A Novel Radiometric Cross-Calibration of GF-6/WFV With MODIS at the Dunhuang Radiometric Calibration Site

Abstract

To obtain more abundant target information for vegetation remote sensing research, the wide field of view (WFV) of the GaoFen-6 (GF-6) satellite utilizes eight bands, including four new bands. Unfortunately, it finds the unavailable reference bands from well-calibrated sensors to implement radiometric crosscalibration of the WFV sensor for these new bands, which severely affects the radiometric quality estimation and the radiometric degradation detection of WFV. Therefore, taking the Dunhuang radiometric calibration site (DRCS) in China as the radiometric transfer platform and treating the Moderate-resolution Imaging Spectroradiometer (MODIS) as a reference sensor, a novel radiometric cross-calibration method for WFV is proposed. The validation results show that compared with the official calibration coefficients (OCCs) published by the China Centre for Resources Satellite Data and Application (CRESDA), the proposed method can obtain reliable radiometric cross-calibration results for each band even without available corresponding reference bands. Moreover, the influences of the interpolation method and the spectral band adjustment factor (SBAF) correction on the calibration results are discussed. The total radiometric crosscalibration uncertainty is less than 4.33%.

Radiometric Cross-Calibration of GF-6/WFV Sensor Using MODIS Images With Different BRDF Models

“…Since the swath of MODIS is approximately 2330 km and that of the WFV is approximately 800 km, as listed in Table I, and the image coordinate of the investigated target is not fixed and changes on different calibrated days, the solar illumination and view geometries over the investigated target are notably different from those of the image center region. Therefore, to reduce the influence of solar and viewing geometry information errors on the cross-calibration results, the MOD03 product and the angle file of the WFV are used to provide accurate solar and viewing geometry information according to the geographical position of the investigated target [16].…”

“…where ESUN W is the exoatmospheric solar spectral irradiance of the WFV listed in sensors in the data preprocessing process [15], [16].…”

“…Consequently, only the radiometric performance attenuation of the GF-6/WFV sensor in four popular spectral bands is evaluated with MODIS, Landsat 8/OLI, and Sentinel-2/MSI sensors [15]. Although Han et al [16] attempted to address this problem with the spectral interpolation method, only the radiometric cross-calibration method with the bottom of atmosphere (BOA) BRDF model was preliminarily applied on five calibrated days. Therefore, the radiometric cross-calibration methods with the BOA and top of atmosphere (TOA) BRDF models are comprehensively compared on a greater number of calibrated days to analyze the applicability and stability of two radiometric cross-calibration methods for the GF-6/WFV sensor.…”

Radiometric Cross-Calibration of GF-4/IRS Based on MODIS Measurements

“…First, both GF-4/IRS and MODIS observe the same test site. Secondly, considering that the atmospheric conditions will not change too much to affect the radiometric response, the transit time between the two sensors is usually less than 1 hour [16]. In our research, we chose Qinghai Lake and Se Lincuo Lake as the radiometric calibration area because the water body has a larger specific heat capacity and will not change significantly in a short period of time.…”

“…The official calibration coefficients, published in 2016 by the China centre for resources satellite data and application (CRESDA), with the site calibration method at Qinghai Lake are treated as the reference information, which has a sufficiently high accuracy to validate the cross-calibration result [16,18,24,25].…”