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Xin Jin 1 , Yong Han 2 , Ninghai Sun 1 , Fuzhong Weng 2 , Denis Tremblay 3 , Yong Chen 4 , Likun Wang 4 , Xiaozhen Xiong 1 1 ERT, Inc., 2 NOAA/NESDIS/STAR, 3 Science Data Processing, Inc., 4 UMCP Contact: [email protected] A Comprehensive Review of SNPP CrIS Instrument Performance and Data Quality Abstract Operationally trending and monitoring the instrument status and data product quality of the Cross-track Infrared Sounder (CrIS) onboard the S-NPP (Suomi National Polar-orbiting Partnership) satellite has been running for more than three and a half years through the NOAA ICVS system. The orbit-wise spectral noise and response of this instrument show very stable performance. No major hardware anomalies are found in the past year. The system is smoothly switched to full-spectral resolution mode since December 04, 2014. A remaining issue for now is the short-wave impulse noise. For the ground processing system, the contamination of Direct Broadcast data which excludes FOV4 and 6 packets for band rate concern is the most seen problem in the IDPS SDR products. Events of missing SDR granules are occasionally seen due to some caveats in the re-tasking procedure. Another processing anomaly is the bug in lunar intrusion detection algorithm. Instrument status LW MW SW LW MW SW Conclusions The instrument performance and data quality are operationally monitored by NOAA ICVS system. It is concluded that SNPP CrIS’ hardware is in great shape. No instrument anomalies are reported in the past year. After implementing Allan variance it is found that the spectral response is very stable: the LW sensors have almost no degradation since the mission; the MW sensors have noticeable but different changes among difference sensors; the SW sensors have suffered a 2~3% degradation. There are some remaining issues, including lunar intrusion algorithm bug, contamination of DB data stream, and the shortwave impulse noise. All of them are under close monitoring. The IDPS re-tasking procedure sometimes fails to produce proper SDR granules. ICVS alert system can catch this anomaly and inform the IDPS personnel in time. Our ICVS system is updated with many enhancements and it is ready to support the JPSS-1 CrIS mission. Introduct ion NOAA/STAR takes the task of operationally trending CrIS hardware status and monitoring SDR product quality through the Integrated Calibration & Validation System (ICVS). CrIS ICVS covers housekeeping RDR, science telemetry RDR and SDR products, archiving critical information for further analysis, and sending alerts automatically when anomaly is detected. ICVS was improved during the past year with the following enhancements: 1)Implementing Allan variation for spectral noise calculation per orbit, removing the 30- scan standard deviation method 2)Calculating/Archiving NEDN, Gain, Offset, cold and hot reference of all frequencies for each orbit, instead of some selected frequencies 3)Supporting full-spectral resolution RDR and SDR products 4)Supporting both SNPP and JPSS-1 CrIS instruments 5)Collecting SDR anomaly events in a JSON structure on a daily basis 6)Implementing a short-wave impulse noise event detection module for the full-spectral resolution module 7)Flexible switch for monitoring original (‘A1’) and repaired/re-tasked (‘A2’) granules Lunar intrusion FSR SDR: Parallel Mode IDPS SDR: Sequential Mode Currently, the first nominal record of cold reference in a 30-scan calibration window is always considered as no LI. This assumption is in general acceptable in IDPS sequential processing mode. However, it fails frequently in parallel mode. Those good references following the first one are marked as LI cases when compared with the first one and then removed, resulting in the failure of whole scan. Another caveat in the current LI algorithm is the threshold values which are too loose, some partially lunar contaminated measurements are allowed in the calibration. The spectral performance of NPP CrIS is as good as usual. The response of short-wave sensors has ~3% degradation. Sampling laser wavelength and internal target temperature are very stable. The laser diode temperature only increased about 0.2 K. Missing packets of FOV4 & 6 The data rate for Direct Broadcast (DB) is tight after CrIS is switched to full-spectral resolution mode, therefore, CrIS FOV 4 and 6 packets are dropped for DB. Sometimes the DB data stream contaminates the IDPS operational processing line, resulting in missing packets in the SDR products as the drop of calibration window size and/or missing ES pixels of all three bands. Short-wave impulse noise events Red line: threshold = 7.384*log(freq(2:e nd))-59 The impulse noise is caused by the hit of charged particles on the sensor onboard a spacecraft. It is most seen on the South Atlantic Anomaly (SAA) area, where the height of Van Allen radiation belts is below 200 km, letting most spacecrafts exposed in the hash outer space environment (see the low left panel). After switched to full-spectral resolution mode, the impulse noise detection mask on NPP CrIS was removed. Moreover, the SW interferogram arm length is three times longer than before, making it easier hit by energetic particles. As a result, more outliers are found on the DS/ICT spectral stability plots when contaminated measurements are included in the calculation. The third upper panel is a collection of these outliers between Jan 01 and May 31, 2015, well matched with the theoretical pattern. Detecting impulse events on the earth scene is more challenging than on the calibration scenes due to the wide variation of earth scene targets. A method based on power spectral density analysis on the imaginary part radiance is developed to detect impulse events on the earth scene. On average, ~300 events are detected for each day. http:// www.bibliotecapleyades.n et/ciencia/ ciencia_earthchanges49.h tm http:// www.star.nesdis.noaa.gov/icvs/ metrics/status/NPP/CrIS_FSR/ 2015/09/20150930_SW_ES_Impulse. png ITSC-XX: Lake Geneva, Wisconsin, USA, 28 October-3 November 2015
