Moreover, the Angstrom exponent tends to be lower, indicating that the ratio of larger particles increased. So it is necessary to enhance the dust source harnessing.

• 而春季气溶胶光学厚度则在近2年有明显增加；源自沙尘天气；且Angstrom指数亦变小；表明大粒子比例增加；因此需要加强对沙尘源的治理.