Validation of Level 2 Temperature and Water Vapor Profiles from JPSS and EUMETSAT Operational Polar Satellites using DOE ARM, SuomiNet, and COSMIC Datasets

Launched in 2002, the Atmospheric Infrared Sounder (AIRS) on the NASA Aqua satellite was the first of a new generation of satellite observations at high spectral resolution in the thermal infrared that combined with coincident microwave observations from the AMSU sensor provided the capability for retrieving profiles with higher vertical resolution over both ocean and land areas. The high spectral resolution infrared brightness temperature observations are able to achieve a new level of absolute accuracy (0.2-0.3K) with traceability to temperature standards pre-launch. The AIRS sensor has now measured a 10-year global dataset of IR brightness temperatures and corresponding derived temperature/water vapor vertical profiles. The operational follow-on to the AIRS is the IASI sensor on the MetOp satellites and the Cross-track Infrared Sounder (CrIS) on the Suomi NPP and the JPSS series of operational satellites. Numerous spectral channels in the thermal infrared have peak emission in the stratosphere and throughout the troposphere. AIRS, IASI, and CrIS have similar sounding capabilities and each or the responsible organizations, NASA, EUMETSAT, and NOAA, have implemented operational algorithms to exploit the large number of microwave and infrared channels from these new sensors to derived temperature and water vapor profiles in near-real time. The latest version of the NASA AIRS science team algorithm (version 6) are publicly available from the Goddard Earth Sciences Data and Information Center spanning the time period from September 2002 through the present (nearly 12 years). These data are particularly useful for evaluating decadal trends in atmospheric quantities. While prior versions of the ARIS data have been extensively evaluated in numerous publications, the version 6 products are relative new and are subject to further validation. The operational record from the IASI sensor has been processed by NOAA using a heritage version of the AIRS algorithm (NOAA-IASI) while in parallel EUMETSAT has processed IASI data using an independent algorithm (EUMETSAT-IASI). The NOAA-IASI product is available from the NOAA CLASS archive while the EUMETSAT-IASI product is available from the EUMETSAT archive. In this study the most recent EUMETSAT L2 product version 6 will be evaluated. The ATMS/CrIS sensor suite on the Suomi-NPP satellite has been processed by NOAA using two independent algorithms; 1) the NUCAPS product based on a heritage AIRS algorithm, and 2) the CrIMSS product based on an algorithm developed by the defunct NPOESS program. Both of these NOAA products are currently available from the NOAA CLASS archive.

In order to provide a consistent validation across multiple satellite platforms, multiple sensor types, and multiple retrieval algorithms, the authors have selected a small set of well-characterized validation datasets. The DOE ARM program has provided ground based in situ and remote sensing observations of the atmosphere from tropical, mid-latitude, and Arctic locations since 1997. The authors have been extensively involved in the ARM program (now ASR) from it's inception and are familiar with the ARM datasets and their absolute accuracy. In particular, this study will make use of the ARM 22-GHz 2-channel microwave radiometer (MWR) for measurements of precipitable water vapor (MWR) at each of three ARM sites (TWP Darwin, SGP Lamont, NSA Barrow). The method is to estimate the PWV at the ARM sites for each satellite overpass from the beginning of each satellite sensor data record through June 2014. The details of this method will be described in the presentation. In a similar manner, water vapor profiles are obtained from the Raman Lidar at the SGP and Darwin sites for each satellite overpass. Vaisala RS92 sonde profiles interpolated to the overpass times are also available for assessment. ARM dedicated sonde launches at Aqua overpass times have been previously reported in the literature by the authors. Similar dedicated launches are being conducted for validation of the Suomi-NPP products and the analysis is in progress. In order to extend the water vapor validation from the point site to regional scales, the UCAR SuomiNet observations of PWV from ground-based GPS receivers has been included in the analysis. GPS signals are also being used for temperature validation of the sounder products through comparison to the UCAR COSMIC temperature profiles. The COSMIC network data are available from the COSMIC Data Analysis and Archive Center and include concurrent processing of the GRAS sensor on the METOP platform as well as coincident NWP reanalysis model profiles. Preliminary results of the inter-comparison of products to the common validation datasets will be presented.