Retrieval validation during the European Aqua Thermodynamic Experiment

Abstract

Atmospheric and surface thermodynamic parameters retrieved with advanced hyperspectral remote sensors aboard Earth observing satellites are critical to weather prediction and scientific research. The retrieval algorithms and retrieved parameters from satellite sounders must be validated to demonstrate the capability and accuracy of both observation and data processing systems. The European Aqua Thermodynamic Experiment (EAQUATE) was conducted not only for validation of the Atmospheric InfraRed Sounder on the Aqua satellite, but also for assessment of validation systems of both ground-based and aircraft-based instruments that will be used for other satellite systems, such as the Infrared Atmospheric Sounding Interferometer on the European MetOp satellite, the Cross-track Infrared Sounder from the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project and the continuing series of NPOESS satellites. Detailed intercomparisons were conducted and presented using different retrieval methodologies: measurements from airborne ultraspectral Fourier transform spectrometers, aircraft in situ instruments, dedicated dropsondes and radiosondes, ground-based Raman lidar, as well as the European Centre for Medium-range Weather Forecasting modelled thermal structures. The results of this study not only illustrate the quality of the measurements and retrieval products, but also demonstrate the capability of the validation systems put in place to validate current and future hyperspectral sounding instruments and their scientific products.

Surface emissivity effects on thermodynamic retrieval of IR spectral radiance

“…Typical emissivity spectra retrieved from water, land, and desert are plotted in comparison with laboratory measurements. These reasonable retrieved surface properties greatly support the accurate atmospheric retrievals which are found elsewhere 14 . Preliminary validation analyses on land emissivity retrieval have been performed 8 ; however, additional validations over different surface types are strongly desired in order to provide more-definitive conclusions.…”

“…This implies that the same technique can be applied to land where the surface emissivity is largely not well known. The same inversion algorithm has been applied to the Atmospheric InfraRed Sounder (AIRS) 13 data from the AQUA satellite 14 . As the satellite data covers a large variety of surface and atmospheric conditions, the retrieval scheme is tested with a large variety of conditions.…”

All weather IASI single field-of-view retrievals: case study – validation with JAIVEx data

“…However, detailed validation in estimating both forward and inversion model errors can be fulfilled with dedicated field campaigns. Here, atmospheric conditions are coincidently captured by multiple instruments from both ground and aircraft validation sites (e.g., Zhou et al, 2007b;Taylor et al, 2008), where dedi- cated coincident radiosondes were launched under satellite overpasses for a reasonable period (e.g., Tobin et al, 2006;Pougatchev, 2008). This atmospheric profile retrieval is a solution of an "ill-posed" problem and its retrieval accuracy is measurement or scene dependent.…”

IASI spectral radiance validation inter-comparisons: case study assessment from the JAIVEx field campaign

“…Continuation of aircraft under-flights for multiple satellites during multiple field campaigns enables longterm monitoring of system performance and inter-satellite cross-validation. Data from campaign under-flights with airborne FTS systems, such as the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed-Interferometer (NAST-I) (Cousins et al, 1997;Smith et al, 1999), have proven to be very useful in earlier Atmospheric InfraRed Sounder (AIRS) Pagano et al, 2003) and Infrared Atmospheric Sounding Interferometer (IASI) (Amato et al, 1995;Blumstein et al, 2004;Cayla, 1993) validation studies (Larar et al, 2003Newman et al, 2009;Tobin et al, 2006;Zhou et al, 2007a). NAST-I, maintained and deployed internationally by NASA Langley Research Center…”

“…infrared spectral radiance), and does so at higher spectral and spatial resolutions. LaRC analysis is further benefited from implementing an independent set of algorithms associated with, e.g., fast radiative transfer modeling and geophysical product retrievals to enable an independent, concurrent validation of derived level-2 products (Liu et al, 2007;Zhou et al, 2007a). Field campaign data from coincident measurement assets (i.e., ground, balloon, aircraft, and satellite) are then available for not only the implementation and improvement of validation methodologies but, also, to implement, validate, and improve radiative transfer and retrieval algorithms and future measurement system specifications (e.g., Carissimo et al, 2006;Grieco et al, 2007;Strow et al, 2006Strow et al, , 2008Liu et al, 2009;Serio et al, 2009;Taylor et al, 2008;Zhou et al, 2009).…”