Temporal Characterization of Dust Activity in the Central Patagonia Desert (Years 1964–2017)

Abstract

Dust emitted from the southern end of South America (SSA) is transported long distances over the Southern Ocean and deposited over this marine ecosystem. Whether the nutrients released through dissolution have a biogeochemical impact is a question with biological as well as climate implications, yet there is no clear answer. Additionally, the provenance of dust recently found in accumulated snow in East Antarctica is still a matter of debate. The Patagonia desert in SSA is the likely source, but there are no detailed records documenting dust activity in this area, thereby preventing any definite assessments. Here we provide a survey of modern dust activity of the largest dust source in SSA, the lake Colhué Huapi in central Patagonia. We analyzed five decades (1964–2017) of surface synoptic observations (World Meteorological Weather Present weather codes) and concurrent satellite aerosol detection (UV Aerosol Index from the Total Ozone Monitoring Sensor and Ozone Monitoring Instrument detectors, 1978–2017). We assessed the seasonal, year‐to‐year variability and periods of major dust activity. Several periods of enhanced activity were found with roughly 2‐ to 10‐year duration each (1970–1976, 1989–1994, 1996–1997, and 1999–2017). While dust activity peaks during summer months, wintertime activity during the most active years can well exceed the summer average of nonactive years. For a period of coincident satellite observations, the occurrence of at least three periods of high activity is confirmed. Since satellite detection is more sensitive to mesoscale dust events, the large events that occurred during these periods brought abundant dust into the SW South Atlantic. Satellites with polar orbits tend to under detect dust events in this region. Significant cloudiness obstructs the direct view of dust, and dust activity tends to occur late in the afternoon after the overpass of polar satellites. These observations have a time span adequate for comparison with transport models and modern records of dust samples collected in East Antarctica. The results contribute to a better understanding of the dynamic of modern dust transport in the Southern Hemisphere, the provenance of dust found in Antarctica, and the provenance of eolian nutrients into the Southern Ocean.

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

“…Dust flux records of (a) IND‐25/B5 ice core from central Dronning Maud Land (South Atlantic sector of Antarctica); number of dust days record over southern South America (after Gassó & Torres, 2019) is shown in red color and (b) James Ross Island (JRI) ice core (Antarctica peninsula). Both records show three major stepwise increases during the last century.…”

“…Data source is 20th century ERA reanalysis. The record of number of dust days over southern South America is taken from Gassó and Torres (2019).…”

“…The trajectories were initialized at 1,000 m above the surface to minimize disturbances from underlying topography (Sinclair et al, 2010). Further, we computed the trajectories of summer (February) and winter (August) periods for the years 1991, 1993, and 2001, when dust activity was high and considered them as dust events in Patagonia as reported by Gassó and Torres (2019).…”

Mapping Areas of the Southern Ocean Where Productivity Likely Depends on Dust‐Delivered Iron

“…The dust sources used in this study were selected from those identified by Ginoux et al (), who provided a global map of major dust‐emitting areas. Some of these major dust‐emitting areas in Australia, Southern Africa, and South America are a focus of several regional studies (e.g., Bullard et al, ; Gassó & Torres, ; Vickery et al, ). In the Southern Hemisphere, dust emissions from Australia and South Africa dominantly occur between September and February, while in South America dust is emitted between December and February (Ginoux et al, ).…”

“…Dominant sources of global dust emissions are found along the so-called "dust belt" that includes arid regions of North Africa, the Arabian Peninsula, Central Asia, and North America (Goudie & Middleton, 2006;Prospero et al, 2002). Although satellite investigations (e.g., Prospero et al, 2002) have shown low dust activity in the Southern Hemisphere, vegetation loss resulting from the combination of climate change and land use could lead to increased dust activity in the region (Bhattachan et al, 2012(Bhattachan et al, , 2013Bhattachan & D'Odorico, 2014;Colazo & Buschiazzo, 2015;Gassó & Torres, 2019;Ginoux et al, 2012;McConnell et al, 2007;Thomas et al, 2005). Moderate Resolution Imaging Spectroradiometer (MODIS)derived dust optical depth data show the existence of dust activity in the Etosha National Park of Namibia and the Makgadikgadi Pans of Botswana in Southern Africa (Ginoux et al, 2012).…”