According to the data, the kosa originated in the Takla Makan Desert reached Korea in four to eight days at 4 to 8 km altitude, the one in the dry area of northern part of China in three to five days at 1 to 5 km, the one in the Loess Plateau in two to four days at 1 to 4 km, and the one in Manchuria (the northeastern part of China) in one to three days at 1 to 3 km.
それによろと、タクラマカン砂漠は経過日数4-8日・高度4-8km、中国北部の乾燥地帯は3-5日・1-5km、黄土高原は2-4日・1-4km、満州（中国東北部）は1-3日・1-3kmなどとなっている。