Polar Vortex Weather

The Polar Vortex Weather model predicts weather anomalies based on the affects of the Birkeland Current to create the Polar Vortex wind speeds. The Polar Vortex wind speed in affect the Jet Stream confinement, as tight in higher speeds, and loose in slower speeds. Polar vortex speed. The chain starts from sunspot number (SSN), which is normalized into a Solar Activity Index (SAI = SSN/200) that scales an electrical current proxy, the Birkeland current (I_B = 300,000 + SSN × 2,800 amps). That current sets the strength of a force-free magnetic field (B0), which is what actually torques and spins the polar vortex — more current, tighter magnetic grip, faster spin, the way current through a coil makes a stronger electromagnet. This flows into a directly computed vortex wind speed, geostrophicWindMS = 45 + SSN × 0.35, which is then normalized (vortexStrength = geostrophicWindMS / 90) to describe how compact and fast-spinning the vortex is on a 0–1 scale. A high vortexStrength means a tight, disciplined vortex holding cold air near the pole; a low one (vortexWeakness = 1 − vortexStrength) means the vortex is loose and lets air spill outward. Jet stream speed. Vortex weakness carries forward into the jet stream math as one of several signed "nudges" around a physical baseline speed, rather than a one-way brake. The baseline (physicalSpeedMS) comes from baseJetSpeedMS scaled by a Coriolis ratio, sin(48°)/sin(latitude) — the jet runs faster the closer it sits to the pole, the same way a spinning ice rink moves faster near the center than the edge. From there, five terms — baroclinicity, thermal gradient, altitude, vortex speed norm, and local path curvature — are each converted into a bounded ±1 "anomaly" (via tanh around a nominal value), weighted, summed, and squashed once more through tanh into a shapeFactor between roughly 0.5× and 1.5× of baseline. Curvature specifically measures how sharply the jet is bending at that point (a trough versus a ridge), so a straight stretch of jet runs near its baseline speed while a tight meander speeds up or slows down locally — like a river running fast through a straight channel and surging or eddying through an S-curve. The final speedMS is just shapeFactor × physicalSpeedMS: a physically-anchored baseline, adjusted symmetrically by how disturbed the vortex, temperature gradient, and path geometry are at that instant.