# Innovative Integration of Severe Weather Forecasts into an Extended Arrival Manager
## 3 AMAN Air Traffic Controller Support
### Dynamic Severe Weather Visualization on a Traffic Display
#### 3.4.2 Moving and Morphing Algorithm Description
Figure 5: Visualization of one morphing intermediate step at the time moment \(t+\frac{t_{0}}{2}\) accordingly to decomposition of boundaries into four parts (marked by different colors). sets of polygons reproducing current and forecasted situations, there is no information in the input data in a merging or splitting case, with part of a pre-image corresponding to a transformed polygon and vice versa. There is no way to exactly retrace the decomposition process for available input data. In the case of an interpolation approach where the forecasted decomposed polygons are mapped to some parts of the current polygon, the free corridors appearing in the visualization may not reflect the real-life situation and can deviate from it significantly. Therefore, from a safety point of view, aircraft should not be directed through these corridors. Additionally, the time periods between the forecasts are relative short (up to ten minutes). Based on these facts, the mapping of polygons without decomposition of the current polygon in the splitting case and without decomposition of the forecasted polygon in the merging case can be taken as a reasonable approach for transformation. This approach is explained and illustrated in the next subsection. Moving and Morphing Polygons with Splitting and Merging  
During the development of occluded fronts, the splitting and merging of individual convective areas always occurs, as well as a shift in the main precipitation areas within the front. For this reason, it is important that an animated presentation format on a traffic situation display can also reproduce these developments as realistically as possible. The mapping of polygons in the splitting case to perform the interpolation of their transformation is shown in Figure 6. The polygon \(Pol^{t|1}\) at the current time t decomposes over the time period \(\Delta t\) in four parts, namely \(Pol^{t+\Delta t|1^{(t|1)}}\),..., \(Pol^{t+\Delta t|4^{(t|1)}}\), as illustrated in Figure 6. However, the splitting contours are unknown and, as a consequence, the space between appearing parts is not safe. Therefore, as was mentioned in the previous subsection, the current polygon \(Pol^{t|1}\) is mapped to all four forecasted polygons \(Pol^{t+\Delta t|1^{(t|1)}}\),..., \(Pol^{t+\Delta t|4^{(t|1)}}\). The morphing of the polygon \(Pol^{t|1}\) into each forecasted polygon \(Pol^{t+\Delta t|1^{(t|1)}}\),..., \(Pol^{t+\Delta t|4^{(t|1)}}\) is then performed simultaneously in the way described above. Figure 6 shows interpolation lines, additional points, and the constellation of the polygons at the time period \(t+\frac{\Delta t}{2}\). Colors correspond to the mapping of the polygons. An approach to transform one polygon into several polygons, and vice versa, is hereby developed. Figure 3:0 Illustration of interpolation without decomposition of the current polygon. On a radar screen, only the envelope curve is presented. Corresponding mapping is visualized in different colors. The mapping of whole polygons can be also used to perform a transformation in the case of the simultaneous splitting and merging of the current and forecasted polygons, i.e., when a part of one polygon splits from the polygon and another part merges with some other polygon at the same time. Figure 7 illustrates this mapping example without decomposition. Consequently, the presented morphing approach is applicable for general interpolation of the transformation between two sets of closed polygons representing current and forecasted adverse weather areas over a short period of time.