Application of φ-IASI to IASI: retrieval products evaluation and radiative transfer consistency

G Masiello,G Grieco,M Matricardi,A Carissimo,C Serio

doi:10.5194/acp-9-8771-2009

Abstract

Abstract. Retrieval products for temperature, water vapour and ozone have been obtained from spectral radiances measured by the Infrared Atmospheric Sounding Interferometer flying onboard the first European Meteorological Operational satellite. These products have been used to check the consistency of the forward model and its accuracy and the expected retrieval performance. The study has been carried out using a research-oriented forward-inverse methodology, called φ-IASI, that the authors have specifically developed for the new sounding interferometer. The performance of the forward-inversion strategy has been assessed by comparing the retrieved profiles to profiles of temperature, water vapour and ozone obtained by co-locating in space and time profiles from radiosonde observations and from the European Centre for Medium-Range Weather Forecasts analysis. Spectral residuals have also been computed and analyzed to assess the quality of the forward model. Two versions of the high-resolution transmission molecular absorption database have been used, which mostly differ for ozone absorption line parameters, line and continuum absorption of both CO2 and H2O molecules. Their performance has been assessed by inter-comparing the results, and a consistent improvement in the spectral residual has been found when using the most updated release.

Highlights

The study presents and describes the application of the φIASI package (Grieco et al, 2007) to the retrieval of temperature, moisture and ozone from IASI (Infrared Atmospheric Sounding Interferometer) data obtained during the commissioning phase of the instrument in 2007
A historical background of the IASI instrument can be found in Bizzarri (1993)
The design of the IASI instrument is based on a Michelson interferometer and its basic concept dates back to the work of Cayla (Cayla, 1993)

Summary

Introduction

The study presents and describes the application of the φIASI package (Grieco et al, 2007) to the retrieval of temperature, moisture and ozone from IASI (Infrared Atmospheric Sounding Interferometer) data obtained during the commissioning phase of the instrument in 2007. The data set consists of 25 clear-sky, sea surface, IASI spectra, with time and space collocated radiosonde observations. The second dataset consists of 647 IASI spectra, which were measured during the IASI commissioning phase on 22 July 2007 over the tropical belts For this second dataset of IASI observations, in-situ (truth) data consist of profiles for temperature, water vapour and ozone from the ECMWF analysis for the same date and location as those of the IASI soundings. This second data set has been mostly used for an independent check of IASI retrieval accuracy.

The φ-IASI package and its expected performance for IASI

The inverse model δ-IASI r

Findings

Background