Long term MODIS spatial characterization using ground target approach

MODerate resolution Imaging Spectroradiometer (MODIS), operated on both Terra and Aqua spacecrafts, measures the Earth scenes with 36 spectral bands allocated into four Focal Plane Assemblies (FPAs). Mis-registration between the spectral bands and FPAs was observed, which will lessen the data quality and reduce the accuracy of science products generated with multiple spectral bands located on different FPAs. An approach using ground targets, developed and validated in our previous work, is an alternative way for characterizing the MODIS Band-to-Band Registration (BBR), by calculating the centroid location difference of same dark targets observed by each band in its own field of view. The long term time series of spatial shift, not only for the band but also for the detector, are presented over sensor's operation years (year 2000-2007 for Terra MODIS and year 2002-2007 for Aqua MODIS). With this ground target approach, the spatial performances of both Terra and Aqua MODIS are evaluated. The results show that spatial shifts are small except they are relatively large between bands on the warm FPA and cold FPA of Aqua MODIS. The discrepancy between detectors is quite small and mainly attribute to the systematic error of the approach. Moreover, the long term results reveal an annual variation for some high resolution bands.