An integrated laser anemometer and dust accumulator for studying wind-induced dust transport on Mars

Windborne dust is one of the most important and dynamic factors affecting the Martian surface and its atmosphere, yet there lacks a detailed physical understanding how it is transported. We present a miniature laser-based optoelectronic instrument for use on a Mars lander. It integrates sensors capable of quantifying important parameters needed for the understanding and modeling of dust transport on Mars, these include wind speed, wind direction, suspended dust concentration, dust deposition and removal rates as well as the electrification of the Martian dust. Dust electrification has been seen from experimental simulations to be of considerable importance to the processes of adhesion and cohesion, specifically prompting the formation of low mass density dust aggregates. Testing of this prototype instrument has been performed under simulated Martian conditions in a wind tunnel facility. The results and analysis of its functionality will be presented.     

VISPO project: visible image-spectrometer for planetary observations

Satellite instrumentations designed for planetary studies are often open to other interesting applications from ground: not only one can efficiently carry out detailed calibrations before space data become available, but also the prototypes of the satellite instruments can be successfully employed in different fields ranging from astrophysics to cosmology. Both possibilities are opened by coupling these instruments with ground based telescopes having short focal ratios, like those designed for far infrared studies. These possibilities are particularly amazing in view of the long delay usually present between the launch and the collection of the first scientific data (months in case of Mars Express, years in case of Rosetta).

We propose in this article to employ immediately this technology, by coupling the developing model of the Image-Spectrometer VIRTIS-M with the ground telescope MITO.

This project will allow us to perform a better calibration of the space qualified instrument and observational campaigns, including some important cosmological investigations.     

月球光照区尘埃静电迁移规律:初步理论结果

空间环境中,暴露在太阳风等离子体和紫外辐射中的尘埃颗粒由于光电发射等而带电。月球光照区带电的尘埃颗粒受静电场驱动或微陨石轰击发生迁移。本文计算结果表明,月球光照区粒径为0.01μm的尘埃颗粒静电迁移达到的最大高度约为1km,而在月球黑暗区亚微米级的尘埃颗粒静电迁移可以到达50km的高度。尽管微陨石轰击溅射的尘埃颗粒可到达~100km的高度,但是尘埃数密度与微陨石轰击事件直接相关,并随着高度变化。由于重力作用,溅射的尘埃快速沉降。溅射和沉降过程中,尘埃颗粒由于光电发射等继续充电。在局部电场强度和德拜鞘高度分别为5V/m和1m条件下,粒径<0.37μm的带电尘埃颗粒以"弹跳模式"运动,而粒径>0.37μm的带电尘埃颗粒返回月表,并再次轰击溅射尘埃。根据本文结果可以推断,月球尘埃实验(LDEX)在月球夜晚20~60km高度记录的尘埃事件可能与尘埃的静电迁移相关,但是月球白天记录的事件可能并不包括静电迁移的部分。     

2017年5月长三角地区一次沙尘重污染天气成因分析

利用地面污染物监测数据、常规气象数据,ECMWF再分析数据以及L-波段无线电探空数据,并结合后向轨迹模型,对2017年5月长三角地区的一次沙尘重污染天气过程进行成因分析。结果表明:此次沙尘重污染过程是天气系统、地面及边界层气象条件共同作用的结果。东亚大槽东移、冷空气南下并配合地面高压的发展使河西走廊、宁夏大部、内蒙古西部出现沙尘天气,为后期长三角地区沙尘的输送提供了沙源; 850 h Pa上较大的风速为上游沙尘源区向下游长三角地区输送提供了通道;高压中心的下沉运动和白天增强的热对流活动使得高层沙尘影响地面具备了足够的动力条件;当沙尘抵达长三角上游地区后,不断减弱的冷空气和趋于静稳的近地面形势不利于污染物扩散,加剧了此次污染过程。     

Assessment of geochemical and sedimentological characteristics of atmospheric dust in Shiraz,southwest Iran

