Abstract
Abstract. Previous observational evidence and numerical simulations have revealed that the surface sensible heating in spring (March–April–May, MAM) over the Tibetan Plateau (TPSH) can affect the Asian regional hydrological cycle, surface energy balance, and climate through altering atmospheric heat source of the Tibetan Plateau (TP). This study aims to investigate the impacts of MAM TPSH on the interannual variability of East Asian dust cycle by using CAM4-BAM (version 4 of the Community Atmosphere Model coupled to a bulk aerosol model), MERRA-2 (version 2 of the Modern-Era Retrospective analysis for Research and Applications) surface dust concentration, and TPSH measurements. Our simulations show that the surface dust concentrations over the East Asian (EA) dust source region and over the northwestern Pacific (NP) in MAM are significantly positively correlated with TPSH, with regionally averaged correlation coefficients of 0.49 for EA and 0.44 for NP. Similar positive correlations are also shown between the MAM TPSH measurements averaged over the 73 observation sites and the surface dust concentration from MERRA-2. Simulation-based comparisons between strongest and weakest TPSH years reveal that, the MAM surface dust concentration in the strongest TPSH years increases with relative differences of 13.1 % over EA and 36.9 % over NP. These corresponding differences are found in MERRA-2 with 22.9 % and 13.3 % over EA and NP, respectively. Further simulated results show that the processes of whole dust cycles (e.g., dust loading, emission, and transport, as well as dust deposition) are also significantly enhanced during the strongest TPSH years over EA and NP. Through enhancing the TP heat source, stronger TPSH in MAM generates an anticyclonic anomaly in middle and upper troposphere over the TP and over the downstream Pacific region, respectively. These atmospheric circulation anomalies induced by the increased TPSH result in increasing the westerly winds over both EA and NP, which in turn increases dust emissions over the dust source, and dust transport over these two regions, as well as the regional dust cycles. These results suggest that addressing the East Asian dust changes in the future climates requires considering not only increasing greenhouse gas emissions but also the variations of the TP's heat source under global warming.
Highlights
East Asia is a major source of global dust aerosols originating from the Taklamakan Desert and the Gobi Desert
It is noted that the simulated TPSH index is defined as the time series of the standard anomalies of the MAM surface sensible heat flux averaged over the Tibetan Plateau (TP) region with height above 2500 m m.s.l. for the 30 model years
The spatial pattern of standard deviation (SD) is similar to its climatological mean pattern, with higher values of SD associated with larger TPSH over the central and eastern TP
Summary
Due to larger dust loading (Zhang et al, 2012) and dust AOD over East Asia (Che et al, 2015), the average dust DRF over this region is much larger than that for the global mean (Zhang et al, 2009; Sun et al, 2012; Han et al, 2012; Xin et al, 2016), which could further influence the East Asian climate significantly (Lau et al, 2006; Sun et al, 2012, 2017; Gu et al, 2016; Tang et al, 2018).
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