Diurnal Cycle of Cloud System Migration over Sumatera Island

This paper describes a diurnal cycle in systematic cloud system migration observed with the GMS IR1 sensor over Sumatera (approximately 1,500 km in length) from May 2001 to April 2002. Convective clouds developed over mountainous areas in the afternoon, and migrated westward and/or eastward for several hundred kilometers (∼ 500 km) from midnight to morning. Westward migration occurred in almost every month except August over southernmost Sumatera Island. Eastward migration occurred when lower-tropospheric winds were westerly and/or when super cloud clusters moved eastward along the Intertropical Convergence Zone (ITCZ), which moves northward and southward with an annual cycle.