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. This study investigates the magnitude of the errorintroduced by the co-registration and interpolation in computing Stokesvector elements from observations by the Multi-viewing, Multi-channel,Multi-polarisation Imager (3MI). The Stokes parameter derivation from the3MI measurements requires the syntheses of three wide-field-of-view imagestaken by the instrument at 0.25 s interval with polarizers at differentangles. Even though the synthesis of spatially or temporally inhomogeneousdata is inevitable for a number of polarimetric instruments, it isparticularly challenging for 3MI because of the instrument design, which prioritizesthe stability during a long life cycle and enables thewide-field-of-view and multiwavelength capabilities. This study thereforefocuses on 3MI's motion-induced error brought in by the co-registrationand interpolation that are necessary for the synthesis of three images. The2-D polarimetric measurements from the Second-generation Global Imager(SGLI) are weighted and averaged to produce two proxy datasets of the 3MImeasurements, with and without considering the effect of the satellitemotion along the orbit. The comparison of these two datasets shows that themotion-induced error is not symmetric about zero and not negligible when theintensity variability of the observed scene is large. The results areanalyzed in five categories of pixels: (1) cloud over water, (2) clear sky over water, (3) coastlines, (4) cloud overland, and (5) clear sky over land. Themost spread distribution of normalized polarized radiance (Lp)difference is in the cloud-over-water class, and the most spreaddistribution of degree of linear polarization (DOLP) difference is in theclear-sky-over-water class. The 5th to 95th percentile ranges of Lp difference foreach class are (1) [-0.0051,0.012], (2) [-0.0040,0.0088], (3)[-0.0033,0.012], (4) [-0.0033,0.0062], and (5) [-0.0023,0.0032]. The samepercentile range of DOLP difference for each class are (1) [-0.023,0.060],(2) [-0.043,0.093], (3) [-0.019,0.082], (4) [-0.0075,0.014], and (5)[-0.011,0.016]. The medians of the Lp difference are (1) 0.00035, (2)0.000049, (3) 0.00031, (4), 0.000089, and (5) 0.000037, whereas the mediansof the DOLP difference are (1) 0.0014, (2) 0.0015, (3) 0.0025, (4) 0.00027,and (5) 0.00014. A model using Monte Carlo simulation confirms that themagnitude of these errors over clouds are closely related to the spatialcorrelation in the horizontal cloud structure. For the cloud-over-watercategory, it is shown that the error model developed in this study canstatistically simulate the magnitude and trends of the 3MI's motion-inducederror estimated from SGLI data. The obtained statistics and the simulationtechnique can be utilized to provide pixel-level quality information for 3MILevel 1B products. In addition, the simulation method can be applied to thepast, current, and future spaceborne instruments with a similar design.

A study of polarimetric error induced by satellite motion: application to the 3MI and similar sensors