard observation mode covers the altitude region between 6 and 68 km. The atmospheric state parameters retrieved from MIPAS measurements using the IMK data analysis processor are compared with a number of other satellite observations. Our comparisons in this paper will focus on temperatures measured by MIPAS, HALOE, SABER, and UKMO Stratospheric Assimilated Data. Both individual profiles and zonal means measured by MIPAS and other instruments at different seasons and geolocations show reasonable agreement, though some differences exist due to characteristics of the individual instruments and observation scenarios. The MIPAS measurements during the stratospheric major sudden warming during the southern hemisphere winter of 2002 are also presented to show the features of this unusual event. The analysis indicates the reliability of MIPAS-IMK data products and their capability for providing valuable scientific information.

Comparison of GPS/SAC-C and MIPAS/ENVISAT Temperature Profiles and Its Possible Implementation for EOS MLS Observations

This analysis presents comparisons of the atmospheric temperatures retrieved from GPS/SAC-C radio occultation observations using the JPL retrieval software, and from MIPAS/ENVISAT infrared spectrum measurements using the IMK data processor. Both individual profiles and zonal means of the atmospheric temperature at different seasons and geo-locations show reasonable agreement. For the temperatures at altitudes between 8–30 km, the mean differences between the correlative measurements are estimated at less than 2 K with rms deviations less than 5 K. A similar cross comparison technique can be used to help validate the observed temperatures from the new EOS MLS instrument, to be launched in 2004.

Comparisons of MIPAS/ENVISAT and GPS-RO/CHAMP Temperatures

The temperatures retrieved from MIPAS/ENVISAT limb mid-infrared emission and CHAMP GPS radio occultation measurements are compared at altitudes between 8 – 30 km during the stratospheric major sudden warming in the southern hemisphere winter of 2002. The mean differences between the correlative measurements of the two instruments are less than ∼1 K with rms deviations of ∼3–5 K. The MIPAS temperatures are slightly higher than those of GPS-RO around 30 km. Possible explanation is discussed.