[1] An evaluation of the temperature and moisture profile retrievals from the Atmospheric Infrared Sounder (AIRS) data is performed using more than 2 years of collocated data sets. The Aqua-AIRS retrievals, global radiosonde (RAOB) measurements, forecast data from the National Center for Environmental Prediction Global Forecasting System (NCEP_GFS), the European Center for Medium Range Forecast (ECMWF), and the operational retrievals from the NOAA 16 satellite Advanced TIROS Operational Vertical Sounder (ATOVS) instrument are used in this validation. Using RAOB observations as the reference, bias and RMS differences are computed for ''sea,'' ''land,'' and ''all'' categories for the AIRS retrievals and other collocated data sets. The results of the intercomparison reveal that temperature and water vapor retrievals from the AIRS are in very good agreement with the RAOBs. The RMS difference for clear-only cases over ''sea'' and ''all'' categories is close to the expected goal accuracies, namely, 1°K in 1 km layers for the temperature and better than 15% in 2-km layers for the water vapor in the troposphere. The overall RMS difference for the cloud-cleared cases is also close to the expected product goal accuracy except for a slight degradation at the surface. When AIRS and ATOVS retrievals are compared with the RAOBs, the AIRS temperature retrievals show an improvement over ATOVS of at least 0.5°K for all the accepted cases. Both the ECMWF and the NCEP_GFS forecasts match the RAOB temperatures within 1°K and water vapor within 14%. With respect to biases, the AIRS final retrieval shows a larger bias with the RAOBs relative to ATOVS, NCEP_GFS, and ECMWF. The bias is highly influenced by a larger bias contribution from ''land'' samples and shows a month-to-month and annual variation that correlates with the CO 2 variations. This coupling suggests a need to include CO 2 and possibly other trace gas climatologies in the AIRS initial guess to partially mitigate the effects in the final physical retrieval.

[1] This paper presents the characterization and validation of retrievals of atmospheric methane (CH 4 ) vertical profiles by the Atmospheric Infrared Sounder (AIRS) on the EOS/Aqua platform. AIRS channels near 7.6 mm are used for CH 4 retrieval, and they are most sensitive to the middle to upper troposphere, i.e., about 200-300 hPa in the tropics and 400-500 hPa in the polar region. The atmospheric temperature-humidity profiles, surface skin temperature, and emissivity required to derive CH 4 are obtained from retrievals using separate AIRS channels and the Advanced Microwave Sounding Unit (AMSU). Comparison of AIRS retrieved profiles with some in situ aircraft CH 4 profiles implied that the forward model used in the AIRS retrieval system V4.0 required a 2% increase in methane absorption coefficients for strong absorption channels, and this bias adjustment was implemented in the AIRS retrieval system V5.0. As a new operational product in V5.0, AIRS CH 4 were validated using in situ aircraft observations at 22 sites of the NOAA Earth System Research Laboratory, Global Monitoring Division (NOAA/ESRL/GMD), ranging from the Arctic to the tropical South Pacific Ocean, but their altitudes are usually above 300 hPa. The results show the bias of the retrieved CH 4 profiles for this version is À1.4$0.1% and its RMS difference is about 0.5-1.6%, depending on altitude. These validation comparisons provide critical assessment of the retrieval algorithm and will continue using more in situ observations together with future improvement to the retrieval algorithm. AIRS CH 4 products include not only the CH 4 profile but also the information content. As examples, the products of AIRS CH 4 in August 2004 and the difference of CH 4 in May and September 2004 are shown. From these results a few features are evident: (1) a large AIRS CH 4 plume southwest of the Tibetan plateau that may be associated with deep convection during the Asian summer monsoon; (2) high mixing ratios of AIRS CH 4 in southeastern Asia and in the high northern hemisphere in the summer; and (3) the increase of AIRS CH 4 from May to September in the high northern hemisphere that is likely linked with wetland emission but needs more study. Further analysis of these data and its comparison with model data will be addressed in a separate paper.

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[1] An evaluation of the Atmospheric Infrared Sounder (AIRS) version 4 (V4) and version 5 (V5) retrieved ozone profiles and the total column ozone is performed using collocated ozonesonde (O 3 SND) profiles and total ozone measurements from the World Ozone and Ultraviolet Radiation Data Center (WOUDC) archives. Using O 3 SNDs and Brewer/Dobson Network (BD) measurements as the truth, bias and root-mean-squared (RMS) difference statistics are computed for the AIRS ozone profile retrievals and the derived total ozone. In addition, global monthly maps of total ozone generated for the AIRS retrievals are compared with the Ozone Monitoring Instrument (OMI) and the Solar Backscatter Ultra Violet (SBUV/2) instrument derived maps to evaluate the characteristic trends and seasonal cycle depicted by the AIRS retrieval. The results of the validation exercise reveal that the AIRS V5 algorithm significantly improves the ozone profile retrieval biases and RMS differences for the lower troposphere and, especially, over the tropical region where the V4 algorithm shows larger discrepancies with the O 3 SND measurements. The V5 retrieval biases with global O 3 SNDs are less than 5% for both the stratosphere and the troposphere. The RMS differences are less than 20% for the upper stratosphere and are close to 20% for the lower stratosphere and the troposphere. Total ozone amounts from both the V4 and V5 versions agree well with the global BD station measurements with a bias of less than 4% and an RMS difference of approximately 8%. Analysis of V5 total ozone monthly maps reveals that the V5 ozone retrievals depict seasonal trends and patterns in concurrence with OMI and SBUV/2 observations. Citation: Divakarla, M., et al. (2008), Evaluation of Atmospheric Infrared Sounder ozone profiles and total ozone retrievals with matched ozonesonde measurements, ECMWF ozone data, and Ozone Monitoring Instrument retrievals,

Abstract:The Joint Polar Satellite System (JPSS) will launch its first JPSS-1 satellite in early 2017. The JPSS-1 and follow-on satellites will carry aboard an array of instruments including the Visible Infrared Imaging Radiometer Suite (VIIRS), the Cross-track Infrared Sounder (CrIS), the Advanced Technology Microwave Sounder (ATMS), and the Ozone Mapping and Profiler Suite (OMPS). These instruments are similar to the instruments currently operating on the Suomi National Polar-orbiting Partnership (S-NPP) satellite. In preparation for the JPSS-1 launch, the JPSS program at the Center for Satellite Applications and Research (JSTAR) Calibration/Validation (Cal/Val) teams, have laid out the Cal/Val plans to oversee JPSS-1 science products' algorithm development efforts, verification and characterization of these algorithms during the pre-launch period, calibration and validation of the products during post-launch, and long-term science maintenance (LTSM). In addition, the team has developed the necessary schedules, deliverables and infrastructure for routing JPSS-1 science product algorithms for operational implementation. This paper presents an overview of these efforts. In addition, this paper will provide insight into the processes of both adapting S-NPP science products for JPSS-1 and performing upgrades for enterprise solutions, and will discuss Cal/Val processes and quality assurance procedures.