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The Suomi National Polar orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) has onboard calibrators called blackbody (BB) and Space View (SV) for Thermal Emissive Band (TEB) radiometric calibration. In normal operation, the BB temperature is set to 292.5 K providing one radiance level. From the NOAA’s Integrated Calibration and Validation System (ICVS) monitoring system, the TEB calibration factors (F-factors) have been trended and show very stable responses, however the BB Warm-Up-Cool-Down (WUCD) cycles provide detectors’ gain and temperature dependent sensitivity measurements. Since the launch of S-NPP, the NOAA Sea Surface Temperature (SST) group noticed unexpected global SST anomalies during the WUCD cycles. In this study, the TEB Ffactors are calculated during the WUCD cycle on June 17th 2015. The TEB F-factors are analyzed by identifying the VIIRS On-Board Calibrator Intermediate Product (OBCIP) files to be Warm-Up or Cool-Down granules. To correct the SST anomaly, an F-factor correction parameter is calculated by the modified C1 (or b1) values which are derived from the linear portion of C1 coefficient during the WUCD. The F-factor correction factors are applied back to the original VIIRS SST bands showing significantly reducing the F-factor changes. Obvious improvements are observed in M12, M14 and M16, but corrections effects are hardly seen in M16. Further investigation is needed to find out the source of the F-factor oscillations during the WUCD.

The performance of the Community Radiative Transfer Model (CRTM) under ice cloud conditions is evaluated and improved with the implementation of MODIS collection 6 ice cloud optical property model based on the use of severely roughened solid column aggregates and a modified Gamma particle size distribution. New ice cloud bulk scattering properties (namely, the extinction efficiency, single-scattering albedo, asymmetry factor, and scattering phase function) suitable for application to the CRTM are calculated by using the most up-to-date ice particle optical property library. CRTM-based simulations illustrate reasonable accuracy in comparison with the counterparts derived from a combination of the Discrete Ordinate Radiative Transfer (DISORT) model and the Line-by-line Radiative Transfer Model (LBLRTM). Furthermore, simulations of the top of the atmosphere brightness temperature with CRTM for the Crosstrack Infrared Sounder (CrIS) are carried out to further evaluate the updated CRTM ice cloud optical property look-up table.

Meteorological Operational (METOP)-B spacecraft was launched on September 17, 2012, and the Advanced Very High Resolution Radiometer (AVHRR) visible and near-infrared channels were activated shortly after the launch. Due to the lack of on-board calibrator, the postlaunch calibration update can only be carried out vicariously. Libyan Desert reflectance with seasonal variation consideration has been used as reference since 1995. The initial updates of the calibration are derived using the seasonal oscillations of previous AVHRR measurements. In this paper, this approach is improved using the seasonal curve regression for the MetOp-B AVHRR measurement over Libyan Desert. A new method is developed using the MetOp-A and MetOp-B inter-comparison with consideration of the Bidirectional Reflectance Distribution Function (BRDF) effect, and applied to the calibration update. Since these two satellites are in the same orbit with half orbit time (~50min) apart, it is feasible to use the inter-comparison of the AVHRR measurement on Libyan Desert between these two instruments. The solar zenith angle and sensor zenith angle are not the same for the collocated measurements, and the BRDF effects on the comparison should be corrected. The zenith angle dependent measurements have been modeled and the comparison of the reflectance with the same solar zenith angle and sensor zenith angle has been derived. The calibrations from these two methods are consistent and the updates are delivered for operational L1B product. This work is also useful to investigate BRDF effect on the inter-comparison for visible and near infrared sensors.

