Abstract
Abstract. We present a 3-D climatology of the desert dust distribution over South and East Asia derived using CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data. To distinguish desert dust from total aerosol load we apply a methodology developed in the framework of EARLINET (European Aerosol Research Lidar Network). The method involves the use of the particle linear depolarization ratio and updated lidar ratio values suitable for Asian dust, applied to multiyear CALIPSO observations (January 2007–December 2015). The resulting dust product provides information on the horizontal and vertical distribution of dust aerosols over South and East Asia along with the seasonal transition of dust transport pathways. Persistent high D_AOD (dust aerosol optical depth) values at 532 nm, of the order of 0.6, are present over the arid and semi-arid desert regions. Dust aerosol transport (range, height and intensity) is subject to high seasonality, with the highest values observed during spring for northern China (Taklimakan and Gobi deserts) and during summer over the Indian subcontinent (Thar Desert). Additionally, we decompose the CALIPSO AOD (aerosol optical depth) into dust and non-dust aerosol components to reveal the non-dust AOD over the highly industrialized and densely populated regions of South and East Asia, where the non-dust aerosols yield AOD values of the order of 0.5. Furthermore, the CALIPSO-based short-term AOD and D_AOD time series and trends between January 2007 and December 2015 are calculated over South and East Asia and over selected subregions. Positive trends are observed over northwest and east China and the Indian subcontinent, whereas over southeast China trends are mostly negative. The calculated AOD trends agree well with the trends derived from Aqua MODIS (Moderate Resolution Imaging Spectroradiometer), although significant differences are observed over specific regions.
Highlights
Airborne mineral dust is a major category of particles in the Earth’s atmosphere that influences climate on a local and regional to a global scale (Huang et al, 2006)
Since the mechanisms of dust generation and transport and the removal processes of aerosols from the atmosphere vary with season we present and discuss the horizontal distribution of aerosols and dust over South and East Asia per season
The countries of mainland Southeast Asia are characterized by inhomogeneities in the observed aerosol load, with larger non-dust AOD values observed during MAM (> 0.5) and December–January– February (DJF) (> 0.3) and lower values during JJA (< 0.15) and SON (< 0.1)
Summary
Airborne mineral dust is a major category of particles in the Earth’s atmosphere that influences climate on a local and regional to a global scale (Huang et al, 2006). Huang et al (2008), using CALIOP, a micropulse lidar and surface meteorological data from the Gansu Meteorological Bureau studied the long-range transport of dust from the Taklimakan and Gobi deserts over east China and the Pacific Ocean during the PACDEX campaign (March to May 2007). They showed that the dust storms over the Gobi region are more intense but less frequent than the dust storms over the Taklimakan region.
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