However, since the reality of kosa phenomena became known in details in 1990s, it became gradually clear that, to grasp the reality of kosa phenomena, it is necessary to deploy a monitoring system for a long period of several tens of years.
しかし、1990年代に黄砂現象の実態が詳しく分かるようになったことで、黄砂の実態把握には、数十年という長期間の監視体制を整える必要があることが次第に明らかになってきた。