Meteorological Operational (METOP)-B spacecraft was launched on September 17, 2012, and the Advanced Very High Resolution Radiometer (AVHRR) IR channels were activated October 18. AVHRR instrument has been tested and characterized pre-launch under thermal vacuum (TV) condition by the instrument vender. The instrument dynamic range, noise equivalent differential temperature (NEDT), and nonlinear response have been characterized in the test. Basing on the TV test data, the calibration coefficients are generated for post-launch. The on-orbit verification tests have been performed to verify the instrument response and performance, including the dynamic range, NEDT, on-board blackbody (BB) temperature, instrument response calibration, and instrument status from the telemetry data. The post-launch Cal/Val test is to improve the calibration accuracy and enhance the L1B data quality. These tests include stray light analysis, instrument gain verification, and uncertainty assessment. The stray light impact on the calibration is estimated as 0.2% for 11 μm channel, 0.3% for 12 μm channel, and 3% for 3.7μm channel. The inter-comparison AVHRR IR channel radiances with the radiance derived from Infrared Atmospheric Sounding Interferometer (IASI) measurement has been performed and the AVHRR bias shoes brightness temperature dependency.

OMPS is the latest advanced hyperspectral sensor suite flying onboard the Suomi National Polar-Orbiting Partnership (Suomi NPP) spacecraft. It measures ozone depletion in total column and vertical profile ozone abundances. OMPS on-orbit calibration is conducted through dark, lamp and solar measurements. Launched on October 28, 2011, OMPS Nadir has successfully undergone a thorough early orbit check (EOC) and is currently in the intensive calibration and validation (ICV) phase. The calibration data gathered during the on-orbit calibration and validation activities allows us to evaluate the sensor’s early orbit performance and establish on-orbit calibration baseline. In this paper, we provide details of the sensor major on-orbit calibrations activities and present sensor level performance and calibration results from OMPS early orbit image data. These results have demonstrated that the OMPS has made a smooth transition from ground to orbit, and its early on-orbit performance meets or exceeds sensor level requirements and agrees with the predicted values determined during the prelaunch calibration and characterization. Examples of Nadir CCD orbital performance monitoring are provided.

Early assessment of the VIIRS thermal emissive bands (TEBs) show that all VIIRS TEBs except M13 are stable and exceed the specifications. M13 is a dual gain band, and is used for determining the surface temperature at low radiance (high gain) and fire detection at high radiance (low gain). At a low gain stage, the onboard blackbody temperature at an operational temperature of 292 Kelvin is far below the lowest temperature at the low gain, which prevents from any attempt to radiometric calibration. This study found that the VIIRS calibration data during the blackbody temperature warm up and cool down (WUCD) may be useful to check the gain stability and to estimate noise equivalent deviation of temperatures (NEdT). During the VIIRS blackbody temperature warm up and cool down, the blackbody temperature was cooled down to 267 K and warmed up to 315 K. The contrast at the low gain for M13 band between blackbody and space views may be useful, although the highest blackbody temperature is still below the low boundary for the low gain. Moon surface temperature can be as hot as 400 Kelvin, high enough for M13 band radiometric calibration at a low gain. The advantages using the observation data of Moon are that it is very stable and there is no gaseous absorption. However, Moon surface emissivity for infrared spectrum needs to be known. This study found that Moon may be used to check measurement range of the VIIRS M13 band at a low gain. We have developed a calibration algorithm to determine the moon temperature and generated the first VIIRS image about moon temperature. There are some other sources such gas flares that may also be used to estimate the radiometric accuracy at low gain.

The Cross-track Infrared Sounder (CrIS) on the newly-launched Suomi National Polar-orbiting Partnership (Suomi NPP) is a Fourier transform spectrometer that provides soundings of the atmosphere with 1305 spectral channels, over 3 wavelength ranges: LWIR (9.14 - 15.38 μm); MWIR (5.71 - 8.26 μm); and SWIR (3.92 - 4.64 μm). An accurate spectral and radiometric calibration as well as geolocation is fundamental for CrIS radiance Sensor Data Records (SDRs). In this study, through inter- and intra-satellite calibration efforts, we focus on assessment of NPP/CrIS post-launch performance. First, we compare CrIS hyperspectral radiance measurements with the Atmospheric Infrared Sounder (AIRS) on NASA Earth Observing System (EOS) Aqua and Infrared Atmospheric Sounding Interferometer (IASI) on Metop-A to examine spectral and radiometric consistence and difference among three hyperspectral IR sounders. Secondly, an accurate collocation algorithm has been developed to collocate high spatial resolution measurements from the Visible Infrared Imager Radiometer Suite (VIIRS) within each CrIS Field of View (FOV). We compare CrIS spectrally-averaged radiances with the spatially-averaged and collocated pixels from the VIIRS IR channels. Since CrIS and VIIRS are onboard on the same satellite platform, the intra-satellite comparison will allow examining the radiometric difference between CrIS and VIIRS with scene temperatures, scan angles, and orbital position. In addition, given a high spatial resolution of VIIRS channels, the VIIRS-CrIS comparison results can access geolocation accuracy of CrIS that have relatively large FOVs (14 km at ndair) using high resolution VIIRS pixel (375m or 750m at nadir).

