Monitoring the NOAA Operational VIIRS RSB and DNB Calibration Stability Using Monthly and Semi-Monthly Deep Convective Clouds Time Series

Abstract

Abstract:The Visible and Infrared Imaging Radiometer Suite (VIIRS) onboard the Joint Polar Satellite System (JPSS)/Suomi National Polar-Orbiting Partnership (SNPP) satellite provide sensor data records for the retrievals of many environment data records. It is critical to monitor the VIIRS long-term calibration stability to ensure quality EDR retrieval. This study investigates the radiometric calibration stability of the NOAA operational SNPP VIIRS Reflective Solar Bands (RSB) and Day-Night-Band (DNB) using Deep Convective Clouds (DCC). Monthly and semi-monthly DCC time series for 10 moderate resolution bands (M-bands, M1-M5 and M7-M11, March 2013-September 2015), DNB (March 2013-September 2015, low gain stage), and three imagery resolution bands (I-bands, I1-I3, January 2014-September 2015) were developed and analyzed for long-term radiometric calibration stability monitoring. Monthly DCC time series show that M5 and M7 are generally stable, with a stability of 0.4%. DNB has also been stable since May 2013, after its relative response function update, with a stability of 0.5%. The stabilities of M1-M4 are 0.6%-0.8%. Large fluctuations in M1-M4 DCC reflectance were observed since early 2014, correlated with F-factor (calibration coefficients) trend changes during the same period. The stabilities of M8-M11 are from 1.0% to 3.1%, comparable to the natural DCC variability at the shortwave infrared spectrum. DCC mean band ratio time series show that the calibration stabilities of I1-I3 follow closely with M5, M7, and M10. Relative calibration changes were observed in M1/M4 and M5/M7 DCC mean band ratio time series. The DCC time series are generally consistent with results from the VIIRS validation sites and VIIRS/MODIS (the Moderate-resolution Imaging Spectroradiometer) simultaneous nadir overpass time series. Semi-monthly DCC time series for RSB M-bands and DNB were compared with monthly DCC time series. The results indicate that semi-monthly DCC time series are useful for stability monitoring at higher temporal resolution.

Using Ground Targets to Validate S-NPP VIIRS Day-Night Band Calibration

“…These results indicate that the VIIRS variability is less than 0.6% per year for RSB and 2.5% for shortwave infrared (SWIR) bands [8,9]. The difference between the absolution calibration of VIIRS and MODIS for most bands are within 2.0% [9,10,30,32]. The global surface classification type products generated using S-NPP VIIRS data maintain (78.64% ± 0.57%) overall accuracy [23].…”

“…Some research used Simultaneous Nadir Overpass (SNO) data with similar geometry angles from two or more sensors which allowed for inter-comparison [9,30,32]. The SNO method is relatively simple and robust.…”

“…Other research uses pseudo-invariant ground targets, such as desert, snow, bridge light power, and deep convective clouds, for sensor calibration and validation [4,8,10,24,32,33]. There are several advantages of using pseudo-invariant ground targets for validation.…”

“…Wu et al [9] have done an assessment of the radiometric calibration stability of the first three years of VIIRS visible and near infrared spectral bands using measurements from Suomi-NPP VIIRS and Aqua MODIS simultaneous nadir overpasses over the Libya 4 and Dome C sites. Bhatt et al [8] and Wang and Cao [32] have also assessed the VIIRS RSB using Libya 4 and deep convective clouds. Chen et al [33] have validated the VIIRS DNB performance at Libya 4 and Dome C using both NOAA Interface Data Processing Segment (IDPS) and the NASA Land Product Evaluation and Algorithm Testing Element (PEATE) data.…”

“…The ground sites are usually accessible for ground-based measurements of the radiometric calibration and the measurements can be done if it is necessary. In addition, monitoring the ground targets long-term trends allows for investigation of the influence from RSRs changes, F-factor calculation, and other onboard calibration events [32,33].…”