Interpolation of the Mean Anomalies for Cloud Filling in Land Surface Temperature and Normalized Difference Vegetation Index

• Published in: IEEE transactions on geoscience and remote sensing Vol. 57; no. 8; pp. 6068 - 6078
• Main Authors: Militino, Ana F., Ugarte, M. Dolores, Perez-Goya, Unai, Genton, Marc G.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anomalies; Artificial clouds; Atmospheric effects; Clouds; Competitors; Computer simulation; Data; Geostatistics; Goodness of fit; Image filters; Imaging techniques; Interpolation; Land surface temperature; moderate resolution imaging spectroradiometer (MODIS); MODIS; Night; Normalized difference vegetative index; Remote monitoring; Remote sensing; Root-mean-square errors; Simulation; smoothing images; Spectroradiometers; Surface temperature; Target recognition; thin-plate splines; Time series; Time series analysis; Vegetation; Vegetation mapping
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2019.2904193

When monitoring time series of remote sensing data, it is advisable to fill gaps, i.e., missing or distorted data, caused by atmospheric effects or technical failures. In this paper, a new method for filling these gaps called interpolation of the mean anomalies (IMA) is proposed and compared with some competitors. The method consists of: 1) defining a neighborhood for the target image from previous and subsequent images across previous and subsequent years; 2) computing the mean target image of the neighborhood; 3) estimating the anomalies in the target image by subtracting the mean image from the target image; 4) filtering the anomalies; 5) averaging the anomalies over a predefined window; 6) interpolating the averaged anomalies; and 7) adding the interpolated anomalies to the mean image. To assess the performance of the IMA method, both a real example and a simulation study are conducted with a time series of Moderate Resolution Imaging Spectroradiometer (MODIS) TERRA and MODIS AQUA images captured over the region of Navarre (Spain) from 2011 to 2013. We analyze the land surface temperature (LST) day and night, and the normalized difference vegetation index (NDVI). In the simulation study, seven sizes of artificial clouds are randomly introduced to each image in the studied time series. The square root of the mean-squared prediction error (RMSE) between the original and the filled data is chosen as an indicator of the goodness of fit. The results show that the IMA method outperforms Timesat, Hants, and Gapfill (GF) in filling small, moderate, and big cloud gaps in both the day and night LST and NDVI data, reaching RMSE reductions of up to 23%.