Preparing for JPSS-1/ATMS Direct Readout Readiness Acknowledgments: This work was performed under contract NAS , sponsored by NASA Nikisa S. George & Kent Anderson Northrop Grumman Electronic Systems, Azusa CA, 91702, U.S.A. Overview The Advanced Technology Microwave Sounder (ATMS), manufactured by Northrop Grumman Electronic Systems (NGES) in Azusa CA, was launched on October 28, 2011 aboard the Suomi National Polar-orbiting Partnership (NPP) spacecraft ATMS works in conjunction with the Cross-track Infrared Sounder (CrIS) to measure atmospheric temperature and humidity profiles and is the follow-on to the Advanced Microwave Sounding Units -A and -B The next ATMS, currently in system-level testing, will be on the Joint Polar Satellite System-1 (JPSS-1), planned for launch in 2017 This study reviews: Our performance assessments from Cal-Val activities Scan-dependent radiometric biases and “striping” Preliminary algorithm options that may be useful for direct readout users Summary of NPP On-orbit Assessments Radiometric Sensitivity: Channels 1-16 reduced by 1/3, for direct comparison to AMSU-A (Figure 2a) Radiometric Accuracy: Analytic model, with parameter updates based on On-orbit Data (Figure 2b) Figure 1. a) ATMS Channelization Compared to AMSU, b) ATMS Proto-flight Model, and c)Ch 18 T B of Hurricane Isaac Figure 3. Channel 1 and channel 17 scan-dependent radiometric biases, observed during pitch-maneuver Figure 4. ATMS Striping example Conclusions Stability of critical temperature-dependent parameters is significantly better than predicted Sensitivity (NEDT) is consistent with ground tests, and is an improvement over AMSU when averaged for equivalent footprint sizes Other phenomena, such as scan-dependent biases and striping, are being characterized and modeled  Basis for deriving related requirements for future units  Algorithm enhancements are under development to mitigate their effects ATMS Description Total-power radiometer, two-point external calibration Continuous cross-track scanning Functional-equivalent follow-on to AMSU-A and MHS, with improved sampling and coverage Figure 2. a) NEDT compared to requirements and AMSU- A / MHS and b) Radiometric Accuracy, with & without quadratic corrections “Striping” Noise “Striping” is due to scan-to-scan (down-track) variations that are greater than sample-to-sample variations within a scan (cross-track) (see Figure 4)  No requirement has yet been established, but it is now recognized that such a requirement needs to be developed  Phenomenon is due to low-frequency gain fluctuations, predominantly in front-end LNAs Associated issue of multi-channel correlation of gain fluctuations is also under investigation ATMS Chan AMSU-A,B Chan Center Freq (GHz) Pre-Detection Bandwidth (MHz) Pol QV QV QH QH QH ± QH QH QH QH QH ± QH ±0.3222± QH ±0.3222± QH ±0.3222±0.0108QH ±0.3222± QH QV QH ± QH ± QH ± QH ± QH ±1.0500QH b) c) a) b) Scan-dependent Radiometric Bias  Primarily due to scanning reflector polarized emissivity  Minor secondary effect, may be due to reflector spillover (TBD)  Causes both a systematic angle-dependent error and an overall bias (due to radiometric offset of cold-calibration measurement) Potential Algorithm Options for JPSS Corrections for the scan-dependent bias, based on modeled effect of reflector emissivity Multi-channel processing to reduce correlated errors Corrections for polarization angle errors and cross-pol contamination More sophisticated techniques (TBD) to reduce striping Feb 20, ATMS Pitch Maneuver; Ch 3 in Kelvin Cross Track Beam Position Down Track Scan  : Emissivity = 0.37% T ref : Reflector Temperature = 0.0° C  : Scan Angle