Assessment of TOVS‐derived stratospheric temperatures up to 10 hPa for episodes of the European Arctic Stratospheric Ozone Experiment campaign

Abstract

The European Arctic Stratospheric Ozone Experiment (EASOE) campaign, conducted during the winter of 1991–1992 to study the evolution of the Arctic stratosphere, has provided the scientific community with a large data set and, in particular, radiosonde reports which yield information up to the lower stratosphere, thereby allowing the validation of satellite‐derived products. Global observations from the satellites of the TIROS N series for several episodes of the EASOE campaign have been analyzed using the improved initialization inversion (3I) algorithm. The use of both the high‐resolution infrared radiometer sounder (HIRS‐2) and the microwave sounding unit (MSU) radiometric observations permits the determination of the temperature profile up to about 10 hPa (about 30 km). The evolution of the thermal fields in the stratosphere is examined for two stratospheric cooling events and a minor stratospheric warming, along with more standard conditions for midwinter and end of winter. For all these cases, colocations between 3I‐retrieved temperature profiles and radiosonde reports, as well as comparisons with analyzed temperatures in the low stratosphere provided by the Stratospheric Research Group of the Free University of Berlin, are presented and discussed in order to assess the accuracy of the retrievals in this part of the atmosphere. The TIROS N operational vertical sounder is able to resolve the stratospheric coolings and warming, but not always with the right intensity. The agreement with the Berlin analyses is better in the layer 50–30 hPa than in the layer 30–10 hPa and better for “regular” than for disturbed situations.