3.2.2. Spatial Differences of Four LAI Climatologies

Figure 7 demonstrates the differences between each pair of LAI products at the pixel scale. For all six pairs, most pixels show small differences (−1~1). However, large differences still exist in southern regions of China located in a temperate climate zone. The highest differences can reach over ±6 but this only occurs on a small proportion of pixels, and these mainly occur between GLOBMAP and MODIS (1149 pixels among total 6596588 pixels, 0.02%), and GLOBALBNU and GLOBMAP (376 pixels among total 6598208 pixels, 0.006%) products in southern Tibet with mixed forest (red rectangles in Figure 7c,f) and Taiwan with broadleaf and needleleaf forest (blue rectangles in Figure 7c,f). Among these six pairs, GLOBALBNU LAI and MODIS are the most similar (see Figure 7b). As shown in the histogram of Figure 8b, most of the different values are located in the −1 to 1 zone, but values from 0 to 1 are dominant (90%). This means GLOBALBNU is generally larger than MODIS. Eighty percent of the difference between GLASS and MODIS is positive (Figure 8a), but the difference between GLOBMAP and MODIS have half positive and half negative values, with some positive difference higher than 2 (Figure 8c). Most of the different pixels between GLASS and GLOBALBNU are located in the range of −2~2; 60% of the difference is positive while 40% is negative (Figure 8d). Eighty percent of the difference is positive between GLASS and GLOBMAP; between them, 75% of the pixels are located in the range of 0–1, and less than 5% of the pixels are located in the range of 1–2. For the rest of the 20% negative difference, about 15% are located in the range of −1~0, less than 5% are located in the range of −2~−1, and the others are in the range of less than −2 (Figure 8e). For GLOBALBNU and GLOBMAP, about 65% of the difference is positive and most of them are located in the range of 0–1. For the negative difference, about 30% are located in the range of −2~0; the other pixels are located in the range of −4~2 (Figure 8f).

**Figure 8.** Frequency histograms of LAI differences: (**a**) GLASS vs. MODIS; (**b**) GLOBALBNU vs. MODIS; (**c**) GLOBMAP vs. MODIS; (**d**) GLASS vs. GLOBALBNU; (**e**) GLASS vs. GLOBMAP; (**f**) GLOBALBNU vs. GLOBMAP.
