利用Terra和Aqua双星MODIS数据协同研究沙尘暴

On Asian Dust Storm in China by Combining Daytime and Nighttime Terra and Aqua MODIS Data

利用2005-04-28上午星Terra和下午星Aqua白天和晚上共4景MODIS数据对影响华北地区的一次沙尘暴进行了研究。对于白天的MODIS数据,利用热红外亮度温度差值法结合可见光近红外波段反射率阈值法,可以很好地把沙尘与背景地物和云分离开来;对于夜晚的MODIS数据,利用热红外亮度温度差值法也能较好地提取沙尘信息。研究表明,MODIS数据在沙尘暴等灾害研究方面具有很大的潜力。

A method to monitor one Asian dust storm occurred on April 28, 2005 by means of four daytime and nighttime MODIS images that are boarded on Terra and Aqua platform is presented. Screening is important for dust storm detection. For daytime Terra and Aqua MODIS data, cloud screening is obtained by using visible and near infrared reflectance, single thermal infrared bright temperature threshold, and the difference of bright temperatures. In the evening TIR bands are only used to remove cloud effects. Then three thermal infrared （TIR）, 8. 5μm, 11μm, and 12μm are used, and a tri-spectral technique presented by Ackerman （1997） to extract dust storm areas. It is found that combining brightness temperature differences BTS. 5-BT11 with negative BT11- BT12 can detect dust storm. The dust storm areas can be separated from cloud and non dust areas both on land and on the ocean. Furthermore,dust storm motion can be analyzed by these four scenes MODIS data within 24 h. The result is reasonable by validation with RGB composition method and meteorology data. The study also shows that MODIS data has great potential in dust storm research.