## 4 Results  
### Spatio-Temporal Patterns of the ESTARFM Time Series  
The overall spatial patterns of the small-scale landscape in the study area are well reproduced by the ESTARFM time series of 2014 (Figure 6). Parts of the river network with its gallery forests exhibiting high mean NDVI values stand out sharply (e.g., north of Wa or south of Bolgatanga), as do the forest patches in the highly fragmented northwest of the study area. Several smal cities emerge from the densely vegetated areas as round patches of low NDVI (e.g., the cities Wa and Tamale). Furthermore, there are no edges, _i.e._, abrupt shifts, in mean NDVI level visible between the four different Landsat tiles. This indicates the general proper functioning of the ESTARFM fusion, since major differences in the prediction of the single tiles would be expressed by edges between them (see also Section 4.2). Figure 6: Annual mean NDVI for the year 2014 derived from the ESTARFM time series (**top left**). Temporal plots of ESTARFM, MODIS and Landsat time series of four different areas for the year 2014 (marked in orange in the map): semi-natural savanna area on Nazinga game ranch (**a**); semi-natural savanna area in the Mole National Park (**b**); rain-fed agricultural area (**c**); irrigated agricultural area (**d**); Spatial transect across the study area from north to south ((**e**), see dashed line in the map); dashed line in the plot represents the linear trend line. The transect in Figure 6e, crossing the study area from north to south, reflects the general vegetation gradient of the study area which is in line with the general gradient of West Africa. From north to south, NDVI level and vegetation density increase with rising annual rainfalls. The comparison of the temporal development of the ESTARFM, MODIS and Landsat NDVI time series is highlighted in four plots (Figure 6a-d): Figure 6a shows the average NDVI development over a semi-natural savanna area on the Nazinga game ranch. Here, the time series of ESTARFM closely follows the one from MODIS and the single Landsat NDVI values are also well matched. Figure 6 also shows that if using only Landsat data for the interpretation of phenology, some features such as the peak NDVI would be missed. The NDVI level of the focus site in the Mole National Park (Figure 6b) is generally higher than for the one from the Nazinga game ranch. This focus site also consists of semi-natural savanna but is more densely vegetated and has a higher percentage of tree cover. These differences again reflect the north\(-\)south gradient of vegetation in the study region. For the Mole focus site, the NDVI values of MODIS and Landsat diverge slightly during the growing season with a higher level for Landsat. In such a case, ESTARFM gives priority to the Landsat input data and the derived ESTARFM time series matches Landsat more closely than MODIS. Figure 6c displays the time series of a rain-fed agricultural area close to the city of Bolgatanga in Ghana. In comparison to the semi-natural savannas, a generally lower NDVI can be observed, especially during the vegetative season between DOY 100 and 320 (mid-April to mid-November). The agricultural area shows a later green-up and a lower peak of NDVI. Figure 6d represents an irrigated agricultural area at the White Volta downstream of the Bagre dam in southern Burkina Faso. Its temporal development is considerably different from the other focus areas since it is independent of the timing of the rainy season. Two crop cycles can be observed in the graph, one around the DOY 100 (mid-April) and a second one around DOY 300 (end of October). When comparing the annual mean NDVI from ESTARFM with Landsat and MODIS NDVI for three focus areas characterizing different landscape types, major differences become apparent (Figure 7). With its 500 m resolution, the MODIS data (second row) cannot reproduce the spatial details of the landscape patterns.