Dust Radiation, Electrification and Alignment in the Middle East (DREAME)

大气中的矿物粉尘主要来自撒哈拉沙漠等干旱地区，对气候有重大影响。正因为如此，它们需要在气候和天气预测模型中得到准确的表示。英国科学家最近对撒哈拉沙漠大气尘埃的观测提供了强有力的证据，证明矿物尘埃层中存在主要垂直排列的颗粒。这种排列被认为是由于与灰尘层相关的大气电。计算机模拟表明，这种排列可以显著改变尘埃层的特性，包括它们透射、吸收和反射的光量。这被称为“百叶窗效应”，因为倾斜的粒子会影响透射的光和热的量。这一特性和其他特性的变化会对卫星对尘埃云的测量产生重大影响，也可能对尘埃在大气中的移动产生重大影响。拟议的项目将利用在中东进行的地面、气球和飞机上的各种测量，回答有关这一现象的确切起源、规模、范围和影响的紧迫问题。该项目将增进对尘埃的了解，并有可能解决有关大陆范围内尘埃云运动的长期谜团。该提案利用了英国气象局MEVEX飞行活动提供的一个重大机会，以很少的额外成本实施该项目。因此，它提供了极好的物有所值。

Mineral dusts in the atmosphere, originating primarily from dry regions like the Sahara desert, have significant influence on climate. Because of this they need to be accurately represented in climate and weather prediction models. Recent observations of atmospheric Saharan dust by UK scientists provide strong evidence for the existence in mineral dust layers of particles that are predominantly vertically aligned. This alignment is thought to be due to atmospheric electricity associated with the dust layers. Computer modelling indicates that the alignment can significantly change the properties of the dust layers, including the amount of light they transmit, absorb and reflect. This has been termed a 'Venetian blind effect' from the way the tilted particles influence the amount of transmitted light and heat. Change in this and other properties can have significant impact on measurements of dust clouds from satellites, and possibly also on dust movement through the atmosphere. The proposed project will answer urgent questions concerning the precise origin, magnitude, extent and impact of this phenomenon by the use of a variety of measurements from the ground, balloons and aircraft, carried out in the Middle East. The project will result in improved understanding of dust and has the potential to solve a long-standing enigma concerning the movement of dust clouds on the continental scale. The proposal takes advantage of a major opportunity offered by the UK Met Office MEVEX flight campaign, to carry out this project at little additional cost. Therefore it provides excellent value for money.