Assessing the Effect of Temporal Interval Length on the Blending of Landsat-MODIS Surface Reflectance for Different Land Cover Types in Southwestern Continental United States

Capturing spatial and temporal dynamics is a key issue for many remote-sensing based applications. Consequently, several image-blending algorithms that can simulate the surface reflectance with high spatial-temporal resolution have been developed recently. However, the performance of the algorithm against the effect of temporal interval length between the base and simulation dates has not been reported. In this study, our aim was to evaluate the effect of different temporal interval lengths on the accuracy using the widely used blending algorithm, Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM), based on Landsat, Moderate-resolution Imaging Spectroradiometer (MODIS) images and National Land Cover Database (NLCD). Taking the southwestern continental United States as the study area, a series of experiments was conducted using two schemes, which were the assessment of STARFM with (i) a fixed base date and varied simulation date and (ii) varied base date and specific simulation date, respectively. The result showed that the coefficient of determination (R), Root Mean Squared Error (RMSE) varied, and overall trend of R decreased along with the increasing temporal interval between the base and simulation dates for six land cover types. The mean R value of cropland was lowest, whereas shrub had the highest value for two schemes. The result may facilitate selection of an OPEN ACCESS ISPRS Int. J. Geo-Inf. 2015, 4 2543 appropriate temporal interval when using STARFM.


Figure S2 .
Figure S2.The R 2 distribution box plot of simulated surface reflectance for six land cover types for a fixed base date of 9 February 2001.For each Landsat band, the five lines from the bottom upward are the minimum, first quartile (q1), median, third quartile (q3), and maximum values of R 2 .The circle indicates the mean value of R 2 for the corresponding Landsat band.The cross symbols indicate outliers in the R 2 distribution.The R 2 value are drawn as outliers if they are larger than q3 + 1.5 × (q3 -q1) or smaller than q1 -1.5 × (q3 -q1).The same for Figures S5, S9, S11 and S14 about outliers.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S3 .
Figure S3.The RMSE distribution of simulated surface reflectance for six land cover types with a fixed base date of 9 February 2001.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S4 .
Figure S4.The R2 distribution of simulated surface reflectance for six land cover types with a fixed base date of 16 May 2001.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S5 .
Figure S5.The R 2 distribution box plot of simulated surface reflectance for six land cover types for a fixed base date of 16 May 2001.For each Landsat band, the five lines from the bottom upward are the minimum, first quartile, median, third quartile, and maximum values of R 2 .The circle indicates the mean value of R 2 for the corresponding Landsat band.The cross symbols indicate outliers in the R 2 distribution.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S6 .
Figure S6.The RMSE distribution of simulated surface reflectance for six land cover types with a fixed base date of 16 May 2001.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S7 .
Figure S7.The R 2 distribution of simulated surface reflectance for six land cover types with a fixed base date of 28 August 2001.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S9 .
Figure S9.The R 2 distribution box plot of simulated surface reflectance for six land cover types for a fixed base date of 28 August 2001.For each Landsat band, the five lines from the bottom upward are the minimum, first quartile, median, third quartile, and maximum values of R 2 .The circle indicates the mean value of R 2 for the corresponding Landsat band.The cross symbols indicate outliers in the R 2 distribution.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S10 .
Figure S10.The R 2 distribution of simulated surface reflectance for six land cover types according to fixed base date of 8 November 2001.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S11 .
Figure S11.The R 2 distribution box plot of simulated surface reflectance for six land cover types for the base date of 8 November 2001.For each Landsat band, the five lines from the bottom upward are the minimum, first quartile, median, third quartile, and maximum values of R 2 .The circle indicates the mean value of R 2 for the corresponding Landsat band.The cross symbols indicate outliers in the R 2 distribution.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S12 .
Figure S12.The RMSE distribution of simulated surface reflectance for six land cover types according to fixed base date of 8 November 2001.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.

Figure S13 .
Figure S13.The R 2 value distribution of simulated surface reflectance for specific simulation date of 14 January 2009.For each land cover type, the simulated surface reflectance for each Landsat band on the simulation date had 44 corresponding base date (12 base dates for 2001 and 2003, and 20 base dates for 2008).The same for Figures S14, S15, S16, S17, S18, S19 and S20.(a) Cropland; (b) Grassland; (c) Shrub; (d) Urban; (e) Water; (f) Wetland.