VIIRS thermal emissive bands (TEB) calibration data (blackbody and space counts) have been analyzed. The analysis results indicate that the Visible Infrared Imaging Radiometer Suite (VIIRS) TEB is stable and exceeds the specification. VIIRS Blackbody temperature is stable, too. The 6 platinum resistance thermometers (PRT) are also stable, except for the 3rd and 6th PRT have a periodic variation of 50 mK. Using the calibration data during the Blackbody temperature cool down and warm up, we found that noise equivalent deviation of temperatures (NEdT) varies with the Blackbody temperature. We developed a model that can predict the scene temperature dependent NEdT for the VIIRS M15 band. Comparisons between the VIIRS and other sensors such as AVHRR, MODIS and CrIS demonstrated that VIIRS TEB agrees generally with those sensors.

The JPSS preceded by NPP is our nation's future generation polar-orbiting operational environmental satellite system. The successful launch of NPP with the key instrument Visible/Infrared Imager Radiometer Suite (VIIRS) ushers in a new era of operational Earth observing capabilities in the afternoon orbit. Since Launch, the VIIRS Sensor Data Record (SDR) postlaunch calibration/validation has been progressing well as planned. This paper provides an overview of the VIIRS calibration performance postlaunch, the overall calibration/validation strategies both onboard and vicarious, and the team effort ensuring the high quality of VIIRS SDRs, as well as the challenges and way forward.

Global Space-based Inter-Calibration System (GSICS) is a critical space component of Global Earth Observation System of Systems (GEOSS) that provided users with high-quality inter-calibrated satellite measurements. As part of the GSICS, imaging instruments on geostationary (GEO) satellites have been inter-calibrated with hyperspectral instrument Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI) on Low Earth Orbit (LEO) satellites. This paper reports the GSICS GEO-LEO inter-calibration at NOAA/NESDIS, for GOES-11/12 with AIRS (since January 2007) and IASI (since June 2007), and of METEOSAT-7/8/9, MTSAT-1R, and FY-2C with AIRS and IASI since August 2008. Major components of the operation are reviewed, including algorithm development, data processing, product generation, results dissemination, and selected inter-calibration examples. The preliminary results of the GSICS correction show that the fully functioning GSICS is a powerful tool to monitor instrument performance, to correct sensor bias, and to diagnose the root cause of calibration anomalies.

A new algorithm is developed to retrieve the land surface emissivity at four SSM/I frequencies. The coefficients used in the algorithm are directly derived from a training data set including land emissivity and SSM/I measured brightness temperatures. The training data set is also derived from SSM/I brightness temperatures by removing the effects of atmospheric emission and surface temperature. In doing so, the upwelling and downwelling brightness temperature as well as atmospheric transmittance are computed directly from the global data assimilation system (GDAS) temperature and moisture profiles, and surface temperature. Global monthly mean emissivity maps are generated from the daily products. The retrievals under rain regions are not used in the averaging. The rainy pixels were screened out using SSM/I precipitation algorithm.

This report presents the atmospheric and surface products derived from the Advanced Microwave Sounding Unit (AMSU) and the physical bases associated with all algorithms. An example of AMSU derived temperature structure in hurricane Bonnie is used to illustrate how cloud contamination on the AMSU measurements is corrected in temperature retrieval. NOAA and other agencies are routinely utilizing the AMSU products to monitor various high-impact weather events, storm-related flooding and hurricane wind-related damages.