资源环境科技发展态势分析平台

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 Colhue 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.

Plain Language Summary Like a peninsula into the Southern Ocean, the vast Patagonia desert in the southern tip of South America is the largest landmass present in the high southern latitudes (40-60S). It is exposed to constant high winds, and dust blown from this region has important impacts thousands of kilometers away, yet these impacts are very difficult to assess. Questions such as the sources of dust found in snow in East Antarctica as well as the provenance of nutrients in the Southern Ocean marine ecosystem remain unanswered. While the Patagonia desert is the likely source there is a dearth of observational records of dust activity from this desert. This study fills the gap in observations by providing a record of 50years of surface and satellite observations of the largest and most active dust source in Patagonia: lake Colhue Huapi. The seasonality, frequency, and periods of major dust activity are identified from meteorological records at a station located 100-km downwind from the lake. Collocated satellite observations confirmed the major periods of dust activity in the last 30years. This data set provides information on how to interpret records of recent dust found in East Antarctica snow as well as help to understand the CO2 cycle in the Southern Ocean.