Geogenic dust is commonly believed to be one of the most important environmental problems in the Middle East.The present study investigated the geochemical characteristics of atmospheric dust particles in Shiraz City(south of Iran).Atmospheric dust samples were collected through a dry collector method by using glass trays at 10 location sites in May 2018.Elemental composition was analysed through inductively coupled plasma optical emission spectrometry.Meteorological data showed that the dustiest days were usually in spring and summer,particularly in April.X-ray diffraction analysis of atmospheric dust samples indicated that the mineralogical composition of atmospheric dust was calcite+dolomite(24%)palygorskite(18%)quartz(14%)muscovite(13%)albite(11%)kaolinite(7%)gypsum(7%)zircon=anatase(3%).The high occurrence of palygorskite(16%-23%) could serve as a tracer of the source areas of dust storms from the desert of Iraq and Saudi Arabia to the South of Iran.Scanning electron microscopy indicated that the sizes of the collected dust varied from 50 μm to0.8 μm,but 10 μm was the predominant size.The atmospheric dust collected had prismatic trigonal-rhombohedral crystals and semi-rounded irregular shapes.Moreover,diatoms were detected in several samples,suggesting that emissions from dry-bed lakes,such as Hoor Al-Azim Wetland(located in the southwest of Iran),also contributed to the dust load.Backward trajectory simulations were performed at the date of sampling by using the NOAA HYSPLIT model.Results showed that the sources of atmospheric dust in the study area were the eastern area of Iraq,eastern desert of Saudi Arabia,Kuwait and Khuzestan Province.The Ca/Al ratio of the collected samples(1.14) was different from the upper continental crust(UCC) value(UCC=0.37),whereas Mg/A1(0.29),K/Al(0.22) and Ti/Al(0.07) ratios were close to the UCC value(0.04).This condition favours desert calcisols as the main mineral dust sources.Analysis of the crustal enrichment factor(EF_(crustal)) revealed geogenic sources for V,Mo,Pb,Sr,Cu and Zn(2),whereas anthropogenic sources affected As,Cd,Cr and Ni.     

空间尘埃等离子体中的重力波特性

建立尘埃等离子体中重力波的基本方程,推导尘埃等离子体中重力波的色散关系,分析地球极区中间层顶处尘埃等离子体层中的重力波特性,研究了重力波在电子密度垂直分层的尘埃等离子体中的反射. 结果表明尘埃等离子体改变了通常大气中的重力内波的色散关系,限制了小水平波数重力内波的传播,改变了波的能量特性,减小了重力波在不均匀大气中垂直向上传播时振幅的增长;在尘埃等离子体中传播时重力波可被电子密度垂直分层的结构反射而导致波能量的集中, 它产生的湍动所导致的空间电子密度的不均匀性分布是极区上空PMSEs的可能机制.     

BN天体尘壳性质的探讨

本文对ＢＮ天体的红外连续辐射多波段测光资料进行理论分析研究，采用光学薄的球对称尘壳模型，推算出ＢＮ天体尘壳的物理参数：光学厚度及红外连续发射率的波长分布，密度与温度的空间分布，尘壳总质量。     

Laboratory analogy of crystalline enstatite grain formation in plasma field

Crystalline enstatite (MgSiO₃) grains were produced by the simultaneous evaporation of SiO grains and Mg vapor in a plasma field. The MgSiO₃ grains were spherical or needlelike. The necessity of a plasma field in astromineralogy is suggested in the present study.     

早全新世石羊河流域沙尘暴活动记录

位于西北干旱区河西走廓东段石羊河流域尾闾地区湖泊沉积中记录到了多层快速风成沉积，通过剖面样品粒度、石英砂表面特征和磁化率、有机碳等多指标的分析表明为沙尘暴的堆积，推断在早全新世10000-6700aB.P.石头号河流域气候最湿润阶段仍存在周期性的沙尘暴活动。