Continuous observations of synoptic-scale dust transport at the Nepal Climate Observatory-Pyramid (5079 m a.s.l.) in the Himalayas

This study presents two years of continuous observations of physical aerosol properties at the GAW-WMO global station "Nepal Climate Observatory – Pyramid" (NCO-P, 27°57' N, 86°48' E), sited at 5079 m a.s.l. in the high Himalayan Khumbu Valley (Nepal). Measurements of aerosol number size distribution, aerosol optical depth (AOD) and single scattering albedo (SSA) are analysed from March 2006 to February 2008. By studying the temporal variations of coarse (1 µm < Dp < 10 µm) particle number concentration, 53 mineral Dust Transport Events (DTEs) are identified, accounting for 22.2% of the analysed data-set. Such events occurred prevalently during pre-monsoon (for 30.6% of the period) and winter (22.1%) seasons. However, uncommon cases of mineral dust transport are observed even during the monsoon season. The main sources of mineral dust reaching NCO-P are identified in the arid regions not far from the measurement site, i.e. from Tibetan Plateau, and Lot-Thar deserts, which account for 52% of the dust transport days. Moreover, a non-negligible contribution can be attributed to the Arabian Peninsula (17%) and the Indo-Gangetic Plains (16%), as indicated by three dimensional (3-D) back-trajectory analyses performed with LAGRANTO model. The observed DTEs lead to significant enhancements in the coarse aerosol number concentration (+513%) and coarse aerosol mass (+655%), as compared with average values observed in "dust-free" conditions ( 0.05 ± 0.11 cm(-3) and 3.4 ± 3.7 µg m(-3), respectively). During DTEs, SSA is higher (0.84–0.89) than on "dust-free" days (0.75–0.83), confirming the importance of this class of events as a driver of the radiative features of the regional Himalayan climate. Considering the dust events, a significant seasonal AOD increase (+37.5%) is observed in the post-monsoon, whereas lower increase (less than +11.1%) characterises the pre-monsoon and winter seasons confirming the influence of synoptic-scale mineral dust transports on the aerosol optical properties observed at NCO-P.

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Paolo Cristofanelli (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Angela Marinoni (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Paolo Bonasoni (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Francescopiero Calzolari (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Rocco Duchi (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Paolo Laj (CNRS Laboratory of Meteorology Physics - Laboratory of Glaciology) - S. Marcq (CNRS Laboratory of Meteorology Physics - Laboratory of Glaciology) - Paolo Villani (Blaise Pascal University,CNRS) - Karine Sellegri (Blaise Pascal University, CNRS,) - Federico Angelini (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Gian Paolo Gobbi (Institute of Atmospheric Sciences and Climate (ISAC) National Research Council) - Elisa Vuillermoz (Ev-K2-CNR) - Gian Pietro Verza (Ev-K2-CNR) - Atindra Sapkota (Department of Environment Science and Engineering, Kathmandu University,) (2011) . Continuous observations of synoptic-scale dust transport at the Nepal Climate Observatory-Pyramid (5079 m a.s.l.) in the Himalayas. Copernicus GmbH (Copernicus Publications) https://geoportal.mountaingenius.org/geonetwork/srv/api/records/f3d82581-df1a-4123-b336-bdeadb80bf18

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File identifier: f3d82581-df1a-4123-b336-bdeadb80bf18 XML

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Protocol: WWW:LINK-1.0-http--related

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Metadata language: eng

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Climatology, meteorology, atmosphere
Environment
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Coupled resource

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SHARE , GAW , ABC

Keywords

Himalayas , Nepal Climate Observatory-Pyramid , Nepal

Keywords ( Theme )

dust transport , single scattering albedo , aerosol , aerosol number size distribution , aerosol optical depth

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Atmospheric Brown Clouds

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Date ( Publication ): 2011-02-04T00:00:00

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"Continuous observations of synoptic-scale dust transport at the Nepal Climate Observatory - Pyramid (5079 m a.s.l.) in the Himalayas". R. Duchi, P. Cristofanelli, A. Marinoni, P. Laj, S. Marcq, P. Villani, Sellegri K.,F. Angelini, F.Calzolari, G.P. Gobbi, G.P. Verza, E. Vuillermoz, A. Sapkota, and P. Bonasoni. Atmos. Chem. Phys. Discuss., 11, 4229-4261, 2011

www.atmos-chem-phys-discuss.net/11/4229/2011/

doi:10.5194/acpd-11-4229-2011

Publication in ACP not foreseen.