Comparison of Column-Averaged Volume Mixing Ratios of Carbon Dioxide Retrieved From IASI/METOP-A Using KLIMA Algorithm and TANSO-FTS/GOSAT Level 2 Products

The ESA research project "Application of KLIMAAlgorithm to CO Retrieval from IASI/METOP-A Observationsand Comparison with TANSO-FTS/GOSAT Products" aims todevelop a dedicated software, based on the KLIMA inversionalgorithm (originally proposed by IFAC-CNR for the 6 cycle ofESA Earth Explorer Core Missions), suited for CO retrieval andintegrated into the ESA grid-based operational environment GridProcessing On-Demand (G-POD) to process Level 1 data acquiredby the infrared atmospheric sounding interferometer (IASI)and to perform a comparison with Thermal And Near-infraredSensor for carbon Observation Fourier Transform Spectrometer(TANSO-FTS), on board of the Greenhouse gases ObservingSATellite (GOSAT), Level 2 data. In order to obtain a reasonablecapacity to bulk processing IASI data, we choose to integratethe KLIMA code into the G-POD system. For this reason, weinvestigated an optimized version of the KLIMA algorithm,aiming at developing a nonoperational retrieval code with ad-equate features for the integration on the G-POD system. Theoptimized version of KLIMA retrieval code has been completedand integrated on the G-POD operational environment and isavailable for bulk processing of IASI data. Using the KLIMAinversion code integrated into the ESA G-POD, it was possibleto perform an extensive comparison of a selected set of IASImeasurements collocated with TANSO-FTS observations. Weperformed an extensive comparison of the column-average COdry air mole fraction (XCO ) retrieved from IASI measurementsby using the KLIMA/G-POD inversion code with the operationalLevel 2 SWIR products (Version 01.xx and Version 02.xx) fromcollocated TANSO-FTS observations. In this work, we describethe strategy adopted for the comparison and we show the resultsof this activity.