Analysis of Dust Aerosol Retrievals Using Satellite Data in Central Asia

Abstract

Several long-term monitoring of aerosol datasets from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Terra/Aqua, Multi-angle Imaging SpectroRadiometer (MISR), Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) were used to derive the dust aerosol optical depth (DOD) in Central Asia based on the Angstrom exponent parameter and/or the particle shape. All sensors agree very well on the interannual variability of DOD. The seasonal analysis of DOD and dust occurrences identified the largest dust loading and the most frequent dust occurrence in the spring and summer, respectively. No significant trend was found during the research period in terms of both DOD and the dust occurrence. Further analysis of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) aerosol products on a case-by-case basis in most dust months of 2007 suggested that the vertical structure is varying in terms of the extension and the dust loading from one event to another, although dust particles of most episodes have similar physical characteristics (particle shape and size). Our analysis on the vertical structure of dust plumes, the layer-integrated color ratio and depolarization ratio indicates a varied climate effect (e.g., the direct radiative impact) by mineral dust, dependent on the event being observed in Central Asia.

Long-term profiling of aerosol light extinction, particle mass, cloud condensation nuclei, and ice-nucleating particle concentration over Dushanbe, Tajikistan, in Central Asia

“…Most DOT values are ≤ 0.2. This is in agreement with findings of Li and Sokolik (2018). These authors concluded from in-depth analysis of long-term spaceborne passive remote sensing over Central Asia that most DOTs are below 0.2 at 550 nm.…”

“…Although Central Asia is a hot spot region of severe environmental problems and potentially dramatic climate-change effects, only a few observational studies on atmospheric aerosols were performed so far (e.g., Pachenko et al, 1993;Golitsyn and Gillette, 1993;Chen et al, 2013; and with a focus on Tajikistan by Abdullaev and Sokolik, 2019). The first systematic characterization of atmospheric aerosol, pollution, and dust conditions in terms of maps of aerosol optical thickness (AOT) and Ångström exponent (AE, describ-ing the spectral dependence of AOT) for Central Asia was recently presented by Li and Sokolik (2018) and Rupakheti et al (2019). AOT is a proxy for the tropospheric aerosol burden in the vertical column and AE can be used to identify and separate dust and non-dust fine-mode aerosol pollution fractions in the observed aerosol mixtures.…”

“…These two studies are based on well-established methods of passive remote sensing from space. However, passive remote sensing does not allow us to adequately resolve the vertical aerosol structures as needed in state-of-the-art environmental and climate research and modeling efforts (Wiggs et al, 2003;Yorks et al, 2009;Lioubimtseva and Henebry, 2009;Huang et al, 2014;Xu et al, 2016;Bi et al, 2016;Kipling et al, 2016;Kok et al, 2018;Shi et al, 2019). Active remote sensing with ground-based and spaceborne lidars is required to provide the missing information on dust plume heights, long-range dust transport features, and to detect even thin dust layers in the upper troposphere which influence cloud and precipitation formation (Creamean et al, 2013;Ansmann et al, 2019a, b).…”

Multi-Sensor Observation of a Saharan Dust Outbreak over Transylvania, Romania in April 2019

“…Collocated lidar measurements ( Figure 2) showed thinner layers of dust over Cluj-Napoca at 10:13 UTC, while thicker layers were observed two hours later (Figure 3). Both AOD and Ångström Exponent satellite data showed strong correlation with the equivalent AERONET parameters [58]. [59].…”

The Elbrus (Caucasus, Russia) ice core record – Part 2: history of desert dust deposition

“…Trajectories were run every 6 h. (Mikhalenko et al, 2015). A study focusing on the long-term trend of black carbon in the Elbrus ice (Lim et al, 2017) is currently underway as well as several studies investigating additional chemical species, including investigations of calcium and of sulfate. Data are discussed in two companion papers including the glaciochemistry of the deep Elbrus ice core drilled in 2009 (Preunkert et al, 2019).…”