Details

Autor(en) / Beteiligte

• Laluraj, C. M.
• Rahaman, Waliur
• Thamban, Meloth
• Srivastava, Rohit

Titel

Enhanced Dust Influx to South Atlantic Sector of Antarctica During the Late‐20th Century: Causes and Contribution to Radiative Forcing

Ist Teil von

• Journal of geophysical research. Atmospheres, 2020-04, Vol.125 (8), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2020

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• Atmospheric dust influences global climate and ocean biogeochemistry. Here we present a high‐resolution ice core dust record (1905–2005 CE) from coastal Dronning Maud Land (71°20′S, 11°35′E), East Antarctica, to understand dust flux variability, its causes, and potential contribution to radiative forcing during the 20th century in the South Atlantic sector of East Antarctica (SASA). The dust flux profile (sum of 1–25 μm size fractions) reveals three stepwise increase during 1905–1929, 1930–1979, and 1980–2005 CE time with an average of 0.83, 4.7, and 12.88 mg·m−2·year−1, respectively. Our investigation for such dramatic dust flux increase reveals that the increased aridity and favorable wind conditions over Southern South America (SSA), a potential dust source to Antarctica, caused increase in dust production and transport during the late 20th century. The dust flux variability in Southern Hemisphere is concomitant with in‐phase relationship between El‐Niño Southern Oscillation and Pacific Decadal Oscillations, which influenced the spatial distribution of global wet‐dry phase (precipitation pattern). Further, shifting of Southern Annular Mode to positive phase made wind conditions more conducive for long‐range dust transport from SSA to coastal Dronning Maud Land region. To the best of our knowledge, this is the first report of past radiative forcing estimates for Antarctica using ice core dust record into a radiative transfer model. Our estimates of radiative forcing corresponding to the enhanced dust flux yield nearly 30% increase in aerosol forcing during the late 20th century. This has resulted 40% decrease in atmospheric cooling rate, which contributed to net atmospheric warming over SASA. Plain Language Summary Atmospheric dust plays an important role in global climate variability through the changes in radiative forcing. Like other parts of Antarctica, the coastal Dronning Maud Land (cDML) in East Antarctic is vulnerable to such changes in radiative balance. However, causative factors for the dust deposition and impact of dust originated radiative forcing on this region remain unknown due to lack of long‐term records of dust‐derived radiative forcing estimates. Toward this, we have undertaken a systematic ice core‐based study from cDML region to reconstruct past records of dust influx, its potential sources, causative factors for the dust production in the Southern Hemispheric continents, and understanding its role on the radiative forcing during the 20th century (1905–2005). Our radiative forcing estimates corresponding to approximately four fold increase in dust influx in the late 20th century indicate an increase in atmospheric warming. The present study would help to better understand the long‐term Antarctic climate variability by providing radiative forcing input to the climate models and to improve our current knowledge about the role of dust in contributing to Southern Hemisphere warming during the 20th century. Key Points Ice core dust record from East Antarctica reveals massive increase in dust influx during the late 20th century Climate variability related to ENSO‐PDO phase changes influenced dust activity over the Southern South America The increased dust influx caused 40% decrease in atmospheric cooling rate, leading to net atmospheric warming in East Antarctica