Figure - available from: Geophysical Research Letters
This content is subject to copyright. Terms and conditions apply.
Schematic illustration of the dust transport to the global tropopause dust layer (GTDL). Transport of dusts originating from (a) Middle East (ME), (b) Indian Peninsula (IND), (c) Northwestern East Asia (NWEA), and (d) North Africa (NAF) to the GTDL. The yellow arrows represent the transport pathways, the numbers in the upper left corner represent the contributions of the dust sources to the GTDL at 100 hPa. EP represents the Ethiopian Plateau, SWTP represents the southwestern slope of the Tibetan Plateau (TP) and RM represents the Rocky Mountains. The green shadings mean the topographic altitude. The purple lines denote the 100 and 150 hPa layers.
Source publication
Previous study of the tropopause aerosol layer is focused on the region surrounding the Tibetan Plateau. However, other transport pathways of the tropopause aerosol layer remain unclear. In this study, by simulating the dusts from different dust sources individually, we detected the Ethiopian Plateau and the Rocky Mountains are two new transport pa...
Similar publications
Teredus Dejean is a genus of the poorly known family Teredidae, which, historically, includes only two species, restricted to Europe and North Africa. Teredus chinensis sp. nov. is here described, representing the first member of Teredidae found in China, which significantly extends the distribution of Teredus to East Asia. The diagnostic character...
Citations
Dust is the predominant type of aerosol over the Tibetan Plateau (TP) due to the existence of surrounding significant dust sources. However, the contributions of different dust sources to the distribution and variation of dust over the TP and corresponding mechanisms are still being explored. By separating emissions from different dust sources in a numerical model, this study detected that dust originating from East Asia, the Middle East, and North Africa are the main contributors to spring dust over the TP, accounting for 42-68%, 13-27% and 9-25% of the total dust concentration, respectively. East Asian dust primarily affects the dust over the central and northern parts of the TP, the Middle Eastern and North African dust mainly contribute to the dust over the western and southern parts of the TP. Additionally, the variation in dust over the TP is related to East Asian and North African dust, which contribute 58% and 35% of the total variation, respectively. The mechanism underlying this association is attributable to the SST over the northern North Atlantic and updrafts over the northern slope of the TP, the increased former enhances westerlies from North Africa to East Asia and northwesterly winds over the northern slope of the TP and combines with the stronger latter to promote the transport of East Asian and North African dust to the TP. Consequently, it is necessary to focus on the impact of multiple dust sources on the dust over the TP.
This paper reviews progress in the study of aerosol-cloud interactions over the Tibetan Plateau (TP) in the past decade. Clarifying the aerosol-cloud-precipitation interactions over the TP is an important issue for both local and downstream precipitation forecasts. By exerting a “dynamic pump” effect due to the elevated heat source in summer, the TP acts as a “transfer station” for aerosols and water vapor, possessing abundant water vapor and enough cloud condensation nuclei (CCN) and ice nuclei (IN) in cloud physical processes. We found that mixtures of aerosols and clouds are frequently observed over the margin areas of the TP, especially the mixture between aerosols and ice clouds. The convective clouds over the TP could be affected by the Taklimakan dusts lifted from the north slope of the TP, inducing higher and more invigorated convective clouds locally. Furthermore, the dust-polluted convective clouds can continuously move eastward and merge with the convective cloud clusters along their motion paths, inducing more intensive rainfall over the downstream regions of the TP. Finally, challenges to further understanding aerosol-cloud interactions over the TP in the future are discussed.
Large amounts of dust aerosols are lifted to the upper troposphere every year and play a major role in cirrus formation by acting as efficient ice nuclei. However, the relative importance of heterogeneous nucleation and spontaneous homogenous nucleation in dust-related cirrus clouds is still not well evaluated globally. Here, based on spaceborne observations, we propose a method to identify two ice-nucleating regimes of dust-related cirrus clouds, i.e., (1) the sole presence of heterogeneous nucleation and (2) competition between heterogeneous and homogeneous nucleation, by characterizing the relationship between dust ice-nucleating particle concentrations (INPCs) calculated from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) using the POlarization LIdar PHOtometer Networking (POLIPHON) method and in-cloud ice crystal number concentration (ICNC) from the DARDAR (lidar–radar) dataset. Two typical cirrus cases over central China are shown as a demonstration. In the first case, the upper part (near the cloud top) of a series of cirrus clouds successfully realized the INPC–ICNC closure, meaning that solely heterogeneous nucleation takes place, while the lower part of cirrus clouds showed the possible competition between heterogeneous and homogeneous nucleation. In the second case, the ICNCs in the cirrus cloud dramatically exceeded the dust INPCs in the vicinity by more than an order of magnitude, revealing that besides dust-induced heterogeneous nucleation, homogeneous nucleation also participated in ice formation and produced additional ice crystals. The proposed identification method is anticipated to apply in the evaluation of the influence of upper-troposphere dust on global cirrus formation and the investigation of the potential positive role of cirrus cloud thinning in the offset of climate warming.
