Storm Polygonization from Weather Rasters

Convert a gridded weather raster (reflectivity in dBZ) into closed, simplified, and buffered storm polygons suitable for use as no-fly constraints in en-route flow management. The pipeline thresholds the raster, traces contours of connected hazardous regions, simplifies the contour, expands it by a lateral safety margin, and uses the resulting polygon to estimate weather-adjusted sector capacity.

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Tutorial

Thresholding the Reflectivity Raster

A weather raster $R$ stores radar reflectivity, measured in decibels of $Z$ (dBZ), at a regular grid of cells. A cell is hazardous to aircraft when its reflectivity exceeds a convective threshold $\tau,$ typically $\tau=40$ dBZ.

We convert the raster into a binary hazard mask $M$ by thresholding each cell:

M[i,j]=\begin{cases} 1 & \text{if } R[i,j] \ge \tau, \\ 0 & \text{if } R[i,j] < \tau. \end{cases}

If each grid cell covers a ground area $a$ (in km $^2$ ), the total raw hazardous area is

A_{\text{raw}} = a\cdot \sum_{i,j} M[i,j].

For instance, with $\tau=40$ dBZ and a single row $R=[25,\,42,\,47,\,38]$ on cells of area $a=9$ km $^2,$ the mask is $M=[0,1,1,0]$ and $A_{\text{raw}}=9\cdot 2=18$ km $^2.$