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A planet-encircling dust storm occurred on Mars in 2001, lasting several months and obscuring the surface from observation. The storm began with regional dust storms that merged to form a global dust haze. Researchers used a technique called sequential data assimilation to study the storm, combining observations from NASA's Mars Global Surveyor with a global circulation model of the Martian atmosphere. The model revealed key events in the storm's evolution, including the initial pulses of dust along the edge of the retreating south polar cap and the movement of dust into the Hellas basin. The storm's growth was influenced by thermal tides and the interaction between localized atmospheric heating and dust particles. A "phase slip" in the diurnal component of the thermal tide allowed a low-pressure system to drift eastwards and settle over the Tharsis region, strengthening local slope winds and creating conditions for a secondary dust lifting center. This teleconnection between distant regions contributed to the storm's global spread. Control simulations using the UK-MGCM and GFDL Martian GCM confirmed the dynamically active nature of this teleconnection.